Mediterranean winter rainfall in phase with African monsoons during the past 1.36 million years - Wagner, Bernd; Vogel, Hendrik; Francke, Alexander; Friedrich, Tobias; Donders, Timme; Lacey, Jack H.; Leng, Melanie J.; Regattieri, Eleonora; Sadori, Laura; Wilke, Thomas; Zanchetta, Giovanni; Albrecht, Christian; et al. (Nature, 2019)

Chronostratigraphic model of a high-resolution drill core record of the past million years from the Koora Basin, south Kenya Rift: Overcoming the difficulties of variable sedimentation rate and hiatuses - Deino, A.L.; Dommain, R.; Keller, C.B.; Potts, R.; Behrensmeyer, A.K.; Beverly, E.J.; King, J.; Heil, C.W.; Stockhecke, M.; Brown, E.T.; Moerman, J.; deMenocal, P. (Quaternary Science Reviews, 2019)
The Olorgesailie Drilling Project and the related Hominin Sites and Paleolakes Drilling Project in East Africa were initiated to test hypotheses and models linking environmental change to hominin evolution by drilling lake basin sediments adjacent to important archeological and paleoanthropological sites. Drill core OLO12-1A recovered 139 m of sedimentary and volcaniclastic strata from the Koora paleolake basin, southern Kenya Rift, providing the opportunity to compare paleoenvironmental influences over the past million years with the parallel record exposed at the nearby Olorgesailie archeological site. To refine our ability to link core-to-outcrop paleoenvironmental records, we institute here a methodological framework for deriving a robust age model for the complex lithostratigraphy of OLO12-1A. Firstly, chronostratigraphic control points for the core were established based on 40Ar/39Ar ages from intercalated tephra deposits and a basal trachyte flow, as well as the stratigraphic position of the Brunhes-Matuyama geomagnetic reversal. This dataset was combined with the position and duration of paleosols, and analyzed using a new Bayesian algorithm for high-resolution age-depth modeling of hiatus-bearing stratigraphic sections. This model addresses three important aspects relevant to highly dynamic, non-linear depositional environments: 1)correcting for variable rates of deposition, 2)accommodating hiatuses, and 3)quantifying realistic age uncertainty with centimetric resolution. Our method is applicable to typical depositional systems in extensional rifts as well as to drill cores from other dynamic terrestrial or aquatic environments. We use the core age model and lithostratigraphy to examine the interconnectivity of the Koora Basin to adjacent areas and sources of volcanism. © 2019 Elsevier Ltd
Keywords: East Africa; East African Rift; Kenya; Kenya Rift; Bayesian networks; Deposition; Drills; Geologic models; Geomagnetism; Infill drilling; Paleolimnology; Sedimentology; Stratigraphy; Bayesian model; East Africa; Kenya rift; Magnetostratigraphy; paleosol; Pleistocene; Radiogenic isotopes; Tephrostratigraphy; algorithm; archaeology; Bayesian analysis; chronostratigraphy; depositional environment; drill bit; drilling; environmental change; extensional tectonics; historical record; hominid; human evolution; hypothesis testing; isotopic analysis; lacustrine deposit; lithostratigraphy; magnetic reversal; magnetostratigraphy; numerical model; paleoenvironment; paleohydrology; paleolimnology; paleosol; Pleistocene; sedimentation rate; sedimentology; tectonostratigraphy; volcaniclastic deposit; volcanism; Core drilling

Cementing Technology Anti Extra-high Temperature in Songke 2 Well (in Chinese with English abstract);[松科2井超高温固井工艺技术] - Liu, X.; Wu, H.; Yan, X.; Li, Y. (Natural Gas Technology and Economy, 2019)

Central Mediterranean explosive volcanism and tephrochronology during the last 630 ka based on the sediment record from Lake Ohrid - Leicher, Niklas; Giaccio, Biagio; Zanchetta, Giovanni; Wagner, Bernd; Francke, Alexander; Palladino, Danilo M.; Sulpizio, Roberto; Albert, Paul G.; Tomlinson, Emma L. (Quaternary Science Reviews, 2019)

Characteristics of spores and pollen assemblages from the Lower Cretaceous Shahezi Formation in the SK2 Borehole - Yuejuan, Zheng; Shuwang, Chen; Dejun, Zhang; Xin, Huang (Geology in China, 2019)

Characterization of Iron in Lake Towuti sediment - Sheppard, Rachel Y.; Milliken, Ralph E.; Russell, James M.; Dyar, M. Darby; Sklute, Elizabeth C.; Bijaksana, Satria; Morlock, Marina A.; Hasberg, Ascelina K.M. (Chemical Geology, 2019)
Sediments collected from Lake Towuti, an ultramafic-hosted lake in Indonesia, preserve a visible alternating pattern of red and green sediments due to variations in clay mineral and Fe-oxide composition and abundance consistent with changes in iron oxidation state through time. Spectral, mineralogical, and chemical analyses on soils, river, and sediment samples from across the lake and its catchment were carried out to better understand the starting composition of these sediments and the processes that affected them before and after deposition. Despite high Fe abundances in all samples and abundant Fe oxides in lateritic source regions, mineralogical analyses (X-ray diffraction (XRD) and M{ossbauer spectroscopy) of the modern lake sediment show almost no well-crystalline iron oxides. In addition, sequential Fe extractions suggest an increasing proportion of easily extractable, poorly crystalline (X-ray amorphous) material with burial depth. XRD, bulk chemistry, and visible-near infrared (VNIR) spectral reflectance measurements demonstrate that clay mineralogy and bulk chemistry can be inferred from VNIR data. These results provide evidence for variations in Fe mineralogy and crystallinity based on location in this source to sink system. Understanding how the mineralogy and chemistry of sediments within a ferruginous lake basin are affected by transport, chemical alteration, physical alteration, and deposition from source to sink on Earth, and the degree to which these trends and underlying processes can be inferred from chemical and spectral properties, may provide useful direction in assessing paleoenvironmental conditions in other terrestrial lakes as well as ancient lacustrine environments preserved in the stratigraphic record of Mars. © 2019 Elsevier B.V.
Keywords: Greater Sunda Islands; Lake Towuti; Malili Lakes; South Sulawesi; Sulawesi; Sunda Isles; Catchments; Chemical analysis; Clay minerals; Crystalline materials; Crystallinity; Deposition; Infrared devices; Lakes; Sedimentation; Sediments; Stratigraphy; X ray diffraction; Fe oxide; Mars analogue; Mineralogical analysis; Modern lake sediments; Spectral reflectance measurements; Ssbauer spectroscopies; Stratified lakes; Stratigraphic records; iron oxide; lacustrine deposit; Mars; paleoenvironment; redox conditions; sediment analysis; sediment chemistry; sedimentation; X-ray diffraction; Iron oxides

Charophytes from the Cretaceous –Paleocene boundary in the Songliao Basin (north-eastern China): a Chinese biozonation and its calibration to the Geomagnetic Polarity Time Scale - Li, S.; Wang, Q.; Wan, X.; Mart'in-Closas, C. (Papers in Palaeontology, 2019)
Charophyte assemblages from the mid-Campanian and lower Paleocene of the SK-1(North) borehole in the Songliao Basin (NE China) are here re-studied. Four charophyte biozones and one superzone are defined in the Sifangtai and Mingshui formations and correlated to the Geomagnetic Polarity Time Scale. These include a mid –late Campanian Atopochara trivolvis ulanensis Zone, a latest Campanian – early Maastrichtian Microchara gobica Zone, a late Maastrichtian Microchara prolixa Zone, and an earliest Danian Peckichara sinuolata Zone. The latter three zones are grouped within the Microchara cristata Superzone, which allows intra- and intercontinental correlation with other basins in China and Europe. Peckichara sinuolata first appears in chron C29r (upper Mingshui Formation) and is proposed as the basal marker of the Paleocene. The biozonation of the K/Pg interval proposed for the Songliao Basin differs from a previous biozonation proposed in the Pingyi Basin since it represents a different biogeographical and palaeoecological context. In the mid-Campanian to Maastrichtian, the flora was limited to freshwater lakes in northern China and Mongolia, whereas in the Pingyi Basin, brackish water dominated. In the Paleocene, the Songliao Basin contained a diverse flora consisting of nine species that thrived in terrigenous and temporary lakes, whereas the flora in the Pingyi Basin was dominated by one species inhabiting permanent alkaline lakes. The species common to the two basins are widely distributed in Eurasia and constitute a useful tool for long-distance correlations, but serve as a less-precise tool for detailed biostratigraphical subdivision within one specific basin. © The Palaeontological Association
cited By 18

Chemical and noble gas isotope compositions of formation gases from a 3 km deep scientific borehole in the Koyna Seismogenic Zone, Western India - Podugu, N.; Mishra, S.; Wiersberg, T.; Roy, S. (Geofluids, 2019)
A 3 km deep research borehole KFD1 was drilled in the Koyna reservoir-triggered seismicity region, Western India, between December 2016 and May 2017. The 1967 M 6.3 Koyna earthquake had generated a NNE-SSW trending surface fissure zone in the Nanel-Donichawadi-Kadoli sector. KFD1 is located 5 km south of Kadoli along the trend of the Donichawadi fault zone. Online gas monitoring was carried out during drilling of KFD1 from 1315 m to 2831 m depth to sample and study the composition of crustal gases. Formation gases CO2, CH4, H2, and He were only observed during water flushing of 100 m intervals following coring runs. Laboratory analyses of gas samples collected between 1737 m and 2831 m depth revealed concentrations of up to 1200 ppmv CO2, 186 ppmv CH4, 139 ppmv H2, and 12.8 ppmv He. Zones enriched in gases are mostly below the 2100 m depth with significant He enhancement ranging from 4.6 to 7.6 ppmv above the atmospheric value. The He-rich zones correlate well with the zones of anomalous physical and mechanical properties identified from geophysical logs and are characterized by high fracture density as revealed from borehole images, indicating that the borehole punctured multiple fracture zones. The helium concentrations are consistent with those previously observed over the surface fissures near Kadoli, suggesting a southward extension of the Donichawadi fault zone up to the KFD1 site and confirming that the fault zone is permeable even after 50 years of the 1967 Koyna earthquake.3He/4He ratios of eleven gas samples fall between 0.426±0.022 and 0.912±0.059 Ra, with 4He/20Ne values between 0.3449±0.0091 and 0.751±0.020. Air-corrected helium isotope ratios indicate that helium is a mixture of atmospheric and crustal radiogenic components but no mantle contribution within 2σ analytical uncertainties. © 2019 Nagaraju Podugu et al.
cited By 10
Keywords: borehole; carbon dioxide; concentration (composition); drilling; earthquake magnitude; earthquake mechanism; enrichment; fracture zone; gas flow; helium; isotopic composition; isotopic ratio; methane; noble gas; research; reservoir-induced seismicity; source rock; India; Koyna; Maharashtra

Chronostratigraphy of the Baringo-Tugen-Barsemoi (HSPDP-BTB13-1A) core – 40Ar/39Ar dating, magnetostratigraphy, tephrostratigraphy, sequence stratigraphy and Bayesian age modeling - Deino, A.L.; Sier, M.J.; Garello, D.; Keller, B.; Kingston, J.; Scott, J.; Dupont-Nivet, G.; Cohen, A. (Palaeogeography, Palaeoclimatology, Palaeoecology, 2019)
The Baringo-Tugen-Barsemoi 2013 drillcore (BTB13), acquired as part of the Hominin Sites and Paleolakes Drilling Project, recovered 228 m of fluviolacustrine sedimentary rocks and tuffs spanning a 3.29 –2.56 Ma interval of the highly fossiliferous and hominin-bearing Chemeron Formation, Tugen Hills, Kenya. Here we present a Bayesian stratigraphic age model for the core employing chronostratigraphic control points derived from 40Ar/39Ar dating of tuffs from core and outcrop, 40Ar/39Ar age calibration of related outcrop diatomaceous units, and core magnetostratigraphy. The age model reveals three main intervals with distinct sediment accumulation rates: an early rapid phase from 3.2 to 2.9 Ma; a relatively slow phase from 2.9 to 2.7 Ma; and the highest rate of accumulation from 2.7 to 2.6 Ma. The intervals of rapid accumulation correspond to periods of high Earth orbital eccentricity, whereas the slow accumulation interval corresponds to low eccentricity at 2.9 –2.7 Ma, suggesting that astronomically mediated climate processes may be responsible for the observed changes in sediment accumulation rate. Lacustrine transgression-regression events, as delineated using sequence stratigraphy, dominantly operate on precession scale, particularly within the high eccentricity periods. A set of erosively based fluvial conglomerates correspond to the 2.9 –2.7 Ma interval, which could be related to either the depositional response to low eccentricity or to the development of unconformities due to local tectonic activity. Age calibration of core magnetic susceptibility and gamma density logs indicates a close temporal correspondence between a shift from high- to low-frequency signal variability at 3 Ma, approximately coincident the end of the mid-Piacenzian Warm Period, and the beginning of the cooling of world climate leading to the initiation of Northern Hemispheric glaciation c. 2.7 Ma. BTB13 and the Baringo Basin records may thus provide evidence of a connection between high-latitude glaciation and equatorial terrestrial climate toward the end of the Pliocene. © 2019 Elsevier B.V.
Keywords: accumulation rate; age determination; Bayesian analysis; chronostratigraphy; core logging; dating method; eccentricity; magnetostratigraphy; modeling; outcrop; paleoclimate; paleolimnology; Pliocene; precession; sequence stratigraphy; tephrochronology

Authigenic Mineral Texture in Submarine 1979 Basalt Drill Core, Surtsey Volcano, Iceland - Jackson, M.D.; Couper, S.; Stan, C.V.; Ivarsson, M.; Czabaj, M.W.; Tamura, N.; Parkinson, D.; Miyagi, L.M.; Moore, J.G. (Geochemistry, Geophysics, Geosystems, 2019)
Micrometer-scale maps of authigenic microstructures in submarine basaltic tuff from a 1979 Surtsey volcano, Iceland, drill core acquired 15 years after eruptions terminated describe the initial alteration of oceanic basalt in a low-temperature hydrothermal system. An integrative investigative approach uses synchrotron source X-ray microdiffraction, microfluoresence, micro-computed tomography, and scanning transmission electron microscopy coupled with Raman spectroscopy to create finely resolved spatial frameworks that record a continuum of alteration in glass and olivine. Microanalytical maps of vesicular and fractured lapilli in specimens from 157.1-, 137.9-, and 102.6-m depths and borehole temperatures of 83, 93.9, and 141.3 °C measured in 1980, respectively, describe the production of nanocrystalline clay mineral, zeolites, and Al-tobermorite in diverse microenvironments. Irregular alteration fronts at 157.1-m depth resemble microchannels associated with biological activity in older basalts. By contrast, linear microstructures with little resemblance to previously described alteration features have nanocrystalline clay mineral (nontronite) and zeolite (amicite) texture. The crystallographic preferred orientation rotates around an axis parallel to the linear feature. Raman spectra indicating degraded and poorly ordered carbonaceous matter of possible biological origin are associated with nanocrystalline clay mineral in a crystallographically oriented linear microstructure in altered olivine at 102.6 m and with subcircular nanoscale cavities in altered glass at 137.9-m depth. Although evidence for biotic processes is inconclusive, the integrated analyses describe the complex organization of previously unrecognized mineral texture in very young basalt. They provide a foundational mineralogical reference for longitudinal, time-lapse characterizations of palagonitized basalt in oceanic environments. ©2019. American Geophysical Union. All Rights Reserved.
cited By 8
Keywords: Basalt; Bioactivity; Clay alteration; Clay minerals; Computerized tomography; Drills; Glass; High resolution transmission electron microscopy; Infill drilling; Micrometers; Nanocrystals; Olivine; Photodegradation; Raman spectroscopy; Scanning electron microscopy; Submarines; Temperature; Textures; Volcanoes; X ray diffraction; X rays; Zeolites; Borehole temperature; Crystallographic preferred orientations; Glass alteration; Microcomputed tomography; Micrometer scale; Scanning transmission electron microscopy; Submarine basalt; X ray microdiffraction; Core drilling; basalt; glass; hydrothermal alteration; hydrothermal system; mineral deposit; Raman spectroscopy; tuff; underwater environment; X-ray diffraction; Iceland; Surtsey

Classifying past climate change in the Chew Bahir basin, southern Ethiopia, using recurrence quantification analysis - Trauth, M.H.; Asrat, A.; Duesing, W.; Foerster, V.; Kraemer, K.H.; Marwan, N.; Maslin, M.A.; Schaebitz, F. (Climate Dynamics, 2019)
The Chew Bahir Drilling Project (CBDP) aims to test possible linkages between climate and evolution in Africa through the analysis of sediment cores that have recorded environmental changes in the Chew Bahir basin. In this statistical project we consider the Chew Bahir palaeolake to be a dynamical system consisting of interactions between its different components, such as the waterbody, the sediment beneath lake, and the organisms living within and around the lake. Recurrence is a common feature of such dynamical systems, with recurring patterns in the state of the system reflecting typical influences. Identifying and defining these influences contributes significantly to our understanding of the dynamics of the system. Different recurring changes in precipitation, evaporation, and wind speed in the Chew Bahir basin could result in similar (but not identical) conditions in the lake (e.g., depth and area of the lake, alkalinity and salinity of the lake water, species assemblages in the water body, and diagenesis in the sediments). Recurrence plots (RPs) are graphic displays of such recurring states within a system. Measures of complexity were subsequently introduced to complement the visual inspection of recurrence plots, and provide quantitative descriptions for use in recurrence quantification analysis (RQA). We present and discuss herein results from an RQA on the environmental record from six short (< 17 m) sediment cores collected during the CBDP, spanning the last 45 kyrs. The different types of variability and transitions in these records were classified to improve our understanding of the response of the biosphere to climate change, and especially the response of humans in the area. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.
cited By 23
Keywords: atmospheric dynamics; climate change; Holocene; paleoclimate; Pleistocene; recurrence interval; time series analysis; Ethiopia

Climatic and sea-level control of Jurassic (Pliensbachian) clay mineral sedimentation in the Cardigan Bay Basin, Llanbedr (Mochras Farm) borehole, Wales - Deconinck, Jean-François; Hesselbo, Stephen P.; Pellenard, Pierre (Sedimentology, 2019)

Climatic and tectonic controls on source-to-sink processes in the tropical, ultramafic catchment of Lake Towuti, Indonesia - Morlock, Marina A.; Nigg, Valentin; Ordoñez, Luis; Hasberg, Ascelina K. M.; Russell, James M.; Bijaksana, Satria (Journal of Paleolimnology, 2019)
Humid tropical landscapes are subject to intense weathering and erosion, which strongly influence sediment mobilisation and deposition. In this setting, we aimed to understand how geomorphology and hydroclimate altered the style and intensity of erosion and sediment composition in a tropical lake and its tectonically active catchment. Lake Towuti (2.75°S, 121.5°E) is one of the oldest and deepest lakes in Indonesia, with uninterrupted lacustrine sedimentation over several glacial –interglacial cycles. Here we present results from a novel set of Lake Towuti surface sediment, bedrock and soil samples from the catchment, and two existing sediment cores that extend to 30,000 and 60,000 years before present. We studied the catchment morphology, soil properties, geochemistry, and clay and bulk mineralogy. Results from several river long profiles show clear signs of tectonic activity, which enhances river incision, favours mass movement processes, and together with remobilisation of fluvial deposits, strongly influences modern sedimentation in the lake. Material from the Mahalona River, the lake’s largest inflow, dominates modern sediment composition in Towuti’s northern basin. The river transports Al-poor and Mg-rich sediments (mainly serpentines) to the lake, indicating river incision into the Mg-rich serpentinised peridotite bedrock. Relatively small, but important additional contributions of material, come from direct laterite-derived input and the Loeha River, which both provide Al-rich and Mg-poor sediment to the lake. Over time, the Al/Mg and kaolinite-to-serpentine ratios varied strongly, primarily in response to lake-level fluctuations driven by hydroclimatic changes. In the past 60,000 years, both the Al/Mg and kaolinite-to-serpentine ratios showed variations sensitive to changes in climate boundary conditions across glacial-interglacial cycles, while tectonic activity had less influence on changes in sediment composition on these short time-scales. © 2018, Springer Nature B.V.
Keywords: Greater Sunda Islands; Lake Towuti; Malili Lakes; South Sulawesi; Sulawesi; Sunda Isles; bank erosion; bedrock; catchment; climate effect; geomorphology; hydrological regime; lacustrine deposit; lake level; paleoclimate; peridotite; sedimentation rate; source-sink dynamics; tectonic setting; tropical region; weathering rate

Constraints on aragonite precipitation in the Dead Sea from geochemical measurements of flood plumes - Belmaker, R.; Lazar, B.; Stein, M.; Taha, N.; Bookman, R. (Quaternary Science Reviews, 2019)
The laminated sequences of the Holocene Dead Sea (DS) and its late Pleistocene precursor Lake Lisan comprise primary aragonite and fine detritus that record the hydro-climate conditions of the late Quaternary Levant. Several studies suggested that the primary aragonite precipitated due to mixing between runoff that brought bicarbonate to the lake and the lake's Ca-chloride brine. However, the factors controlling the aragonite precipitation were not robustly established. Here, we addressed this issue by measuring the chemical composition (pH, Na+, K+, Ca2+, Mg2+, Sr2+, Cl−, Br−, B, alkalinity) of flood plumes where the mixing occurs. The results indicate that: (a) Na+, Mg2+, K+ and Cl− are conservative during the floodwater-brine mixing whereas Ca2+ and Sr2+ adsorb on flood's suspended sediments; (b) Boron (an important alkalinity species in the DS) adsorption on flood's suspended load enabled the bicarbonate that entered the lake via runoff to react with the Ca2+ thus facilitating aragonite precipitation (c) Dissolution of calcite dust blown from the Sahara during winter storm is the source of bicarbonate which is required for aragonite precipitation. These observations explain the occurrence of aragonite laminae both during the wet last glacial period and during the dry last 3000yr. Although the water input during these two periods was completely different, they both were characterized by high dust fluxes and a stratified lake configuration in which the boron concentrations in the epilimnion were low enough to enable the bicarbonate that entered the lake via runoff to react with the lake brine Ca2+ and precipitate aragonite. © 2019 Elsevier Ltd
cited By 19
Keywords: Alkalinity; Boron; Brines; Calcite; Chlorine compounds; Dust; Floods; Lakes; Mixing; pH; Runoff; Storms; Suspended sediments; Boron concentrations; Carbonate alkalinity; Chemical compositions; Dead sea; Flood plumes; Geochemical measurements; Last glacial period; Primary aragonite; Carbonate minerals; alkalinity; aragonite; borate; brine; carbonate; chemical composition; climate conditions; dissolution; dust; epilimnion; flood; geochemistry; Holocene; hydrometeorology; measurement method; Pleistocene; precipitation (chemistry); Dead Sea

Continuous measurement of stress-induced travel-time variations at SAFOD - Yang, C.; Niu, F.; Daley, T.M.; Taira, T. (Seismological Research Letters, 2019)
In situ stress measurement at seismogenic depth is critically important for deciphering fault zone processes. In this study, we conducted a second active-source crosswell field experiment at the Parkfield San Andreas Fault Observatory at Depth (SAFOD) drill site to investigate the detectability of stress-induced seismic velocity changes at the top part of the seismogenic zone. We employed the same configuration of our previous experiments, which deployed a piezoelectric source and a three-component (3C) accelerometer at 1 km deep inside the pilot and main holes, respectively. We also added a hydrophone, which is attached to the source, to monitor the repeatability of the source waveforms. Over a 40-day recording period, we confirmed an ∼0:04% travel-time variation in S wave and coda that roughly follows the fluctuation of barometric pressure. We attributed this correlation to stress sensitivity of seismic velocity and the stress sensitivity is estimated to be 2:0 × 10 −7 Pa −1 , which is approximately two orders of magnitude higher than those measured in laboratory with dry rock samples, but is consistent with our previous results. Our results confirm the hypothesis that substantial cracks and/or pore spaces exist at seismogenic depths and thus may be used to monitor the subsurface stress field with active-source crosswell seismic. © 2019 Seismological Society of America. All Rights Reserved.
cited By 2
Keywords: Atmospheric pressure; Seismic waves; Seismology; Shear waves; Stresses; Strike-slip faults; Barometric pressure; Continuous measurements; In-situ stress measurement; Orders of magnitude; San Andreas fault; Seismic velocities; Stress sensitivity; Sub-surface stress field; Traffic control; fault zone; in situ measurement; in situ stress; San Andreas Fault; seismic velocity; seismic zone; seismology; travel time; waveform analysis; California; Parkfield; United States

Contrasting rainfall-runoff characteristics of floods in desert and Mediterranean basins - Zoccatelli, Davide; Marra, Francesco; Armon, Moshe; Rinat, Yair; Smith, James A.; Morin, Efrat (Hydrology and Earth System Sciences, 2019)

Bajocian transgressive-regressive sequences of the tecocoyunca group, southern Mexico, with maximum flooding surfaces marked by thalassinoides - Pie'nkowski, Grzegorz; Martini, Michelangelo; Zepeda-Mart'inez, Mildred (Geological Quarterly, 2019)

Assessment of heterogeneities of the shallow crust from geophysical logging in the Koyna-Warna region, Deccan Volcanic Province, India - Dhulipudi, G.; Nittala, S.; Arora, K.; Mannepalli, S.R.; K.N.S.S.S, S.; Yadavally, S.; Potharaju, S.V.K.; H.V.S., S. (Physics of the Earth and Planetary Interiors, 2019)
Analysis and comparison of geophysical logs from seven exploratory boreholes of 1 –1.5 km depth in the Koyna-Warna region of India illustrate variations in physical properties and structural characteristics of the basalts and underlying granite-gneiss basement in and around the seismogenic zone. In the north, south of the Koyna reservoir, densities are higher, gamma values are lower, fractures dip at high angles with low fracture permeabilities. To the south, around the Warna reservoir, densities are lower, gamma values higher, and resistivity values are low. In the southernmost borehole at Khadi, basement is highly fractured, and there are significant amounts of water outflow associated with the fracture system. The fracture density increases to the south, with fracture dips ranging from medium to low angles with permeability values two orders of magnitude higher than in the northern boreholes. These variations in physical and structural properties resulting in a highly heterogeneous crust, reflect the cumulative effect of episodes of tectonic activity over millions of years that this region has undergone. © 2019 Elsevier B.V.
cited By 3
Keywords: Boreholes; Buildings; Exploratory boreholes; Fracture; Geophysics; Reservoirs (water); Structural geology; ATV images; Crustal heterogeneity; Fracture pattern; Geophysical logs; Koyna-Warna; Well logging; assessment method; borehole; fracture propagation; geophysical method; heterogeneity; permeability; tectonic setting; Deccan; India; Ambystoma tigrinum stebbensi virus

Crystalline Disposal R &D at LBNL: FY19 Progress Report. Spent Fuel and Waste Disposition. - Guglielmi, Yves; Cook, Paul; Dobson, Patrick; Nakagawa, Seiji; Zheng, Liange; Niemi, Auli; Juhlin, Chris; Lorenz, Henning; Rosberg, Jan-Erik; Dessirier, Benoît; Tsang, Chin-Fu; Tatomir, Alexandru; et al. (Lawrence Berkeley National Laboratory (LBNL), 2019)

A new Dead Sea pollen record reveals the last glacial paleoenvironment of the southern Levant - Miebach, A.; Stolzenberger, S.; Wacker, L.; Hense, A.; Litt, T. (Quaternary Science Reviews, 2019)
The southern Levant is a key region for studying vegetation developments in relation to climate dynamics and hominin migration processes in the past due to the sensitivity of the vegetation to climate variations and the long history of different anthropogenic occupation phases. However, paleoenvironmental conditions in the southern Levant during the Late Pleistocene were still insufficiently understood. Therefore, we investigated the vegetation and fire history of the Dead Sea region during the last glacial period. We present a new palynological study conducted on sediments of Lake Lisan, the last glacial precursor of the Dead Sea. The sediments were recovered from the center of the modern Dead Sea within an ICDP campaign. The palynological results suggest that Irano-Turanian steppe and Saharo-Arabian desert vegetation prevailed in the Dead Sea region during the investigated period (ca. 88,000 –14,000 years BP). Nevertheless, Mediterranean woodland elements significantly contributed to the vegetation composition, suggesting moderate amounts of available water for plants. The early last glacial was characterized by dynamic climate conditions with pronounced dry phases and high but unstable fire activity. Anatomically modern humans entered the southern Levant during a climatically stable phase (late MIS 4 –MIS 3)with diverse habitats, constant moisture availability, and low fire activity. MIS 2 was the coldest phase of the investigated timeframe, causing changes in woodland composition and a widespread occurrence of steppe. We used a biome modeling approach to assess regional vegetation patterns under changing climate conditions and to evaluate different climate scenarios for the last glacial Levant. The study provides new insights into the environmental responses of the Dead Sea region to climate variations through time. It contributes towards our understanding of the paleoenvironmental conditions in the southern Levant, which functioned as an important corridor for human migration processes. © 2019 Elsevier Ltd
cited By 24
Keywords: Charcoal; Fires; Glacial geology; Lakes; Sensitivity analysis; Anatomically modern humans; Deep drilling; Eastern Mediterranean; Fire history; Late Pleistocene; Paleoclimates; Vegetation dynamics; Vegetation; anatomy; biome; charcoal; ecological modeling; fire history; hominid; Last Glacial; marine isotope stage; paleoclimate; paleoenvironment; palynology; vegetation dynamics; Dead Sea; Levant; Mediterranean Region

Medieval climate in the Eastern Mediterranean: Instability and evidence of solar forcing - Kushnir, Y.; Stein, M. (Atmosphere, 2019)
This paper examines the hydroclimate history of the Eastern Mediterranean (EM) region during the 10th to 14th centuries C.E., a period known as the Medieval Climate Anomaly (MCA), a time of significant historical turmoil and change in the region. The study assembles several regional hydroclimatic archives, primarily the Dead Sea reconstructed lake level curve together with the recently extracted deep-lake sediment record, the Soreq Cave speleothem record and its counterpart, the EM marine sediment record and the Cairo Nilometer record of annual maximum summer flood levels in lower Egypt. The Dead Sea record is a primary indicator of the intensity of the EM cold-season storm activity while the Nilometer reflects the intensity of the late summer monsoon rains over Ethiopia. These two climate systems control the annual rainfall amounts and water availability in the two regional breadbaskets of old, in Mesopotamia and Egypt. The paleoclimate archives portray a variable MCA in both the Levant and the Ethiopian Highlands with an overall dry, early-medieval climate that turned wetter in the 12th century C.E. However, the paleoclimatic records are markedly punctuated by episodes of extreme aridity. In particular, the Dead Sea displays extreme low lake levels and significant salt deposits starting as early as the 9th century C.E. and ending in the late 11th century. The Nile summer flood levels were particularly low during the 10th and 11th centuries, as is also recorded in a large number of historical chronicles that described a large cluster of droughts that led to dire human strife associated with famine, pestilence and conflict. During that time droughts and cold spells also affected the northeastern Middle East, in Persia and Mesopotamia. Seeking an explanation for the pronounced aridity and human consequences across the entire EM, we note that the 10th-11th century events coincide with the medieval Oort Grand Solar Minimum, which came at the height of an interval of relatively high solar irradiance. Bringing together other tropical and Northern Hemisphere paleoclimatic evidence, we argue for the role of long-term variations in solar irradiance in shaping the early MCA in the EM and highlight their relevance to the present and near-term future. © 2019 by the authors.
cited By 11
Keywords: Chloride minerals; Drought; Floods; Food supply; Lakes; Rain; Solar radiation; Submarine geology; Climate variability; Eastern Mediterranean; Extreme events; Lake-sediment records; Medieval Climate Anomaly (MCA); Mediterranean; Northern Hemispheres; Paleoclimatic record; Climate change; aridity; climate change; climate variation; extreme event; lacustrine deposit; marine sediment; monsoon; paleoclimate; speleothem; Dead Sea; Ethiopia; Mediterranean Region

3-D fluid channel location from noise tremors using matched field processing - Umlauft, J.; Korn, M. (Geophysical Journal International, 2019)
Presently ongoing geodynamic processes within the intracontinental lithospheric mantle give rise to different natural phenomena in the NW Bohemia/Vogtland region (Czech Republic, Germany), amongst others: earthquake swarms, mineral springs and degassing zones of mantle-derived fluids as well as highly concentrated CO2 (mofettes). Their interaction mechanisms and relations are not yet fully understood, but fluid pathways within the crust are assumed, that allow efficient fluid transport between the main hypocentral swarm quake region and the degassing areas at the surface. Here, we focus on the location of the presumed fluid channels as well as on the investigation of their near-surface spatio-temporal variability, targeting a depth of a few hundreds of metmetres. We applied a 3-D matched field processing (MFP) approach in the frequency band of 10?20 Hz considering the fluid flow as seismic noise source. Within three campaigns in 2015/2016, we recorded continuous seismic noise data on the Hartoušov Mofette Field within the Cheb Basin (NW Bohemia, CZ), which is a key site to study fluid flow as it is characterized by strong and continuous surface degassing of CO2.We used temporary arrays varying in extent (70-600 m aperture) and in the amount of stations (25?95 units). Assuming a homogeneous velocity model and applying conventional MFP phase-matching over a 3-D grid search, we located two channel-like structures beneath the test site, which could be traced down to a common source area down to 2000 m depth. We thereby evaluated the influence of amplitude normalization of the measured noise signal on the MFP location considering water-filled or dry mofette channels. Additionally, a spatiotemporal analysis using time windows with a length of 10 min during 5 hr of noise record shows variability of fluid flow activity in space and time and hence, its migration beneath the test site on a short timescale. © 2019. Published by Oxford University Press on behalf of The Royal Astronomical Society.
Keywords: Bohemia; Czech Republic; Germany; Vogtland; Degassing; Earthquakes; Flow of fluids; Location; Mineral springs; Numerical models; Phase matching; Time series analysis; Continuous surface; Geodynamic process; Interaction mechanisms; Lithospheric mantle; Matched field processing; Seismic noise; Spatiotemporal analysis; Spatiotemporal variability; carbon dioxide; degassing; earthquake hypocenter; earthquake swarm; flow field; fluid flow; geodynamics; lithospheric structure; mantle structure; numerical model; seismic migration; seismic noise; seismic velocity; spatiotemporal analysis; three-dimensional modeling; time series analysis; Transport properties

40Ar-39Ar step heating ages of North American tektites and of impact melt rock samples from the Chesapeake Bay impact structure - Assis Fernandes, V.; Hopp, J.; Schwarz, W.H.; Fritz, J.P.; Trieloff, M.; Povenmire, H. (Geochimica et Cosmochimica Acta, 2019)
This study presents 40Ar-39Ar step heating ages of four North American tektites (three bediasites and one georgiaite) and of two groundmass samples extracted at different depths from clast-rich impact melt rocks (CB-W61 and CB-W84) recovered by the USGS-ICDP Eyreville B drill-core about 9 km from the centre of the Chesapeake Bay impact structure. Radiometric age determination on both North American tektites and impact melt rocks from within Chesapeake Bay crater offers the first possibility to confirm the origin of these tektites. For this aim, argon isotopic data from 13 samples/aliquots of tektite rims, cores and bulk, and 4 samples/aliquots from two impact melt rocks were obtained over 15 to 26 step heating extractions. Age spectra of all tektite samples show plateaux comprising 62 –98% of the 39Ar release over consecutive intermediate and high temperature heating steps. Few low temperature extractions indicate excess 40Ar. Inverse isochron 40Ar/36Ar intercepts of tektite samples are indistinguishable from air (295.5). However, impact melt rock spectra presented complex Ar-release affecting primarily the low temperature heating-steps. Inverse isochrones indicate excess argon from which the 40Ar/36Ar intercept was used to correct the age calculation. CB-W61 and CB-W61-2 40Ar/36Ar intercepts are 354.5 ± 2.5 and 327.2 ± 6.3, respectively, and those for CB-W84 and CB-W84-2 are 332.0 ± 7.3 and 329.6 ± 5.6, respectively. The inverse isochron weighted mean age (according to currently suggested K-decay constants revisions by Schwarz et al. (2011) and Renne et al. (2011)) for all four tektites is 34.86 ± 0.25 Ma (MSWD = 0.96, P = 0.41; n = 4) and for the two impact melt rocks is 37.16 ± 3.65 Ma (MSWD = 0.83, P = 0.36). The combined tektite and impact melt rocks isochron mean age of 34.86 ± 0.23 (0.32) Ma (MSWD = 0.87, P = 0.43) is slightly – though not significantly – higher than the plateau mean age of 34.55 ± 0.27 (0.36) Ma (MSWD = 0.66, P = 0.62). Placing this age in the Global Stratotype Section and Point (GSSP) marine section exposed at Massignano, Italy, it falls below the Eocene/Oligocene (E/O) boundary overlapping with the 10.28 m Ir-anomaly. These results agree within errors with previously reported ages of 35.20 ± 0.54 Ma, especially those derived from K-Ar and Ar-Ar total fusion analysis. An age of 34.86 ± 0.32 Ma sets the Chesapeake Bay impact event close to the youngest of the three Ir anomalies at ∼35.0 Ma in the case the impactor was Ir-rich (e.g, a chondrite, primitive achondrite, stony-iron or iron meteorite). The concordance with the E/O boundary at ∼33.9 Ma seems only marginally possible, and only if the Ir contribution from the ejecta were, potentially, due either to its small amount becoming diluted in the geologic record or the impactor being Ir poor, e.g., of differentiated achondritic composition. This study also brings to front the need to re-establish the stratigraphic and palaeo-magnetic correlations across the globe for the Ir-anomalies and the magneto-stratigraphy during the mid- to late-Eocene and early-Oligocene, and the need to re-evaluate the markers for the Eocene-Oligocene boundary. © 2019 Elsevier Ltd
cited By 9
Keywords: argon-argon dating; Eocene-Oligocene boundary; geochronology; impact structure; magnetostratigraphy; melt; meteorite; paleomagnetism; tektite; Ascoli Piceno; Chesapeake Bay; Italy; Marche; Massignano; United States

A method of diametrical core deformation analysis and its application on stress investigation in SK2 Well; [岩芯直径变形分析法及其在松科2井深部地应力调查中的应用] - Yang, Yuehui; Sun, Dongsheng; Zheng, Xiuhua; Lin, Weiren; Li, Awei (Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology), 2019)
The basic principle of diametrical core deformation analysis method(DCDA) in-situ stress testing method, core diameter testing instrument and testing process based on laser rangefinder were introduced, and the method was applied on the in-situ stress measurement of igneous rock strata on the base of 6 645-6 846 m in SK2. The results show that the core diameter curves after stress relief are sinusoidal with a periodic change of π, and the long axis and the short axis of the ellipse are nearly orthogonal. The test results conform with the theory results of DCDA method and can reflect the in-situ stress information. The direction of the elliptical long axis of core section is the direction of the maximum horizontal principal stress. According to the results of core paleomagnetic orientation, the maximum horizontal principal stress direction of 6 645-6 845 m in SK2 is determined to NE72°-83°. By taking into account the core elastic modulus and Poisson's ratio, the horizontal principal stress difference of 6 645 m in SK2 is determined to be about 35 MPa, and the horizontal principal stress difference of 6 845-6 846 m is about 55 MPa, which are almost consistent with the results of ASR in situ stress measurement. The successful application of DCDA method in the field of 6 645-6 846 m in SK2 well provides a new way to obtain the information of the deep in-situ stress, especially in the complex geological conditions of ultra deep or high temperature drilling and relatively broken formation. In this case, when the stress relief method and hydraulic fracturing method are difficult to implement, while the method can still obtain more reliable in-situ stress data. At the same time, this method is not limited by the depth and temperature environment of the borehole, and only needs nearly homogeneous and isotropic cylindrical core, and does not involve cutting and grinding the core, which is conducive to the reuse of the deep precious core. © 2019, Central South University Press. All right reserved.
Keywords: Deformation; Igneous rocks; Indium compounds; Instrument testing; Range finders; Stress measurement; Stresses; Complex geological condition; Core diameters; Homogeneous and isotropic; Hydraulic fracturing methods; In-situ stress measurement; Insitu stress; Maximum horizontal principal stress; Temperature environments; Stress relief

A model for effective permeability in an unconsolidated hydrate reservoir - Hinz, D.; Arastoopour, H.; Abbasian, J. (Journal of Natural Gas Science and Engineering, 2019)
Numerous experimental studies have shown that hydrate dissociation can result in significant strength reduction leading to sediment failure and unconsolidated flow behavior. In this work, a constitutive model for the effective permeability is developed that is capable of accurately modeling the evolution of permeability in hydrate reservoirs exhibiting unconsolidated behavior. A production phase that promotes sand production from an unconsolidated hydrate reservoir will result in a significant increase in permeability, such that the reservoir essentially behaves like a naturally fracking reservoir. Furthermore, installation of a sand screen to prevent sand production will throttle gas production due to the significant decrease in permeability as solids accumulate and compact at the sand screen. Our model was developed and verified using experimental data from the Mallik 2007/2008 production tests and can be applied in simulations of the coupled hydrodynamics, heat transfer, mass transfer, and geomechanics in the unconsolidated hydrate reservoir. © 2019 Elsevier B.V.
cited By 11
Keywords: Gas industry; Heat transfer; Hydrates; Hydration; Mass transfer; Sand; Effective permeability; Gas productions; Hydrate dissociation; Mallik; Production phase; Simulation; Strength reduction; Unconsolidated; Petroleum reservoir engineering

A roadmap for amphibious drilling at the Campi Flegrei caldera: Insights from a MagellanPlus workshop - Sacchi, M.; De Natale, G.; Spiess, V.; Steinmann, L.; Acocella, V.; Corradino, M.; De Silva, S.; Fedele, A.; Fedele, L.; Geshi, N.; Kilburn, C.; Insinga, D.; et al. (Scientific Drilling, 2019)
Large calderas are among the Earth's major volcanic features. They are associated with large magma reservoirs and elevated geothermal gradients. Caldera-forming eruptions result from the withdrawal and collapse of the magma chambers and produce large-volume pyroclastic deposits and later-stage deformation related to post-caldera resurgence and volcanism. Unrest episodes are not always followed by an eruption; however, every eruption is preceded by unrest. The Campi Flegrei caldera (CFc), located along the eastern Tyrrhenian coastline in southern Italy, is close to the densely populated area of Naples. It is one of the most dangerous volcanoes on Earth and represents a key example of an active, resurgent caldera. It has been traditionally interpreted as a nested caldera formed by collapses during the 100-200 km3 Campanian Ignimbrite (CI) eruption at ∼ 39 ka and the 40 km3 eruption of the Neapolitan Yellow Tuff (NYT) at ∼ 15 ka. Recent studies have suggested that the CI may instead have been fed by a fissure eruption from the Campanian Plain, north of Campi Flegrei. A MagellanPlus workshop was held in Naples, Italy, on 25-28 February 2017 to explore the potential of the CFc as target for an amphibious drilling project within the International Ocean Discovery Program (IODP) and the International Continental Drilling Program (ICDP). It was agreed that Campi Flegrei is an ideal site to investigate the mechanisms of caldera formation and associated post-caldera dynamics and to analyze the still poorly understood interplay between hydrothermal and magmatic processes. A coordinated onshore-offshore drilling strategy has been developed to reconstruct the structure and evolution of Campi Flegrei and to investigate volcanic precursors by examining (a) the succession of volcanic and hydrothermal products and related processes, (b) the inner structure of the caldera resurgence, (c) the physical, chemical, and biological characteristics of the hydrothermal system and offshore sediments, and (d) the geological expression of the phreatic and hydromagmatic eruptions, hydrothermal degassing, sedimentary structures, and other records of these phenomena. The deployment of a multiparametric in situ monitoring system at depth will enable near-real-time tracking of changes in the magma reservoir and hydrothermal system. © Author(s) 2019.
cited By 5
Keywords: Biology; Infill drilling; Offshore oil well production; Sedimentology; Volcanoes; Biological characteristic; Caldera-forming eruption; Campanian Ignimbrite; Geothermal gradients; Hydromagmatic eruptions; Hydrothermal products; Neapolitan yellow tuffs; Sedimentary structure; Offshore drilling

Archaeal communities in deep terrestrial subsurface underneath the deccan traps, india - Dutta, Avishek; Sar, Pinaki; Sarkar, Jayeeta; Gupta, Srimanti Dutta; Gupta, Abhishek; Bose, Himadri; Mukherjee, Abhijit; Roy, Sukanta (Frontiers in Microbiology, 2019)

A simplified MEV formulation to model extremes emerging from multiple nonstationary underlying processes - Marra, Francesco; Zoccatelli, Davide; Armon, Moshe; Morin, Efrat (Advances in Water Resources, 2019)

Abies cuitlahuacii sp. nov., a mummified late Quaternary fossil wood from Chalco, Mexico - Cevallos-Ferriz, S.R.S.; R'ios-Santos, C.; Lozano-Garc'ia, S. (Boletin de la Sociedad Geologica Mexicana, 2019)
A fragment of mummified wood collected from a Quaternary sedimentary sequence of Lake Chalco, Central Mexico, in the depocenter of the Basin (19°15'26N, 98°58'32W), has anatomical characteristics of Abies. Identification is based on the presence of a warty layer in the walls of the tracheids, prismatic crystals in ray cells, taxodioid pits in the cross-fields, and lack of ray tracheids and normal intercellular canals, among other well-preserved characteristics. This specimen represents the first macrofossil evidence of the genus in this region and suggests that by the late Quaternary it was already established in the surroundings of Lake Chalco, and most probably in what is now central Mexico. Unfortunately, as with morphological and genetic characteristics, the anatomical attributes of the wood of the genus have not been useful for the delimitation of species. Most wood characteristics have been considered of little diagnostic value. However, comparison of available anatomical descriptions of fossil and living species highlight differences among them, even with Abies religiosa wood, which is the closest species to Lake Chalco. Other characteristics or plant organs are needed to assemble a whole plant that can be used to establish phylogenetic relationships and clarify the evolutionary history of the genus. Meanwhile this wood is assigned to a new fossil taxon, Abies cuitlahuacii Cevallos-Ferriz, R'ios-Santos & Lozano-Garc'ia. © Bolet'in de la Sociedad Geol'ogica Mexicana 2019.
cited By 1

AMT survey in the Outokumpu ore belt, eastern Finland - Lahti, Ilkka; Kontinen, Asko; Nyk{anen, Vesa (Exploration Geophysics, 2019)
The Outokumpu belt in eastern Finland is known for numerous polymetallic (Cu-Co-Zn-Ni-Ag-Au) sulphide ore deposits and it is a potential area for new discoveries. Audiomagnetotelluric (AMT) data have recently been collected to image the subsurface conductivity structure of the belt. The data were acquired along five profiles aiming to explore deep conductors, study their geometry and investigate the deep conductivity structure of the belt.The acquired AMT data were mostly adequate for 2D inversion, as the survey area is characterised by thin, laterally extensive conductors indicated by airborne electromagnetic data, deep drillings and regional strike analysis of the impedance tensor data. 2D smooth inversion was carried out jointly for transverse electric and transverse magnetic data. The results show southeast-dipping and sub-horizontal continuous conductors southeast of the Outokumpu old mine, suggesting the presence of prospective Outokumpu assemblage rocks. One ∼ 1 km deep sub-horizontal conductor is verified by a deep drill-hole located ∼ 8 km southeast of the mine. The results demonstrate a similar southeast-dipping structure in the Vuonos mine area, which is located ∼ 7 km northeast of the Outokumpu old mine. An eastwards-dipping conductor detected in the Miihkali serpentinite area indicates deep exploration potential in this area. Besides the smooth 2D inversion, a sharp-boundary 2D inversion was performed and the resulting model was assessed with the existing geological interpretation of the Miihkali area. In the area of the Sotkuma gneiss inlier, conductors are absent from the uppermost ∼ 6 km. This feature may represent an uplifted fault block rather than a thin thrust sheet of Archaean basement rocks. © 2019 Australian Society of Exploration Geophysics.
Keywords: Finland; Outokumpu; Pohjois-Karjala; Gold compounds; Gold deposits; Infill drilling; Magnesite; Magnetotellurics; Sulfur compounds; Surveys; Zinc deposits; 2D modelling; Airborne electromagnetic; Conductivity structures; Exploration potential; Geological interpretation; Horizontal conductors; Transverse electrics; Transverse magnetic; Archean; basement rock; fault zone; geometry; gneiss; mineral exploration; mining industry; ore body; serpentinite; Mineral exploration

An Analysis of Thermal Conductivity in Songliao Basin Based on Logging Parameters; [利用测井资料获取松辽盆地深部热物性参数] - Ma, Feng; Wang, Gui-Ling; Sun, Zhan-Xue; Zhang, Wei; Hou, He-Sheng; Guo, Xiao-Yang (Acta Geoscientica Sinica, 2019)
Thermal conductivity is an important parameter to study the deep thermal structure of the sedimentary basin. The traditional way to obtain the thermal conductivity by measurement of deep core test is limited by funding, sampling conditions and some other factors. Meanwhile, due to the reason that geothermal wells are affected by temperature and pressure conditions, indoor test results cannot represent the in-situ thermal conductivity of the rocks. In this study, the measured thermal conductivity and logging parameters of cores from 3 289 to 4 536 meters in the third spudding of well Songke 2 are obtained, and the relationship between thermal conductivity of sandstone, mudstone and rhyolite and logging parameters was analyzed. The results show that correlation between porosity, wave velocity and thermal conductivity of sandstone logging parameters is obvious, but the correlation for mudstone and rhyolite is not high. On such a basis, the authors analyzed the influence of temperature and pressure on the thermal conductivity of the Songliao Basin. It is concluded that the thermal conductivity of the third spudding of well Songke 2 in Songliao Basin is reduced by about 30% due to temperature effect, and the thermal conductivity is increased by about 10% due to pressure effect compared with 36the measured values in laboratory. The results of this study can provide a new idea for the acquisition of deep thermal conductivity and geothermal flow value of basins in China, especially for some abandoned wells with logging dates but can not obtain deep cores. © 2019, Science Press. All right reserved.

An Overview of the Status and Challenges of CO2 Storage in Minerals and Geological Formations - Kelemen, Peter; Benson, Sally M.; Pilorg'e, H'elène; Psarras, Peter; Wilcox, Jennifer (Frontiers in Climate, 2019)

Anisotropic Kirchhoff pre-stack depth migration at the COSC-1 borehole, central Sweden - Simon, H.; Hedin, P.; Juhlin, C.; Krau{s, F.; Giese, R. (Geophysical Journal International, 2019)
SUMMARY. A remarkably well preserved representation of a deeply eroded Palaeozoic orogen is found in the Scandinavian Caledonides, formed by the collision of t
Publisher: Oxford Academic

Crustal fracturing, unconformities, and barite deposition, 3.26 –3.23 Ga, Barberton Greenstone Belt, South Africa - Lowe, Donald R.; Drabon, Nadja; Byerly, Gary R. (Precambrian Research, 2019)

2019 status report: Drilling into seismogenic zones of M2.0 –M5.5 earthquakes in South African gold mines (DSeis project) - Ogasawara, H; Liebenberg, B; Rickenbacher, M; Ziegler, M; Esterhuizen, H; Onstott, TC; Durrheim, MSD; Mngadi, S; Yabe, Y; Kaneki, S; Cason, E; Vermeuren, J-G; et al. (Deep Mining 2019: Proceedings of the Ninth International Conference on Deep and High Stress Mining, 2019)
In 2014, a M5.5 earthquake ruptured the range of depths between 3.5 km and 7 km near Orkney, South Africa. The main and aftershocks were very well monitored in the nearfield by dense, surface, strong motion meters and a dense underground seismic network in the deep gold mines. The mechanism of this M5.5 earthquake was left-lateral strike-slip faulting, differing from typical mining-induced earthquakes with normal-faulting mechanisms on the mining horizons shallower than 3.5 km depth. To understand why such an unusual event took place, the aftershock zone was probed by full-core NQ drilling during 2017-2018, with a total length of about 1.6 km, followed by in-hole geophysical logging, core logging, core testing, and monitoring in the drilled holes. These holes also presented a rare opportunity to investigate deep life. In addition, seismogenic zones of M2 –M3 earthquakes were probed on mine horizons that were also very well monitored by acoustic emission networks. This paper reviews the early results of the project.

Delineation of Damage Zones From 3 km Downhole Geophysical Logs in the Koyna Seismogenic Zone, Western India - Goswami, D.; Roy, S.; Akkiraju, V.V. (Journal of Geophysical Research: Solid Earth, 2019)
Delineation of subsurface faults and damage zones is a major goal of scientific drilling projects in seismically active areas. Geophysical logs acquired in a 3-km deep scientific borehole KFD1 in the Koyna seismogenic zone, a site of recurrent reservoir triggered seismicity over the past 55 years, provide an unprecedented opportunity to investigate the rock properties and delineate the fault zones. KFD1 passed through 1,247-m thick Deccan traps and continued for 1,767 m into the underlying granitic basement rocks that host the seismic activity in the depth range 2 –10 km. We have studied the physical properties and acoustic behavior of basement granitoids from the analysis of geophysical logs from 1,500 to 3,000 m. Salient results are as follows. (1) Seven anomalous zones are identified below 2,100-m depth based on electrical resistivity, caliper, density, neutron porosity, self-potential, and sonic data. (2) The anomalous zones are characterized by significant shear wave velocity anisotropy (up to 25%), as revealed by cross-dipole sonic data. (3) Dispersion analysis of dipole flexural modes confirms that the anisotropy is primarily stress induced; fast polarized shear wave azimuth (FSA) therefore indicates the orientation of maximum horizontal compressive stress SHmax. (4) Comparison of FSA with independent estimates of SHmax orientations obtained from drilling induced tensile fractures and strike of inclined fractures in the anisotropic zones shows that FSA is controlled mainly by the stress regime. Therefore, the stress rotations inferred from anisotropy analyses in the anomalous zones indicate their association with subsurface fault damage zones. ©2019. American Geophysical Union. All Rights Reserved.
cited By 14
Keywords: acoustic logging; damage; fault zone; granitoid; reservoir-induced seismicity; rock property; seismic anisotropy; seismic zone; sonic boom; stress field; structural control; India; Koyna; Maharashtra

Large-scale electrical resistivity tomography in the Cheb Basin (Eger Rift) at an International Continental Drilling Program (ICDP) monitoring site to image fluid-related structures - Nickschick, T.; Flechsig, C.; Mrlina, J.; Oppermann, F.; L{obig, F. (Solid Earth, 2019)
The Cheb Basin, a region of ongoing swarm earthquake activity in the western Czech Republic, is characterized by intense carbon dioxide degassing along two known fault zones - the N-S-striking Počatky-Plesn'a fault zone (PPZ) and the NW-SE-striking Mari'ansk'e L'azne fault zone (MLF). The fluid pathways for the ascending <span classCombining double low lineinline-formula>CO2 of mantle origin are one of the subjects of the International Continental Scientific Drilling Program (ICDP) project Drilling the Eger Rift in which several geophysical surveys are currently being carried out in this area to image the topmost hundreds of meters to assess the structural situation, as existing boreholes are not sufficiently deep to characterize it. As electrical resistivity is a sensitive parameter to the presence of conductive rock fractions as liquid fluids, clay minerals, and also metallic components, a large-scale dipole-dipole experiment using a special type of electric resistivity tomography (ERT) was carried out in June 2017 in order to image fluid-relevant structures. We used permanently placed data loggers for voltage measurements in conjunction with moving high-power current sources to generate sufficiently strong signals that could be detected all along the 6.5 <span classCombining double low lineinline-formula>km long profile with 100 and 150 <span classCombining double low lineinline-formula>m dipole spacings. After extensive processing of time series for voltage and current using a selective stacking approach, the pseudo-section is inverted, which results in a resistivity model that allows for reliable interpretations depths of up than 1000 <span classCombining double low lineinline-formula>m. The subsurface resistivity image reveals the deposition and transition of the overlying Neogene Vildštejn and Cypris formations, but it also shows a very conductive basement of phyllites and granites that can be attributed to high salinity or rock alteration by these fluids in the tectonically stressed basement. Distinct, narrow pathways for <span classCombining double low lineinline-formula>CO2 ascent are not observed with this kind of setup, which hints at wide degassing structures over several kilometers within the crust instead. We also observed gravity and GPS data along this profile in order to constrain ERT results. A gravity anomaly of ca. <span classCombining double low lineinline-formula>-9 <span classCombining double low lineinline-formula>mGal marks the deepest part of the Cheb Basin where the ERT profile indicates a large accumulation of conductive rocks, indicating a very deep weathering or alteration of the phyllitic basement due to the ascent of magmatic fluids such as <span classCombining double low lineinline-formula>CO2. We propose a conceptual model in which certain lithologic layers act as caps for the ascending fluids based on stratigraphic records and our results from this experiment, providing a basis for future drillings in the area aimed at studying and monitoring fluids. . © Author(s) 2019.
cited By 7
Keywords: Buildings; Carbon dioxide; Degassing; Drilling fluids; Electric conductivity; Geophysics; Global positioning system; Infill drilling; Stratigraphy; Weathering; Continental scientific drillings; Earthquake activity; Electric resistivity tomography; Electrical resistivity tomography; Geophysical surveys; Resistivity modeling; Sensitive parameter; Stratigraphic records; Electric lines; carbon dioxide; degassing; earthquake swarm; electrical resistivity; fault zone; monitoring; tomography; Cheb Basin; Czech Republic; Karlovarsky

ICDP approves funding for drilling project on the Bushveld Complex - Trumbull, R; Khoza, D; Roelofse, F; Webb, S; Klemd, R; Ashwal, L (Geobulletin, 2019)

ICDP workshop on scientific drilling of Nam Co on the Tibetan Plateau: 1 million years of paleoenvironmental history, geomicrobiology, tectonics and paleomagnetism derived from sediments of a high-altitude lake - Haberzettl, T.; Daut, G.; Schulze, N.; Spiess, V.; Wang, J.; Zhu, L.; Party (Scientific Drilling, 2019)

Impact-Induced Porosity and Microfracturing at the Chicxulub Impact Structure - Rae, A.S.P.; Collins, G.S.; Morgan, J.V.; Salge, T.; Christeson, G.L.; Leung, J.; Lofi, J.; Gulick, S.P.S.; Poelchau, M.; Riller, U.; Gebhardt, C.; Grieve, R.A.F.; et al. (Journal of Geophysical Research: Planets, 2019)
Porosity and its distribution in impact craters has an important effect on the petrophysical properties of impactites: seismic wave speeds and reflectivity, rock permeability, strength, and density. These properties are important for the identification of potential craters and the understanding of the process and consequences of cratering. The Chicxulub impact structure, recently drilled by the joint International Ocean Discovery Program and International Continental scientific Drilling Program Expedition 364, provides a unique opportunity to compare direct observations of impactites with geophysical observations and models. Here, we combine small-scale petrographic and petrophysical measurements with larger-scale geophysical measurements and numerical simulations of the Chicxulub impact structure. Our aim is to assess the cause of unusually high porosities within the Chicxulub peak ring and the capability of numerical impact simulations to predict the gravity signature and the distribution and texture of porosity within craters. We show that high porosities within the Chicxulub peak ring are primarily caused by shock-induced microfracturing. These fractures have preferred orientations, which can be predicted by considering the orientations of principal stresses during shock, and subsequent deformation during peak ring formation. Our results demonstrate that numerical impact simulations, implementing the Dynamic Collapse Model of peak ring formation, can accurately predict the distribution and orientation of impact-induced microfractures in large craters, which plays an important role in the geophysical signature of impact structures. ©2019. American Geophysical Union. All Rights Reserved.
cited By 17

Initial report of continental scientific drilling project of the Cretaceous Songliao Basin (SK-1) in China / Wang Chengshan, [and 3 others], et al. - Wang, Chengshan (Initial report of continental scientific drilling project of the Cretaceous Songliao Basin (SK-1) in China, 2019)
Keywords: Boring – China – Heilongjiang Sheng; Boring – China – Jilin Sheng; Boring – China – Liaoning Sheng

Integration of underground mapping, petrology, and high-resolution microseismicity analysis to characterise weak geotechnical zones in deep South African gold mines - Mngadi, S.B.; Durrheim, R.J.; Manzi, M.S.D.; Ogasawara, H.; Yabe, Y.; Yilmaz, H.; Wechsler, N.; Van Aswegen, G.; Roberts, D.; Ward, A.K.; Naoi, M.; Moriya, H.; et al. (International Journal of Rock Mechanics and Mining Sciences, 2019)

Koyna, India, an ideal site for near field earthquake observations - Gupta, Harsh K. (Proceedings of the Indian National Science Academy, 2019)
The Koyna earthquake of M 6.3 on December 10, 1967 is the largest artificial water reservoir triggered earthquake globally. It claimed ∼ 200 human lives and devastated the Koyna township. Before the impoundment of the Shivaji Sagar Lake created by the Koyna Dam, there were no earthquakes reported from the region. Initially a few stations were operated in the region by the CentralWater and Power Research Station (CWPRS). The seismic station network grew with time and currently the National Geophysical Research Institute (NGRI), Hyderabad is operating 23 broadband seismographs and 6 bore hole seismic stations. Another reservoir, Warna, was created in 1985, which provided a further impetus to Reservoir Triggered Seismicity (RTS). Every year following the monsoon, water levels rise in the two reservoirs and there is an immediate increase in triggered earthquakes in the vicinity of Koyna-Warna reservoirs in the months of August –September. Peak RTS is observed in September and later during December.Another spurt in triggered earthquakes is observed during the draining of the reservoirs in the months of April- May. A comparative study of RTS earthquake sequences and the ones occurring in nearby regions made it possible to identify four common characteristics of RTS sequences that discriminate them from normal earthquake sequences. As the RTS events continue to occur at Koyna in a large number in a limited area of 20 km x 30 km, at shallow depths (mostly 2 to 9 km), the region being accessible for all possible observations and there being no other source of earthquakes within 100 km of Koyna Dam, it was suggested to be an ideal site for near field observations of earthquakes. This suggestion was discussed by the global community at an ICDP sponsored workshop held at Hyderabad and Koyna in 2011. There was an unanimous agreement about the suitability of the site for deep scientific drilling; however, a few additional observations/experiments were suggested. These were carried out in the following three years and another ICDP workshop was held in 2014, which totally supported setting up a borehole laboratory for near field investigations at Koyna. Location of a Pilot Bore-hole was decided on the basis of seismic activity and other logistics. The 3 km deep Pilot Borehole was spudded on December 20, 2016 and completed on June 11, 2017. © 2017, Geological Society of India.
Keywords: comparative study; earthquake event; earthquake trigger; reservoir; reservoir-induced seismicity; seismic discrimination; seismograph; site investigation; India; Koyna Dam; Maharashtra

Late Quaternary lacustrine deposits of the Dead Sea basin: high resolution sequence stratigraphy from downhole logging data - Coianiz, L.; Bialik, O.M.; Ben-Avraham, Z.; Lazar, M. (Quaternary Science Reviews, 2019)
Sequence architecture and depositional sequences of the Quaternary lacustrine succession deposited in the northern Dead Sea sub-basin were examined using logging data collected during the 2010-2011 ICDP campaign. Methods borrowed from sequence stratigraphy techniques were used to investigate the characteristics of sediments deposited in the central part of the northern lake. High resolution wire logging data combined with a detailed lithological description of the ICDP 5017-1-A deep borehole were used to examine depositional systems and related processes controlling their formation. Analysis of sedimentary stacking patterns and stratal surfaces within the late Pleistocene-Holocene lacustrine succession revealed 10 depositional sequences. It was possible to identify key stratal boundaries and to discern between three sedimentary stacking patterns interpreted here as representing lowstand systems tracts (LST), transgressive systems tracts (TST) and highstand systems tracts (HST). Examined together, they may be interpreted in terms of relative lake level changes. On the basis of the stratigraphic analysis complemented with new age dating, this article presents a record of the sediment accumulation pattern and a relative lake level curve reconstructed for the last ca 225 ka. Results show that stratigraphic units and depositional and erosional surfaces examined in the deep 5017-1-A borehole can be correlated to the proximal area of the basin. This means that changes in relative lake levels were generally synchronous and uniform across the Dead Sea basin. The creation of accommodation space in the northern Dead Sea was found to generally be in phase with paleoclimatic modulating lake levels, and not due to tectonics. © 2019 Elsevier Ltd
cited By 5
Keywords: Boreholes; Deposition; Lakes; Lithology; Sedimentology; Depositional sequences; High resolution sequence stratigraphy; Highstand systems tract; Late Pleistocene-Holocene; Sequence architectures; Sequence stratigraphy; Stratigraphic analysis; Transgressive systems tracts; Stratigraphy; data set; depositional environment; depositional sequence; lacustrine deposit; lake level; paleoclimate; Pleistocene-Holocene boundary; Quaternary; reconstruction; sequence stratigraphy; Dead Sea

High-resolution correlations of strata within a sand-rich clinothem using grain fabric data, offshore New Jersey, USA - Cosgrove, G.I.E.; Hodgson, D.M.; Mountney, N.P.; McCaffrey, W.D. (Geosphere, 2019)
Trajectories of successive clinoform rollovers are widely applied to predict patterns of spatio-temporal sand distribution. However, the detailed internal architecture of individual clinothems is rarely documented. Understanding the textural complexities of complete topset-foreset-bottomset clinothem sequences is a key factor in understanding how and when sediment is transferred basinward. This study used high-resolution, core-based analyses of 267 samples from three research boreholes from quasi-coeval topset, foreset, and bottomset deposits of a single Miocene intrashelf clinothem recovered during Integrated Ocean Drilling Program (IODP) Expedition 313, offshore New Jersey, USA. Topset deposits were subdivided into three sedimentary packages based on grain character and facies analysis, consisting of upper and lower river-dominated topset process-regime packages separated by a middle wave- and storm-dominated process-regime package. Temporal variability in topset process regime exerts a quantifiable effect on grain character across the complete depositional profile, which was used here to correlate topset deposits with time-equivalent sedimentary packages in foreset and bottomset positions. River-dominated sedimentary packages have higher sand-to-mud ratios; however, the grain character of river-dominated sedimentary packages is texturally less mature than that of wave- and storm-dominated deposits. Differences in grain character between packages dominated by different process regimes increase basinward. The novel use of quantitative grain-character data allows intraclinothem time lines to be established at a higher resolution than is possible using chronostratigraphic techniques. Additionally, stratigraphic changes in grain character were used to refine the placement of the basal sequence boundary. These results challenge the idea that clinoform trajectories and stacking patterns are sufficient to describe spatio-temporal sand-body evolution across successive clinothems. © 2019 The Authors.
cited By 3
Keywords: Deposits; Offshore boreholes; Offshore oil well production; Rivers; Sedimentology; Storms; Stratigraphy; Higher resolution; Integrated ocean drilling programs; Internal architecture; Sand distribution; Sedimentary packages; Stratigraphic changes; Temporal variability; Textural complexity; Sand; chronostratigraphy; correlation; deposition; facies analysis; Miocene; Ocean Drilling Program; offshore application; resolution; sand; sedimentary structure; New Jersey; United States

Late-Holocene sedimentation and sodium carbonate deposition in hypersaline, alkaline Nasikie Engida, southern Kenya Rift Valley - De Cort, Gijs; Mees, Florias; Renaut, Robin W.; Sinnesael, Matthias; Meeren, Thijs; Goderis, Steven; Keppens, Edward; Mbuthia, Anthony; Verschuren, Dirk (Journal of Paleolimnology, 2019)

Limited off-set consideration in de-multiple process of seismic Lake Towuti - Andika, Ryan Bobby; Triyoso, Wahyu; Bijaksana, Satria; Hafidz, Abd.; Russell, James M.; Watruss, Nigel (IOP Conference Series: Earth and Environmental Science, 2019)
Multiple attenuation effect study in Lake Towuti seismic data is based on limited offset recording. The goal of this study is to better understand the sediments structure of Lake Towuti that layered above East Sulawesi ophiolitic and metamorphic rocks for stratigraphic interpretation. Surface-related multiple and internal multiple are a common noise signal that recorded in this seismic data, alongside the primary signal from the sediments layer. In order to get a representative subsurface image of the lake, a combination of some de-multiple method to suppress this noise signal has been applied in previous study. However, the line seismic that used in this seismic recording is less than 100 m. From our perspective, this limited offset line fact have to be considered carefully. It's because some application of de-multiple method in this case will not effectively suppress the noise. In this study, we give an alternative combination method in function to put out the surface-related multiple of the case. First, we enhance the S/N ratio and velocity analysis of the data by Common Reflection Surface (CRS) method. From this enhancement, CRS can give a direct advantage when applying some de-multiple method, especially in Predictive Deconvolution and SRME method. Moreover, we combine the application of de-multiple theory with the strict arrangement of Predictive Deconvolution, Surface-Related Multiple Elimination (SRME), and the last is F-K filter. Those combination methods precisely give a better imaging of Lake Towuti sediments layer in this seismic processing study. © 2019 Published under licence by IOP Publishing Ltd.
Keywords: Metamorphic rocks; Sediments; Seismic prospecting; Seismic response; Seismic waves; Stratigraphy; Combination method; Common reflection surfaces; Multiple attenuation; Predictive deconvolution; Seismic processing; Seismic recording; Subsurface images; Surface-related multiple elimination; Lakes

Log response characteristics and lithological evaluation of volcanic rocks in Yingcheng Formation from the second scientific drilling borehole (SK-2 east borehole) in Songliao basin of Northeast China - ZHAO, Jinhuan; Zou, Changchun; Wang, Wenshi; ZHANG, Xiaohuan; Zhu, Yongyi; Zhang, Jinchang; Zhang, Hengchun; Ding, Yujiao; Lin, Feng; QIN, Yuxing; ZHOU, Hai; SUN, Wenlong (Geology in China, 2019)
In order to conduct long-term deep observation, fluid experiments and investigate volcanic events in Songliao basin, the authors carried out lithological evaluation of volcanic rocks in Yingcheng Formation by using abundant and complete geophysical logs from SK-2 east borehole. The log response analysis of volcanic rocks shows that the radioactivity and electric conductivity of tuffs are the strongest. Agglomeratic lavas have low density because of high porosity. The density of rhyolites is the highest and the electric conductivity is the weakest. Volcanic rocks of Yingcheng Formation along SK-2 east borehole consist of rhyolites, transitional tuffl lavas, agglomeratic lavas and a little tuffs by using cross plots and imaging models. A volcanic eruptive gap may exist, as evidenced by tuff with high GR, low RD and low DEN. Rhyolites are characterized by high alkali, high Si, low Fe and low clay mineral. T2 analysis suggests that the rhyolites are favorable for carrying out long-term observations and fluid experiments. The results provide a reference of interpretation for subsequent volcanic rock in Huoshilin Formation and research of volcanic rocks in the whole basin.
Keywords: deep exploration engineering; SK-2 east borehole; volcanic rocks; log response characteristics; lithological evaluation

Magnetic fabric development in the Lower Seve thrust from the COSC-1 drilling, Swedish Caledonides - Merz, Lena; Almqvist, Bjarne S. G.; Grimmer, Jens C.; Kontny, Agnes (Tectonophysics, 2019)
The COSC-1 project drilled the several hundred meters thick basal shear zone of the Lower Seve nappe with mylonites in mica schists, amphibole schists and gneisses. In zones of high magnetic susceptibility from 1910 to 2450 m we studied magnetic and petrographic fabrics, and magnetic mineralogy. Borehole imaging allowed for geographic reorientation of the samples and offered the opportunity to study anisotropy of magnetic susceptibility (AMS) in relation to tectonic evolution of the Seve thrust. We measured AMS at room temperature, added low-temperature and field-dependent AMS for a subset of samples, and compared magnetic with petrographic fabrics. Triaxial and prolate magnetic fabrics with degree of anisotropy (P′) up to 3.2 together with abundant S-C fabrics and strain partitioning around porphyroclasts indicate dominant simple shear until 2300 m. Magnetite and ilmenohematite mimic the rock fabric due to fabric parallel alignment and/or magnetic interaction and either contribute to increase or decrease of P′, depending on the dominating rock fabric elements. Field-dependency of pyrrhotite and magnetite in kmax-direction further increases P′. Homogeneous and oblate petrographic and magnetic fabrics in the greenschist-grade overprinted rocks below 2300 m with subhorizontal kmax-kint-girdle distributions indicate dominant flattening. AMS depicts shear fabrics including magnetite and ilmenohematite, and is additionally increased by retrograde magnetite-rutile intergrowth in ilmenohematites. We interpret that shape and degree of AMS are controlled by (a) tectonic deformation and strain, (b) alteration and magnetic grain interaction, and (c) field-dependency of deformed pyrrhotite and/or magnetite. We observed that all petrographic and magnetic subfabrics are coaxial, and lineations are mainly E-W to SE-NW directed confirming the transport direction of the Caledonian allochthonous. From our microstructural and AMS results we suggest that thrusting of the Lower Seve unit commenced under simple shear conditions at higher metamorphic grades and subsequently switched to more pure shear under greenschist-grade conditions.
Keywords: Anisotropy of magnetic susceptibility (AMS); Crustal shear zone; Magnetic fabric; Seve nappe complex

Magnetochronology of the Entire Chinle Formation (Norian Age) in a Scientific Drill Core From Petrified Forest National Park (Arizona, USA) and Implications for Regional and Global Correlations in the Late Triassic - Kent, Dennis V.; Olsen, Paul E.; Lepre, Christopher; Rasmussen, Cornelia; Mundil, Roland; Gehrels, George E.; Giesler, Dominique; Irmis, Randall B.; Geissman, John W.; Parker, William G. (Geochemistry, Geophysics, Geosystems, 2019)

Design of the subsurface observatory at Surtsey volcano, Iceland - T{urke, A.; Jackson, M.D.; Bach, W.; Kahl, W.-A.; Grzybowski, B.; Marshall, B.; Gudmundsson, M.T.; Jørgensen, S.L. (Scientific Drilling, 2019)
Surtsey, the youngest of the islands of Vestmannaeyjar, is an oceanic volcano created by explosive basaltic eruptions during 1963-1967 off the southern coast of Iceland. The subsurface deposits of the volcano were first sampled by a cored borehole in 1979. In summer 2017, three cored boreholes were drilled through the active hydrothermal system of the volcano by the International Continental Scientific Drilling Program (ICDP) SUSTAIN Expedition 5059. These cores are expected to provide the first glimpse of microbial life in very young and native basaltic tuff of the oceanic crust. To reduce the contamination of the subsurface environment, seawater circulating fluid was filtered and passed through two UV-sterilizing treatments. One of the boreholes has been equipped with a subsurface observatory dedicated in situ experiments for monitoring water-rock interactions and microbial processes in sterile, artificial basaltic glass and in olivine granules. With temperatures ranging from 25 to 125 °C, the subsurface observatory provides a precise geothermal window into an active hydrothermal system and thus represents an exceptional natural laboratory for studying fluid-rock-microbe interactions at different temperature regimes and facilitates experimental validation of active submarine microbial processes at the limit of functional life, about 121 °C. Comparisons with the 1979 and 2019 drill cores will provide time-lapse observations of hydrothermal processes over a 50-year timescale. Here, we present the technical design of the observatory and the incubation chamber experiments deployed from September 2017 to summer 2019. © Author(s) 2019.
cited By 3
Keywords: Basalt; Boreholes; Boring; Infill drilling; Microorganisms; Observatories; Silicate minerals; Volcanoes; Chamber experiments; Continental scientific drillings; Experimental validations; Hydrothermal process; Hydrothermal system; Natural laboratories; Subsurface environment; Water rock interactions; Core drilling

High-temperature core drilling fluid technology of Well Songke-2; [松科二井取心钻进高温钻井液技术] - Xu, Jie; Zhu, Yongyi; Wu, Xiaoming; Wang, Wenshi; Zhang, Hengchun; Yan, Jia; Cao, Longlong; Xu, Lin; Zhang, Linsheng; Zheng, Wenlong (Geology in China, 2019)
The completion depth of Well Songke 2 is 7108.88 m. At the time 38h after the well completion, the bottom hole temperature was 241℃. Three kinds of drilling fluids were investigated in laboratory according to the formation and temperature conditions, and they respectively are the potassium chloride-polysulfonate system which is resistant to temperature of 180℃, the polymer drilling fluid which is resistant to 230℃ and formate-polymer drilling fluid which is resistant to 250℃. The experimental data show that these drilling fluids have good high temperature stability and low HTHP filtration loss. Through detecting the quality of drilling fluid real time, the predicted problems could happen through over- temperature detection, which make indoor experiments to guide in- site maintenance in the project construction, ensure the stability performance at high temperature interval, and guarantee the coring operation smoothly. In addition, the drilling fluid of each system achieves a safe and smooth transition during the conversion, without any waste slurry, which greatly saves the cost. The logging and casing running before cementing could be successfully completed at one time, which further proves that the drilling fluid used has good high temperature stability. © 2019 Editorial Board of Geology in China. All rights reserved.

Long-term monitoring with fiber optics distributed temperature sensing at campi flegrei: The campi flegrei deep drilling project - Somma, Renato; Troise, Claudia; Zeni, Luigi; Minardo, Aldo; Fedele, Alessandro; Mirabile, Maurizio; De Natale, Giuseppe (Sensors (Switzerland), 2019)
Monitoring volcanic phenomena is a key question, for both volcanological research and for civil protection purposes. This is particularly true in densely populated volcanic areas, like the Campi Flegrei caldera, which includes part of the large city of Naples (Italy). Borehole monitoring of volcanoes is the most promising way to improve classical methods of surface monitoring, although not commonly applied yet. Fiber optics technology is the most practical and suitable way to operate in such high temperature and aggressive environmental conditions. In this paper, we describe a fiber optics Distributed Temperature Sensing (DTS) sensor, which has been designed to continuously measure temperature all along a 500 m. deep well drilled in the west side of Naples (Bagnoli area), lying in the Campi Flegrei volcanic area. It has then been installed as part of the international Campi Flegrei Deep Drilling Project’, and is continuously operating, giving insight on the time variation of temperature along the whole borehole depth. Such continuous monitoring of temperature can in turn indicate volcanic processes linked to magma dynamics and/or to changes in the hydrothermal system. The developed monitoring system, working at bottom temperatures higher than 100 ◦ C, demonstrates the feasibility and effectiveness of using DTS for borehole volcanic monitoring. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.
Keywords: Boreholes; Boring; Environmental technology; Fiber optics; Fibers; Infill drilling; Temperature sensors; Volcanoes; Well drilling; Campi Flegrei; Continuous monitoring; Distributed temperature sensing; Environmental conditions; Hydrothermal system; Long term monitoring; Temperature calibration; Volcanic monitoring; Monitoring

Heterogeneity of melts in impact deposits and implications for their origin (Ries suevite, Germany) - Siegert, S.; Hecht, L. (Meteoritics and Planetary Science, 2019)
Impact melt-bearing clastic deposits (suevites) are one of the most important records of the impact cratering process. A deeper understanding of their composition and formation is therefore essential. This study focuses on impact melt particles in suevite at Ries, Germany. Textures and chemical evidence indicate that the suevite contains three melt types that originate from different shock levels in the target. The most abundant melt type (“melt type 1”) represents well-mixed whole-rock melting of crystalline basement and includes incompletely mixed mafic melt schlieren (“melt type 1 mafic”). Polymineralic melt type 2 comprises mixes between monomineralic melt types 3 and melt type 1. Melt types 2 and 3 are located within melt type 1 as small patches or schlieren but also isolated within the suevite matrix. The main melt type 1 is heterogeneous with respect to trace elements, varying geographically around the crater: in the western sector, it has lower values in trace elements, e.g., Ba, Zr, Th, and Ce, than in the eastern sector. The west –east zoning likely reflects the heterogeneous nature of crystalline basement target rocks with lower trace element contents, e.g., Ba, Zr, Th, and Ce, in the west compared to the east. The chemical zoning pattern of suevite melt type 1 indicates that mixing during ejection and emplacement occurred only on a local (hundreds of meters) scale. The incomplete larger scale mixing indicated by the preservation of these local chemical signatures, and schlieren corroborate the assumption that mixing, ejection, and quenching were very rapid, short-lived processes. © The Meteoritical Society, 2018.
cited By 4

Event couple spectral ratio Q method for earthquake clusters: Application to northwest Bohemia - Kriegerowski, Marius; Cesca, Simone; Ohrnberger, Matthias; Dahm, Torsten; Kruger, Frank (Solid Earth, 2019)
We develop an amplitude spectral ratio method for event couples from clustered earthquakes to estimate seismic wave attenuation (<span classCombining double low lineinline-formula>Qĝ'1) in the source volume. The method allows to study attenuation within the source region of earthquake swarms or aftershocks at depth, independent of wave path and attenuation between source region and surface station. We exploit the high-frequency slope of phase spectra using multitaper spectral estimates. The method is tested using simulated full wave-field seismograms affected by recorded noise and finite source rupture. The synthetic tests verify the approach and show that solutions are independent of focal mechanisms but also show that seismic noise may broaden the scatter of results. We apply the event couple spectral ratio method to northwest Bohemia, Czech Republic, a region characterized by the persistent occurrence of earthquake swarms in a confined source region at mid-crustal depth. Our method indicates a strong anomaly of high attenuation in the source region of the swarm with an averaged attenuation factor of <span classCombining double low lineinline-formula>Qp <100. The application to S phases fails due to scattered P-phase energy interfering with S phases. The <span classCombining double low lineinline-formula>Qp anomaly supports the common hypothesis of highly fractured and fluid saturated rocks in the source region of the swarms in northwest Bohemia. However, high temperatures in a small volume around the swarms cannot be excluded to explain our observations. © 2019. This work is distributed under the Creative Commons Attribution 4.0 License.
Keywords: Bohemia; Czech Republic; Transport properties; Amplitude spectral ratio; Attenuation factors; Earthquake swarms; High frequency HF; High temperature; Seismic wave attenuations; Spectral estimate; Spectral ratios; aftershock; earthquake swarm; seismic attenuation; seismic source; seismic wave; spectral analysis; Earthquake effects

Effects of temperature on the frictional behavior of material from the Alpine Fault Zone, New Zealand - Valdez, II; Kitajima, H.; Saffer, D.M. (Tectonophysics, 2019)
Temperature is widely believed to act as a primary control on fault rheology, and therefore on the distribution of seismicity along plate boundary faults. However, there are few detailed measurements of the frictional strength and stability of natural fault gouges at elevated temperatures. Here, we report on a suite of shearing experiments designed to investigate the frictional behavior of fault rocks sampled from depths of 111.5 –142.9 m along the Alpine Fault in New Zealand obtained by the International Continental Scientific Drilling Program (ICDP) Deep Fault Drilling Project (DFDP). We tested five samples from the DFDP-1B pilot hole: two hanging wall chloritic cataclasites, two footwall granitic cataclasites, and a fault gouge from the principal slip zone (PSZ-1). Each sample was sheared at a range of temperatures from 23 to 500 °C and at an effective normal stress of 80 MPa. The wall rock cataclasites exhibit an increase in the friction coefficient (μ) with temperature, from μ = 0.45 –0.64 at 23 °C to μ = 0.87 at 500 °C. The PSZ-1 gouge exhibits lower friction coefficient values than the wall rock at temperatures ≤180 °C (μ = 0.35 –0.46 vs 0.45 –0.65), but comparable values (μ = 0.87 –0.90) at 500 °C. The variation in frictional strength is accompanied by a transition from velocity-strengthening to velocity-weakening behavior at temperatures ≥180 °C for all materials. Extrapolation of the experimentally defined rheological critical stiffness of the fault material and the estimated in situ stiffness of the surrounding crust suggests upper and lower stability boundaries at 1.8 –2.5 km and 8.5 –8.8 km depth, respectively. The upper stability boundary is also consistent with the observed depth-frequency distribution of earthquakes. © 2019
cited By 5
Keywords: Earthquakes; Friction; Infill drilling; Stiffness; Temperature; Continental scientific drillings; Effective normal stress; Effects of temperature; Frequency distributions; Friction coefficients; High temperature; Scientific drilling; Stability boundaries; Faulting; cataclasite; drilling; earthquake; fault gouge; fault zone; friction; high temperature; rheology; stiffness; temperature effect; Alpine Fault Zone; New Zealand; South Island

Empowering conventional Rock-Eval pyrolysis for organic matter characterization of the siderite-rich sediments of Lake Towuti (Indonesia) using End-Member Analysis - Ordoñez, Luis; Sebag, David; Ariztegui, Daniel; Adatte, Thierry; Russell, James M.; Kallmeyer, Jens; Vuillemin, Aurèle; Friese, Andr'e; Crowe, Sean A.; Bauer, Kohen W.; Simister, Rachel; Henny, Cynthia; et al. (Organic Geochemistry, 2019)
Qualitative and quantitative changes of organic and carbonate carbon in sedimentary records are frequently used to reconstruct past environments, paleoproductivity and sediment provenance. Amongst the most commonly used proxies are Total Organic Carbon (TOC), Mineral Carbon (MinC), as well as Hydrogen (HI) and Oxygen Indices (OI) of organic matter (OM). Rock Eval pyrolysis enables the assessment of these quantitative and qualitative parameters with a single analysis. This is achieved through transient pyrolysis of the samples up to 650 °C followed by combustion up to 850 °C, with hydrocarbons, CO and CO2 measured during the thermal decomposition of both OM and carbonate minerals. Carbonate minerals with low thermal cracking temperatures, such as siderite (<400 °C), can induce significant matrix effects which bias the TOC, MinC and OI Rock-Eval parameters. Here we assess the applicability of End-Member Analysis (EMA) as a means of correcting Rock-Eval thermograms for siderite matrix effects. For this, we performed Rock-Eval pyrolysis on sideritic sediments of Lake Towuti (Indonesia). New thermal boundaries were constrained in Rock-Eval thermograms using EMA to limit siderite matrix effects and improve TOC, MinC and OI calculations. Our approach allowed us to: (1) evaluate the influence of siderite matrix effects on Rock-Eval thermograms; (2) properly exploit a Rock-Eval dataset to characterize the type and sources of OM in siderite-rich sediments and (3) identify the OM behind degradation and mineralization processes. The Rock-Eval dataset revealed sediments with a substantial amount of refractory OM, especially in those where TOC is high and HI characteristic of autochthonous biomass. These results, associated to alternative indices used to assess OM preservation, suggest that refractory OM is residually enriched following strong degradation of labile compounds. Finally, relatively labile and refractory organic fractions may be consumed in the formation of siderite during this sequential process of OM mineralization. © 2019 The Authors
Keywords: Greater Sunda Islands; Lake Towuti; Malili Lakes; South Sulawesi; Sulawesi; Sunda Isles; Biogeochemistry; Biological materials; Carbonate minerals; Carbonation; Iron ores; Lakes; Mineralogy; Organic carbon; Pyrolysis; Refractory materials; Sediments; Temperature measuring instruments; Thermoanalysis; Thermography (temperature measurement); Endmembers; Mineralization process; Qualitative parameters; Quantitative changes; Rock-Eval pyrolysis; Siderite; Total Organic Carbon; Tropical lakes; degradation; lacustrine deposit; lacustrine environment; mineralization; organic matter; paleoproductivity; provenance; pyrolysis; sediment chemistry; siderite; thermal decomposition; total organic carbon; Rocks

Discovery of Triassic volcanic-sedimentary strata in the basement of Songliao Basin - Yin, Y.; Gao, Y.; Wang, P.; Qu, X.; Liu, H. (Science Bulletin, 2019)
cited By 12

Evaluating the influence of meteorite impact events on global potassium feldspar availability to the atmosphere since 600 ma - Coldwell, B.C.; Pankhurst, M.J. (Journal of the Geological Society, 2019)
Potassium feldspar present in global mineral aerosol (<5%) plays a disproportionate role in modulating the microphysics of mixed-phase cloud. Via exceptional ice nucleation properties, it is capable of changing cloud properties and behaviour. Here we identify times of substantial and abrupt change in the global availability of potassium feldspar since 600 Ma. Normally, weathering and vegetation cover contribute to low availability, with clay dominating mineral aerosol. Periods of maximum availability are reasoned to follow the emplacement and remobilization of ejecta blankets from major meteorite impact events, before returning to background after some hundreds to thousands of years. We review the 44 largest confirmed craters and evaluate the potassium feldspar content of their target rocks, which range from c. 0 to >30%. By combining crater size and tectonic reconstructions, we are able to provide a quantitative and self-consistent assessment of changes to global potassium feldspar availability. Considerable differences in potassium feldspar availability following meteorite impact events are revealed. Different impact events generated dust containing different amounts of potassium feldspar. Differing levels of influence upon climate are hypothesized, and should now be tested by looking at stratigraphic records of these events to reveal the sensitivity of climate to different dust mineralogy. © 2018 The Author(s).
cited By 1

Evaluation of drilling parameters in gas hydrate exploration wells - Merey, Ş. (Journal of Petroleum Science and Engineering, 2019)
Gas hydrates are crystalline ice-like structures formed from water and gas molecules at high pressure and low temperature conditions. They are considered as near-future energy resources. Recently, there have been many drilling activities in gas hydrates in both permafrost regions (mainly Mallik wells, Canada; Ignik Sikumi #1 well, Alaska; Mount Elbert #1, Alaska) and marine sediments (the wells drilled in Gulf of Mexico and India drilling expeditions). In this study, it is aimed to evaluate and analyze logging-while drilling data (LWD) and other drilling data of these drilling activities. Initially, all drilling parameters (i.e. rate of penetration, weight on bit, torques, mud logs, etc.) of these wells were collected and drawn to see the change in parameters with depths. In order to indicate the changes in drilling parameters in the sediments containing gas hydrates, gas hydrate saturations were estimated from resistivity logs and NMR logs in this study. High resistivity log values and methane peaks in drilling fluid were good indicators of gas hydrate existence. During the drilling of permafrost formations and gas hydrates deposited in coarse sands as pore filling, the rate of penetration generally decreased. Differently, there was not almost any change in the rate of penetration during the drilling of fracture-filling gas hydrates within silts/clay in India. Borehole enlargements (washouts) were commonly seen in the wells drilled in marine sediments (Gulf of Mexico and Indian expeditions). However, this effect was minimum during the drilling of the wells in permafrost regions. This difference is due to the loose sediments in marine environment. Furthermore, gamma and density logs were seriously affected by washouts, mainly in marine sediments. It was observed that pore-filling gas hydrates affect the rate of penetration and keep the sediments stable because well collapses mainly occurred in the sediments without any gas hydrates. However, the temperature of drilling fluid should be close to the temperature of gas hydrate zones to reduce the effect of drilling on gas hydrate dissociation for the wells both in permafrost and marine sediments. In Gulf Mexico and Indian drilling expeditions, riser and wellhead equipment were not used. However, the usage of surface casing might decrease the risk of borehole collapses due to very loose sediments close to sea floor. Another important outcome of this study is that the pressure gradient follows hydrostatic pressure gradients according to the pressure analysis within gas hydrate stability zones of marine sediments. Finally, the analyses of drilling parameters revealed that drilling through gas hydrate bearing strata is not as risky as it might have been considered. The key is hidden in appropriate drilling design. © 2018 Elsevier B.V.
cited By 25
Keywords: Boring; Drilling; Drilling equipment; Drilling fluids; Electric logging; Filling; Gases; Hydration; Hydrostatic pressure; Infill drilling; Methane; Nuclear magnetic logging; Parameter estimation; Permafrost; Petroleum prospecting; Petroleum reservoir evaluation; Pressure gradient; Radioactivity logging; Renewable energy resources; Sediments; Submarine geology; Temperature; Well drilling; Borehole enlargements; Drilling of permafrost; Gas hydrate exploration wells; Gas hydrate saturations; Gas hydrate stability zones; Logging while drilling; Low temperature conditions; Methane hydrates; Gas hydrates; borehole; drilling; exploration; gas hydrate; gas well; marine sediment; methane; permafrost; pressure gradient; Atlantic Ocean; Gulf of Mexico; India

Heat flow in the Dead Sea from the ICDP boreholes and its implication for the structure of the basin - Oryan, B.; Villinger, H.; Lazar, M.; Schwab, M.J.; Neugebauer, I.; Ben-Avraham, Z. (Quaternary Science Reviews, 2019)
Numerical simulations emulating the formation of the Dead Sea Basin (DSB) infer that it could not have been formed as a pull-apart basin with a surface heat flow lower than 50[Formula presented]. However, previous measurements determined values of 32−40[Formula presented]. This contradiction is known as the “Dead Sea heat flow paradox”. Here we set to re-examine the “paradox” by analyzing heat flow data in boreholes drilled by the ICDP (International Continental Drilling Program) in the northern DSB. The boreholes and the extracted sediment cores offer a unique opportunity to re-measure the heat flow in the DSB and assess the “paradox”. Heat flow was determined by obtaining in situ temperature profiles from the boreholes and conducting 469 thermal conductivity measurements on the cores. The newly computed values are in agreement with those previously obtained for the DSB and fall below the threshold of 50[Formula presented]. Different explanations proposed to justify higher heat flow seem to fail leaving the “Dead Sea heat flow paradox” unresolved. Heat flow values and the sedimentation corrections determined in this research are consistent with the Ginzburg and Ben-Avraham subsurface model for the DSB, suggesting deeper sediment filling in the southern part of the basin. © 2019 Elsevier Ltd
cited By 3
Keywords: Boreholes; Boring; Chloride minerals; Heat transfer; Infill drilling; Thermal conductivity; Dead sea basins; Deep drilling; In-situ temperature; International continental drilling program (ICDP); Salt diapirs; Subsurface model; Surface heat flow; Thermal conductivity measurements; Flow measuring instruments; borehole; correction; Deep Sea Drilling Project; diapir; heat flow; saline lake; sediment core; sedimentation; thermal conductivity; Calluna vulgaris

Evaluation of the geothermal potential of the western Snake River Plain based on a deep corehole on the Mountain Home AFB near Mountain Home, Idaho - Lachmar, T.E.; Freeman, T.G.; Kessler, J.A.; Batir, J.F.; Evans, J.P.; Nielson, D.L.; Shervais, J.W.; Chen, X.; Blackwell, D.D. (Geothermal Energy, 2019)
A geothermal exploration corehole was drilled to a total depth of 1821.5 m on the Mountain Home Air Force Base near Mountain Home, Idaho. The corehole was used to collect an unusually large amount of data, including uniaxial compressive stress (UCS) experiments on core samples, to evaluate the geothermal potential of the western Snake River Plain. In addition, unlike many exploration holes in this region, a fluid entry was encountered at 1745.3 m and flowed artesian to the surface. A maximum temperature of 149.4 °C was calculated for the entry. A temperature log run on the corehole from 3 to 1675 m is nearly linear with little variation. The average geothermal gradient is 73 °C/km, and the average heat flow between 200 and 1500 m is 102 ± 15 mW/m2. Chemical analyses of a sample from the fluid entry suggest that a significant proportion of the water is not meteoric. Five geothermometers show equilibrium temperature in the range of 133 –157 °C. Furthermore, based on the unconfined UCS experiments on basalt core samples, a brittle unit was found to comprise the fractured reservoir that the geothermal water flows from, while an overlying ductile unit acts as a hydrothermal caprock. This implies that the reservoir/caprock pair may be a target for future exploration wells drilled to delineate the extent of the potential resource and the boundaries of the connected fracture network. © 2019, The Author(s).
cited By 3
Keywords: Basalt; Chemical analysis; Core samples; Geothermal prospecting; Heat transfer; Infill drilling; Landforms; Thermal logging; Equilibrium temperatures; Geothermal exploration; Geothermal gradients; Geothermal potential; Geothermometers; Potential resources; Temperature log; Uniaxial compressive; Geothermal energy; basalt; compressive strength; experimental study; geothermal energy; geothermal power; geothermometry; heat flow; temperature effect; uniaxial strength; Idaho; Snake River Plain; United States; Calluna vulgaris

Evidence for shock-induced anhydrite recrystallization and decomposition at the UNAM-7 drill core from the Chicxulub impact structure - Salge, T.; Stosnach, H.; Rosatelli, G.; Hecht, L.; Reimold, W.U. (Meteoritics and Planetary Science, 2019)
Drill core UNAM-7, obtained 126 km from the center of the Chicxulub impact structure, outside the crater rim, contains a sequence of 126.2 m suevitic, silicate melt-rich breccia on top of a silicate melt-poor breccia with anhydrite megablocks. Total reflection X-ray fluorescence analysis of altered silicate melt particles of the suevitic breccia shows high concentrations of Br, Sr, Cl, and Cu, which may indicate hydrothermal reaction with sea water. Scanning electron microscopy and energy-dispersive spectrometry reveal recrystallization of silicate components during annealing by superheated impact melt. At anhydrite clasts, recrystallization is represented by a sequence of comparatively large columnar, euhedral to subhedral anhydrite grains and smaller, polygonal to interlobate grains that progressively annealed deformation features. The presence of voids in anhydrite grains indicates SOx gas release during anhydrite decomposition. The silicate melt-poor breccia contains carbonate and sulfate particles cemented in a microcrystalline matrix. The matrix is dominated by anhydrite, dolomite, and calcite, with minor celestine and feldspars. Calcite-dominated inclusions in silicate melt with flow textures between recrystallized anhydrite and silicate melt suggest a former liquid state of these components. Vesicular and spherulitic calcite particles may indicate quenching of carbonate melts in the atmosphere at high cooling rates, and partial decomposition during decompression at postshock conditions. Dolomite particles with a recrystallization sequence of interlobate, polygonal, subhedral to euhedral microstructures may have been formed at a low cooling rate. We conclude that UNAM-7 provides evidence for solid-state recrystallization or melting and dissociation of sulfates during the Chicxulub impact event. The lack of anhydrite in the K-Pg ejecta deposits and rare presence of anhydrite in crater suevites may indicate that sulfates were completely dissociated at high temperature (T > 1465 °C)–whereas ejecta deposited near the outer crater rim experienced postshock conditions that were less effective at dissociation. © The Trustees of the Natural History Museum, London, 2019.
cited By 3

Evolution of an Archean fan delta and its implications for the initiation of uplift and deformation in the Barberton Greenstone Belt, South Africa - Drabon, Nadja; Heubeck, Christoph E.; Lowe, Donald R. (Journal of Sedimentary Research, 2019)

Exploring the piezotolerant/piezophilic microbial community and genomic basis of piezotolerance within the deep subsurface Deccan traps - Dutta, Avishek; Peoples, Logan M.; Gupta, Abhishek; Bartlett, Douglas H.; Sar, Pinaki (Extremophiles, 2019)

Fine description and geological age delineation of sedimentary sequences of the second member of Denglouku Formation based on ICDP scientific drilling borehole in Songliao Basin (SK2) - Basin, Songliao; LIU, Shuo; GAO, You-feng; YIN, Yong-kang; LIU, Hai-bo; LI, Hong-hao; WANG, Pu-jun (2019)

Fine structure of the lithosphere beneath the Well SK-2 and its adjacent: Revealed by deep seismic reflection profile [松科二井邻域岩石圈精细结构特征及动力学环境-深地震反射剖面的揭示] - Fu, W.; Hou, H.; Gao, R.; Liu, C.; Yang, J.; Guo, R. (Acta Geophysica Sinica, 2019)
In order to reveal the fine structure of the lithosphere adjacent to Well SK-2, a deep seismic reflection profile crossing Well SK-2 was laid out in the Songliao Basin (SB), with the trend north to south. Data acquisition was featured in the shooting technique of multi-scale explosive source and data reception by large offset with smaller trace distance in key area. Besides, processing flow of high fidelity and amplitude-preservation was undertaken to get the pre-stack migrated seismic reflection profile with high resolution and high signal-to-noise ratio. As the result, the profile shows strong reflections from settled layers alternate with and weak reflections of igneous rock beneath T4 reflector, and two residuals of upper Paleozoic stratums are distinguished out, one is beneath Well SK-2 (TWT, 3.5 4 s), the other is beneath the Renmin-Yong'an Terrace (CDP, 3500 4500, TWT, 3.5 4 s). Some paralleled seismic patterns dipping north can be observed in the middle and lower crust, as well as some strong but short lenticular reflectors are observed beneath Zhonghe Fault Depression, and the overall contour of these lenticular reflectors is like a mushroom cloud, we interpret this phenomenon as the hot material from downward in the lithosphere extension environment. The Moho in the north part shows strong near-horizontal continuous reflection, while the Moho in the Xujiaweizi Fault Depression in the south shows weak reflection. Three types of upper mantle reflections are distinguished on the deep seismic profile, including inclined mantle reflections, near-horizontal mantle reflections and super-deep reflections in the mantle. It is inferred that they are the early subduction relics, bottom of early thickened crust and the present lithosphere-asthenosphere boundary (LAB). Based on the latest results of deep seismic profile detecting crossing Well SK-2, this paper study structure features preserved in the lithosphere of Songnen Massif with tectonic superposition of Palo-Asia Ocean regime, Mongol-Okhotsk regime and Palo-Pacific regime, thus providing a new perspective for the discussion of the formation cause, tectonic background and dynamic factors of Songliao Basin. © 2019, Science Press. All right reserved.
cited By 7
Keywords: Atomic physics; Data acquisition; Faulting; Igneous rocks; Reflection; Seismic waves; Seismology; Signal to noise ratio; Deep seismic reflection profiles; Deep seismic reflections; Lithosphere-asthenosphere boundary; Mantle reflections; Moho; Seismic reflection profiles; Songliao basin; Xujiaweizi Fault Depression; Structural geology; fault zone; igneous rock; lithospheric structure; mantle structure; Moho; Paleozoic; seismic reflection; signal-to-noise ratio; subduction; upper mantle; China; Fujian; Heilongjiang; Mongol-Okhotsk Fold Belt; Songliao Basin; Xujiaweizi; Yongan; Basidiomycota

Formation of diagenetic siderite in modern ferruginous sediments - Vuillemin, Aurèle; Kemnitz, Helga; Friese, Andr'e; Bauer, Kohen W.; Simister, Rachel; Nomosatryo, Sulung; Ordoñez, Luis; Ariztegui, Daniel; Henny, Cynthia; Crowe, Sean A.; Benning, Liane G.; Kallmeyer, Jens; et al. (Geology, 2019)
Ferruginous conditions prevailed in the world's deep oceans during the Archean and Proterozoic Eons. Sedimentary iron formations deposited at that time may provide an important record of environmental conditions, yet linking the chemistry and mineralogy of these sedimentary rocks to depositional conditions remains a challenge due to a dearth of information about the processes by which minerals form in analogous modern environments. We identified siderites in ferruginous Lake Towuti, Indonesia, which we characterized using high-resolution microscopic and spectroscopic imaging combined with microchemical and geochemical analyses. We infer early diagenetic growth of siderite crystals as a response to sedimentary organic carbon degradation and the accumulation of dissolved inorganic carbon in pore waters. We suggest that siderite formation proceeds through syntaxial growth on preexisting siderite crystals, or possibly through aging of precursor carbonate green rust. Crystal growth ultimately leads to spar-sized ( > 50 μm) mosaic single siderite crystals that form twins, bundles, and spheroidal aggregates during burial. Early-formed carbonate was detectable through microchemical zonation and the possible presence of residual phases trapped in siderite interstices. This suggests that such microchemical zonation and mineral inclusions may be used to infer siderite growth histories in ancient sedimentary rocks including sedimentary iron formations. © 2019 Geological Society of America.
Keywords: Greater Sunda Islands; Lake Towuti; Malili Lakes; South Sulawesi; Sulawesi; Sunda Isles; Analytical geochemistry; Iron; Iron ores; Organic carbon; Sedimentology; Depositional condition; Diagenetic growth; Dissolved inorganic carbon; Environmental conditions; Geochemical analysis; Mineral inclusions; Proterozoic eons; Spectroscopic imaging; diagenesis; dissolved inorganic carbon; formation mechanism; iron; mineralogy; organic carbon; porewater; sediment analysis; sediment chemistry; sedimentary rock; siderite; Sedimentary rocks

Gas hydrate production testing - Knowledge gained - Collett, T.S. (Proceedings of the Annual Offshore Technology Conference, 2019)
Since their initial discovery in the 1960's, gas hydrates have been considered to be an important potential source of unconventional natural gas. Significant progress has been made relative to our understanding of the geologic and engineering controls on the ultimate energy potential of gas hydrate; however, more work is required to realize the promise of gas hydrates as a future energy source. Gas hydrates have been encountered, recovered or inferred to exist in numerous sedimentary basins in Arctic permafrost settings, regions of alpine permafrost, marine sediments of outer continental margins and in deep lakes. Despite the great abundance of potential gas hydrate resources in the world, a large portion of these resources reside in clay-rich sediments and fracture dominated reservoir systems, and are not generally considered producible with existing technology, but may have future potential with the emergence of new technologies. For a large portion of the world, gas hydrate in sand reservoirs have become a viable production target and the focus of the first production testing efforts. Production tests in Arctic Canada (Mackenzie Delta) and Alaska have shown that gas can be produced from highly-concentrated gas hydrate accumulations in coarse-grained (i.e., sand rich) reservoir systems with conventional production technologies. Production can be achieved through the depressurization method and by more complex methods such as molecular substitution (e.g., CO2-CH4 exchange). In 2013, the gas hydrate production test was conducted in a marine setting in the offshore of Japan. An additional test was conducted in Japan in 2017 to further evaluate alternative well completion technologies. Also in 2018, China initiated a 60-day gas hydrate production test in the Shenhu region of the South China Sea. This report reviews the results of gas hydrate engineering and production testing studies associated with the Mallik, Mount Elbert, and Iġnik Sikumi projects in northern Canada and Alaska. The results of the marine gas hydrate producing testing efforts in the Nankai Trough (Japan) and in the South China Sea (China) are also summarized. © 2019 Offshore Technology Conference. All rights reserved.
cited By 20
Keywords: Gas engineering; Gases; Hydration; Offshore oil well production; Offshore technology; Permafrost; Renewable energy resources; Submarine geology; Well completion; Completion technology; Depressurization methods; Engineering controls; Gas-hydrate production; Hydrate accumulations; Molecular substitution; Production technology; Unconventional natural gas; Gas hydrates

Giving the legacy seismic data the attention they deserve - Manzi, Musa; Malehmir, Alireza; Durrheim, Raymond (First Break, 2019)

Chesapeake Bay Impact Structure–Development of “Brim” Sedimentation in a Multilayered Marine Target - Dypvik, Henning; Gohn, Gregory S.; Edwards, Lucy E.; Horton, Jr.; Powars, David S.; Litwin, Ronald J. (Chesapeake Bay Impact Structure–Development of “Brim” Sedimentation in a Multilayered Marine Target, 2018)
The late Eocene Chesapeake Bay impact structure was formed in a multilayered target of seawater underlain sequentially by a sediment layer and a rock layer in a continental-shelf environment. Impact effects in the “brim” (annular trough) surrounding and adjacent to the transient crater, between the transient crater rim and the outer margin, primarily were limited to the target-sediment layer. Analysis of published and new lithostratigraphic, biostratigraphic, sedimentologic, petrologic, and mineralogic studies of three core holes, and published studies of a fourth core hole, provided information for the interpretation of the impact processes, their interactions and relative timing, their resulting products, and sedimentation in the brim.Most studies of marine impact-crater materials have focused on those found in the central crater. There are relatively few large, complex marine craters, of which most display a wide brim around the central crater. However, most have been studied using minimal data sets. The large number of core holes and seismic profiles available for study of the Chesapeake Bay impact structure presents a special opportunity for research.The physical and chronologic records supplied by study of the sediment and rock cores of the Chesapeake Bay impact indicate that the effects of the initial, short-lived contact and compression and excavation stages of the impact event primarily were limited to the transient crater. Only secondary effects of these processes are evident in the brim. The preserved record of the brim was created primarily in the subsequent modification stage.In the brim, the records of early impact processes (e.g., outgoing tsunamis, overturned flap collapse) were modified or removed by later processes. Transported and rotated, large and small clasts of target sediments, and intervals of fluidized sands indicate that seismic shaking fractured and partially fluidized the Cretaceous and Paleogene target sediments, which led to their inward transport by collapse and lateral spreading toward the transient crater. The succeeding inward seawater-resurge flow quickly overtook and interacted with the lateral spreading, further facilitating sediment transport across the brim and into the transient crater. Variations in the cohesion and relative depth of the target sediments controlled their degree of disaggregation and redistribution during these events. Melt clasts and shocked and unshocked rock clasts in the resurge sediments indicate fallout from the ejecta curtain and plume.Basal parautochthonous remnant sections of target Cretaceous sediments in the brim thin toward the collapsed transient crater. Overlying seawater-resurge deposits consist primarily of diamictons that vary laterally in thickness, and vertically and laterally in maximum grain size. After cessation of resurge flow and re-establishment of pre-impact sea level, sandy sediment gravity flows moved from the margin to the center of the partially filled impact structure (shelf basin). The uppermost unit consists of stratified sediments deposited from suspension. Postimpact clayey silts cap the crater fill and record the return to shelf sedimentation at atypically large paleodepths within the shelf basin.An unresolved question involves a section of gravel and sand that overlies Neoproterozoic granite in the inner part of the brim in one core hole. This section may represent previously unrecognized, now parautochthonous Cretaceous sediments lying nonconformably above basement granite, or it may represent target sediments that were moved significant distances by lateral spreading above basement rocks or above a granite megaclast from the overturned flap.The Chesapeake Bay impact structure is perhaps the best documented example of the small group of multilayer, marine-target impacts formed in continental shelves or beneath epeiric seas. The restriction of most impact effects to the target-sediment layer in the area outside the transient cavity, herein called the brim, and the presence of seawater-resurge sediments are characteristic features of this group. Other examples include the Montagnais (offshore Nova Scotia, Canada) and Mjølnir (offshore Norway) impact structures.

Norian vegetation history and related environmental changes: New data from the Chinle Formation, Petrified Forest National Park (Arizona, SW USA) - Baranyi, V.; Reichgelt, T.; Olsen, P.E.; Parker, W.G.; K{urschner, W.M. (Bulletin of the Geological Society of America, 2018)
Fossil plant assemblages including spores and pollen grains provide useful information on past ecosystems and the response of terrestrial biotas to various environmental perturbations. New quantitative palynological data from the Chinle Formation of the American Southwest suggest that a floral turnover occurred in the middle Norian (between 217 and 213 Ma). Analysis of plant communities reveals that this turnover was followed by a complete reorganization of the riparian vegetation, driven by changes in fluvial styles and the tectonic regime of the basin, as well as a gradual transition toward a more arid climate. Marked increases in Klausipollenites gouldii, Patinasporites spp., and Froelichsporites traversei are probable indicators of environmental stress, such as increased aridity, perturbations of atmospheric pCO2, acid rain, and atmospheric aerosol accumulation due to volcanism in connection with the Pangean rifting and uplift of the Cordilleran arc. Comparison of the vegetation turnover with younger assemblages from the Chinle Formation in New Mexico revealed similar floral turnover patterns, suggesting two distinct drier periods as a result of multiple climatic oscillations. The climate-induced floral turnover may have contributed to the vertebrate faunal turnover as the loss of wetland habitat space and an increase in xerophytic plants may have dwindled the supply of palatable vegetation for herbivores. The onset of the floral turnover in Arizona roughly corresponds to the Manicouagan impact event, but a direct causal link is still speculative. © 2017 Geological Society of America.
cited By 25
Keywords: Acid rain; Atmospheric aerosols; Ecosystems; Climatic oscillations; Environmental change; Environmental perturbations; Environmental stress; Gradual transition; Plant communities; Riparian vegetation; Vegetation history; Vegetation; aridity; environmental change; Norian; paleoclimate; paleoenvironment; paleogeography; palynology; plant community; vegetation history; Arizona; Petrified Forest National Park; United States; Klausipollenites; Vertebrata

On the backs of giants: Geology of the Kentland impact structure, Newton County (Kentland) Quarry, Indiana (USA)-building on ray gutschick's legacy - Weber, J.C.; Douglas Elmore, R.; Hamilton, C.; Alder, A.; Koeberl, C.; Pope, M. (GSA Field Guides, 2018)
We summarize and then build on the three decades of geological mapping and analyses done by Ray Gutschick at the Newton County (Kentland) quarry. We present our own new data and ideas on the kinematics and significance of radial faults, shock metamorphism, petrography and diagenesis of impact breccia dikes, impactite geochemistry, and a preliminary new paleomagnetically determined Jurassic age for the crater. We list and describe the stops for this field excursion. © 2018 The Geological Society of America.
cited By 0

Origins and evolution of rhyolitic magmas in the central snake river plain: Insights from coupled high-precision geochronology, oxygen isotope, and hafnium isotope analyses of zircon - Col'on, D.P.; Bindeman, I.N.; Wotzlaw, J.-F.; Christiansen, E.H.; Stern, R.A. (Contributions to Mineralogy and Petrology, 2018)
We present new high-precision CA-ID-TIMS and in situ U –Pb ages together with Hf and O isotopic analyses (analyses performed all on the same grains) from four tuffs from the 15−10 Ma Bruneau –Jarbidge center of the Snake River Plain and from three rhyolitic units from the Kimberly borehole in the neighboring 10−6 Ma Twin Falls volcanic center. We find significant intrasample diversity in zircon ages (ranges of up to 3 Myr) and in δ18 O (ranges of up to 6‰) and εHf (ranges of up to 24 ε units) values. Zircon rims are also more homogeneous than the associated cores, and we show that zircon rim growth occurs faster than the resolution of in situ dating techniques. CA-ID-TIMS dating of a subset of zircon grains from the Twin Falls samples reveals complex crystallization histories spanning 104 –106 years prior to some eruptions, suggesting that magma genesis was characterized by the cyclic remelting of buried volcanic rocks and intrusions associated with previous magmatic episodes. Age-dependent trends in zircon isotopic compositions show that rhyolite production in the Yellowstone hotspot track is driven by the mixing of mantle-derived melts (normal δ18 O and εHf) and a combination of Precambrian basement rock (normal δ18 O and εHf down to − 60) and shallow Mesozoic and Cenozoic age rocks, some of which are hydrothermally altered (to low δ18 O values) by earlier stages of Snake River Plain magmatism. These crustal melts hybridize with juvenile basalts and rhyolites to produce the erupted rhyolites. We also observe that the Precambrian basement rock is only an important component in the erupted magmas in the first eruption at each caldera center, suggesting that the accumulation of new intrusions quickly builds an upper crustal intrusive body which is isolated from the Precambrian basement and evolves towards more isotopically juvenile and lower-δ18 O compositions over time. © Springer-Verlag GmbH Germany, part of Springer Nature 2018.
cited By 20
Keywords: geochronology; hafnium; isotopic analysis; magma; oxygen isotope; rhyolite; tuff; uranium-lead dating; zircon; Idaho; Snake River Plain; United States

Palynology of the Last Interglacial Complex at Lake Ohrid: palaeoenvironmental and palaeoclimatic inferences - Sinopoli, G.; Masi, A.; Regattieri, E.; Wagner, B.; Francke, A.; Peyron, O.; Sadori, L. (Quaternary Science Reviews, 2018)
In this article, we present new, high-resolution, pollen results obtained from the DEEP site sequence recovered from Lake Ohrid (Albania/FYROM) for the Last Interglacial Complex (LIC), corresponding to Marine Isotope Stage 5 (MIS 5) of the marine isotope stratigraphy. LIC covers the period between 130 and 70 ka and includes the Eemian (Last Interglacial, LI) and the succession of stadial and interstadial phases of the Early Last Glacial. During the LIC, the pollen record shows an alternation of periods characterized by forest and open vegetation, clearly resembling the well-known vegetational succession of other European records. Our results reveal three key phases for the LI: a first period (128-125 ka) with a rapid increase in temperature and precipitation, a central phase (125 –118.5 ka) characterized by a slight cooling, and a late phase (118.5 –112 ka), with a decline both in temperatures and precipitation. Besides the LI, we identify four more forested periods dominated by mesophilous trees and intercalated by colder and drier steppe phases, during which, however, most arboreal taxa never disappear. During the Early Last Glacial we also identify several abrupt events that can be correlated to the succession of cold events recorded in the Greenland ice core records, associated to a weakening of the North Atlantic Meridional Overturning Circulation. The new high-resolution record indicates that Lake Ohrid is an important site to understand the response of vegetation to fluctuations in regional moisture availability and temperature changes, and thus provides new evidence for the connection between the Mediterranean Region and Northern Hemisphere climate oscillations. © 2017 Elsevier Ltd
cited By 32
Keywords: Climatology; Convolution; Forestry; Glacial geology; Isotopes; Stratigraphy; Vegetation; Albania; Lake Ohrid; Last interglacial; Palaeoclimatology; Palynology; Vegetation change; Lakes; cooling; Eemian; forest-steppe; ice core; interstadial; Last Glacial; Last Interglacial; marine isotope stage; meridional circulation; Northern Hemisphere; paleoclimate; paleoenvironment; paleotemperature; palynology; pollen; precipitation (climatology); vegetation dynamics; Albania; Arctic; Atlantic Ocean; Atlantic Ocean (North); Greenland; Greenland Ice Sheet; Lake Ohrid; Mediterranean Region

Rapid recovery of life at ground zero of the end-Cretaceous mass extinction - Lowery, C.M.; Bralower, T.J.; Owens, J.D.; Rodr'iguez-Tovar, F.J.; Jones, H.; Smit, J.; Whalen, M.T.; Claeys, P.; Farley, K.; Gulick, S.P.S.; Morgan, J.V.; Green, S.; et al. (Nature, 2018)
The Cretaceous/Palaeogene mass extinction eradicated 76% of species on Earth 1,2. It was caused by the impact of an asteroid 3,4 on the Yucat'an carbonate platform in the southern Gulf of Mexico 66 million years ago 5, forming the Chicxulub impact crater 6,7. After the mass extinction, the recovery of the global marine ecosystem - measured as primary productivity - was geographically heterogeneous 8 ; export production in the Gulf of Mexico and North Atlantic-western Tethys was slower than in most other regions 8-11, taking 300 thousand years (kyr) to return to levels similar to those of the Late Cretaceous period. Delayed recovery of marine productivity closer to the crater implies an impact-related environmental control, such as toxic metal poisoning 12, on recovery times. If no such geographic pattern exists, the best explanation for the observed heterogeneity is a combination of ecological factors - trophic interactions 13, species incumbency and competitive exclusion by opportunists 14 - and 'chance' 8,15,16. The question of whether the post-impact recovery of marine productivity was delayed closer to the crater has a bearing on the predictability of future patterns of recovery in anthropogenically perturbed ecosystems. If there is a relationship between the distance from the impact and the recovery of marine productivity, we would expect recovery rates to be slowest in the crater itself. Here we present a record of foraminifera, calcareous nannoplankton, trace fossils and elemental abundance data from within the Chicxulub crater, dated to approximately the first 200 kyr of the Palaeocene. We show that life reappeared in the basin just years after the impact and a high-productivity ecosystem was established within 30 kyr, which indicates that proximity to the impact did not delay recovery and that there was therefore no impact-related environmental control on recovery. Ecological processes probably controlled the recovery of productivity after the Cretaceous/Palaeogene mass extinction and are therefore likely to be important for the response of the ocean ecosystem to other rapid extinction events. © 2018 Macmillan Publishers Ltd., part of Springer Nature.
cited By 86

Phreatic explosions during basaltic fissure eruptions: Kings Bowl lava field, Snake River Plain, USA - Hughes, S.S.; Kobs Nawotniak, S.E.; Sears, D.W.G.; Borg, C.; Garry, W.B.; Christiansen, E.H.; Haberle, C.W.; Lim, D.S.S.; Heldmann, J.L. (Journal of Volcanology and Geothermal Research, 2018)
Physical and compositional measurements are made at the 7 km-long ( 2200 years B.P.) Kings Bowl basaltic fissure system and surrounding lava field in order to further understand the interaction of fissure-fed lavas with phreatic explosive events. These assessments are intended to elucidate the cause and potential for hazards associated with phreatic phases that occur during basaltic fissure eruptions. In the present paper we focus on a general understanding of the geological history of the site. We utilize geospatial analysis of lava surfaces, lithologic and geochemical signatures of lava flows and explosively ejected blocks, and surveys via ground observation and remote sensing. Lithologic and geochemical signatures readily distinguish between Kings Bowl and underlying pre-Kings Bowl lava flows, both of which comprise phreatic ejecta from the Kings Bowl fissure. These basalt types, as well as neighboring lava flows from the contemporaneous Wapi lava field and the older Inferno Chasm vent and outflow channel, fall compositionally within the framework of eastern Snake River Plain olivine tholeiites. Total volume of lava in the Kings Bowl field is estimated to be 0.0125 km3, compared to a previous estimate of 0.005 km3. The main (central) lava lake lost a total of 0.0018 km3 of magma by either drain-back into the fissure system or breakout flows from breached levees. Phreatic explosions along the Kings Bowl fissure system occurred after magma supply was cut off, leading to fissure evacuation, and were triggered by magma withdrawal. The fissure system produced multiple phreatic explosions and the main pit is accompanied by others that occur as subordinate pits and linear blast corridors along the fissure. The drop in magma supply and the concomitant influx of groundwater were necessary processes that led to the formation of Kings Bowl and other pits along the fissure. A conceptual model is presented that has relevance to the broader range of low-volume, monogenetic basaltic fissure eruptions on Earth, the Moon and other planetary bodies. © 2018 Elsevier B.V.
cited By 8
Keywords: Basalt; Geochemical surveys; Geochemistry; Groundwater; Lakes; Moon; Remote sensing; Silicate minerals; Fissure eruptions; Geo-spatial analysis; Geochemical signatures; Geological history; Ground observations; Phreatic explosions; Pit craters; Snake river plains; Explosions; basalt; crater; fissure; lava flow; magma; volcanic eruption; Idaho; Snake River Plain; United States

Pollen data of the last 500 ka BP at Lake Ohrid (south-eastern Europe) - Sadori, Laura; Koutsodendris, Andreas; Panagiotopoulos, Konstantinos; Masi, Alessia; Bertini, Adele; Combourieu-Nebout, Nathalie; Francke, Alexander; Kouli, Katerina; Kousis, Ilias; Joannin, S'ebastien; Mercuri, Anna Maria; Peyron, Odile; et al. (PANGAEA, 2018)

Pore Fluid Pressure Development in Compacting Fault Gouge in Theory, Experiments, and Nature - Faulkner, D.R.; Sanchez-Roa, C.; Boulton, C.; Hartog, S.A.M. (Journal of Geophysical Research: Solid Earth, 2018)
The strength of fault zones is strongly dependent on pore fluid pressures within them. Moreover, transient changes in pore fluid pressure can lead to a variety of slip behavior from creep to unstable slip manifested as earthquakes or slow slip events. The frictional properties of low-permeability fault gouge in nature and experiment can be affected by pore fluid pressure development through compaction within the gouge layer, even when the boundaries are drained. Here the conditions under which significant pore fluid pressures develop are analyzed analytically, numerically, and experimentally. Friction experiments on low-permeability fault gouge at different sliding velocities show progressive weakening as slip rate is increased, indicating that faster experiments are incapable of draining the pore fluid pressure produced by compaction. Experiments are used to constrain the evolution of the permeability and pore volume needed for numerical modeling of pore fluid pressure build up. The numerical results are in good agreement with the experiments, indicating that the principal physical processes have been considered. The model is used to analyze the effect of pore fluid pressure transients on the determination of the frictional properties, illustrating that intrinsic velocity-strengthening behavior can appear velocity weakening if pore fluid pressure is not given sufficient time to equilibrate. The results illustrate that care must be taken when measuring experimentally the frictional characteristics of low-permeability fault gouge. The contribution of compaction-induced pore fluid pressurization leading to weakening of natural faults is considered. Cyclic pressurization of pore fluid within fault gouge during successive earthquakes on larger faults may reset porosity and hence the capacity for compaction weakening. ©2017. The Authors.
cited By 70
Keywords: deformation mechanism; experimental study; fault gouge; fault zone; fluid pressure; friction; permeability; pore pressure; slip rate; theoretical study

Postshock Thermally Induced Transformations in Experimentally Shocked Magnetite - Kontny, A.; Reznik, B.; Boubnov, A.; G{ottlicher, J.; Steininger, R. (Geochemistry, Geophysics, Geosystems, 2018)
We studied the effect of 973 K heating in argon atmosphere on the magnetic and structural properties of a magnetite-bearing ore, which was previously exposed to laboratory shock waves between 5 and 30 GPa. For this purpose magnetic properties were studied using temperature-dependent magnetic susceptibility, magnetic hysteresis and low-temperature saturation isothermal remanent magnetization. Structural properties of magnetite were analyzed using X-ray diffraction, high-resolution scanning electron microscopy and synchrotron-assisted X-ray absorption spectroscopy. The shock-induced changes include magnetic domain size reduction due to brittle and ductile deformation features and an increase in Verwey transition temperature due to lattice distortion. After heating, the crystal lattice is relaxed and apparent crystallite size is increased suggesting a recovery of lattice defects documented by a mosaic recrystallization texture. The structural changes correlate with modifications in magnetic domain state recorded by temperature-dependent magnetic susceptibility, hysteresis properties and low-temperature saturation isothermal remanent magnetization. These alterations in both, magnetic and structural properties of magnetite can be used to assess impact-related magnetic anomalies in impact structures with a high temperature overprint. © 2018. American Geophysical Union. All Rights Reserved.
cited By 9

Punctuated changes in the morphology of an endemic diatom from Lake Titicaca - Spanbauer, Trisha L.; Fritz, Sherilyn C.; Baker, Paul A. (Paleobiology, 2018)
High levels of biodiversity and endemism in ancient lakes have motivated research on evolutionary processes in these systems. Drill-core records from Lake Titicaca (Bolivia, Peru), an ancient lake in the high-elevation Altiplano, record the history of climate, landscape dynamics, and diatom evolution. That record was used to examine the patterns and drivers of morphological evolution of an endemic species complex of diatoms in the lake, the Cyclostephanos andinus complex. In an attempt to delineate species within the complex based on morphology, no discernible evidence was found for species separation based on an ordination analysis of multiple characters, but multiple populations were detected based on the distribution of valve size in individual samples. Likelihood modeling of phyletic evolution showed that size evolved through punctuated change. Correlation of size trends with environmental variables indicates that C. andinus size responded to regional environmental change driven by global processes that influenced Lake Titicaca by affecting lake level and thermal stratification. © 2018 The Paleontological Society. All rights reserved.
Keywords: Altiplano; Bolivia; Lake Titicaca; Peru; Bacillariophyta; Cyclostephanos andinus; biodiversity; diatom; endemic species; endemism; environmental change; fossil record; lake level; morphology; paleoenvironment; species complex

Quantitative reconstruction of early Holocene and last glacial climate on the Balkan Peninsula using coupled hydrological and isotope mass balance modelling - Lacey, J.H.; Jones, M.D. (Quaternary Science Reviews, 2018)
We investigate the modern hydrology of Lake Ohrid (Macedonia/Albania) using a combined hydrological and isotope-based modelling approach and present a new evaluation of contemporary water balance and palaeoclimate estimates. The combined model is able to estimate hydrological components that cannot be directly measured, and indicates that sublacustrine spring inflow is in the order of 50% higher than previous estimates and groundwater outflow comprises approximately a third of overall water outflow. In combination with sediment core oxygen isotope data, we used the combined model to quantitatively reconstruct past climate, in particular precipitation, during the early Holocene and last glacial period. Calculated precipitation in the early Holocene was higher than the value for present day and was approximately 44% lower than present during the last glacial, assuming the majority of precipitation fell as snow. The estimated amount of precipitation in the last glacial would have been high enough to provide refugial conditions at Lake Ohrid and to support the continuous existence of arboreal vegetation in the catchment. The improved understanding of the modern isotope hydrology of Lake Ohrid is fundamental for explaining the systematics of past isotope variation and providing context for extended sediment records from the lake, which will provide longer-term palaeoclimate reconstructions covering multiple glacial-interglacial cycles. © 2018 Elsevier Ltd
cited By 10
Keywords: Catchments; Glacial geology; Groundwater; Isotopes; Lakes; Models; Precipitation (chemical); Salinity measurement; Balkan peninsulas; Glacial-interglacial cycles; Isotope variation; Lake Ohrid; Last glacial period; Palaeoclimate reconstruction; Stable isotopes; Water balance; Climate models; chemical mass balance; glacial-interglacial cycle; Holocene; hydrological modeling; hydrology; inflow; isotopic analysis; Last Glacial; outflow; oxygen isotope; paleoclimate; precipitation (climatology); quantitative analysis; reconstruction; sediment core; stable isotope; water budget; Albania; Balkans; Lake Ohrid; Macedonia [Southern Europe]

Rare biosphere archaea assimilate acetate in Precambrian terrestrial subsurface at 2.2 km depth - Nuppunen-Puputti, Maija; Purkamo, Lotta; Kiet{av{ainen, Riikka; Nyyss{onen, Mari; It{avaara, Merja; Ahonen, Lasse; Kukkonen, Ilmo; Bomberg, Malin (Geosciences (Switzerland), 2018)
The deep biosphere contains a large portion of the total microbial communities on Earth, but little is known about the carbon sources that support deep life. In this study, we used Stable Isotope Probing (SIP) and high throughput amplicon sequencing to identify the acetate assimilating microbial communities at 2260 m depth in the bedrock of Outokumpu, Finland. The long-term and short-term effects of acetate on the microbial communities were assessed by DNA-targeted SIP and RNA targeted cell activation. The microbial communities reacted within hours to the amended acetate. Archaeal taxa representing the rare biosphere at 2260 m depth were identified and linked to the cycling of acetate, and were shown to have an impact on the functions and activity of the microbial communities in general through small key carbon compounds. The major archaeal lineages identified to assimilate acetate and metabolites derived from the labelled acetate were Methanosarcina spp., Methanococcus spp., Methanolobus spp., and unclassified Methanosarcinaceae. These archaea have previously been detected in the Outokumpu deep subsurface as minor groups. Nevertheless, their involvement in the assimilation of acetate and secretion of metabolites derived from acetate indicated an important role in the supporting of the whole community in the deep subsurface, where carbon sources are limited. © 2018 by the authors. Licensee MDPI, Basel, Switzerland.

Morphology of detrital zircon and its application in provenance analysis: Example from Cretaceous Continental Scientific Drilling borehole in Songliao Basin - Song, Y; Qian, Z; Zhang, J; Andrei, S (Diqiu Kexue, 2018)

Late Santonian-early Campanian lake-level fluctuations in the Songliao Basin, NE China and their relationship to coeval eustatic changes - Yang, D.; Huang, Y.; Huang, Q.; Ren, Y.; Wang, C. (Cretaceous Research, 2018)
In contrast to glacio-eustasy, which is mainly controlled by the waxing and waning of continental ice sheets during icehouse climate stages, the concept of aquifer or limno-eustasy suggests that the effects of groundwater storage and release may have been the main driver of short-term (10s kyr to a few Myr) sea-level changes in the Cretaceous ice-free world. Presumably climate-controlled hydrological cycling could change the water volumes of continental reservoirs and oceans by transporting water between continents and oceans, resulting in out-of-phase relation between lake and sea levels. In the present study, we present lake-level fluctuations in Members 1 and 2 of the Nenjiang Formation (late Santonian-early Campanian) in the Songliao Basin that are indicated by basin-scale correlations of Fischer Plots based on natural gamma-ray logging data. Meanwhile, the Al/K ratios of the SK1 core indicate that changes in precipitation forced lake-level fluctuations in the basin. Compared to global sea-level changes, lake-level fluctuations show an out-of-phase relation with sea-level variations in the lacustrine phase of the basin, suggesting that climate-driven water transport between continents and oceans controlled short-term sea-level changes in the late Santonian-early Campanian. During the phase of marine-lake connectivity (basal Nenjiang Member 1), although the marine regression-driven decrease in lake-level corresponds to salinity stratification and strongly reducing water conditions, increasing precipitation in the basin implies that the hydrological cycle transported more water from the oceans toward continents. Based on the results we suggest that limno-eustasy controlled water levels in the Songliao basin in the late Santonian-early Campanian. © 2018 Elsevier Ltd
cited By 10
Keywords: Campanian; eustacy; hydrological cycle; lake level; limnology; Santonian; China; Songliao Basin

Monitoring of helium and carbon isotopes in the western Eger Rift area (Czech Republic): Relationships with the 2014 seismic activity and indications for recent (2000 –2016) magmatic unrest - Br{auer, Karin; K{ampf, Horst; Niedermann, Samuel; Strauch, Gerhard (Chemical Geology, 2018)
We report new data of the regional distribution pattern of total gas compositions as well as He and CO2 isotopic compositions from 25 gas exhalations in the western Eger Rift and its surroundings. Additionally, the first time-series data from gas exhalations in a clay pit within the Cheb Basin (CB) are given. At 21 degassing locations, the first data were obtained >20 years ago. From 7 locations within the degassing center CB and from 3 degassing sites belonging to the Mari'ansk'e L'azně (ML) degassing center, neon and argon isotope compositions were determined also. CO2 is the major component at all degassing sites. The δ13C values display a small range (−1.7 to −5.1‰) and the 3He/4He ratios vary from 1.9 to 5.9 Ra. The highest 3He/4He ratios are found at locations along the Počatky-Plesn'a Fault Zone, followed by the degassing site in the clay pit on the Nov'a Ves Fault and the locations on the ML fault at the edge of the CB. Although gas flow and CO2 concentrations in all degassing centers are very high, the fractions of mantle-derived helium are different, with presently up to 94% (in relation to the SCLM 3He/4He of 6.32 Ra) in the CB, up to 73% in the ML and up to 35% in the Karlovy Vary degassing center. At the locations in the eastern part of the CB a clear, progressive increase of the 3He/4He ratio has been observed since the first sampling campaigns there in 1993 and 1994, whereas at the other degassing sites the helium isotope ratio remained essentially the same. The progressive increase of the 3He/4He ratio in the eastern part of the CB, together with further short-time increases up to 6.3 Ra at one location (Bubl'ak) before both the 2000 and 2008 earthquake swarms, indicate an ongoing magmatic process beneath this area, which seems to be associated with the occurrence of seismicity. The CB is located close to the Nov'y Kostel focal zone where since the beginning of our investigations four strong periods of seismicity (with magnitudes >3) occurred. The latest gas data confirm our earlier findings: time-series studies showed that in relation with seismic events, decreased 3He/4He ratios were repeatedly observed due to admixed seismically released crustal helium. Presently, the eastern part of the CB is the most active non-volcanic region in the European Cenozoic Rift System, with gas signatures similar to those found in free mantle-derived gases from the East African Rift system. © 2018 Elsevier B.V.
Keywords: Cheb Basin; Czech Republic; Karlovarsky; Carbon; Carbon dioxide; Degassing; Flow of gases; Gases; Helium; Inert gases; Isotopes; Location; Seismology; Time series; Earthquake swarms; Eger Rift; Isotopic composition; Magmatic CO2; Regional distribution; Sampling campaigns; SCLM; ^3He/^4He ratios; carbon dioxide; carbon isotope; helium isotope; isotopic composition; isotopic ratio; magmatism; monitoring; noble gas; rift zone; seismicity; Earthquakes

Microstructures imply cataclasis and authigenic mineral formation control geomechanical properties of New Zealand's Alpine Fault - Schuck, B.; Janssen, C.; Schleicher, A.M.; Toy, V.G.; Dresen, G. (Journal of Structural Geology, 2018)
The Alpine Fault is capable of generating large (MW > 8) earthquakes and is the main geohazard on South Island, NZ, and late in its 250 –291-year seismic cycle. To minimize its hazard potential, it is indispensable to identify and understand the processes influencing the geomechanical behavior and strength-evolution of the fault. High-resolution microstructural, mineralogical and geochemical analyses of the Alpine Fault's core demonstrate wall rock fragmentation, assisted by mineral dissolution, and cementation resulting in the formation of a fine-grained principal slip zone (PSZ). A complex network of anastomosing and mutually cross-cutting calcite veins implies that faulting occurred during episodes of dilation, slip and sealing. Fluid-assisted dilatancy leads to a significant volume increase accommodated by vein formation in the fault core. Undeformed euhedral chlorite crystals and calcite veins that have cut footwall gravels demonstrate that these processes occurred very close to the Earth's surface. Microstructural evidence indicates that cataclastic processes dominate the deformation and we suggest that powder lubrication and grain rolling, particularly influenced by abundant nanoparticles, play a key role in the fault core's velocity-weakening behavior rather than frictional sliding. This is further supported by the absence of smectite, which is reasonable given recently measured geothermal gradients of more than 120 °C km−1 and the impermeable nature of the PSZ, which both limit the growth of this phase and restrict its stability to shallow depths. Our observations demonstrate that high-temperature fluids can influence authigenic mineral formation and thus control the fault's geomechanical behavior and the cyclic evolution of its strength. © 2018 Elsevier Ltd
cited By 6
Keywords: Analytical geochemistry; Calcite; Complex networks; Deformation; Earthquakes; Faulting; Geomechanics; Hazards; Microstructure; Rock bursts; Structural geology; Alpine Faults; Authigenic minerals; Brittle deformation; Fault rock; Fluid-rock interaction; Minerals; authigenic mineral; brittle deformation; fault; fluid-structure interaction; microstructure; nanoparticle; rock mechanics; New Zealand; South Island

Microearthquakes preceding a M4.2 Earthquake Offshore Istanbul - Malin, Peter E.; Bohnhoff, Marco; Bl{umle, Felix; Dresen, Georg; Mart'inez-Garz'on, Patricia; Nurlu, Murat; Ceken, Ulubey; Kadirioglu, Filiz Tuba; Kartal, Recai Feyiz; Kiliç, Tuğbay; Yanik, Kenan (Scientific Reports, 2018)

Microbial community composition along a 50 000-year lacustrine sediment sequence - Vuillemin, Aurèle; Ariztegui, Daniel; Horn, Fabian; Kallmeyer, Jens; Orsi, William; Anselmetti, Flavio; Corbella, Hugo; Francus, Pierre; L{ucke, Andreas; Maidana, Nora I.; Ohlendorf, Christian; Zolitschka, Bernd; et al. (FEMS Microbiology Ecology, 2018)

Metabolic potential of microbial communities from ferruginous sediments - Vuillemin, Aurèle; Horn, Fabian; Friese, Andr'e; Winkel, Matthias; Alawi, Mashal; Wagner, Dirk; Henny, Cynthia; Orsi, William D.; Crowe, Sean A.; Kallmeyer, Jens (Environmental Microbiology, 2018)

Main technical innovations of Songke Well No.2 Drilling Project - Zhu, Y.-Y.; Wang, W.-S.; Wu, X.-M.; Zhang, H.-C.; Xu, J.; Yan, J.; Cao, L.-L.; Ran, H.-Q.; Zhang, J.-C. (China Geology, 2018)
Songke Well No.2, one of the main part of the scientific drilling project in Songliao Basin, which was drilled 7018 m and acquired the part of cores continuously from the Low Cretaceous to the Carboniferous and the Permian from the 2843 m deep, can be considered as the deepest continental drilling project in Asia. Aiming at the features of longer well sections, larger diameters and multiple spud-ins for coring of Songke Well No.2, this project broke through the “coring in small diameter and reaming in large diameter” spud-in drilling-completion procedures which are always used in large-diameter-well coring for continental scientific drilling projects in domestic and overseas and the drilling method of short-single-cylinder roundtrip footage. At the same time, “coring in the same diameter and completing drilling at one single diameter” was achieved at all φ311 mm and φ216 mm coring sections of more than one thousand meters long, high-efficient operation with “drilling long footage with drill tools combined in multi-cylinders” was achieved at deep coring section. Four world drilling records were created which include more than a thousand meters continuous coring at φ311 mm, and the footage per roundtrip footage at φ311 mm, φ216 mm and φ152 mm is all more than 30 m, all of these breakthroughs reduced at least 300 days for this project; moreover, considering the characteristics of formations that the geothermal gradient is high in the drilled sections and the inside-well temperature is over 240°C after drilling completion, a formate-polymer water-based mud system was developed by compounding attapulgite and sodium bentonite and by adding independently developed high-temperature stabilizer, which can provide critical technical support for successful well completion at 7018 m in the super-high-temperature environment It is the first time that the water-based mud is operated at the working temperature higher than 240°C in China; Besides, considering the high-quality requirement on cores imposed by the project, the method “mechanical cored is charge” to discharge core nondestructively on the ground was worked out, and more than 4000 m scatheless cores were discharged out of the drill pipes while maintaining original stratum structures. © 2019 Elsevier B.V.
cited By 10

Magnetostratigraphy of the Toarcian Stage (Lower Jurassic) of the Llanbedr (Mochras Farm) Borehole, Wales: Basis foraglobal standard and implications for volcanic forcing of palaeoenvironmental change - Xu, Weimu; Niocaill, Conall Mac; Ruhl, Micha; Jenkyns, Hugh C.; Riding, James B.; Hesselbo, Stephen P. (Journal of the Geological Society, 2018)
The Lower Jurassic Toarcian Stage (c. 183 –174 Ma) is marked by one of the largest global exogenic carbon-cycle perturbations of the Phanerozoic, which is associated with the early Toarcian Oceanic Anoxic Event (T-OAE; c. 183 Ma). Climatic and environmental change at the T-OAE is reasonably well constrained in the marine realm, with marine anoxic or euxinic conditions developing locally across both hemispheres, at the same time as the T-OAE negative carbon-isotope excursion. However, high-resolution stratigraphic comparison between different palaeo-ocean basins and with the continental realm can be complicated. Palaeomagnetic reversals can provide a precise and accurate stratigraphic correlation tool between marine and continental sedimentary archives, and even between sedimentary and igneous successions. Here, we present a high-resolution magnetostratigraphic record for the Toarcian Stage in the biostratigraphically complete and expanded Llanbedr (Mochras Farm) Borehole, Cardigan Bay Basin, Wales. This study provides the first geomagnetic polarity reversal scale that is integrated with high-resolution biostratigraphy and carbon-isotope stratigraphy for the entire Toarcian Stage. This stratigraphic framework also provides a new, precise correlation with the basalt lava sequence of the Karoo –Ferrar Large Igneous Province, linking the Pliensbachian – Toarcian boundary and T-OAE climatic and environmental perturbations directly to this episode of major volcanic activity. © 2018 The Author(s).
Keywords: United Kingdom; Wales; Carbon; Geomagnetism; Isotopes; Sedimentology; Volcanoes; Carbon isotope stratigraphy; Environmental perturbations; Geomagnetic polarity reversal; Large igneous provinces; Negative carbon isotope excursions; Precise correlations; Stratigraphic correlation; Stratigraphic framework; carbon cycle; climate variation; environmental change; magnetostratigraphy; paleoclimate; paleoenvironment; paleomagnetism; Toarcian; Stratigraphy

Large-volume basaltic hyaloclastite eruption along a propagating land/lake lithosphere fracture at Lake Van (Eastern Anatolia): impact of volcanism on the evolution of Lake Van V - Schmincke, H.-U.; Sumita, M.; Cukur, D. (Bulletin of Volcanology, 2018)
The Incekaya hyaloclastite cone (eastern Anatolia, Turkey), the focal point along a major eruptive fissure, was the main source of an unusually large explosive basaltic eruption. The ca. 80 ka-old eruption began onshore with scoria cones from a 5 km N-S fracture propagating toward Lake Van (surface area of 3755 km2). At the intersection with the fault-bounded lake basin, a ca. 400-m-high subaerial hyaloclastite edifice formed, which can be crudely subdivided into a main lower massive bulk of hydrothermally altered lithic-rich hyaloclastites (CL) topped unconformably by a > 30-m-thick, well-bedded fallout tephra (CU). The CU tephras are correlated with (1) widespread onshore hyaloclastite fallout deposits mostly west-southwest of the cone and (2) a ca. 2-m-thick, ca 80-ka-old bedded hyaloclastite (V-60), part of a 220 m ICDP (International Continental Scientific Drilling Program) core, drilled in Lake Van, 27 km N of Incekaya. The hyaloclastite unit was seismically identified as being the most widespread and well-defined reflector throughout much of western Lake Van. A minimum volume of > 9 km3 fallout hyaloclastite tephra is estimated when the area of the seismic reflector is extrapolated to the coast and 2 km inland. Seismic reflectors also suggest at least two (hyaloclastite?) intralake cones rising up to 388 m above the lake sediment surface 1.5 km NW off Incekaya cone and were possibly erupted along the same fracture. The total volume of hyaloclastites includes (a) subaerial Incekaya cone, (b) the inferred subaqueous continuation of the cone(s), (c) the bedded intralake and onshore deposits, and, tentatively, (d) a widespread (seismically defined) mass flow deposits directly beneath Incekaya reflector of roughly 20 km3 and may represent the deposits of explosively erupted basaltic magma. Sideromelane shards, the main clast type, are dominantly angular, and most show ≪ 50 vol.% vesicles. Less common tachylite clasts are poorly vesicular ( < 50 vol.%). Structural transitions and interlayering between tachylite and sideromelane are ubiquitous. Fluidal and pumiceous lapilli are present in the basal massive facies. Bulk rock and glass compositions indicate constant composition of the slightly evolved Al-rich basalt magma. Olivine (Fo78 –82) and plagioclase (An70 –80) microphenocrysts, many skeletal with growth features, and microlites make up < 1 vol.% and suggest rapid magma ascent. The high explosive energy of the eruption is interpreted to be due to (1) high magma discharge rates and shearing in the eruptive jet and (2) magma-water interaction conditions. Approximate temporal coincidences with the Incekaya eruption include the following: (a) an abrupt cessation in the supply of evolved tephra from the adjacent S{uphan Volcano to the lake sediments, which ended abruptly for ca. 60 ky, (b) an extreme fall in lake level by ca. 150 m, and (c) a drastic increase in pore water salinity (Na+ and Cl− (g/L)) and pH. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.
cited By 0
Keywords: fissure; hyaloclastite; phreatomagmatism; plinian eruption; pyroclastic deposit; volcanic eruption; volcanism; Lake Van; Turkey

LabVIEW-Based Songliao Scientific Drilling Project (SK2) Management System (in Chinese with English abstract);[基于LabVIEW的松科二井项目管理系统] - Zhang, H.; Yan, J.; Tan, X.; Meng, Q.; Wang, W.; Cao, L.; Zhu, Y.; Xu, J. (Drilling Engineering, 2018)

LabVIEW-Based Songliao Scientific Drilling Project (SK2) Management System (in Chinese with English abstract); [基于LabVIEW的松科二井项目管理系统] - Zhang, H.; Yan, J.; Tan, X.; Meng, Q.; Wang, W.; Cao, L.; Zhu, Y.; Xu, J. (Exploration Engineering (Rock &, Soil Drilling and Tunneling), 2018)

Krafla magma testbed: Understanding and using the magma-hydrothermal connection - Eichelberger, John; Ingolfsson, Hjalti Pall; Carrigan, Charles; Lavallee, Yan; Tester, Jefferson William; Markusson, Sigurdur H. (Transactions - Geothermal Resources Council, 2018)
The Krafla Magma Testbed (KMT), Krafla Caldera, Iceland, is proposed to be the first magma observatory, an international multi-borehole facility where teams will conduct scientific experiments and engineering tests focused on the magma-hydrothermal interface in a superhot geothermal systems (SHGS). Objectives are to: 1) Core and monitor from the roots of the hydrothermal system to the top of the magma body; 2) Provide ground-truth testing of surface-based techniques for locating magma; 3) Perturb the deep system to understand signals interpreted as volcano “unrest”; 4) Advance drilling and completion technology so that superhot and supercritical fluids can be produced from the magma roof zone; and 5) Advance sensor technology so that magma bodies can be monitored directly, vastly improving the eruption warnings important to 10% of Earth's population. KMT will provide a vanguard view of magma and hydrothermal circulation as the single system that it is. It will integrate the separate communities of practice of geothermal energy, which relies heavily on direct drilling observations; and volcanology, which relies on surface observations and theoretical models. The driving force is that geothermal drilling hit magma in Iceland, Kenya, and Hawaii, revealing how close to the surface magma exists and how closely connected magma is to the hydrothermal system. KMT is a 3 rd path in efforts to expand geothermal use. One path is to go deeper in cooler places, the Enhanced Geothermal System (EGS) concept, relying on advances in drilling and reservoir stimulation for economic viability, e.g. Frontier Observatory for Research in Geothermal Energy (FORGE) of the U.S. Department of Energy. Another, within SHGS, is to drill to conditions where fluids should be supercritical, e.g. IDDP-2 of Iceland Deep Drilling Program (IDDP) at Reykjanes. The 3 rd , also SHGS and pursued by KMT, is to access the vicinity of a magma body. This takes advantage of magma's high energy density due to latent heat of crystallization and delivered by convection to sustain high power output. Not only have SHGS wells proximal to magma at Krafla Caldera, Iceland, exhibited high flow rates equivalent to >100 MWt, but the expected efficiency of conversion to electricity is 30% vs. 10% for conventional geothermal. When combined with the new efficiencies of High Voltage Direct Current (HVDC) tranmission, the economic balance could shift from low-grade geothermal sources near the consumer to high-grade sources farther from the consumer. © 2018 International Journal of Caring Sciences. All rights reserved.
Keywords: Effluent treatment; Geothermal fields; Geothermal wells; Heat convection; HVDC power transmission; Infill drilling; Latent heat; Observatories; Power markets; Quenching; Supercritical fluids; Testbeds; Geothermal; High temperature; Hydrothermal; Magma; Volcanology; Drilling fluids

Krafla magma testbed (KMT): Engineering challenges of drilling into magma and extracting its energy - H'olmgeirsson, Sveinbj{orn; Ingolfsson, Hjalti Pall; Eichelberger, John; Pye, Stephen; Normann, Randy; Kaldal, Gunnar Sk'ulason; Blankenship, Doug; Mortensen, Anette; Mark'usson, Sigurður; Karlsd'ottir, Sigrun Nanna; Wallevik, Sunna Ólafsd'ottir; Garðarsson, Sigurður Magn'us; et al. (Transactions - Geothermal Resources Council, 2018)
Preparations are underway for drilling well KMT-1 of the Krafla Magma Testbed at Krafla, Iceland to sample and instrument the margin of a rhyolite magma body. The project is driven by the need to understand magmatic systems, to improve volcano monitoring strategies, and to develop next-generation, high-enthalpy geothermal energy. The planned depth of the well is 2100 m with cemented casings to 2040 m and a 8 extonehalf” open hole section for coring to 2010 m. The geology for KMT-1 is well known and the well will be located close to IDDP-1 where magma was unexpectedly intersected at 2102 m depth in 2009. © 2018 International Journal of Caring Sciences. All rights reserved.
Keywords: Commerce; Drilling; Geothermal energy; Geothermal fields; Power markets; Testbeds; Coring; Engineering challenges; Magma; Magma bodies; Magmatic systems; Open holes; Volcano monitoring; Well design; Infill drilling

Iron release in aqueous environment by fresh volcanic ash from Mount Etna (Italy) and Popocat'epetl (Mexico) volcanoes - Capitani, Giancarlo; Miyajima, Nobuyoshi; Sulpizio, Roberto; D’Addabbo, Maria; Galimberti, Lucia; Guidi, Massimo; Andreozzi, Giovanni B. (Environmental Earth Sciences, 2018)

Regional two-dimensional magnetotelluric profile in West Bohemia/Vogtland reveals deep conductive channel into the earthquake swarm region - Muñoz, Gerard; Weckmann, Ute; Pek, Josef; Kov'ačikov'a, Světlana; Klanica, Radek (Tectonophysics, 2018)
The West Bohemia/Vogtland region, characterized by the intersection of the Eger (Ohře) Rift and the Mari'ansk'e L'azně fault, is a geodynamically active area exhibiting repeated occurrence of earthquake swarms, massive CO2 emanations and mid Pleistocene volcanism. The Eger Rift is the only known intra-continental region in Europe where such deep seated, active lithospheric processes currently take place. We present an image of electrical resistivity obtained from two-dimensional inversion of magnetotelluric (MT) data acquired along a regional profile crossing the Eger Rift. At the near surface, the Cheb basin and the aquifer feeding the mofette fields of Bubl'ak and Hartoušov have been imaged as part of a region of very low resistivity. The most striking resistivity feature, however, is a deep reaching conductive channel which extends from the surface into the lower crust spatially correlated with the hypocentres of the seismic events of the Nov'y Kostel Focal Zone. This channel has been interpreted as imaging a pathway from a possible mid-crustal fluid reservoir to the surface. The resistivity model reinforces the relation between the fluid circulation along deep-reaching faults and the generation of the earthquakes. Additionally, a further conductive channel has been revealed to the south of the profile. This other feature could be associated to fossil hydrothermal alteration related to M'ytina and/or Neualbenreuth Maar structures or alternatively could be the signature of a structure associated to the suture between the Saxo-Thuringian and Tepl'a-Barrandian zones, whose surface expression is located only a few kilometres away. © 2018 Elsevier B.V.
Keywords: Bohemia; Czech Republic; Germany; Vogtland; Aquifers; Clay alteration; Faulting; Fluids; Magnetotellurics; Conductive channels; Earthquake swarms; Hydrothermal alterations; Lithospheric process; Resistivity modeling; Surface expression; Vogtland; West Bohemia; earthquake swarm; electrical resistivity; fault; hydrothermal alteration; lower crust; magnetotelluric method; Earthquakes

Integrative taxonomy of freshwater ostracodes (Crustacea: Ostracoda) of the Yucat'an Peninsula, implications for paleoenvironmental reconstructions in the northern Neotropical region - Macario-Gonz'alez, Laura; Cohuo, Sergio; El'ias-Guti'errez, Manuel; Vences, Miguel; P'erez, Liseth; Schwalb, Antje (Zoologischer Anzeiger, 2018)
A three-step integrative taxonomy approach combining molecular, morphological and ecological methods was successfully used to delimit species boundaries within three freshwater ostracode taxa of the Yucat'an Peninsula (Mexico): Darwinulidae, Cypretta and Cypridopsis. These species groups were selected because they are well-suited paleobioindicators for late Pleistocene-early Holocene climatic reconstructions in the region, but their high inter-population morphological variability in recent communities represents a challenge for accurate transfer of information to fossil assemblages. As a first step, we analyzed the congruence of two genes of different inheritance, the mitochondrial COI (cytochrome c-oxidase subunit 1), and the nuclear 18S rDNA (small-subunit rDNA). Second, we tested the lineages discriminated for concordant differentiation in morphology, using morphometry of the carapace and typological analysis of the appendages. The third step assessed the association of occurrences and abundances of lineages to environmental variables. The integration of these methods revealed six hidden species within clades previously considered as a single widely distributed nominal species. Of these, Cypretta elongata sp. nov. and Alicenula yucatanensis sp. nov. are herein formally named and described given their morphological distinctness. Three species of Cypridopsis: Cypridopsis sp. [Ca1 ECO-CH-Z-09396], Cypridopsis sp. [Ca2 ECO-CH-Z-09398], Cypridopsis sp. [Ca3 ECO-CH-Z-09401] and a species that may represent a new genus, Cyprididae sp. [Ca1 ECO-CH-Z-09402], are allocated to a confirmed candidate full species status. Cypretta maya and Cypretta sp., considered a priori as separate species, are recognized as a single species with phenotypic plasticity, attributed to its broad ecological tolerances. For paleoenvironmental reconstructions these results have relevance because the particular carapace morphology of the new species can be correlated with specific ecological traits, thus constituting a potential tool for refining interpretations of fossil assemblages. © 2018 Elsevier GmbH
Keywords: Yucatan Peninsula; Alicenula; Crustacea; Cypretta; Cyprididae; Cypridopsis; Darwinulidae; Ostracoda; crustacean; DNA; fossil assemblage; gene expression; Neotropical Region; paleoecology; paleoenvironment; reconstruction; taxonomy

Reconnaissance study of an inferred Quaternary maar structure in the western part of the Bohemian Massif near Neualbenreuth, NE-Bavaria (Germany) - Rohrm{uller, J.; K{ampf, H.; Gei{s, E.; Gro{smann, J.; Grun, I.; Mingram, J.; Mrlina, J.; Plessen, B.; Stebich, M.; Veress, C.; Wendt, A.; Nowaczyk, N. (International Journal of Earth Sciences, 2018)
After a comprehensive geophysical prospecting the Quaternary M'ytina Maar, located on a line between the two Quaternary scoria cones Komorn'i hůrka/Kammerb{uhl and Železn'a hůrka/Eisenb{uhl, could be revealed by a scientific drilling at the German –Czech border in 2007. Further geophysical field investigations led to the discovery of another geological structure about 2.5 km ESE of the small town Neualbenreuth (NE-Bavaria, Germany), inferred to be also a maar structure, being the fourth volcanic feature aligned along the NW –SE trending Tachov fault zone. It is only faintly indicated as a partial circular rim in the digital elevation model. Though not expressed by a clear magnetic anomaly, geoelectric and refraction seismic tomography strongly indicates a bowl-shaped depression filled with low-resistivity and low-velocity material, correlating well with the well-defined negative gravity anomaly of − 2.5 mGal. Below ca. 15 m-thick debris layer, successions of mostly laminated sediments were recovered in a 100 m-long sediment core in 2015. Sections of finely laminated layers, likely varves, rich in organic matter and tree pollen, were recognized in the upper (22 –30 m) and lower (70 –86 m) part of the core, respectively, interpreted as interglacials, whereas mostly minerogenic laminated deposits, poor in organic matter, and (almost) barren of tree pollen are interpreted as clastic glacial deposits. According to a preliminary age model based on magnetostratigraphy, palynology, radiocarbon dating, and cyclostratigraphy, the recovered sediments span the time window from about 85 ka back to about 270 ka, covering marine isotope stages 5 –8. Sedimentation rates are in the range of 10 cm ka−1 in interglacials and up to 100 cm ka−1 in glacial phases. The stratigraphic record resembles the one from M'ytina Maar, with its eruption date being derived from a nearby tephra deposit at 288 ± 17 ka, thus supporting the age model of the inferred Neualbenreuth Maar. © 2017, Springer-Verlag GmbH Germany.
Keywords: Bavaria; Bohemian Massif; Czech Republic; Eger; Germany; Heves; Hungary; digital elevation model; fault zone; geophysical method; maar; magnetostratigraphy; paleoclimate; palynology; Quaternary; radiocarbon dating; tephra; volcanism

Study on speed characteristics of hydraulic top drive under fluctuating load - Sun, Y.; Shi, Y.; Wang, Q.; Yao, Z. (Journal of Petroleum Science and Engineering, 2018)
A hydraulic top drive is a high-power gyrator used in oil or scientific drilling rigs, whose shaft is connected to drill pipe when it drives drilling tools to excavate well. The output speed of top drive determines the speed of drill bit directly. Load acting on the top drive shaft fluctuates randomly, which will cause top drive output speed hard to be in consistent with the setting value. This paper presents a main transmission system of a hydraulic top drive designed for deep continental scientific drilling, which was built with a multi-stage mechanical structure and a closed circuit hydraulic system with variable displacement pumps and motors. Electro-hydraulic proportional control was applied to vary the speed of the hydraulic top drive. A theoretical model is detailed for the hydraulic top drive main transmission system. Among the new techniques proposed in this paper is a simulation model for studying the performance of hydraulic top drive and capturing speed characteristics under fluctuant load. A drilling experiment of the hydraulic top drive was performed on the CRUST-I drilling rig in CCSD-SK-II well site. This paper concludes by comparing the results of the simulation model with theoretical results and drilling experimental data gathered in the hydraulic top drive possessing the same architecture, components, and control methods used within the simulation model. The drilling experiment and the analysis result showed that the hydraulic top drive could meet the requirements of deep continental scientific drilling and that the speed could be output according to the setting speed with very small oscillation. The simulation model can be used for several applications such as hydraulic top drive design and performance analysis of various drilling conditions. © 2018 Elsevier B.V.
cited By 8
Keywords: Digital storage; Drilling rigs; Drills; Electric power transmission; Hydraulic tools; Oil well drilling; Speed; Continental scientific drillings; Electro-hydraulic proportional control; Fluctuating loads; Main transmission systems; Mechanical structures; Speed characteristics; Theoretical modeling; Variable displacement; Transmissions; acceleration; deep drilling; drilling rig; loading; numerical model; performance assessment; velocity

Replacement reactions and deformation by dissolution and precipitation processes in amphibolites - Giuntoli, Francesco; Menegon, Luca; Warren, Clare J. (Journal of Metamorphic Geology, 2018)
The deformation of the middle to lower crust in collisional settings occurs via deformation mechanisms that vary with rock composition, fluid content, pressure, and temperature. These mechanisms are responsible for the accommodation of large tectonic transport distances during nappe stacking and exhumation. Here, we show that fracturing and fluid flow triggered coupled dissolution –precipitation and dissolution –precipitation creep processes, which were responsible for the formation of a mylonitic microstructure in amphibolites. This fabric is developed over a crustal thickness >500 m in the Lower Seve Nappe (Scandinavian Caledonides). Amphibolites display a mylonitic foliation that wraps around albite porphyroclasts appearing dark in panchromatic cathodoluminescence (CL). The albite porphyroclasts were dissected and fragmented by fractures preferentially developed along the (001) cleavage planes and display lobate edges with embayments and peninsular features. Two albite/oligoclase generations, bright in CL, resorbed and overgrew the porphyroclasts, sealing the fractures. Electron backscattered diffraction shows that the two albite/oligoclase generations grew both pseudomorphically and topotaxially at the expense of the albite porphyroclasts and epitaxially around them. These two albite/oligoclase generations also grew as neoblasts elongated parallel to the mylonitic foliation. The amphibole crystals experienced a similar microstructural evolution, as evidenced by corroded ferrohornblende cores surrounded by ferrotschermakite rims that preserve the same crystallographic orientation of the cores. Misorientation maps highlight how misorientations in amphibole are related to displacement along fractures perpendicular to its c-axis. No crystal plasticity is observed in either mineral species. Plagioclase and amphibole display a crystallographic preferred orientation that is the result of topotaxial growth on parental grains and nucleation of new grains with a similar crystallographic orientation. Amphibole and plagioclase thermobarometry constrains the mylonitic foliation development to the epidote amphibolite facies (˜600°C, 0.75 –0.97 GPa). Our results demonstrate that at middle to lower crustal levels, the presence of H2O-rich fluid at grain boundaries facilitates replacement reactions by coupled dissolution –precipitation and favours deformation by dissolution –precipitation creep over dislocation creep in plagioclase and amphibole.
_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/jmg.12445
Keywords: Caledonides; dissolution & ndash; precipitation processes; electron backscatter diffraction; replacement reactions; X-ray mapping

Synoptic conditions of fine-particle transport to the last interglacial Red Sea-Dead Sea from Nd-Sr compositions of sediment cores - Palchan, D.; Stein, M.; Goldstein, S.L.; Almogi-Labin, A.; Tirosh, O.; Erel, Y. (Quaternary Science Reviews, 2018)
The sediments deposited at the depocenter of the Dead Sea comprise high-resolution archive of hydrological changes in the lake's watershed and record the desert dust transport to the region. This paper reconstructs the dust transport to the region during the termination of glacial Marine Isotope Stage 6 (MIS 6; ∼135 –129 ka) and the last interglacial peak period (MIS5e, ∼129 –116 ka). We use chemical and Nd and Sr isotope compositions of fine detritus material recovered from sediment core drilled at the deepest floor of the Dead Sea. The data is integrated with data achieved from cores drilled at the floor of the Red Sea, thus, forming a Red Sea-Dead Sea transect extending from the desert belt to the Mediterranean climate zone. The Dead Sea accumulated flood sediments derived from three regional surface cover types: settled desert dust, mountain loess-soils and loess-soils filling valleys in the Dead Sea watershed termed here “Valley Loess”. The Valley Loess shows a distinct 87Sr/86Sr ratio of 0.7081 ± 1, inherited from dissolved detrital calcites that originate from dried waterbodies in the Sahara and are transported with the dust to the entire transect. Our hydro-climate and synoptic conditions reconstruction illustrates the following history: During glacial period MIS6, Mediterranean cyclones governed the transport of Saharan dust and rains to the Dead Sea watershed, driving the development of both mountain soils and Valley Loess. Then, at Heinrich event 11, dry western winds blew Saharan dust over the entire Red Sea - Dead Sea transect marking latitudinal expansion of the desert belt. Later, when global sea-level rose, the Dead Sea watershed went through extreme aridity, the lake retreated, depositing salt and accumulating fine detritus of the Valley Loess. During peak interglacial MIS 5e, enhanced flooding activity flushed the mountain soils and fine detritus from all around the Dead Sea and Red Sea, marking a significant “contraction” of the desert belt. At the end of MIS 5e the effect of the regional precipitation diminished and the Dead Sea and Red Sea areas re-entered sever arid conditions with extensive salt deposition at the Dead Sea. © 2017 Elsevier Ltd
cited By 15
Keywords: Binary alloys; Chloride minerals; Climatology; Dust; Floods; Floors; Glacial geology; Isotopes; Lakes; Landforms; Neodymium; Neodymium alloys; Sea level; Seawater; Soils; Storms; Strontium; Strontium alloys; Watersheds; Dead sea; Dust sources; Late quaternary; Levant; Loess; Nd-Sr isotopes; Paleo-climate; Paleo-synoptic; Red sea; Sediments; depocenter; dust; flood; flooding; Heinrich event; hydrological change; isotopic composition; Last Interglacial; loess; marine isotope stage; Mediterranean environment; paleoclimate; particle size; precipitation (climatology); Quaternary; sea level change; sediment core; strontium; strontium isotope; watershed; Dead Sea; Indian Ocean; Levantine Sea; Mediterranean Sea; Red Sea [Indian Ocean]; Sahara

Influence of CO2 degassing on the microbial community in a dry mofette field in Hartoušov, Czech Republic (Western Eger Rift) - Liu, Qi; K{ampf, Horst; Bussert, Robert; Krauze, Patryk; Horn, Fabian; Nickschick, Tobias; Plessen, Birgit; Wagner, Dirk; Alawi, Mashal (Frontiers in Microbiology, 2018)
The Cheb Basin (CZ) is a shallow Neogene intracontinental basin filled with fluvial and lacustrine sediments that is located in the western part of the Eger Rift. The basin is situated in a seismically active area and is characterized by diffuse degassing of mantle-derived CO2 in mofette fields. The Hartoušov mofette field shows a daily CO2 flux of 23-97 tons of CO2 released over an area of 0.35 km2 and a soil gas concentration of up to 100% CO2. The present study aims to explore the geo-bio interactions provoked by the influence of elevated CO2 concentrations on the geochemistry and microbial community of soils and sediments. To sample the strata, two 3-m cores were recovered. One core stems from the center of the degassing structure, whereas the other core was taken 8 m from the ENE and served as an undisturbed reference site. The sites were compared regarding their geochemical features, microbial abundances, and microbial community structures. The mofette site is characterized by a low pH and high TOC/sulfate contents. Striking differences in the microbial community highlight the substantial impact of elevated CO2 concentrations and their associated side effects on microbial processes. The abundance of microbes did not show a typical decrease with depth, indicating that the uprising CO2-rich fluid provides sufficient substrate for chemolithoautotrophic anaerobic microorganisms. Illumina MiSeq sequencing of the 16S rRNA genes and multivariate statistics reveals that the pH strongly influences microbial composition and explains around 38.7% of the variance at the mofette site and 22.4% of the variance between the mofette site and the undisturbed reference site. Accordingly, acidophilic microorganisms (e.g., OTUs assigned to Acidobacteriaceae and Acidithiobacillus) displayed a much higher relative abundance at the mofette site than at the reference site. The microbial community at the mofette site is characterized by a high relative abundance of methanogens and taxa involved in sulfur cycling. The present study provides intriguing insights into microbial life and geo-bio interactions in an active seismic region dominated by emanating mantle-derived CO2-rich fluids, and thereby builds the basis for further studies, e.g., focusing on the functional repertoire of the communities. However, it remains open if the observed patterns can be generalized for different time-points or sites. © 2018 Frontiers Media S.A. All Rights Reserved.
Keywords: carbon dioxide; RNA 16S; Acidithiobacillus; amplicon; Article; bioinformatics; DNA extraction; DNA purification; dsrB gene; gasification; gene; gene amplification; geochemical analysis; microbial community; nonhuman; pH; population abundance; real time polymerase chain reaction; stratigraphy

Ultra-high temperature drilling fluid technology of well Songke-2 - Jie, Xu; Xiaoming, Wu; Wenshi, Wang; Jia, Yan; Hengchun, Zhang; Longlong, Cao (钻井液与完井液, 2018)
The well Songke-2 is a high temperature deep scientific exploration well deployed in the Songliao Basin, its purpose is to penetrate the Cretaceous formations to obtain the records of basal continental deposit. The bottom hole temperature has been predicted to be over 220 ℃. Measures for preventing borehole wall collapse are especially important in drilling the fourth and fifth intervals since borehole wall collapse has occurred previously in drilling the interbedded mudstone and sandstone in the Shahezi formation, and the broken tuff, mudstone and coal seam in the Huoshiling formation, which were to be penetrated by the fourth and fifth intervals of the well. Continuous coring was to be conducted in the fourth and fifth intervals, and frequent tripping of drill string gave a big challenge to borehole wall stabilization because of long time contact of the open hole with drilling fluid. The adoption of different drilling techniques in turn gave a challenge to drilling fluid. A high temperature polymer drilling fluid has been formulated to deal with these challenges. The composition of the drilling fluid is as follows: 1.0% bentonite + 2% attapulgite +0.2%KOH +(0.5%-1.0%) high MW filter loss reducer +1% moderate MW filter loss reducer + 2.5% filming agent + (2%-4%)SMC +2%FT +3%KCl + 2%NaCOOH +3% white oil. At the beginning of the fourth interval, the mud left over from the third interval was evaluated and converted for re-use in the fourth interval based on large amount of pilot tests. In the fifth interval, the property of the mud was greatly modified because of the needs for dealing with downhole troubles. When the downhole troubles were resolved, the mud property was gradually adjusted to a stable state. In field application the mud property was adjusted at all times in accordance with the requirements of drilling operations. The mud had good rheology at high temperatures and good high temperature stability. High temperature resistance of the mud formulation was 240 ℃ based on laboratory test. The mud property was still satisfactory even after hot rolling for 72 ℃, providing strong technical support for the success of drilling operation. The drilling fluid technology used in drilling the well Songke-2 is of guiding significance in improving job quality of drilling and reducing exploration cost. © 2018, The Editorial Board of Drilling Fluid & Completion Fluid. All right reserved.

Transmission electron microscopy of impact-generated platinum group element alloys from Barberton spherule layers: New clues to their formation - Mohr-Westheide, T.; Greshake, A.; Wirth, R.; Reimold, W.U. (Meteoritics and Planetary Science, 2018)
The oldest known large bolide impacts onto Earth are represented by approximately 3.47 –3.2 Ga old Archean spherule layers of the Barberton Greenstone Belt (BGB) in South Africa and the Pilbara craton in West Australia. These layers were recognized as impact deposits by their excessively high platinum group element (PGE) contents that are indicative of an extraterrestrial component. This was followed by measurements of extraterrestrial Cr isotopic ratios, in some cases. Recently, the extraterrestrial PGE signature in Archean spherule layers from the BGB was localized and positively associated with the presence of submicrometer PGE alloy micronuggets associated with Ni,Cr-rich spinel. The actual formation of these platinum group mineral (PGM) phases has, however, not yet been resolved. Primary meteoritic particles from the impacting body, the products of impact melting, or condensation from impact vapor plumes have all been proposed as possible genetic process. Resolving this requires detailed microanalytical investigation of the internal microchemical and microstructural compositions, textural characteristics, and crystallographic relationships between the different phases. Here, we report the results of a first transmission electron microscopy (TEM) study of six such PGE microparticles enclosed in Ni-Cr spinel or occurring in groundmass of Barberton spherule layers from the BARB5 ICDP drill core and from the CT3 exploration core. Results include a variety of chemical and structural PGM compositions that are difficult to explain by a single process, leading to the conclusion that several processes may have been involved in the formation of PGMs in Archean spherule layers from the BGB. There is evidence supporting formation of these PGMs by exsolution from the spinel host phase, precipitation from a melt phase, and condensation from a gas phase (of the impact vapor plume). © The Meteoritical Society, 2018.

Towards an understanding of climate proxy formation in the Chew Bahir basin, southern Ethiopian Rift - Foerster, V.; Deocampo, D.M.; Asrat, A.; G{unter, C.; Junginger, A.; Kr{amer, K.H.; Stroncik, N.A.; Trauth, M.H. (Palaeogeography, Palaeoclimatology, Palaeoecology, 2018)
Deciphering paleoclimate from lake sediments is a challenge due to the complex relationship between climate parameters and sediment composition. Here we show the links between potassium (K) concentrations in the sediments of the Chew Bahir basin in the Southern Ethiopian Rift and fluctuations in the catchment precipitation/evaporation balance. Our micro-X-ray fluorescence and X-ray diffraction results suggest that the most likely process linking climate with potassium concentrations is the authigenic illitization of smectites during episodes of higher alkalinity and salinity in the closed-basin lake, due to a drier climate. Whole-rock and clay size fraction analyses suggest that illitization of the Chew Bahir clay minerals with increasing evaporation is enhanced by octahedral Al-to-Mg substitution in the clay minerals, with the resulting layer charge increase facilitating potassium-fixation. Linking mineralogy with geochemistry shows the links between hydroclimatic control, process and formation of the Chew Bahir K patterns, in the context of well-known and widely documented eastern African climate fluctuations over the last 45,000 years. These results indicate characteristic mineral alteration patterns associated with orbitally controlled wet-dry cycles such as the African Humid Period ( 15 –5 ka) or high-latitude controlled climate events such as the Younger Dryas ( 12.8 –11.6 ka) chronozone. Determining the impact of authigenic mineral alteration on the Chew Bahir records enables the interpretation of the previously established μXRF-derived aridity proxy K and provides a better paleohydrological understanding of complex climate proxy formation. © 2018
cited By 25
Keywords: alkalinity; authigenic mineral; catchment; clay mineral; climate variation; concentration (composition); evaporation; illitization; lacustrine deposit; mineral alteration; paleoclimate; potassium; precipitation (climatology); proxy climate record; salinity; wetting-drying cycle; Younger Dryas; zeolite; East African Rift; Ethiopian Rift

Topographic control on shallow fault structure and strain partitioning near Whataroa, New Zealand demonstrates weak Alpine Fault - Upton, P.; Song, B.R.; Koons, P.O. (New Zealand Journal of Geology and Geophysics, 2018)
It is notoriously difficult to characterise the strength and stress states of major plate boundaries. By taking advantage of the well-constrained stress contribution of topography adjacent to a segmented section of the Alpine Fault, New Zealand, we have identified a mechanical mix that produces the distinct fault segmentation pattern seen in field observations. Slope-generated shear and normal stresses rotate the principal stresses relative to the regional tectonically derived stress state and under certain strength states influence the displacement pattern. Three-dimensional models show that the scale and form of the near-surface partitioning depend on both topographic relief and local fault strength relative to the bedrock. The models suggest the Alpine Fault is weak to moderately weak relative to the bedrock and is a single structure to within c. 500 m of the surface, above which segmentation occurs. Adjacent to the Alpine Fault, the stress state is highly variable. The intermediate principal stress, σ2, is rotated from tectonically dominated, near-vertical beneath ridges to near-horizontal beneath large valleys. Individual segments along the Alpine Fault dominated by strike-slip faulting, oblique thrusting or thrusting, can be identified by extracting the topographic contribution to the stress state from numerical models. © 2017 The Royal Society of New Zealand.
cited By 10
Keywords: bedrock; fault; mechanical property; numerical model; plate boundary; strain partitioning; strength; stress field; tectonics; topographic effect; Alpine Fault Zone; New Zealand; South Island; West Coast [South Island]; Whataroa

Three novel species of bacillariophyta (Diatoms) in the genera surirella and thalassiosira from pleistocene paleolake lorenyang ( 2-1.6 ma) turkana basin, Kenya - Brindle, Matthew; Mohan, Joseph; Beck, Catherine; Stone, Jeffery R. (Phytotaxa, 2018)
Three novel species of Bacillariophyta (diatom) are described from the sediments of Paleolake Lorenyang, a large lake that existed in the Turkana Basin, Kenya during the Gelasian age of the Pleistocene Epoch. Sediment cores extracted as part of the Hominin Sites and Paleolakes Drilling Project (HSPDP) were sampled to provide a diatom-based paleoecological record of Paleolake Lorenyang. Preliminary results of the paleoecological analysis unearthed three novel species of diatoms belonging to Surirella and Thalassiosira in the Natoo Member of the Nachukui Formation. Comparisons of Surirella from Paleolake Lorenyang are made to previous reports of Surirella from modern lakes in East Africa and comparisons of Thalassiosira species from the paleolake are made to modern and fossil species reported from East Africa. This is a first report of diatoms in the Natoo Member, which has previously been described as a floodplain deposit, and thus provides evidence of the last occurrence of Paleolake Lorenyang within the Turkana Basin. Herein we describe a new species of Surirella and two Thalassiosira with remarks on morphology and evolution of East African Surirella and Thalassiosira. © 2018 Magnolia Press.

The world’s largest late to post-archaean asteroid impact structures - Glikson, A.Y.; Pirajno, F. (Modern Approaches in Solid Earth Sciences, 2018)
As distinct from small to medium-size impact events, large asteroid impacts producing explosions more powerful than 107 TNT-equivalent, represented by craters and rebound domes larger than about 100 km in diameter have major consequences including the triggering of major seismic events, tsunami events and extinction episodes. Such events are manifested by the Archaean 3.25 –3.24 Ga impact cluster and associated transformation from greenstone-granite terrains to semi-continental assemblages (Glikson AY, Vickers J, Earth Planet Sci Lett 241:11 –20, 2006). These impact events are considered in Chap. 6. The oldest identified mega-impact is the 3 Ga Maniitsoq structure in southwest Greenland, while younger mega-impact structures >100 km in diameter include the Vredefort and Sudbury structures. Phanerozoic mega-impacts include the Woodleigh impact structure, Warburton twin structures, Chicxulub and Popigai structures. The global tectonic consequences of some of these mega-impacts are yet to be elucidated. © 2018, Springer International Publishing AG.
cited By 0

The world's largest late to post-archaean asteroid impact structures - Glikson, A.Y.; Pirajno, F. (Modern Approaches in Solid Earth Sciences, 2018)
As distinct from small to medium-size impact events, large asteroid impacts producing explosions more powerful than 107 TNT-equivalent, represented by craters and rebound domes larger than about 100 km in diameter have major consequences including the triggering of major seismic events, tsunami events and extinction episodes. Such events are manifested by the Archaean 3.25 –3.24 Ga impact cluster and associated transformation from greenstone-granite terrains to semi-continental assemblages (Glikson AY, Vickers J, Earth Planet Sci Lett 241:11 –20, 2006). These impact events are considered in Chap. 6. The oldest identified mega-impact is the 3 Ga Maniitsoq structure in southwest Greenland, while younger mega-impact structures >100 km in diameter include the Vredefort and Sudbury structures. Phanerozoic mega-impacts include the Woodleigh impact structure, Warburton twin structures, Chicxulub and Popigai structures. The global tectonic consequences of some of these mega-impacts are yet to be elucidated. © 2018, Springer International Publishing AG.
cited By 0

The Lake CHAd Deep DRILLing project (CHADRILL) - targeting 10 million years of environmental and climate change in Africa - Sylvestre, Florence; Schuster, Mathieu; Abdheramane, Moussa; Ariztegui, Daniel; Salzmann, Ulrich; Waldmann, Nicolas; Adeaga, Olusegun; Ahounta, Dave; Izuchukwu, Mike Akaegbobi; Andossa, Likius; Armitage, Simon; Augustin, Laurent; et al. (Scientific Drilling, 2018)
At present, Lake Chad ( 13°0 N, 14° E) is a shallow freshwater lake located in the Sahel/Sahara region of central northern Africa. The lake is primarily fed by the Chari-Logone river system draining a 600 000 km2 watershed in tropical Africa. Discharge is strongly controlled by the annual passage of the intertropical convergence zone (ITCZ) and monsoon circulation leading to a peak in rainfall during boreal summer. During recent decades, a large number of studies have been carried out in the Lake Chad Basin (LCB). They have mostly focused on a patchwork of exposed lake sediments and outcrops once inhabited by early hominids. A dataset generated from a 673m long geotechnical borehole drilled in 1973, along with outcrop and seismic reflection studies, reveal several hundred metres of Miocene-Pleistocene lacustrine deposits. CHADRILL aims to recover a sedimentary core spanning the Miocene-Pleistocene sediment succession of Lake Chad through deep drilling. This record will provide significant insights into the modulation of orbitally forced changes in northern African hydroclimate under different climate boundary conditions such as high CO2 and absence of Northern Hemisphere ice sheets. These investigations will also help unravel both the age and the origin of the lake and its current desert surrounding. The LCB is very rich in early hominid fossils (Australopithecus bahrelghazali; Sahelanthropus tchadensis) of Late Miocene age. Thus, retrieving a sediment core from this basin will provide the most continuous climatic and environmental record with which to compare hominid migrations across northern Africa and has major implications for understanding human evolution. Furthermore, due to its dramatic and episodically changing water levels and associated depositional modes, Lake Chad's sediments resemble maybe an analogue for lake systems that were once present on Mars. Consequently, the study of the subsurface biosphere contained in these sediments has the potential to shed light on microbial biodiversity present in this type of depositional environment. We propose to drill a total of 1800m of poorly to semi-consolidated lacustrine, fluvial, and eolian sediments down to bedrock at a single on-shore site close to the shoreline of present-day Lake Chad. We propose to locate our drilling operations on-shore close to the site where the geotechnical Bol borehole (13°280 N, 14°440 E) was drilled in 1973. This is for two main reasons: (1) nowhere else in the Chad Basin do we have such detailed information about the lithologies to be drilled; and (2) the Bol site is close to the depocentre of the Chad Basin and therefore likely to provide the stratigraphically most continuous sequence. © Author(s) 2018.
Keywords: Biodiversity; Boring; Deposition; Infill drilling; Lakes; Sediments; Water levels; Continuous sequences; Depositional environment; Environmental records; Intertropical convergence zone; Microbial biodiversity; Monsoon circulations; Pleistocene sediments; Subsurface biosphere; Climate change

The circulation of the Dead Sea brine in the regional aquifer - Weber, Nurit; Yechieli, Yoseph; Stein, Mordechai; Yokochi, Reika; Gavrieli, Ittai; Zappala, Jake; Mueller, Peter; Lazar, Boaz (Earth and Planetary Science Letters, 2018)

The Alpine Fault Hangingwall Viewed From Within: Structural Analysis of Ultrasonic Image Logs in the DFDP-2B Borehole, New Zealand - Massiot, C.; C'el'erier, B.; Doan, M.-L.; Little, T.A.; Townend, J.; McNamara, D.D.; Williams, J.; Schmitt, D.R.; Toy, V.G.; Sutherland, R.; Janku-Capova, L.; Upton, P.; et al. (Geochemistry, Geophysics, Geosystems, 2018)
Ultrasonic image logs acquired in the DFDP-2B borehole yield the first continuous, subsurface description of the transition from schist to mylonite in the hangingwall of the Alpine Fault, New Zealand, to a depth of 818 m below surface. Three feature sets are delineated. One set, comprising foliation and foliation-parallel veins and fractures, has a constant orientation. The average dip direction of 145° is subparallel to the dip direction of the Alpine Fault, and the average dip magnitude of 60° is similar to nearby outcrop observations of foliation in the Alpine mylonites that occur immediately above the Alpine Fault. We suggest that this foliation orientation is similar to the Alpine Fault plane at ∼1 km depth in the Whataroa valley. The other two auxiliary feature sets are interpreted as joints based on their morphology and orientation. Subvertical joints with NW-SE (137°) strike occurring dominantly above ∼500 m are interpreted as being formed during the exhumation and unloading of the Alpine Fault's hangingwall. Gently dipping joints, predominantly observed below ∼500 m, are interpreted as inherited hydrofractures exhumed from their depth of formation. These three fracture sets, combined with subsidiary brecciated fault zones, define the fluid pathways and anisotropic permeability directions. In addition, high topographic relief, which perturbs the stress tensor, likely enhances the slip potential and thus permeability of subvertical fractures below the ridges, and of gently dipping fractures below the valleys. Thus, DFDP-2B borehole observations support the inference of a large zone of enhanced permeability in the hangingwall of the Alpine Fault. ©2018. American Geophysical Union. All Rights Reserved.
cited By 14
Keywords: Anisotropy; Boreholes; Fracture; Stress relief; Ultrasonic imaging; Unloading; Alpine Faults; Anisotropic permeability; Enhanced permeability; Fluid pathways; foliation; Hydrofractures; Slip potential; Stress tensors; Well logging; anisotropy; borehole logging; fault zone; foliation; fracture zone; hanging wall; image analysis; mylonite; outcrop; permeability; structural geology; ultrasonics; well logging; Alpine Fault Zone; New Zealand; South Island

Textural changes of graphitic carbon by tectonic and hydrothermal processes in an active plate boundary fault zone, Alpine Fault, New Zealand - Kirilova, M.; Toy, V.G.; Timms, N.; Halfpenny, A.; Menzies, C.; Craw, D.; Beyssac, O.; Sutherland, R.; Townend, J.; Boulton, C.; Carpenter, B.M.; Cooper, A.; et al. (Geological Society Special Publication, 2018)
Graphitization in fault zones is associated both with fault weakening and orogenic gold mineralization. We examine processes of graphitic carbon emplacement and deformation in the active Alpine Fault Zone, New Zealand by analysing samples obtained from Deep Fault Drilling Project (DFDP) boreholes. Optical and scanning electron microscopy reveal a microtextural record of graphite mobilization as a function of temperature and ductile then brittle shear strain. Raman spectroscopy allowed interpretation of the degree of graphite crystallinity, which reflects both thermal and mechanical processes. In the amphibolite-facies Alpine Schist, highly crystalline graphite, indicating peak metamorphic temperatures up to 640°C, occurs mainly on grain boundaries within quartzo-feldspathic domains. The subsequent mylonitization process resulted in the reworking of graphite under lower temperature conditions (500-600°C), resulting in clustered (in protomylonites) and foliation-aligned graphite (in mylonites). In cataclasites, derived from the mylonitized schists, graphite is most abundant ( < 50% as opposed to < 10% elsewhere), and has two different habits: inherited mylonitic graphite and less mature patches of potentially hydrothermal graphitic carbon. Tectonic-hydrothermal fluid flow was probably important in graphite deposition throughout the examined rock sequences. The increasing abundance of graphite towards the fault zone core may be a significant source of strain localization, allowing fault weakening. © 2018 The Author(s).
cited By 17
Keywords: active fault; carbon; emplacement; fault zone; grain boundary; graphite; mobilization; plate boundary; strain; tectonic setting; texture; Alpine Fault Zone; New Zealand; South Island

Synoptic-scale control over modern rainfall and flood patterns in the Levant drylands with implications for past climates - Armon, Moshe; Dente, Elad; Smith, James A.; Enzel, Yehouda; Morin, Efrat (Journal of Hydrometeorology, 2018)

Structural disorder of graphite and implications for graphite thermometry - Kirilova, M.; Toy, V.; Rooney, J.S.; Giorgetti, C.; Gordon, K.C.; Collettini, C.; Takeshita, T. (Solid Earth, 2018)
Graphitization, or the progressive maturation of carbonaceous material, is considered an irreversible process. Thus, the degree of graphite crystallinity, or its structural order, has been calibrated as an indicator of the peak metamorphic temperatures experienced by the host rocks. However, discrepancies between temperatures indicated by graphite crystallinity versus other thermometers have been documented in deformed rocks. To examine the possibility of mechanical modifications of graphite structure and the potential impacts on graphite thermometry, we performed laboratory deformation experiments. We sheared highly crystalline graphite powder at normal stresses of 5 and 25 megapascal (MPa) and aseismic velocities of 1, 10 and 100μms1. The degree of structural order both in the starting and resulting materials was analyzed by Raman microspectroscopy. Our results demonstrate structural disorder of graphite, manifested as changes in the Raman spectra. Microstructural observations show that brittle processes caused the documented mechanical modifications of the aggregate graphite crystallinity. We conclude that the calibrated graphite thermometer is ambiguous in active tectonic settings. © Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License.
cited By 28
Keywords: Calibration; Metamorphic rocks; Statistical mechanics; Thermometers; Active tectonic settings; Carbonaceous materials; Crystalline graphite; Degree of structural order; Irreversible process; Micro-structural observations; Raman microspectroscopy; Structural disorders; Graphite; crystal structure; crystallinity; crystallography; experimental mineralogy; graphite; thermometry

Report on ICDP Post –Operations International Workshop on “Scientific Deep Drilling in Koyna, India” - Podugu, N.; Yadav, A.; Mallika, K.; Goswami, D.; Anuradha, M.U. (Journal of the Geological Society of India, 2018)
cited By 7

Spatial patterns of diatom diversity and community structure in ancient Lake Ohrid - Cvetkoska, Aleksandra; Pavlov, Aleksandar; Jovanovska, Elena; Tofilovska, Slavica; Blanco, Saul; Ector, Luc; Wagner-Cremer, Friederike; Levkov, Zlatko (Hydrobiologia, 2018)
The extraordinary diversity in long-lived lakes is largely driven by distinct eco-evolutionary processes. With their unique biota and numerous endemic taxa, these lakes are key settings for fundamental studies related to ecology, diversity, and evolution. Here, we test how the environment shapes diatom diversity and community patterns over space in ancient Lake Ohrid. By applying Bray –Curtis similarity analyses of diatom community data, including widespread and endemic taxa, we identified two major zones: littoral and sublittoral. The latter one is being characterized with higher endemic diversity. The α and β diatom diversity and community distribution in the northern and eastern part of the lake are influenced by the presence of vertical (bathymetrical) and horizontal barriers. The zonation of the diatom communities appears driven by two large-scale factors: (i) water depth, and (ii) water chemistry, primarily, the concentration of total phosphorus, nitrogen ammonia, and conductivity. Both drivers appear to equally influence diatom diversity and community patterns. We present initial data on diatom –environment relations, where the results support earlier ecological studies emphasizing the relevance of ongoing human-induced eutrophication in the northern lake area. This study provides background information on the role of the environment in structuring contemporary diatom diversity. However, future research needs to focus on the biotic component including species competition in order to reveal the mechanisms driving spatial community dynamics in Lake Ohrid. © 2018, The Author(s).
Keywords: Bacillariophyta

Shelf hypoxia in response to global warming after the Cretaceous- Paleogene boundary impact - Vellekoop, J.; Woelders, L.; Helmond, N.A.G.M.; Galeotti, S.; Smit, J.; Slomp, C.P.; Brinkhuis, H.; Claeys, P.; Speijer, R.P. (Geology, 2018)
The Chicxulub asteroid impact at the Cretaceous-Paleogene (K-Pg) boundary resulted in one of the most abrupt global warming events in the past 100 m.y., presenting an analogue to current global warming. Here, we present high-resolution geochemical, micropaleontological, and palynological records of the Brazos-1 (Texas, USA), Stevns Klint (Denmark), and Caravaca (Spain) K-Pg boundary sections to assess the rapid environmental changes during the global warming following the brief K-Pg boundary impact winter. Warming during the first millennia after the impact is associated with hypoxic bottom waters at the studied shelf sites, as indicated by molybdenum enrichments, causing major stress for benthic communities. We attribute this decline in dissolved oxygen to a combination of decreased gas solubility and ocean ventilation resulting from the warming of the sea water, and increased oxygen demand in shelf bottom waters due to increased nutrient inputs and associated high productivity. © 2018 Geological Society of America.
cited By 25

Serpentinite-Rich Gouge in a Creeping Segment of the Bartlett Springs Fault, Northern California: Comparison With SAFOD and Implications for Seismic Hazard - Moore, D.E.; McLaughlin, R.J.; Lienkaemper, J.J. (Tectonics, 2018)
An exposure of a creeping segment of the Bartlett Springs Fault (BSF), part of the San Andreas Fault system in northern California, is a 1.5-m-wide zone of serpentinite-bearing fault gouge cutting through Late Pleistocene fluvial deposits. The fault gouge consists of porphyroclasts of antigorite serpentinite, talc, chlorite, and tremolite-actinolite, along with some Franciscan metamorphic rocks, in a matrix of the same materials. The Mg-mineral assemblage is stable at temperatures above 250 –300 °C. The BSF gouge is interpreted to have been tectonically incorporated into the fault from depths near the base of the seismogenic zone and to have risen buoyantly to the surface where it is now undergoing right-lateral displacement. The ultramafic-rich composition, frictional properties, and inferred mode of emplacement of the BSF serpentinitic gouge correspond to those of the creeping traces of the San Andreas Fault identified in the SAFOD (San Andreas Fault Observatory at Depth) drill hole. This suggests a common origin for creep at both locations. A tectonic model for the source of the ultramafic-rich materials in the BSF is proposed that potentially could explain the distribution of creep throughout the northernmost San Andreas Fault system. Published 2018. This article is a US Government work and is in the public domain in the USA.
cited By 4
Keywords: Creep; Kaolinite; Magnesite; Metamorphic rocks; Serpentine; Strike-slip faults; Fault creep; Metasomatic rocks; SAFOD; San Andreas fault; Serpentinite; Structural geology; comparative study; data interpretation; displacement; emplacement; fault gouge; San Andreas Fault; seismic hazard; seismic zone; serpentinite; California; San Andreas; United States

Seismic imaging and attribute analysis of chicxulub crater central sector, Yucat'an platform, Gulf of Mexico - Canales-Garc'ia, I.; Urrutia-Fucugauchi, J.; Aguayo-Camargo, E. (Geologica Acta, 2018)
Chicxulub Crater, formed 66Ma ago by an asteroid impact on the southern Gulf of Mexico, is the best preserved of the three large multi-ring basins in the terrestrial record. The crater structure is characterized by a semi-circular concentric ring pattern, marking the crater basin, peak ring, terrace zone and basement uplift. Analysis of a grid of 19 seismic reflection profiles using seismic attributes, marker horizons, contour surfaces and 3-D views is used to investigate the stratigraphy of the central zone. We used interactive software and routine applications to map the impact breccias, breccia-carbonate contact and post-impact carbonates. Four horizons marked by high-amplitude reflectors representing high-impedance contrasts were identified and laterally correlated in the seismic images. Complex trace attribute analysis was applied for petrophysical characterization. Surface contour maps of base and top of stratigraphic packages were constructed, which mapped the impactites and post-and pre-impact carbonate stratigraphy. Basin floor, marked by the contact between the impact breccias and overlying carbonates is shown by laterally discontinuous high-amplitude reflectors. Discontinuous scattered reflectors interpreted as the upper breccias beneath the crater floor, have an average thickness of 300msm. The Paleogene sedimentary units are characterized by multiple reflectors with lateral continuity, which contrast with the seismic response of underlying breccias. The basal Paleocene sediments follow the basin floor relief. Upwards in the section, the carbonate strata are characterized by horizontal reflectors, which are interrupted by a regional unconformity. Onlap/downlap packages over the unconformity record a period of sea level change. ©I. Canales-Garc'ia, J. Urrutia-Fucugauchi, E. Aguayo-Camargo, 2018 CC BY-SA.
cited By 4

Sediment reflectance spectroscopy as a paleo-hydrological proxy in East Africa - Meyer, I.; Van Daele, M.; Fiers, G.; Verleyen, E.; De Batist, M.; Verschuren, D. (Limnology and Oceanography: Methods, 2018)
This study presents the merit of visible-spectrum scanning reflectance spectroscopy (VIS-RS) as a rapid technique for determining the concentration of chlorophyll a (Chl a) and its derivatives in lake sediments. In a 25,000-yr sediment record from Lake Challa, in East Africa, we found that VIS-RS values correlate with Chl a concentrations measured by High Performance/Pressure Liquid Chromatography. Observed variation in sedimentary values of RABD660;670 appears linked to proxies of climatic moisture balance as well as to a seismically-derived lake-level reconstruction over this period, indicating that VIS-RS can be used as a proxy for long-term paleo-hydrological change. Changes in the reflectance of Lake Challa sediments are likely related to differences in the preservation/degradation of algal pigments in response to changes in water-column depth and the stability of stratification. The connecting mechanism may be that during lake lowstands, more frequent injection of oxygen to (near-) bottom waters enhance the breakdown of labile organic compounds before permanent burial. We suggest that fast and inexpensive VIS-RS scanning, although less specific than HPLC in quantifying individual pigments, provides accurate data on down-core variations in the concentration of Chl a and its derivatives in lake sediments, hence allows to reconstruct long-term changes in the hydrology of climate-sensitive lakes. The main prerequisite for its successful application is that temporal variation in lake hydrology over the period of interest has not appreciably affected sedimentation dynamics at the core site, since major changes in sediment texture and organic content are likely to create confounding effects in the VIS-RS signature. © 2017 Association for the Sciences of Limnology and Oceanography
cited By 9

Seasonal and diurnal evaporation from a deep hypersaline lake: The Dead Sea as a case study - Hamdani, I.; Assouline, S.; Tanny, J.; Lensky, I.M.; Gertman, I.; Mor, Z.; Lensky, N.G. (Journal of Hydrology, 2018)

Scientific Results of Geophysical Logging in the Upper Cretaceous Strata, CCSD SK-2 East Borehole in the Songliao Basin of Northeast China [松辽盆地科学钻探工程松科二井东孔上白垩统地球物理测井科学成果] - Zou, C.-C.; Zhang, X.-H.; Zhao, J.-H.; Peng, C.; Zhang, S.-X.; Li, N.; Xiao, L.; Niu, Y.-X.; Ding, Y.-J.; Qin, Y.-X.; Lin, F. (Acta Geoscientica Sinica, 2018)
The Continental Scientific Drilling Project in the Songliao Basin, a major scientific project, was aimed at solving a variety of scientific problems involved in resources on deep strata, paleoclimate and paleoenvironment. As the main borehole of this project, the SK-2 East Borehole was designed to reach a depth of 6 400 m to penetrate the Cretaceous strata until reaching the base of the basin. Geophysical logs played an important role in the subsequent geoscience researches because very few core samples were recovered over the Upper Cretaceous intervals (i.e., Spud 1 and Spud 2). After the borehole was officially drilled, 4 uncased and cased hole logging operations were carried out in the Upper Cretaceous intervals using advanced imaging logging tools. Comprehensive log evaluation was implemented systematically. The preliminary scientific results were summarized as follows: (1) Abundant logs including conventional logs special logs and CBL logs (more than 20 parameters) were obtained in situ, and continuous and standard petrophysical parameters profiles of the Upper Cretaceous interval were established; (2) Stratigraphic division, lithological identification and fine interpretation of sediments and structures were completed; (3) Hydrocarbon reservoirs in the Quantou Formation, source rocks in the Nenjiang and Qingshankou Formation, abnormally high radioactivity interval in the Nenjiang Formation, and potential geothermal development layers over the Upper Cretaceous strata were identified; (4) Favorable geophysical log indexes for paleoclimate analysis in the Qingshankou Formation were studied; (5) The key drilling engineering information including accurate temperature, caliper, borehole trajectory and cementing quality was provided in time. The scientific results are crucial for establishing the scientific scale of geophysical exploration in the Songliao Basin, investigating paleoclimate and paleoenvironment, and implementing drilling engineering, which have established good foundations for achieving the whole scientific goals of this drilling project. © 2018, Science Press. All right reserved.
cited By 8

Sampling bias of fracture orientation: Tests using data from the kimama borehole, Snake River Plain, Idaho, USA - Bullock, E.A.L.; Haraksingh, I. (52nd U.S. Rock Mechanics/Geomechanics Symposium, 2018)
Acoustic image logs from a borehole located at Kimama, Idaho in the Snake River Province were interpreted using WellCAD™ to match and generate orientation data of the natural fractures intersected. One well known problem with such data, however, is the bias imposed towards perpendicular features from linear scanline’ sampling along the borehole axis. This leads to an inaccurate representation of the one-dimensional (1-D) fracture intensity (P10). To correct for this bias, the methodology relies on the assumption that the borehole is truly vertical. An analysis using the Terzaghi, 1965 correction gives 3% of all fracture orientations to be sub-parallel, 41% sub-horizontal and to demonstrate a uniform-biased distribution. The Fouch'e, 2004 correction yields the highest weighting factor of 9 for a sub-parallel set, in comparison to 14 using the Terzaghi, 1965 method. The chi-squared (χ2) test proves independence between observed and expected fracture distributions. The Kolmogorov-Smirnov (two-sample KS) test shows a substantial mismatch between the cumulative distribution functions (cdf) of the observed and modeled distribution for any sample chosen from the population. Results corroborate the scanline theory, but despite stronger theoretical justifications these methods do not substantially change the corrected statistics for the borehole. Copyright © 2018 ARMA, American Rock Mechanics Association.
cited By 0
Keywords: Boreholes; Distribution functions; Rock mechanics; Well logging; Cumulative distribution function; Fracture distributions; Fracture orientations; Kolmogorov-Smirnov; Natural fracture; Orientation data; Snake river plains; Weighting factors; Fracture

Sample-scale carbon isotopic variability and diverse biomass in the Paleoproterozoic Zaonega Formation, Russia - Qu, Yuangao; Lepland, Aivo; Zuilen, Mark A; Whitehouse, Martin; Črne, Alenka E; Fallick, Anthony E (Precambrian Research, 2018)

Salt precipitation and dissolution in the late Quaternary Dead Sea: Evidence from chemical and δ37Cl composition of pore fluids and halites - Levy, E.J.; Yechieli, Y.; Gavrieli, I.; Lazar, B.; Kiro, Y.; Stein, M.; Sivan, O. (Earth and Planetary Science Letters, 2018)
The chemical composition and δ37Cl of pore fluids from the ICDP core drilled in the deepest floor of the terminal and hypersaline Dead Sea, and halites from the adjacent Mount Sedom salt diapir, are used to establish the dynamics of halite precipitation and dissolution during the last interglacial and glacial periods. Between ∼132 and 116 thousand years ago (ka) halites precipitated in the lake resulting in the expulsion of Na+ and Cl− from the residual solution. Over 50% of the Cl− reservoir was removed, resulting in a decrease in the Na/Cl ratio from 0.57 to 0.19. This process was accompanied by a decrease in δ37Cl values in the precipitating halites and the associated residual Cl− in the lake. The observed decrease fits a Rayleigh distillation curve with a fractionation factor of Δ(NaCl –Dead Sea solution) = +0.32‰ (±0.12) determined in the present study. This behavior implies negligible contribution of external sources of Cl− to the lake during the main peak of the last interglacial, MIS5e. Subsequently, during the last glacial (ca. 117 to 17 ka) dissolution of halite took place, the Na+ and Cl− inventory were replenished, accompanied by an increase in Na/Cl from 0.21 to 0.55 and in the δ37Cl values from −0.46‰ to −0.12‰. While the lake underwent significant dilution during that time, the decrease in salinity was somewhat suppressed by the dissolution of the halite which was mostly derived from Mount Sedom salt diapir. © 2018 Elsevier B.V.
cited By 13
Keywords: Curve fitting; Dissolution; Distillation; Glacial geology; Lakes; Precipitation (chemical); Reservoirs (water); Salt tectonics; Sodium chloride; Chemical compositions; Dead sea; Fractionation factors; ICDP; Rayleigh distillation; Residual solutions; Salt diapirs; Salt precipitation; Chloride minerals; chemical composition; chlorine isotope; dissolution; fluid composition; fractionation; halite; hydrochemistry; precipitation (chemistry); Quaternary; reservoir; salt dome; Dead Sea; Israel; Mount Sedom; Southern District

Rock fluidization during peak-ring formation of large impact structures - Riller, U.; Poelchau, M.H.; Rae, A.S.P.; Schulte, F.M.; Collins, G.S.; Melosh, H.J.; Grieve, R.A.F.; Morgan, J.V.; Gulick, S.P.S.; Lofi, J.; Diaw, A.; McCall, N.; et al. (Nature, 2018)
Large meteorite impact structures on the terrestrial bodies of the Solar System contain pronounced topographic rings, which emerged from uplifted target (crustal) rocks within minutes of impact. To flow rapidly over large distances, these target rocks must have weakened drastically, but they subsequently regained sufficient strength to build and sustain topographic rings. The mechanisms of rock deformation that accomplish such extreme change in mechanical behaviour during cratering are largely unknown and have been debated for decades. Recent drilling of the approximately 200-km-diameter Chicxulub impact structure in Mexico has produced a record of brittle and viscous deformation within its peak-ring rocks. Here we show how catastrophic rock weakening upon impact is followed by an increase in rock strength that culminated in the formation of the peak ring during cratering. The observations point to quasi-continuous rock flow and hence acoustic fluidization as the dominant physical process controlling initial cratering, followed by increasingly localized faulting. © 2018, Springer Nature Limited.
cited By 52

Review: Reservoir triggered seismicity (RTS) at Koyna, India, over the past 50 yrs - Gupta, H.K. (Bulletin of the Seismological Society of America, 2018)
Reservoir triggered seismicity (RTS) is an anthropogenic effect of creating artificial water reservoirs. Worldwide, the biggest RTS earthquake of magnitude M 6.3 occurred on 10 December 1967 at Koyna, India. From among RTS sites globally, at four sites destructive earthquakes exceeding magnitude 6 occurred. RTS at Koyna has continued until now, whereas at other sites it ceased in a year to a few years. Detailed studies of RTS sequences carried out in 1970s led to delineating common characteristics of RTS events that also help in differentiating RTS sequences from normal earthquake sequences. Association of water level changes in the Koyna and Warna reservoirs and RTS in the Koyna region has been well established. The part played by reservoirs in triggering the earthquakes is not well understood, due to lack of near-field studies. Koyna is found to be a very suitable site for such studies. The suitability of the Koyna site for setting up a deep borehole laboratory and the scientific work to be carried out were discussed in an International Continental Drilling Program (ICDP) supported workshop held in India in 2011. The suggested additional work to be carried out was undertaken from 2011 to 2014 and discussed in the second ICDP Workshop held in 2014. A go-ahead was given for putting up a pilot borehole of 3000-m depth. The pilot borehole drilling started in December 2016 and was completed in June 2017, along with necessary observations and studies. These were presented in the Post Operation Workshop held during October 2017. A few salient features of the work carried out in the last 50 yrs are presented here. © 2018, Seismological Society of America. All rights reserved.
cited By 19
Keywords: Boreholes; Boring; Infill drilling; Reservoirs (water); Water levels; Anthropogenic effects; Artificial water; Borehole drilling; Deep boreholes; Earthquake sequences; Near field study; Salient features; Water level changes; Earthquakes; anthropogenic effect; earthquake magnitude; earthquake trigger; reservoir-induced seismicity; trigger mechanism; water level; India; Koyna; Maharashtra

Research on the protection technology and the effects of cores in well SK-2 - Liwei, CUI; Chenguang, ZHANG; Sujiang, ZHANG; Ailing, JIANG; Guiyun, LIU (CHINA MINING MAGAZINE, 2018)

Integrated Paleoseismic Chronology of the Last Glacial Lake Lisan: From Lake Margin Seismites to Deep-Lake Mass Transport Deposits - Kagan, Elisa; Stein, Mordechai; Marco, Shmuel (Journal of Geophysical Research: Solid Earth, 2018)

In situ carbon mineralization in ultramafic rocks: Natural processes and possible engineered methods - Kelemen, Peter B; Aines, Roger; Bennett, Emma; Benson, Sally M; Carter, Emma; Coggon, Jude A; De Obeso, Juan C; Evans, Ondati; Gadikota, Greeshma; Dipple, Gregory M; et al. (Energy Procedia, 2018)

Increased frequency of torrential rainstorms during a regional late Holocene eastern Mediterranean drought - Ahlborn, M.; Armon, M.; Ben Dor, Y.; Neugebauer, I.; Schwab, M.J.; Tjallingii, R.; Shoqeir, J.H.; Morin, E.; Enzel, Y.; Brauer, A. (Quaternary Research (United States), 2018)
Identifying climates favoring extreme weather phenomena is a primary aim of paleoclimate and paleohydrological research. Here, we present a well-dated, late Holocene Dead Sea sediment record of debris flows covering 3.3 to 1.9 cal ka BP. Twenty-three graded layers deposited in shallow waters near the western Dead Sea shore were identified by microfacies analysis. These layers represent distal subaquatic deposits of debris flows triggered by torrential rainstorms over the adjacent western Dead Sea escarpment. Modern debris flows on this escarpment are induced by rare rainstorms with intensities exceeding >30 mm h-1 for at least one hour and originate primarily from the Active Red Sea Trough synoptic pattern. The observed late Holocene clustering of such debris flows during a regional drought indicates an increased influence of Active Red Sea Troughs resulting from a shift in synoptic atmospheric circulation patterns. This shift likely decreased the passages of eastern Mediterranean cyclones, leading to drier conditions, but favored rainstorms triggered by the Active Red Sea Trough. This is in accord with present-day meteorological data showing an increased frequency of torrential rainstorms in regions of drier climate. Hence, this study provides conclusive evidence for a shift in synoptic atmospheric circulation patterns during a late Holocene drought. Copyright © University of Washington. Published by Cambridge University Press, 2018.
cited By 15
Keywords: Climatology; Debris; Drought; Floods; Dead sea; Debris flows; Holocenes; Lake sediments; Levant; Paleoclimates; Red sea; Thunderstorms; atmospheric circulation; cyclone; debris flow; drought; facies analysis; flood; geological record; Holocene; lacustrine deposit; microfacies; paleoclimate; paleohydrology; rainstorm; trough; Dead Sea; Indian Ocean; Levant; Mediterranean Region; Red Sea [Indian Ocean]

Centennial-scale vegetation dynamics and climate variability in SE Europe during Marine Isotope Stage 11 based on a pollen record from Lake Ohrid - Kousis, Ilias; Koutsodendris, Andreas; Peyron, Odile; Leicher, Niklas; Francke, Alexander; Wagner, Bernd; Giaccio, Biagio; Knipping, Maria; Pross, J{org (Quaternary Science Reviews, 2018)
To better understand climate variability during Marine Isotope Stage (MIS) 11, we here present a new, centennial-scale-resolution pollen record from Lake Ohrid (Balkan Peninsula) derived from sediment cores retrieved during an International Continental Scientific Drilling Program (ICDP) campaign. Our palynological data, augmented by quantitative pollen-based climate reconstructions, provide insight into the vegetation dynamics and thus also climate variability in SE Europe during one of the best orbital analogues for the Holocene. Comparison of our palynological results with other proxy data from Lake Ohrid as well as with regional and global climate records shows that the vegetation in SE Europe responded sensitively both to long- and short-term climate change during MIS 11. The chronology of our palynological record is based on orbital tuning, and is further supported by the detection of a new tephra from the Vico volcano, central Italy, dated to 410 ± 2 ka. Our study indicates that MIS 11c (∼424 –398 ka) was the warmest interval of MIS 11. The younger part of the interglacial (i.e., MIS 11b –11a; ∼398 –367 ka) exhibits a gradual cooling trend passing over into MIS 10. It is characterized by considerable millennial-scale variability as inferred by six abrupt forest-contraction events. Interestingly, the first forest contraction occurred during full interglacial conditions of MIS 11c; this event lasted for ∼1.7 kyrs (406.2 –404.5 ka) and was characterized by substantial reductions in winter temperature and annual precipitation. Most notably, it occurred ∼7 ka before the end of MIS 11c and ∼15 ka before the first strong ice-rafted debris event in the North Atlantic. Our findings suggest that millennial-scale climate variability during MIS 11 was established in Southern Europe already during MIS 11c, which is earlier than in the North Atlantic where it is registered only from MIS 11b onwards. © 2018 Elsevier Ltd
Keywords: Atlantic Ocean; Atlantic Ocean (North); Balkans; Europe; Italy; Lake Ohrid; Lazio; Mediterranean Sea; Mediterranean Sea (East); Vico; Forestry; Glacial geology; Isotopes; Lakes; Repair; Vegetation; Abrupt climate change; Balkan peninsulas; Climate reconstruction; Eastern Mediterranean; Lake Ohrid; Marine isotope stages; Southern Europe; Tephrostratigraphy; Terrestrial ecosystems; Vico tephra; chronology; climate change; climate variation; global climate; ice-rafted debris; interglacial; marine isotope stage; paleoclimate; palynology; pollen; precipitation (climatology); reconstruction; sediment core; tephra; vegetation dynamics; Climate change

Deep Continental Scientific Drilling Engineering Project in Songliao Basin: progress in Earth Science research - Hou, H.-S.; Wang, C.-S.; Zhang, J.-D.; Ma, F.; Fu, W.; Wang, P.-J.; Huang, Y.-J.; Zou, C.-C.; Gao, Y.-F.; Gao, Y.; Zhang, L.-M.; Yang, J.; et al. (China Geology, 2018)
The Songke No.2 well (eastern hole) (referred to as Well SK-2), one of the “two wells and four holes” of the Deep Continental Scientific Drilling Engineering Project in the Songliao Basin, is in Anda City, Heilongjiang Province, and was officially completed on May 26, 2018. The scientific goals of Well SK-2 cover four aspects: paleoclimate research, resource and energy exploration, primary geological research, and development of deep earth exploration techniques. Since the official commencement of drilling in 2014, the Well SK-2 scientific drilling engineering team has organized and implemented drilling for coring, in situ logging, chemical analysis of core elements, and deep structural exploration around the well. Currently, the following preliminary scientific research progress has been made: 4334.81 m in situ core data has been obtained; the centimeter-level high-resolution characterization of the most complete and continuous Cretaceous continental strata ever unearthed has been completed, and the standard profile of continental strata has been initially established; the unconventional natural gas resources and basin-type hot dry rocks in the deep Songliao Basin were found to have good prospects for exploration and development; the climatic evolutionary history of the Cretaceous continental strata was rebuilt for the first time, covering hundreds of thousands to millions of years, and the major events of Cretaceous climate fluctuations have been discovered; all these reveal strong evidence for the subduction and aggregation of paleo-ocean plates, providing a theoretical basis for the re-recognition of the genesis of the Songliao Basin and for deep earth oil and gas exploration. The implementation of the Deep Continental Scientific Drilling Engineering Project in the Songliao Basin is of great significance for exploring the mysteries of the Earth and solving major problems such as those related to the deep energy environment. It is a solid step along the road of “going deep into the Earth”. © 2019 Elsevier B.V.
cited By 16

Deep continental scientific drilling engineering in Songliao Basin: Progress in earth science research - Hou, H.; Wang, C.; Zhang, J.; Ma, F.; Fu, W.; Wang, P.; Huang, Y.; Zou, C.; Gao, Y.; Zhang, L.; Yang, J.; Guo, R. (Geology in China, 2018)
The eastern borehole of Well SK-2, among the two wells and four boreholes of the deep continental scientific drilling engineering in Songliao Basin, is situated in Anda of Heilongjiang Province and was finished officially on May 26th, 2018. Well SK- 2 mainly focused on four scientific objections, i.e., paleoclimate research, resource and energy exploration, basic geological research and development of deep exploration technology. During the process if drilling which began in 2014, drilling, coring, logging, analysis of chemical element and structural exploration of surrounding areas were carried out during the SK-2 drilling engineering, and some preliminary progresses were made in scientific research: 4134.8 m-long in-situ core data were acquired, and the most complete and continuous continental strata of the cretaceous were described with high resolution of centimeter-level, thus building the standard continental stratigraphic profile. Besides, evolution history of the continental facies in the Cretaceous period from scale of one million to one hundred thousand years was reconstructed for the first time, and an important climatic event of the Cretaceous was found. Apart from these achievements, evidence of Paleo- Pacific plate subduction and convergence in the deep was found, which contributes to genetic re- recognition and deep hydrocarbon exploration in Songliao basin. The implementation of deep continental scientific drilling engineering in Songliao Basin is of great significance in exploring the earth's mystery, seeking for deep energy and solving environmental problems. It is considered to be a solid step in the way of heading deep of the earth. © 2018 Editorial Board of Geology in China. All rights reserved.
cited By 33
Keywords: Cretaceous; drilling; Earth science; energy resource; geographical research; hydrocarbon exploration; Pacific plate; paleoclimate; China; Heilongjiang; Songliao Basin

Deccan volcanism caused coupled pCO2 and terrestrial temperature rises, and pre-impact extinctions in northern China - Zhang, L.; Wang, C.; Wignall, P.B.; Kluge, T.; Wan, X.; Wang, Q.; Gao, Y. (Geology, 2018)
Evaluating the terrestrial climate record provides a critical test of the roles of Chicxulub impact and Deccan Traps volcanism during the Cretaceous-Paleogene (K-Pg) mass extinction. Most evidence came from marine records, but our new clumped isotopes data from paleosol carbonates in the Songliao Basin provide a terrestrial climate history from northern China. This reveals there was a pre-impact warming caused by the onset of Deccan Traps volcanism, whereas the following short-term cooling then another warming episode were likely caused by Chicxulub impact and post-boundary volcanism. Our study suggests that the pCO2 levels were probably the main control on the latest Cretaceous cooling and the climatic fluctuations across the K-Pg boundary interval in northern China. In the Songliao Basin, the pre-impact Deccan Traps volcanism links to losses of half of the lacustrine algae species (charophytes) and almost all of the lacustrine ostracodes; this suggests that the Deccan Traps volcanism had already destabilized the ecosystem and caused extinctions prior to the Chicxulub impact. © 2018 Geological Society of America.
cited By 40
Keywords: Chicxulub impact; Climate history; Climate record; Climatic fluctuations; Clumped isotopes; K-pg boundaries; Mass extinction; Temperature rise; Geology; carbon dioxide; Cretaceous-Paleogene boundary; mass extinction; paleosol; volcanism; China; Songliao Basin; algae; Characeae; Ostracoda

Dead Sea pollen provides new insights into the paleoenvironment of the southern Levant during MIS 6 –5 - Chen, C.; Litt, T. (Quaternary Science Reviews, 2018)
The paleoclimate of the southern Levant, especially during the last interglacial (LIG), is still under debate. Reliable paleovegetation information for this period, as independent evidence to the paleoenvironment, was still missing. In this study, we present a high-resolution pollen record encompassing 147 –89 ka from the Dead Sea deep drilling core 5017-1A. The sediment profile is marked by alternations of laminated marl deposits and thick massive halite, indicating lake-level fluctuations. The pollen record suggests that steppe and desert components predominated in the Dead Sea surroundings during the whole investigated interval. The late penultimate glacial (147.3 –130.9 ka) and early last glacial (115.5 –89.1 ka) were cool and relatively dry, with sub-humid conditions confined to the mountains that sustained moderate amounts of deciduous oaks. Prior to the LIG optimum, a prevalence of desert components and a concomitant increase in frost-sensitive pistachio trees demonstrate the occurrence of an arid initial warming phase (130.9 –124.2 ka). The LIG optimum (124.2 ka –115.5 ka) was initiated by an abrupt grass expansion that was followed by a rapid spread of woodlands in the mountains due to increased moisture availability. The remarkable sclerophyllous expansion points to a strong seasonal moisture deficit. These results contradict previous Dead Sea lake-level investigations that suggested pluvial glacials and a warm, dry LIG in the southern Levant. Prominent discrepancies between vegetation and Dead Sea lake stands are also registered at 128 –115 ka, and the potential causes are discussed. In particular, while the pollen spectra mirror increased effective moisture during the LIG optimum, the massive halite deposition is indicative of an extremely low lake level. Given that the climate amelioration triggered the migration of early modern humans to the southern Levant, we speculate that the diverse ecosystems in the region provided great potential for their residence. Across the eastern Mediterranean region, an analogous vegetation succession pattern is observed. © 2018 Elsevier Ltd
cited By 23
Keywords: Chloride minerals; Fertilizers; Glacial geology; Landforms; Moisture; Sodium chloride; Vegetation; Eastern Mediterranean; Human migration; Lake levels; Last interglacial; Paleovegetation; Lakes; deciduous tree; deep drilling; desert; dicotyledon; grass; interglacial; lake level; Last Glacial; marine isotope stage; migration; paleobotany; paleoclimate; paleoenvironment; pollen; sediment analysis; steppe; warming; Dead Sea; Levant; Mediterranean Region; Mediterranean Sea; Mediterranean Sea (East); Pistacia vera; Quercus

Crystallization and partial melting of rhyolite and felsite rocks at Krafla volcano: A comparative approach based on mineral and glass chemistry of natural and experimental products - Masotta, M.; Mollo, S.; Nazzari, M.; Tecchiato, V.; Scarlato, P.; Papale, P.; Bachmann, O. (Chemical Geology, 2018)

Coupled δ18O-δ17O and 87Sr/86Sr isotope compositions suggest a radiogenic and 18O-enriched magma source for Neapolitan volcanoes (Southern Italy) - Iovine, Raffaella Silvia; Mazzeo, Fabio Carmine; W{orner, Gerhard; Pelullo, Carlo; Cirillo, Gianluca; Arienzo, Ilenia; Pack, Andreas; D'Antonio, Massimo (Lithos, 2018)
The origin of large variations in stable and radiogenic isotope compositions of magmas erupted from the Neapolitan volcanoes, including Somma-Vesuvius and Campi Flegrei (Southern Italy), has always been contentious. Indeed, the role and relative importance of sediment subduction versus crustal assimilation to explain the chemical and isotopic variations of the erupted magmas remain unclear. Isotopic disequilibrium between minerals and their host indicate that bulk rock analyses are incapable of constraining the isotopic composition of the source. Therefore, we use isotopic (87Sr/86Sr, 18O/16O and 17O/16O) data on separated minerals (feldspar, clinopyroxene and olivine phenocrysts) from pyroclastic successions and lava flows of the Neapolitan volcanic area (Phlegrean Volcanic District and Somma-Vesuvius complex) to better constrain magmatic oxygen and strontium isotope ratios. Magmatic values recalculated from δ18O of olivine and clinopyroxene phenocrysts range from typical mantle values of 5.2‰ to almost 9‰ relative to SMOW. These compositions are very different from those of typical mantle sources. In order to assess the degree of magma evolution from which these minerals formed, the Mg# of clinopyroxene and olivine were converted into host melt Mg#, resulting in the range 44 to 76. Simple assimilation of silicic crustal rocks is difficult to reconcile with the mafic nature of these estimated host magma compositions. This indicates that some mafic, mantle-derived magmas, having unusually heavy oxygen isotope (up to 9‰) and high Sr isotope compositions (0.7050 to 0.7085), must exist. Crustal assimilation of carbonates can be excluded by the lack of a link between isotopes and major and trace element signatures. Assimilation of either Hercynian-like crust or altered pyroclastic rocks, however, cannot be ruled out completely. However, assimilation of partial melts from a Hercynian-like crust would have to be 12% and 21% to explain the heavy oxygen isotope values of Campi Flegrei and Somma-Vesuvius, respectively. Such degrees of assimilation are unlikely since the magmas are either too mafic or too alkaline to be consistent with such high proportion of crustal components. Other, less mafic Campi Flegrei, Somma-Vesuvius and Ischia magmas with more typical mantle oxygen isotopes, have been possibly generated in a mantle source affected by minor contamination by pelagic and carbonate sediments and subsequent assimilation of Hercynian-like crust. Sr-O mixing models indicate that such magmas were derived from a mantle source that was contaminated by up to 10% of a 1:1 mixture of pelagic and carbonate sediments. These findings together demonstrate the highly complex and varied magma sources in the Campania volcanic district. Triple oxygen isotope variations (Δ17O), based on measurements of both 18O/16O and 17O/16O ratios in potential assimilants are in agreement with these conclusions. © 2018 Elsevier B.V.
Keywords: Campania [Italy]; Campi Flegrei; Italy; Napoli [Campania]; Somma Vesuviana; crustal structure; isotopic composition; magma; mantle structure; oxygen isotope; stable isotope; strontium isotope; volcano

Corrigendum to Effect of methane hydrate morphology on compressional wave velocity of sandy sediments: Analysis of pressure cores obtained in the Eastern Nankai Trough (Marine and Petroleum Geology (2015) 66(Part 2) (425 –433) (S0264817215000537) (10.1016/j.marpetgeo.2015.02.021)) - Konno, Y.; Jin, Y.; Yoneda, J.; Kida, M.; Egawa, K.; Ito, T.; Suzuki, K.; Nagao, J. (Marine and Petroleum Geology, 2018)
The authors would like to replace the section 1. 1ntroduction (pp. 425) with the following: Introduction Methane hydrate, which is a crystalline compound formed from methane and water, is found in arctic and marine continental margin sediments worldwide (Sloan and Koh, 2008). The P-wave velocity of hydrate-bearing sediments is higher than that of hydrate-free unconsolidated sediments (e.g., Yuan et al., 1996), and laboratory experiments have shown that there is a strong relationship between the P-wave velocity and hydrate saturation (e.g., Berge et al., 1999). Through the comparison with model predictions such as those of Dvorkin et al. (2000), it was found that this relationship depends on the hydrate morphology, such as grain coating, cementing, pore-filling, and sediment frame component (or load-bearing) within the pore space (M. Lee et al., 1996; Berge et al., 1999; Reister, 2003; Yun et al., 2005; Priest et al., 2009; J. Lee et al., 2010; Hu et al., 2010, Li et al., 2011; Best et al., 2013; Kim et al., 2013a). This suggests that the P-wave velocity obtained from logging and seismic surveys can be used to estimate the in situ hydrate saturation if the hydrate morphology in actual reservoirs is revealed. P-wave velocity changes during CH4eCO2 replacement in hydrates have also been studied to estimate the sediment stiffness (Espinoza and Santamarina, 2011; Liu et al., 2013). It is therefore important to understand the relationship between the P-wave velocity, hydrate saturation, and hydrate morphology because these properties are deeply linked to the physical properties of hydrate-bearing sediments, such as their permeability, thermal properties, electrical conductivity, and shear strength (Waite et al., 2009; Santamarina and Ruppel, 2010). Quantitative detection of methane hydrate in natural sediments has been attempted over the years. Wood et al. (1994) analyzed seismic interval velocities at the Blake Ridge for quantitative detection of methane hydrate. Chand et al. (2004) compared P- wave velocities predicted by four models and field data from the Mallik field in the Mackenzie Delta and the Blake Ridge. At the Mallik field, Carcione and Gei (2004) estimated hydrate saturation from well logging data and vertical seismic profiles by assuming that the hydrate filled pore space (pore-filling). Dash and Spence (2011) estimated hydrate saturation at the northern Cascadia margin using P-wave and S-wave velocities. They concluded that the hydrate is distributed as part of the load-bearing matrix. For other areas, such as the Nankai Trough, Mount Elbert, the KrishnaeGodavari basin, the Tsushima Basin, and the Shenhu area of the South China Sea, estimations of hydrate saturation have also been conducted (Inamori et al., 2010; Lee and Collett, 2011; Kim et al., 2013b; Shankar and Riedel, 2011; Lee and Collett, 2013; Wang et al., 2014). Hydrate morphology was estimated as load-bearing at the Nankai Trough, Mount Elbert, and the KrishnaeGodavari basin, whereas it was estimated to be pore-filling at the Tsushima Basin. Winters et al. (2004) reported that the mildly-disturbed samples recovered from the 2L-38 well at the Mallik field are best modeled as part of the sediment frame (load-bearing). Laboratory experiments using artificial cores have also provided insight into the relationship between P-wave velocity and hydrate saturation; however, there are some limitations to the use of artificial cores in estimating hydrate saturation in natural sediments. One of the reasons is that it is difficult to control hydrate morphology in such a way as to mimic natural features in artificial cores. Hydrate formed in a gas-rich environment, which is a conventional method used in laboratory studies, generally shows a cementing morphology (Winters et al., 2004; Priest et al., 2005, 2006). In contrast, hydrate formed from methane dissolved in the pore fluid, which is considered as common in natural environments, may not show a cementing morphology (Spangenberg et al., 2005, 2008; Winters et al., 2007). Using a non-methane hydrate former, Yun et al. (2005) and Lee et al. (2010) documented a transition between pore-filling and load-bearing hydrates at saturation of 40%e50% of pore space. Gas hydrate morphology in natural sediments is depends on the hydrate occurrence mechanism; however, it is difficult to know the occurrence mechanism for each reservoir. Analysis of logging data seems to be effective in estimating the actual relationship between P-wave velocity, hydrate saturation, and hydrate morphology in natural sediments. However, the spatial resolution of P-wave velocity data and hydrate saturation data, as estimated from resistivity logging, is larger than that of core data, and the various datasets are not usually entirely coincident. Thus, cross-plots of P- wave velocity and hydrate saturation are often so scattered that it is difficult to accurately constrain the hydrate morphology. In addition, the frequency used for in situ exploration is much lower than that used in laboratory experiments, which results in differences in the depth and spatial resolution of measurements. In situ exploration data are spatially-averaged and appropriate for the determination of the hydrate distribution in bulk sediments. However, such data are difficult to apply to the investigation of local properties, such as the pore space hydrate morphology. Consequently, high frequency laboratory experiments using natural sediments are more favorable for the analysis of pore space hydrate morphology. Pressure core analysis technologies now enable the study of relatively undisturbed samples recovered from hydrate-bearing natural sediments, and pressure core analyses of P-wave veloc ities have been conducted for hydrate-bearing natural sediments (Yun et al., 2006, 2010, 2011; Schultheiss et al., 2011). Lee et al. (2013) successfully determined the relationship between P-wave velocity and hydrate saturation from pressure cores recovered from the Tsuhima Basin. They concluded that the hydrate morphology is pore-filling at low hydrate saturations, but gradually deviates from pore-filling toward cementation as hydrate saturation increases, in accordance with studies of Yun et al. (2005) and Lee et al. (2010). They used the Pressure Core Analysis and Transfer System (PCATS) developed by Geotek Ltd. (Schultheiss et al., 2011) to measure P- wave velocity through the core liner at high resolution. However, the study noted that the data resolving hydrate saturation was much lower than that of P-wave velocity because hydrate saturation was calculated based on a dissociation experiment conducted on the whole core including both high and low P-wave velocity sections (Lee et al., 2013). In this study, a newly developed pressure core cutting, manipulating, and analyzing system was used to overcome the discrepancy of data resolution between P-wave velocity and hydrate saturation. P-wave velocity was measured by the PCATS at a high resolution using pressure cores recovered from the Eastern Nankai Trough offshore Japan. After the P-wave velocity measurements, the cores were cut into pieces under pressure for separate P-wave velocity intervals on the basis of visual observation enabled by our pressure core system. To obtain high resolution hydrate-saturation data, each sub-sampled core was depressurized and the gas volume was measured. By comparing experimental data with physical model predictions, hydrate morphology in pore space was studied in detail. The authors would like to apologise for any inconvenience caused. DOI of original article: dx.doi.org/10.1016/j.marpetgeo.2015.02.021 © 2018
cited By 0

Controls on fault zone structure and brittle fracturing in the foliated hanging wall of the Alpine Fault - Williams, J. N.; Toy, V. G.; Massiot, C.; McNamara, D. D.; Smith, S. A. F.; Mills, S. (Solid Earth, 2018)
Three datasets are used to quantify fracture density, orientation, and fill in the foliated hanging wall of the Alpine Fault: (1) X-ray computed tomography (CT) images of drill core collected within 25gm of its principal slip zones (PSZs) during the first phase of the Deep Fault Drilling Project that were reoriented with respect to borehole televiewer images, (2) field measurements from creek sections up to 500gm from the PSZs, and (3) CT images of oriented drill core collected during the Amethyst Hydro Project at distances of ĝ1/4 g0.7-2gkm from the PSZs. Results show that within 160gm of the PSZs in foliated cataclasites and ultramylonites, gouge-filled fractures exhibit a wide range of orientations. At these distances, fractures are interpreted to have formed at relatively high confining pressures and/or in rocks that had a weak mechanical anisotropy. Conversely, at distances greater than 160gm from the PSZs, fractures are typically open and subparallel to the mylonitic or schistose foliation, implying that fracturing occurred at low confining pressures and/or in rocks that were mechanically anisotropic. Fracture density is similar across the g1/4 g500gm width of the field transects. By combining our datasets with measurements of permeability and seismic velocity around the Alpine Fault, we further develop the hierarchical model for hanging-wall damage structure that was proposed by Townend et al. (2017). The wider zone of foliation-parallel fractures represents an outer damage zone that forms at shallow depths. The distinct g160gm wide interval of widely oriented gouge-filled fractures constitutes an inner damage zone. This zone is interpreted to extend towards the base of the seismogenic crust given that its width is comparable to (1) the Alpine Fault low-velocity zone detected by fault zone guided waves and (2) damage zones reported from other exhumed large-displacement faults. In summary, a narrow zone of fracturing at the base of the Alpine Fault's hanging-wall seismogenic crust is anticipated to widen at shallow depths, which is consistent with fault zone flower structure models. © Author(s) 2018.
cited By 13
Keywords: Anisotropy; Core drilling; Damage detection; Drills; Fracture; Guided electromagnetic wave propagation; Hierarchical systems; Rock pressure; Fault zone structures; High confining pressure; Large displacements; Low confining pressure; Low velocity zones; Mechanical anisotropy; Parallel fractures; X-ray computed tomography; Computerized tomography; brittle fracture; data set; fault zone; foliation; fracture orientation; hanging wall; permeability; seismic velocity; Alpine Fault Zone; New Zealand; South Island

Comment on “The Campi Flegrei Deep Drilling Project (CFDDP): New Insight on Caldera Structure, Evolution and Hazard Implications for the Naples Area (Southern Italy)” by G. De Natale et al. - Torrente, Maurizio M.; Milia, Alfonsa (Geochemistry, Geophysics, Geosystems, 2018)
The paper by De Natale et al. (2016, https://doi.org/10.1002/2015GC006183) reported new stratigraphic and geochronological data for a borehole located at Campi Flegrei volcanic area. The authors failed to mention several significant articles on the geological evolution of the region and proposed an interpretation of their data according to the caldera model. Herein, we provide tectonic and stratigraphic data to support a fault model of ignimbrite emission. This comment will also show the inconsistency of the proposed Campi Flegrei caldera. ©2018. American Geophysical Union. All Rights Reserved.
Keywords: Geochronology; Stratigraphy; Caldera; Campi Flegrei; Deep drilling; Fault model; Geological evolution; Southern Italy; Stratigraphic data; Volcanic areas; Faulting

Colorado Plateau Coring Project, Phase I (CPCP-I): A continuously cored, globally exportable chronology of Triassic continental environmental change from western North America - Olsen, P.E.; Geissman, J.W.; Kent, D.V.; Gehrels, G.E.; Mundil, R.; Irmis, R.B.; Lepre, C.; Rasmussen, C.; Giesler, D.; Parker, W.G.; Zakharova, N.; K{urschner, W.M.; et al. (Scientific Drilling, 2018)
Phase 1 of the Colorado Plateau Coring Project (CPCP-I) recovered a total of over 850m of stratigraphically overlapping core from three coreholes at two sites in the Early to Middle and Late Triassic age largely fluvial Moenkopi and Chinle formations in Petrified Forest National Park (PFNP), northeastern Arizona, USA. Coring took place during November and December of 2013 and the project is now in its post-drilling science phase. The CPCP cores have abundant detrital zircon-producing layers (with survey LA-ICP-MS dates selectively resampled for CA-ID-TIMS U-Pb ages ranging in age from at least 210 to 241 Ma), which together with their magnetic polarity stratigraphy demonstrate that a globally exportable timescale can be produced from these continental sequences and in the process show that a prominent gap in the calibrated Phanerozoic record can be filled. The portion of core CPCP-PFNP13-1A for which the polarity stratigraphy has been completed thus far spans 215 to 209Ma of the Late Triassic age, and strongly validates the longer Newark-Hartford Astrochronostratigraphic-calibrated magnetic Polarity Time-Scale (APTS) based on cores recovered in the 1990s during the Newark Basin Coring Project (NBCP). Core recovery was 100% in all holes (Table 1). The coreholes were inclined 60-75° approximately to the south to ensure azimuthal orientation in the nearly flat-lying bedding, critical to the interpretation of paleomagentic polarity stratigraphy. The two longest of the cores (CPCP-PFNP13-1A and 2B) were CT-scanned in their entirety at the University of Texas High Resolution X-ray CT Facility in Austin, TX, and subsequently along with 2A, all cores were split and processed at the CSDCO/LacCore Facility, in Minneapolis, MN, where they were scanned for physical property logs and imaging. While remaining the property of the Federal Government, the archive half of each core is curated at the NSF-sponsored LacCore Core Repository and the working half is stored at the Rutgers University Core Repository in Piscataway, NJ, where the initial sampling party was held in 2015 with several additional sampling events following. Additional planned study will recover the rest of the polarity stratigraphy of the cores as additional zircon ages, sedimentary structure and paleosol facies analysis, stable isotope geochemistry, and calibrated XRF core scanning are accomplished. Together with strategic outcrop studies in Petrified Forest National Park and environs, these cores will allow the vast amount of surface paleontological and paleoenvironmental information recorded in the continental Triassic of western North America to be confidently placed in a secure context along with important events such as the giant Manicouagan impact at 215:5 Ma (Ramezani et al., 2005) and long wavelength astronomical cycles pacing global environmental change and trends in atmospheric gas composition during the dawn of the dinosaurs. © Author(s) 2018.
cited By 17
Keywords: Computerized tomography; Exploratory geochemistry; Forestry; Lead alloys; Recovery; Sedimentology; Silicate minerals; Stratigraphy; Thallium alloys; Zircon; Additional sampling; Azimuthal orientation; Environmental change; Federal governments; Global environmental change; Rutgers University; Sedimentary structure; University of Texas; Magnetic polarity

Clay mineralogy of the first and second members of the Nenjiang Formation, Songliao Basin: Implications for paleoenvironment in the Late Cretaceous - Gao, Y.; Xi, D.P.; Qin, Z.H.; Ma, P.F.; Wang, C.S. (Science China Earth Sciences, 2018)
The first and second members of the Nenjiang Formation (K2n1+2) in the Songliao Basin, northeast China, are an interval of dark-colored mudstone. Paleoenvironmental studies of these strata are useful for understanding the terrestrial environment under a greenhouse climate and hydrocarbon accumulation in lake basins. In this study, clay mineralogy of the K2n1+2 from four borehole or outcrop sections is investigated to understand terrestrial paleoenvironment during the depositional period in the Late Cretaceous. In the mudstone samples, smectite and illite are the predominant clay minerals, and were derived from weathering of parent rocks in a temperate, sub-humid to sub-arid climate; kaolinite and chlorite are minor clay species. The difference in the clay-mineral assemblages between the eastern and western margins of the basin was primarily controlled by provenance lithology, and the high smectite content in the western basin resulted from alteration of volcanic rocks exposed in the Greater Xing’an Range area. The increasing illite content and ratio of illite/smectite percentages in the upper part of the first member of the Nenjiang Formation indicate paleoenvironmental change. This temporal change in the clay-mineral composition was primarily caused by a regionally cooler and drier paleoclimate, consistent with previous paleoenvironmental reconstructions. © 2017, Science China Press and Springer-Verlag GmbH Germany, part of Springer Nature.
cited By 11
Keywords: Clay alteration; Kaolinite; Lithology; Minerals; Sedimentary rocks; Volcanic rocks; Weathering; Clay mineral assemblages; Clay mineral compositions; Late cretaceous; Nenjiang Formation; Paleo-environment; Paleoenvironmental change; Paleoenvironmental reconstruction; Songliao basin; Clay minerals; clay mineral; Cretaceous; illite; lithology; mudstone; paleoenvironment; parent body; smectite; weathering; China; Songliao Basin

Chronological evolution of some morphological, tectonic and volcanic features in Lake Van, based on correlation of seismic and core data - Damcı, E.; Çağatay, M.N. (Quaternary International, 2018)
The Lake Van is the largest Lake in Turkey and the fourth largest soda lake in the World. High resolution (HR) seismic data acquired during 2012 reveals sub-lacustrine terraces, delta clinoforms, channel-networks, active faults and volcanic edifices. The seismic data were correlated with the cores recovered during the 2008 coring and 2010 ICDP PaleoVan drilling campaigns, using synthetic seismograms produced from the MSCL data of the age-modelled cores, thus allowing to date seismic reflector surfaces and to discuss the temporal evolution of the some of the morphological features and structures. Sub-lacustrine channel-network systems are well developed on the shelf areas connect with the river drainage systems on land and extend to water depths of more than 100 m. These drainage systems developed during the major low-stand periods of Lake Van, the last two of which occurred during 15 ka BP and the Younger Dryas with water levels at −200 m and −70 m, respectively. High lake levels similar to today during the early Holocene were followed by lake level oscillations with some low-stands during the Late Holocene. The low stands are characterized by terraces and berms located at 15 m below lake surface (mbls), 25 mbls, 35 mbls and 60 mbls, 70 mbls and 105 mbls. They were most likely related to the rapid climate change (RCC) events such as the 4.2 ka aridity event, Dark Age Cold Period, Medieval Warm Period and Little Ice. The volcanic features are located along the Southern Boundary Fault (SBF). A significant NW-SE trending active fault in the eastern shelf left-laterally offsets a channel by about 500 m and has a small reverse component in the HR seismic profiles. This fault is considered to be the source of Mw = 5.7 Edremit Earthquake of 9 November 2011. NW-SE trending normal faults with a right-lateral strike slip component north of the Northern Basin provides extension in the area. Normal faults are also dominant in the Erciş Strait. Using ages of reflector surfaces we estimate a vertical slip rate of 0.40 mm/yr to ∼0.5 mm/yr on the normal faults in the shelf areas over the last 2 –3 ka. © 2017 Elsevier Ltd and INQUA
cited By 2
Keywords: active fault; chronology; climate variation; correlation; geomorphology; Holocene; paleoclimate; seismic data; seismic reflection; seismogram; tectonic setting; Lake Van; Turkey

Characteristics of top boundary of Shahezi Formation in Xujiaweizi fault depression, northern Songliao Basin: Illustrated by continental scientific drilling borehole SK2 - Honghao, Li; GaoYoufeng, WangPujun; Xuejiao, Qu; Xiang, Gao; Haichao, Chen (Global Geology, 2018)

Cementing technology for ultra-high temperature well Songke-2 - Shaoli, LI; Shaoguang, SONG (钻井液与完井液, 2018)
A cement slurry used to deal with difficulties cementing the exploratory well Songke-2 in main land China, has been formulated with a quadripolymer filter loss reducer and a terpolymer phosphonate retarding agent to improve its thermal stability and avoid the risks of “thermal thinning” of the cement slurry. The filter loss and thickening time of the cement slurry were controlled to satisfy the needs of cementing ultra-high temperature wells by adjusting the concentrations of the two additives. Meanwhile, based on particle sizing and the close-packing principle, the particle sizes and concentration of silica sand were optimized, adjusting the ratio of silicon over calcium closing to 1, thereby preventing the decaying of the late-stage strength of set cement at ultra-high temperatures. Furthermore, an elastic tough material developed with particles and fibers was used to enhance the elasticity and toughness of the cement slurry. By optimizing the ratio of these additives, a cement slurry able to tolerate 260 ℃ well temperature was designed. This cement slurry has good stability, density difference between the upper and the lower parts of the cement slurry less than 0.03 g/cm3, thickening time between 200 min and 420 min, filter loss less than 100 mL, 48 h compressive strength greater than 20 MPa, and 7 d compressive strength greater than 38 MPa. The late-stage strength of the set cement is not declining. By optimizing the liner hanging and cementing techniques, and strictly controlling cement slurry density, the integrity of the formations penetrated by the well was maintained, without being fractured during cementing operations. Using high temperature high efficiency flushing spacers, the displacing efficacy was increased, and job safety and cementing job quality were ensured. Well cementing has been performed successfully with high job quality on the Well Songke-2, whose static bottom hole temperature is 260 ℃, and circulating bottom hole temperature 210 ℃. © 2018, The Editorial Board of Drilling Fluid & Completion Fluid. All right reserved.

Depositional processes of impactites from the YAX-1 drill core in the Chicxulub impact structure inferred from vertical profiles of PDF orientations and grain size distributions of shocked quartz - Chang, Y.; Goto, K.; Sekine, Y.; Tajika, E. (Meteoritics and Planetary Science, 2018)
Core samples from the Chicxulub impact structure provide insights into the formation processes of a shallow-marine-target, complex crater. Although previous studies investigated the impactites (generally suevitic and polymict breccias) of the Yaxcopoil-1 (YAX-1) drill core in the Chicxulub impact structure, the interpretation of its deposition remains controversial. Here, we analyze planar deformation features (PDFs), grain size, and abundance of shocked quartz throughout the YAX-1 impactite sequence (794 –895 m in depth). PDF orientations of most quartz grains in YAX-1 impactites show a distribution of both low angles (10 (Formula presented.) 4, 10 (Formula presented.) 3, 10 (Formula presented.) 2) and high angles (orientations higher than 55° to c-axis), while the lower part of the impactite sequence contains quartz showing only PDF orientations of low angles. High-abundance, coarse-grained shocked quartz is found from the lower to middle parts of the impactites, whereas it abruptly changes to low-abundance, fine-grained shocked quartz within the upper part. In the uppermost part of the impactites, repeated oscillations in contents of these two components are observed. PDF orientation pattern suggests most of the shocked quartz grains experienced a range of shock pressure, except two samples in the lower part of impactites, which experienced only a high level of shock. We suggest that the base and lower part of the impactite sequence were formed by ejecta curtain and melt surge deposits, respectively. Our results are also consistent with the interpretation that the middle part of the impactite sequence is fallback ejecta from the impact plume. Additionally, we support the contention that massive seawater resurges into the crater occurred during the deposition of the upper and uppermost part of the impactites. © The Meteoritical Society, 2018.
cited By 2

Carbon dioxide generation and drawdown during active orogenesis of siliciclastic rocks in the Southern Alps, New Zealand - Menzies, C.D.; Wright, S.L.; Craw, D.; James, R.H.; Alt, J.C.; Cox, S.C.; Pitcairn, I.K.; Teagle, D.A.H. (Earth and Planetary Science Letters, 2018)
Collisional mountain building influences the global carbon cycle through release of CO2 liberated by metamorphic reactions and promoting mechanical erosion that in turn increases chemical weathering and drawdown of atmospheric CO2. The Southern Alps is a carbonate-poor, siliciclastic mountain belt associated with the active Australian Pacific plate boundary. On-going, rapid tectonic uplift, metamorphism and hydrothermal activity are mobilising carbon. Here we use carbon isotope measurements of hot spring fluids and gases, metamorphic host rocks, and carbonate veins to establish a metamorphic carbon budget. We identify three major sources for CO2 within the Southern Alps: (1) the oxidation of graphite; (2) consumption of calcite by metamorphic reactions at the greenschist –amphibolite facies boundary, and (3) the dissolution of groundmass and vein-hosted calcite. There is only a minor component of mantle CO2 arising on the Alpine Fault. Hot springs have molar HCO3 −/Ca2+ ∼9, which is substantially higher than produced by the dissolution of calcite indicating that deeper metamorphic processes must dominate. The total CO2 flux to the near surface environment in the high uplift region of the Southern Alps is estimated to be ∼6.4 × 108 mol/yr. Approximately 87% of this CO2 is sourced from coupled graphite oxidation (25%) and disseminated calcite decarbonation (62%) reactions during prograde metamorphism. Dissolution of calcite and mantle-derived CO2 contribute ∼10% and ∼3% respectively. In carbonate-rich orogens CO2 production is dominated by metamorphic decarbonation of limestones. The CO2 flux to the atmosphere from degassing of hot springs in the Southern Alps is 1.9 to 3.2 × 108 mol/yr, which is 30 –50% of the flux to the near surface environment. By contrast, the drawdown of CO2 through surficial chemical weathering ranges between 2.7 and 20 × 109 mol/yr, at least an order of magnitude greater than the CO2 flux to the atmosphere from this orogenic belt. Thus, siliciclastic mountain belts like the Southern Alps are net sinks for atmospheric CO2, in contrast to orogens involving abundant carbonate rocks, such as the Himalaya, that are net CO2 sources. © 2017 The Author(s)
cited By 9
Keywords: Atmospheric chemistry; Budget control; Calcite; Carbonation; Dissolution; Geochemistry; Graphite; Hot springs; Isotopes; Landforms; Metamorphic rocks; Weathering; Carbon cycles; Carbon isotopes; Chemical weathering; metamorphism; Mountain building; Carbon dioxide; carbon budget; carbon cycle; carbon dioxide; carbon isotope; chemical weathering; host rock; metamorphism; orogeny; siliciclastic deposit; thermal spring; vein (geology); New Zealand; South Island; Southern Alps

Asteroids and associated mineral systems: By Franco Pirajno - Glikson, A.Y.; Pirajno, F. (Modern Approaches in Solid Earth Sciences, 2018)
In this chapter we discuss hydrothermal and metasomatic processes that have taken place in impact structures, subsequent to the collapse of the transient cavity and the cooling of the melt sheet and melt rocks. Most of what follows is drawn from Pirajno et al. (Aust J Earth Sci 50:775 –796, 2003), Pirajno (Aust J Earth Sci 52:587 –620, 2005) and Pirajno and Van Kranendonk (Aust J Earth Sci 52:329 –352, 2005), particularly for the Australian examples. The flow of hot aqueous solutions commonly results in the formation of mineral deposits. Therefore, knowledge of post-impact hydrothermal activity is important because it may have resulted in economic mineral deposits. The world-class and widely known Sudbury mineral deposits (Ni, Cu, PGE, Pb, Zn, Au) are perhaps the best and most celebrated expression of mineralization directly related to a meteorite impact (Lightfoot, Nickel sulfide ores and impact melts – origin of the Sudbury Igneous Complex. Elsevier, Amsterdam, 662pp, 2016). Several lines of evidence suggest that the giant gold deposits of the Witwatersrand in South Africa may have been reworked or even enhanced by the effects of the large Vredefort impact structure. These cases will be examined briefly in the sections that follow. Hydrothermal circulation systems associated with impact events have been reported from the Ries (Germany), Puchezh-Katunki (Russia), J{amtland (Sweden), Roter Kamm (Namibia), Manson (USA), the above-mentioned Vredefort, K{ardla (Estonia), Sudbury and Haughton (Canada) structures (Newsom et al., J Geophys Res 91:E239 –E251, 1986; Koeberl et al., Geoch Cosmo Acta 53:2113 –2118, 1989; Naumov, Meteoritics 28:408 –409, 1993; Sturkel et al., Eur J Miner 10: 589 –609, 1998; Ames et al., Geology 26: 447 –450, 1998; McCarville and Crossey, Geol Soc Am Sp Pap 302:347 –379, 1996); Grieve and Thierriault, Annu Rev Earth Planet Sci 28: 305 –338, 2000; Osinski et al., Meteor Planet Sci 36:731 –745, 2001; Moln'ar et al., Econ Geol 96:1645 –1670, 2001; Puura et al., Impact-induced replacement of plagioclase by K-feldspar in granitoids and amphibolites at the K{ardla crater, Estonia. In: Gilmour I, Koeberl C (eds) Impacts and the early earth. Springer-Verlag, Berlin, pp 417 –445, 2000 and Geochemistry of K-enriched impactites, based on drillings into the K{ardla Crater, Estonia. Geol Soc Am Abs with Programs, Denver, Oct. 2002, p 341, 2002). Recently, aspects of hydrothermal alteration in the Chicxulub impact structure have been published in Meteoritic and Space Science (L{uders and Rickers, Meteor Planet Sci 39:1187 –1198, 2004; Z{urcher and Kring, Meteor Planet Sci 39:1199 –1222, 2004; Goto et al., Meteor Planet Sci 39:1233 –1247, 2004). © 2018, Springer International Publishing AG.
cited By 0

Archie's Saturation Exponent for Natural Gas Hydrate in Coarse-Grained Reservoirs - Cook, A.E.; Waite, W.F. (Journal of Geophysical Research: Solid Earth, 2018)
Accurately quantifying the amount of naturally occurring gas hydrate in marine and permafrost environments is important for assessing its resource potential and understanding the role of gas hydrate in the global carbon cycle. Electrical resistivity well logs are often used to calculate gas hydrate saturations, Sh, using Archie's equation. Archie's equation, in turn, relies on an empirical saturation parameter, n. Though n = 1.9 has been measured for ice-bearing sands and is widely used within the hydrate community, it is highly questionable if this n value is appropriate for hydrate-bearing sands. In this work, we calibrate n for hydrate-bearing sands from the Canadian permafrost gas hydrate research well, Mallik 5L-38, by establishing an independent downhole Sh profile based on compressional-wave velocity log data. Using the independently determined Sh profile and colocated electrical resistivity and bulk density logs, Archie's saturation equation is solved for n, and uncertainty is tracked throughout the iterative process. In addition to the Mallik 5L-38 well, we also apply this method to two marine, coarse-grained reservoirs from the northern Gulf of Mexico Gas Hydrate Joint Industry Project: Walker Ridge 313-H and Green Canyon 955-H. All locations yield similar results, each suggesting n ≈ 2.5 ± 0.5. Thus, for the coarse-grained hydrate bearing (Sh > 0.4) of greatest interest as potential energy resources, we suggest that n = 2.5 ± 0.5 should be applied in Archie's equation for either marine or permafrost gas hydrate settings if independent estimates of n are not available. ©2018. American Geophysical Union. All Rights Reserved.
cited By 76
Keywords: carbon cycle; electrical resistivity; gas hydrate; hydrocarbon reservoir; marine environment; natural gas; permafrost; saturation; wave velocity; Atlantic Ocean; Gulf of Mexico

Analysis of a fragmentary diatom record from Lake Van (Turkey) reveals substantial lake-level variability during previous interglacials MIS7 and MIS5e - North, S.M.; Stockhecke, M.; Tomonaga, Y.; Mackay, A.W. (Journal of Paleolimnology, 2018)
Ancient lake sediments provide opportunities to reconstruct aquatic ecosystems during previous interglacials. In the summer of 2010, the ICDP project PALEOVAN drilled a complete succession of the lacustrine sedimentary sequence deposited during the last 600,000 years in Lake Van, eastern Anatolia (Turkey). Previous palaeolimnological analysis of the Lake Van sediment record has shown diatoms to be absent over most of the sequence apart from a short interval during the Holocene. Here, we demonstrate the preservation of additional fragmentary diatom records during Marine Isotope Stage (MIS) 7 (243,000 –191,000 years ago; Lisiecki and Raymo in Paleoceanography 20:PA1003, 2005; Jouzel et al. in Science 317:793 –796, 2007) and MIS5e (130,000 –116,000 years ago; Lisiecki and Raymo 2005; Jouzel et al. 2007), each spanning no more than a few thousand years. Although brief, the presence of contrasting diatom assemblages between these two interglacials provide a snapshot of varying water depth and, by inference, climate. Analysis of MIS7e samples suggests that lake water levels were low after a period when the lake was open (i.e., high lake levels with the presence of an outflow present), resulting in higher salinities and possibly less stable bottom waters, which switched between anoxic and oxic states more frequently. By contrast, the diatom assemblages during MIS5e are characteristic of fresh, relatively nutrient rich waters. This suggests that lake levels were high, that the lake was hydrologically open with an outlet, and that the bottom waters were anoxic for long periods of time. Furthermore, our palaeoconductivity estimates and modelling of the past lake volumes with respect to its salt content support the presence of an outflow. © 2017, The Author(s).
cited By 10
Keywords: biostratigraphy; chemical environmental conditions; deposition; depositional environment; diatom; dissolution; fossil record; Holocene; interglacial; lacustrine deposit; lake ecosystem; lake level; marine isotope stage; paleohydrology; paleolimnology; project assessment; salinity; sedimentary sequence; water depth; Anatolia; Lake Van; Turkey; Bacillariophyta

Abrupt or gradual? Change point analysis of the late Pleistocene-Holocene climate record from Chew Bahir, southern Ethiopia - Trauth, M.H.; Foerster, V.; Junginger, A.; Asrat, A.; Lamb, H.F.; Schaebitz, F. (Quaternary Research (United States), 2018)
We used a change point analysis on a late Pleistocene-Holocene lake-sediment record from the Chew Bahir basin in the southern Ethiopian Rift to determine the amplitude and duration of past climate transitions. The most dramatic changes occurred over 240 yr (from 15,700 to 15,460 yr) during the onset of the African Humid Period (AHP), and over 990 yr (from 4875 to 3885 yr) during its protracted termination. The AHP was interrupted by a distinct dry period coinciding with the high-latitude Younger Dryas stadial, which had an abrupt onset (less than 100 yr) at 13,260 yr and lasted until 11,730 yr. Wet-dry-wet transitions prior to the AHP may reflect the high-latitude Dansgaard-Oeschger cycles, as indicated by cross-correlation of the potassium record with the NorthGRIP ice core record between 45-20 ka. These findings may contribute to the debates regarding the amplitude, and duration and mechanisms of past climate transitions, and their possible influence on the development of early modern human cultures. © University of Washington. Published by Cambridge University Press, 2018.
cited By 19
Keywords: Hierarchical systems; Principal component analysis; Change-point analysis; Dansgaard-Oeschger cycles; Holocenes; Humid periods; Late Pleistocene; Paleoclimatology; Southern Ethiopian Rift; Younger Dryas; Climate change

Abnormally high natural radioactivity zones in the main borehole of the Continental Scientific Drilling Project of Cretaceous Songliao Basin: Geophysical log responses and genesis analysis [松科2井东孔营城组高放射性异常层测井响应特征及成因初探] - Zhang, S.; Zou, C.; Peng, C.; Zhao, J.; Li, N.; Zhang, X.; Ma, H.; Niu, Y. (Acta Geophysica Sinica, 2018)
SK-2 East Borehole (SK-2e) is the main borehole of Continental Scientific Drilling Project of Cretaceous Songliao Basin, which is designed to acquire the geophysical log data in the whole borehole, to provide accurate, comprehensive geophysical information for resource exploration and research on paleoclimate and paleoenvironment. Among various well logging methods, natural gamma-ray logging and natural gamma-ray spectral logging can measure natural gamma-ray intensity and uranium (U), thorium (Th), potassium (K) contents, and are effectively applied to radioactive deposit exploration, especially to uranium exploration and research. Conventional logging (including resistivity, acoustic, density and neutron logging) and special logging (including nuclear magnetic resonance, resistivity imaging and elemental capture spectroscopy logging) can obtain lithologic and physical parameters of strata, offering strong support for uranium exploration. In this study, the natural gamma-ray log data was used to identify abnormally high natural radioactivity zones. Based on conventional log data, special log data and previous geological research achievements, the characteristics and genesis of radioactive abnormality were analyzed. The results show that two abnormally high natural radioactivity zones are located in deep-seated Yingcheng Formation. And their depths are 3096.8 3102.8m (Layer I) and 3168.3 3170.9 m (Layer II) respectively. According to the comprehensive analysis of various log data and core data, Layer I is conglomerate, with the maximum gamma of 360 API and high uranium content (20.5 29.3 ppm). Therefore, Layer I has uranium mineralization potential. Analysis shows that tectonic conditions and epigenetic alteration are probably the key factors affecting uranium enrichment which causes abnormally high gamma-ray intensity. It was speculated that fault movements, volcanic activity, and the basin's uplift and erosion provide uranium-bearing groundwater, oil and gas with the migration channel to I layer. The epigenetic reduction of oil and gas eventually leads to uranium enrichment of Layer I. Layer II consists of agglomerate lava and tuff, with the maximum gamma of 250 API, high thorium content (22.4 37.3 ppm) and high uranium content (5.9 11.0 ppm). The rhyolitic components of high thorium content and uranium adsorption by clay minerals may cause the abnormally high gamma-ray intensity in Layer II. The abnormally high radioactivity zones of Yingcheng Formation in SK-2e are characterized by deep burial depths and high uranium contents, indicating uranium prospecting potential in deep zones of Songliao Basin. © 2018, Science Press. All right reserved.
cited By 5
Keywords: Acoustic logging; Acoustic spectroscopy; Boreholes; Boring; Core analysis; Gamma rays; Geophysics; Groundwater; Infill drilling; Neutron logging; Nuclear magnetic logging; Nuclear magnetic resonance spectroscopy; Petroleum prospecting; Radioactivity; Uranium; Continental scientific drillings; Elemental capture spectroscopy; Genesis; Geophysical information; Log response; Natural radioactivity; Songliao basin; Uranium mineralization; Oil well logging; abnormality; adsorption; borehole; Cretaceous; geophysical survey; mineralization; nutrient enrichment; paleoclimate; potassium; radioactivity; radionuclide; thorium; uranium; well logging; China; Songliao Basin

A unified effective medium model for gas hydrates in sediments - Terry, D.A.; Knapp, C.C. (Geophysics, 2018)
A unified effective medium model is developed to incorporate the endpoints of perfectly smooth and infinitely rough sphere components and to allow partitioning between rough and smooth grains. We incorporate the unified model into the framework for gas hydrates in unconsolidated sediments using pore-fluid and rock-matrix configurations for grain placement, while reviewing other developments that have taken place in the past four decades. The unified rock-matrix model is validated with data available from the 2002 Mallik gas hydrates project well 5L-38. Gas-hydrate saturation and neutron-porosity logs from this well are used to generate synthetic P- and S-wave velocity models for several values of the friction coefficient. First, we overlaid crossplots of P- versus S-wave velocities for synthetic and measured velocities, and we compared the match until a good choice was found for the friction coefficient. Second, we plotted the synthetic velocities as separate logs of P- and S-wave velocities for each friction coefficient; the synthetic velocity logs were then overlaid on the measured velocities calculated from the sonic logs. Results of a direct comparison of the synthetic and measured velocity logs provide valuable insights into the validation of the unified effective medium model. Recognizing the significance of the Hertz-Mindlin-type effective medium models for gas hydrates in unconsolidated sediments, we incorporate the previous efforts into a single unified model and define a common nomenclature. Although we attempt to assign a single friction coefficient value to each hydrate window, it is not surprising that in a real and heterogeneous environment, the value might vary with depth, as it does here at the larger spatial scales. We determine and quantitatively estimate that gas hydrates in sediments are well-predicted with a friction coefficient closer to a smooth sphere model than a rough sphere model. © 2018 Society of Exploration Geophysicists. All rights reserved.
cited By 8
Keywords: Algorithms; Elastic moduli; Friction; Gases; Hydration; Models; Neutron logging; Sediments; Shear waves; Spheres; Velocity; Wave propagation; Effective medium model; Friction coefficients; Gas hydrate saturations; Heterogeneous environments; Neutron porosity logs; P- and S-wave velocities; Rock physics; Unconsolidated sediment; Gas hydrates; algorithm; bulk modulus; gas hydrate; numerical model; P-wave; S-wave; sediment analysis; shear modulus; surface roughness; wave velocity

A study of secondary pyrite deformation and calcite veins in SAFOD damage zone with implications for aseismic creep deformation mechanism at depths >3 km - Hadizadeh, J.; Boyle, A.P. (Journal of Structural Geology, 2018)
Previous studies of the San Andreas Fault damage-zone samples from the San Andreas Fault Observatory at Depth (SAFOD) have identified a variety of tectonic microstructures including pressure solution cleavage, calcite-sealed fractures vein fabric, and pyrite and anhydrite hydrothermal fracture sealing. Understanding the deformation provenance of the damage zone rocks and operative deformation mechanism(s) based on preserved microstructures provide insight into overall deformation behavior of the entire seismogenic zone in the creeping section of this transform fault. We analysed the deformation of hydrothermal secondary pyrite in connection with network of calcite veins in a sample of foliated ultracataclasites bordering the actively creeping Southwestern Deforming Zone (SDZ), using SEM, EBSD and CL microscopy. The results show that calcite veins associated with the pressure solution cleavage are crosscut by the secondary pyrite deformed under a range of P-T conditions. Relatively undeformed secondary pyrite is found sealing implosion microbreccia. Our review of previously available data indicates that the damage zone rocks may represent a collage of structural and compositional domains from both locked and creeping sections of the SAF. This interpretation together with results of this study suggest that weak-clay frictional deformation mechanism(s) is likely to be the predominant aseismic creep mechanism at depths below the SAFOD. © 2018
cited By 2
Keywords: Calcite; Microstructure; Pyrites; Strike-slip faults; Structural geology; Transform faults; Aseismic creep in the SAF; Calcite veins; Creep deformation mechanisms; Deformation behavior; Deformation mechanism; Pressure solution; SAFOD; Seismogenic zones; Creep; calcite; cathodoluminescence; creep; deformation mechanism; pressure solution; pyrite; vein (geology)

A new approach to probabilistic lava flow hazard assessments, applied to the Idaho National Laboratory, eastern Snake River Plain, Idaho, USA - Gallant, E.; Richardson, J.; Connor, C.; Wetmore, P.; Connor, L. (Geology, 2018)
We present a new probabilistic lava flow hazard assessment for the U.S. Department of Energy's Idaho National Laboratory (INL) nuclear facility that (1) explores the way eruptions are defined and modeled, (2) stochastically samples lava flow parameters from observed values for use in MOLASSES, a lava flow simulator, (3) calculates the likelihood of a new vent opening within the boundaries of INL, (4) determines probabilities of lava flow inundation for INL through Monte Carlo simulation, and (5) couples inundation probabilities with recurrence rates to determine the annual likelihood of lava flow inundation for INL. Results show a 30% probability of partial inundation of the INL given an effusive eruption on the eastern Snake River Plain, with an annual inundation probability of 8.4 × 10-5 to 1.8 × 10-4. An annual probability of 6.2 × 10-5 to 1.2 × 10-4 is estimated for the opening of a new eruptive center within INL boundaries. © 2018 Geological Society of America.
cited By 15
Keywords: Floods; Intelligent systems; Monte Carlo methods; Probability; Annual probabilities; Effusive eruptions; Hazard Assessment; Idaho national laboratories; Nuclear facilities; Recurrence rates; Snake river plains; U.S. Department of Energy; Hazards

A MIS 9/MIS 8 speleothem record of hydrological variability from Macedonia (F.Y.R.O.M.) - Regattieri, Eleonora; Zanchetta, Giovanni; Isola, Ilaria; Bajo, Petra; Perchiazzi, Natale; Drysdale, Russell N.; Boschi, Chiara; Hellstrom, John C.; Francke, Alexander; Wagner, Bernd (Global and Planetary Change, 2018)

A leaf wax biomarker record of early Pleistocene hydroclimate from West Turkana, Kenya - Lupien, R.L.; Russell, J.M.; Feibel, C.; Beck, C.; Castaneda, I.; Deino, A.; Cohen, A.S. (Quaternary Science Reviews, 2018)

A high-resolution, 60 kyr record of the relative geomagnetic field intensity from Lake Towuti, Indonesia - Kirana, Kartika Hajar; Bijaksana, Satria; King, John; Tamuntuan, Gerald Hendrik; Russell, James; Ngkoimani, La Ode; Dahrin, Darharta; Fajar, Silvia Jannatul (Physics of the Earth and Planetary Interiors, 2018)
Past changes in the Earth's magnetic field can be highlighted through reconstructions of magnetic paleointensity. Many magnetic field variation features are global, and can be used for the detailed correlation and dating of sedimentary records. On the other hand, sedimentary magnetic records also exhibit features on a regional, rather than a global scale. Therefore, the development of regional scale magnetic field reconstructions is necessary to optimize magnetic paleointensity dating. In this paper, a 60 thousand year (kyr) paleointensity record is presented, using the core TOW10-9B of Lake Towuti, located in the island of Sulawesi, Indonesia, as a part of the ongoing research towards understanding the Indonesian environmental history, and reconstructing a high-resolution regional magnetic record from dating the sediments. Located in the East Sulawesi Ophiolite Belt, the bedrock surrounding Lake Towuti consists of ultramafic rocks that render the lake sediments magnetically strong, creating challenges in the reconstruction of the paleointensity record. These sediment samples were subject to a series of magnetic measurements, followed by testing the obtained paleointensity records resulting from normalizing natural remanent magnetization (NRM) against different normalizing parameters. These paleointensity records were then compared to other regional, as well as global, records of magnetic paleointensity. The results show that for the magnetically strong Lake Towuti sediments, an anhysteretic remanent magnetization (ARM) is the best normalizer. A series of magnetic paleointensity excursions are observed during the last 60 kyr, including the Laschamp excursion at 40 kyr BP, that provide new information about the magnetic history and stratigraphy of the western tropical Pacific region. We conclude that the paleointensity record of Lake Towuti is reliable and in accordance with the high-quality regional and global trends. © 2017 Elsevier B.V.
Keywords: Greater Sunda Islands; Lake Towuti; Malili Lakes; South Sulawesi; Sulawesi; Sulawesi; Sunda Isles; Geomagnetism; Lakes; Lithology; Magnetic fields; Magnetization; Repair; Sedimentology; Sediments; Stratigraphy; Anhysteretic remanent magnetizations; Earth' s magnetic field; Environmental history; Laschamp excursions; Magnetic field variations; Natural remanent magnetization; Normalizing parameters; Relative paleointensity; geological record; geomagnetic field; lacustrine deposit; magnetic intensity; ophiolite; paleoenvironment; paleointensity; paleomagnetism; reconstruction; stratigraphic correlation; Magnetism

3.4 Ga biostructures from the Barberton greenstone belt of South Africa: New insights into microbial life; [Strutture biosedimentarie di 3.4 miliardi di anni fa del Barberton greenstone belt in Sudafrica: nuove prospettive sull’origine della biosfera primitiva] - Greco, Francesco; Cavalazzi, Barbara; Hofmann, Axel; Hickman-Lewis, Keyron (Bollettino della Societa Paleontologica Italiana, 2018)

Depositional environment of the Late Santonian lacustrine source rocks in the Songliao Basin (NE China): Implications from organic geochemical analyses - Tong, X.; Hu, J.; Xi, D.; Zhu, M.; Song, J.; Peng, P. (Organic Geochemistry, 2018)
The Songliao Basin (SLB) located in northeastern China is one of the largest Cretaceous continental sedimentary basins in the world. The SLB is filled with sediments deposited in the Upper Jurassic, the Lower Cretaceous and the Upper Cretaceous epochs. The Nenjiang Formation (K2n) is subdivided into five members, where Member 2 (K2n2) was deposited in the late Santonian in the lower part of the Nenjiang Formation. This member is characterized by a thick succession of organic-rich source rocks. However, the complexity of the depositional environment raises questions about the specific factors that drove this accumulation of organic material. Here, we present data on the total organic carbon (TOC) contents and their stable carbon isotope values (δ13Corg), as well as biomarker data from 50 outcrop samples collected from the Yuewangcheng (YWC) section, in the southeastern SLB. According to the variations of the bulk organic parameters (TOC and δ13Corg) and biomarker indices, the profile could be divided into three stages (stages I –III). The distribution of biomarkers (n-alkanes, steranes and hopanes) and δ13Corg values indicate that the organic matter (OM) in the Lower K2n2 is derived largely from algae and macrophytes, with a minor input from bacteria and land plants. The water column was stratified, as indicated by the presence of gammacerane. Variations in the pristane/phytane (Pr/Ph) and aryl isoprenoids relative to phenanthrene ratio (A-i/P) suggest that bottom waters were anoxic during Stage I (31.5 –26.0 m) and Stage II (26.0 –16.3 m), with the anoxic layer impinging on the euphotic zone and a relative oxic environment at Stage III (16.3 –0 m). This brackish environment persisted in the water over the interval represented by the section, as reflected by methytrimethyltridecyl chromans (MTTCs) Index (MTTCI) and α-MTTC/γ-MTTC ratios. Marine transgressions, with subsequent seawater incursions, can be detected with the presence of 24-n-propyl-cholestanes and 24-isopropyl-cholestanes in the Lower K2n2 sediments, especially during Stage I. These seawater incursions are closely correlated with anoxic conditions and the deposition of organic-rich source rocks. © 2018 Elsevier Ltd
cited By 31
Keywords: Analytical geochemistry; Biomarkers; Deposition; Paraffins; Seawater; Sediments; Depositional environment; Lacustrine source rocks; Marine transgression; Organic-rich sediment; Organic-rich source rock; Santonian; Stable carbon isotopes; Water columns; Organic carbon; anoxic conditions; biomarker; carbon isotope; Cretaceous; depositional environment; estuarine environment; euphotic zone; Jurassic; macrophyte; organic geochemistry; organic matter; outcrop; phenanthrene; Santonian; seawater; sediment chemistry; sedimentary basin; source rock; total organic carbon; water column; China; Songliao Basin; algae; Embryophyta

Changing flood frequencies under opposing late Pleistocene eastern Mediterranean climates - Ben Dor, Y.; Armon, M.; Ahlborn, M.; Morin, E.; Erel, Y.; Brauer, A.; Schwab, M.J.; Tjallingii, R.; Enzel, Y. (Scientific Reports, 2018)
Floods comprise a dominant hydroclimatic phenomenon in aridlands with significant implications for humans, infrastructure, and landscape evolution worldwide. The study of short-term hydroclimatic variability, such as floods, and its forecasting for episodes of changing climate therefore poses a dominant challenge for the scientific community, and predominantly relies on modeling. Testing the capabilities of climate models to properly describe past and forecast future short-term hydroclimatic phenomena such as floods requires verification against suitable geological archives. However, determining flood frequency during changing climate is rarely achieved, because modern and paleoflood records, especially in arid regions, are often too short or discontinuous. Thus, coeval independent climate reconstructions and paleoflood records are required to further understand the impact of climate change on flood generation. Dead Sea lake levels reflect the mean centennial-millennial hydrological budget in the eastern Mediterranean. In contrast, floods in the large watersheds draining directly into the Dead Sea, are linked to short-term synoptic circulation patterns reflecting hydroclimatic variability. These two very different records are combined in this study to resolve flood frequency during opposing mean climates. Two 700-year-long, seasonally-resolved flood time series constructed from late Pleistocene Dead Sea varved sediments, coeval with significant Dead Sea lake level variations are reported. These series demonstrate that episodes of rising lake levels are characterized by higher frequency of floods, shorter intervals between years of multiple floods, and asignificantly larger number of years that experienced multiple floods. In addition, floods cluster into intervals of intense flooding, characterized by 75% and 20% increased frequency above their respective background frequencies during rising and falling lake-levels, respectively. Mean centennial precipitation in the eastern Mediterranean is therefore coupled with drastic changes in flood frequencies. These drastic changes in flood frequencies are linked to changes in the track, depth, and frequency of mid-latitude eastern Mediterranean cyclones, determining mean climatology resulting in wetter and drier regional climatic episodes. © 2018 The Author(s).
cited By 19
Keywords: article; budget; climate change; flooding; human; hurricane; latitude; precipitation; sediment; time series analysis; Upper Pleistocene; watershed; Dead Sea

Design and application of an immersive virtual reality system to understanding the cores of the “SK2” (in Chinese with English abstract); [松科二井岩芯认知沉浸式虚拟现实系统设计与开发] - Liu, X.; Cui, L.; Guo, H.; Wang, Z.; Chen, K. (China Mining Magazine, 2018)

Experimental microbial alteration and Fe mobilization from basaltic rocks of the ICDP HSDP2 drill core, Hilo, Hawaii - Stranghoener, M.; Schippers, A.; Dultz, S.; Behrens, H. (Frontiers in Microbiology, 2018)
The interaction of a single bacterial species (Burkholderia fungorum) with basaltic rocks from the ICDP HSDP2 drill core and synthetic basaltic glasses was investigated in batch laboratory experiments to better understand the role of microbial activity on rock alteration and Fe mobilization. Incubation experiments were performed with drill core basaltic rock samples to investigate differences in the solution chemistry during biotic and abiotic alteration. Additionally, colonization experiments with synthetic basaltic glasses of different Fe redox states and residual stresses were performed to evaluate their influence on microbial activity and surface attachment of cells. In biotic incubation experiments bacterial growth was observed and the release of Fe and other major elements from drill core basaltic rocks to solution exceeded that of abiotic controls only when the rock sample assay was nutrient depleted. The concentration of dissolved major elements in solution in biotic colonization experiments with synthetic basaltic glasses increased with increasing residual stress and Fe(II) content. Furthermore, the concentration of dissolved Fe and Al increased similarly in biotic colonization experiments indicating that their dissolution might be triggered by microbial activity. Surface morphology imaging by SEM revealed that cells on basaltic rocks in incubation experiments were most abundant on the glass and surfaces with high roughness and almost absent on minerals. In colonization experiments, basaltic glasses with residual stress and high Fe(II) content were intensely covered with a cellular biofilm. In contrast, glasses with high Fe(III) content and no residual stress were sparsely colonized. We therefore conclude that structurally bound Fe is most probably used by B. fungorum as a nutrient. Furthermore, we assume that microbial activity overall increased rock dissolution as soon as the environment becomes nutrient depleted. Our results show that besides compositional effects, other factors such as redox state and residual stress can control microbial alteration of basaltic glasses. © 2018 Stranghoener, Schippers, Dultz and Behrens.
cited By 13
Keywords: glass; abiotic stress; Article; bacterial growth; biotic stress; chemical analysis; glucose intake; Gram negative bacterium; Hawaii; incubation time; microbial activity; microbial colonization; microbial growth; organismal interaction; pH; scanning electron microscopy

Improving geothermal economics by utilizing supercritical and superhot systems to produce flexible and integrated combinations of electricity, hydrogen, and minerals - Elders, Wilfred A.; Shnell, James; Friðleifsson, Guðmundur Ó.; Albertsson, Albert; Zierenberg, Robert A. (Transactions - Geothermal Resources Council, 2018)

Design and Application of Long Servce Life Bit in Hard Rock Drilling for SK-Ⅱ Well - Li, C; Shen, LN (Exploration Engineering (Rock & Soil Drilling and Tunneling), 2018)

Implementation Overview of Chinese Continental Scientific Drilling (CCSD) Project and Technical Systems of Core Boring (in Chinese with English abstract); [我国大陆科学钻探工程实施概况及其取心钻进技术体系] - Zhu, Y.; Wang, W.; Zhang, H.; Yan, J.; Cao, L.; Xu, J.; Meng, Q.; Tan, X. (Acta Geologica Sinica, 2018)

High-resolution reflection seismics reveal the structure and the evolution of the Quaternary glacial Tannwald Basin - Burschil, Thomas; Buness, Hermann; Tanner, David C.; Wielandt-Schuster, Ulrike; Ellwanger, Dietrich; Gabriel, Gerald (Near Surface Geophysics, 2018)

High-latitude vegetation and climate changes during the Mid-Pleistocene Transition inferred from a palynological record from Lake El'gygytgyn, NE Russian Arctic - Zhao, W.; Tarasov, P.E.; Lozhkin, A.V.; Anderson, P.M.; Andreev, A.A.; Korzun, J.A.; Melles, M.; Nedorubova, E.Y.; Wennrich, V. (Boreas, 2018)
A continuous pollen record from Lake El'gygytgyn (northeastern Russian Arctic) provides detailed information concerning the regional vegetation and climate history during the Mid-Pleistocene Transition (MPT), between 1091 ka (end of Marine Isotope Stage (MIS) 32) and 715 ka (end of MIS 18). Pollen-based qualitative vegetation reconstruction along with biome reconstruction indicate that the interglacial regional vegetation history during the MPT is characterized by a gradual replacement of forest and shrub vegetation by open herbaceous communities (i.e. tundra/cold steppe). The pollen spectra reveal seven vegetation successions that have clearly distinguishable glacial-interglacial cycles. These successions are represented by the intervals of cold deciduous forest (CLDE) biome scores changing from high to low, which are basically in phase with the variations of obliquity from maxima to minima. The dominating influence of obliquity forcing on vegetation successions contradicts with the stronger power of eccentricity, as demonstrated by the result of wavelet analysis based on landscape openness reconstruction. This discrepancy shows that a single index is insufficient for catching signals of all the impacting factors. Comparisons with vegetation and environmental changes in the Asian interior suggest that global cooling during the MPT was probably the key force driving long-term aridification in the Arctic region. The accelerated aridification after MIS 24 –22 was probably caused by the additional effect of the Tibetan Plateau uplift, which played an important role on intensification of the Siberian High and westerly jet systems. © 2017 Collegium Boreas. Published by John Wiley & Sons Ltd
cited By 13
Keywords: biome; climate variation; forest; herb; paleoclimate; palynology; Pleistocene; shrub; uplift; vegetation; Arctic; China; Chukchi; Elgygytgyn Lake; Qinghai-Xizang Plateau; Russian Federation

Heat flow and geothermal gradients of the Campania region (Southern Italy) and their relationship to volcanism and tectonics - Carlino, Stefano (Journal of Volcanology and Geothermal Research, 2018)
The heat flow and distribution of temperatures at depth in the Campania region were analysed and correlated with the volcanism and tectonics of the area. The temperature data, a part of the inventory of the AGIP, SAFEN and ENEL Companies (Inventario delle Risorse Geotermiche Nazionali), were gathered during drilling campaigns that began in 1940. The Campania region is characterised by the presence of two active and high-risk volcanic districts (the Campi Flegrei, Ischia and Vesuvius) emerging at the western boundary of the Campania Plain structural graben, and by the outcropping of the carbonate basement along the borders of the plain. The thermal anomalies have been correlated to different processes: the rising of the upper mantle (at about 20 km depth), the heat flow mass transport due to advection of hot fluids above magma reservoirs and the pure conductive heat transport of deeper crust. Furthermore, the presence of the carbonate basement has possibly buffered the deeper crustal thermal processes. The data also provided an estimation of the brittle-ductile transition zone that has been compared with the seismicity cut-off depth of the area. © 2018 Elsevier B.V.
Keywords: Campania [Italy]; Italy; Calluna vulgaris; Buildings; Heat transfer; Tectonics; Transport properties; Brittle-ductile transition zone; Campania; Distribution of temperature; Geothermal gradients; Magma reservoirs; Thermal anomalies; Volcanic district; Volcanism; geothermal gradient; heat flow; magma chamber; mass transport; tectonic evolution; temperature gradient; thermal convection; volcanism; Geothermal energy

Hadean zircon from a 3.3 Ga sandstone, Barberton greenstone belt, South Africa - Byerly, Benjamin L.; Lowe, Donald R.; Drabon, Nadja; Coble, Matthew A.; Burns, Dale H.; Byerly, Gary R. (Geology, 2018)

Gas and seismicity within the Istanbul seismic gap - G'eli, L.; Henry, P.; Grall, C.; Tary, J.-B.; Lomax, A.; Batsi, E.; Riboulot, V.; Cros, E.; G{urb{uz, C.; Işlk, S.E.; Sengor, A.M.C.; Le Pichon, X.; et al. (Scientific Reports, 2018)
Understanding micro-seismicity is a critical question for earthquake hazard assessment. Since the devastating earthquakes of Izmit and Duzce in 1999, the seismicity along the submerged section of North Anatolian Fault within the Sea of Marmara (comprising the Istanbul seismic gap) has been extensively studied in order to infer its mechanical behaviour (creeping vs locked). So far, the seismicity has been interpreted only in terms of being tectonic-driven, although the Main Marmara Fault (MMF) is known to strike across multiple hydrocarbon gas sources. Here, we show that a large number of the aftershocks that followed the M 5.1 earthquake of July, 25th 2011 in the western Sea of Marmara, occurred within a zone of gas overpressuring in the 1.5-5 km depth range, from where pressurized gas is expected to migrate along the MMF, up to the surface sediment layers. Hence, gas-related processes should also be considered for a complete interpretation of the micro-seismicity ( M < 3) within the Istanbul offshore domain. © 2018 The Author(s).
cited By 17
Keywords: article; earthquake; sediment; Turkey (republic); Marmara Sea

Formation of large-scale impact melt dikes: A case study of the Foy Offset Dike at the Sudbury impact structure, Canada - Pilles, E.A.; Osinski, G.R.; Grieve, R.A.F.; Smith, D.; Bailey, J. (Earth and Planetary Science Letters, 2018)
Hypervelocity impacts frequently result in the formation of dikes in the crater floor and central uplift. Impact melt-bearing dikes in large terrestrial impact basins – such as the Offset Dikes at the Sudbury impact structure – occur at a large scale, often tens of meters wide and several kilometers in length. The Offset Dikes host significant Ni –Cu –PGE deposits, which include several well-known mines, such as Totten and Copper Cliff that have been mined for nearly 100 years. The Offset Dikes typically consist of a clast- and sulfide-rich core and clast-poor margins. Their formation has been a subject of debate for decades. The most widely proposed model is the early emplacement of clast-poor impact melt shortly after the impact event, followed by the later emplacement of clast- and sulfide-rich impact melt in the center of the dike. An alternative hypothesis is that a single pulse of clast-rich impact melt flowed into the fractured target rocks and flow differentiation resulted in a clast-rich core and a clast-poor margin. In this study, we examine field and petrographic relationships of the Foy Offset Dike to better understand its emplacement. Our results show that the characteristics of the Foy Offset Dike – namely the gradational nature of the contact between the clast-rich and clast-poor phases, the alignment of clasts sub-parallel to this contact, the geochemical similarities and the presence of sulfides within both phases of the dike – are more consistent with the single injection and flow differentiation hypothesis. © 2018 Elsevier B.V.
cited By 10

Field-scale permeability and temperature of volcanic crust from borehole data: Campi Flegrei, southern Italy - Carlino, Stefano; Piochi, Monica; Tramelli, Anna; Mormone, Angela; Montanaro, Cristian; Scheu, Bettina; Klaus, Mayer (Journal of Volcanology and Geothermal Research, 2018)
We report combined measurements of petrophysical and geophysical parameters for a 501-m deep borehole located on the eastern side of the active Campi Flegrei caldera (Southern Italy), namely (i) in situ permeability by pumping tests, (ii) laboratory-determined permeability of the drill core, and (iii) thermal gradients by distributed fiber optic and thermocouple sensors. The borehole was drilled during the Campi Flegrei Deep Drilling Project (in the framework of the International Continental Scientific Drilling Program) and gives information on the least explored caldera sector down to pre-caldera deposits. The results allow comparative assessment of permeability obtained from both borehole (at depth between 422 a 501 m) and laboratory tests (on a core sampled at the same depth) for permeability values of 10−13 m2 (borehole test) and 10−15 m2 (laboratory test) confirm the scale-dependency of permeability at this site. Additional geochemical and petrophysical determinations (porosity, density, chemistry, mineralogy and texture), together with gas flow measurements, corroborate the hypothesis that discrepancies in the permeability values are likely related to in-situ fracturing. The continuous distributed temperature profile points to a thermal gradient of about 200 °C km−1. Our findings (i) indicate that scale-dependency of permeability has to be carefully considered in modelling of the hydrothermal system at Campi Flegrei, and (ii) improve the understanding of caldera dynamics for monitoring and mitigation of this very high volcanic risk area. © 2018 Elsevier B.V.
Keywords: Campania [Italy]; Campi Flegrei; Italy; Napoli [Campania]; Boreholes; Core drilling; Drilling; Fiber optic sensors; Flow of gases; Mechanical permeability; Minerals; Risk assessment; Temperature; Thermal gradients; Thermocouples; Volcanoes; Campi Flegrei; Combined measurements; Comparative assessment; Continental scientific drillings; Geophysical parameters; Petrophysics; Temperature profiles; Thermocouple sensors; borehole; caldera; crustal structure; deep drilling; hydrothermal system; permeability; temperature profile; volcano; Boring

Facies architecture of Miocene subaqueous clinothems of the New Jersey passive margin: Results from IODP-ICDP Expedition 313 - Proust, J.-N.; Pouderoux, H.; Ando, H.; Hesselbo, S.P.; Hodgson, D.M.; Lofi, J.; Rabineau, M.; Sugarman, P.J. (Geosphere, 2018)
Understanding the history, causes, and impact of sea-level changes is a challenge for our societies that face accelerated global sea-level rise. In this context, improvement of our knowledge of sea-level changes and shoreline migration at geological time scales is critical. The preserved, laterally correlative sedimentary record of continental erosion on passive margins has been used to reconstruct past sea level. However, the detailed nature of a basic clinothem progradational pattern observed on many of these margins is still poorly known. This paper describes the sedimentary facies and interprets the depositional environments and the architecture of the clinothems of the New Jersey shelf (offshore northeastern USA) to depict the origin and controls of the distribution of the sediment on the margin. We analyze 612 cores totaling 1311 m in length collected at three sites 60 km offshore Atlantic City, New Jersey, during International Ocean Discovery Program-International Continental Scientific Drilling Program (IODP-ICDP) Expedition 313. The three sites sampled the lower to middle Miocene passive margin sediments of the New Jersey shelf clinothems. We also collected wireline logs at the three sites and tied the sedimentary architecture to the geometry observed on seismic profiles. The observed sediment distribution in the clinoform complex differs from that of current models based on seismic data, which predict a progressive increase in mud and decrease in sand contents in a seaward direction. In contrast, we observe that the clinoforms are largely composed of muds, with sands and coarser material concentrated at the rollover, the bottomset, and the toe of the slope. The shelf clinothem topsets are storm-influenced mud whereas the foreset slope is composed of a mud wedge largely dominated by density current deposits (e.g., low-density turbidites and debrites). The architecture of the clinothem complex includes a composite stack of 30-m-thick clinothem units each made up of four systems tracts (Transgressive, Highstand, Forced- Regressive, and Lowstand Systems Tract) building individual transgressiveregressive sequences. The presence of mud-rich facies deposited during highstands on the topset of the clinoform, 40-60 km offshore from the sand-prone shoreface deposit (observed in the New Jersey onshore delta plain), and the lack of subaerial erosion (and continental depositional environments) point to a depositional model involving a subaerial delta (onshore) feeding a distant subaqueous delta. During forced regressions, shelf-edge deltas periodically overstep the stacks of flood-influenced, offshore-marine mud wedges of the New Jersey subaqueous delta, bringing sand to the rollover and building up the large-scale shelf-prism clinothems. The clinothem complex develops on a gently dipping platform with a ramp-like morphology (apparent dip of 0.75°-0.5°) below mean storm wave base, in 30-50 m of water depth, 40-60 km seaward of the coastal area. Its shape depends on the balance between accommodation and sedimentation rates. Subaqueous deltas show higher accumulation rates than their subaerial counterparts and prograde three times further and faster than their contemporaneous shoreline. The increase in the intensity of waves (height and recurrence intervals) favors the separation between subaqueous and subaerial deltas, and as a consequence, the formation of a flat topset geometry, a decrease in flood events and fluvial discharge, an overall progressive decrease in sediment grain size (from sequence m5.45, ca. 17.8-17.7 Ma, onwards), as well as an increase in sedimentation rates on the foresets of the clinoforms. All of these are recognized as preliminary signals that might characterize the entry into the Neogene icehouse world. © 2018 The Authors.
cited By 8
Keywords: Deposits; Erosion; Floods; Sand; Sea level; Sedimentology; Seismic waves; Seismology; Storms; Tectonics; Continental scientific drillings; Depositional environment; Depositional models; Facies architecture; Global sea level rise; Recurrence intervals; Sediment distribution; Sedimentary architecture; Sediments; continental margin; depositional environment; facies analysis; Miocene; passive margin; progradation; reconstruction; sea level change; spatial distribution; Atlantic Ocean; New Jersey Shelf

Extreme durability in ancient Roman concretes - Jackson, Marie D; Oleson, John P; Moon, Juhyuk; Zhang, Yi; Chen, Heng; Gudmundsson, Magnus T (Am. Ceram. Soc. Bull, 2018)

Extraordinary rocks from the peak ring of the Chicxulub impact crater: P-wave velocity, density, and porosity measurements from IODP/ICDP Expedition 364 - Christeson, G.L.; Gulick, S.P.S.; Morgan, J.V.; Gebhardt, C.; Kring, D.A.; Le Ber, E.; Lofi, J.; Nixon, C.; Poelchau, M.; Rae, A.S.P.; Rebolledo-Vieyra, M.; Riller, U.; et al. (Earth and Planetary Science Letters, 2018)
Joint International Ocean Discovery Program and International Continental Scientific Drilling Program Expedition 364 drilled into the peak ring of the Chicxulub impact crater. We present P-wave velocity, density, and porosity measurements from Hole M0077A that reveal unusual physical properties of the peak-ring rocks. Across the boundary between post-impact sedimentary rock and suevite (impact melt-bearing breccia) we measure a sharp decrease in velocity and density, and an increase in porosity. Velocity, density, and porosity values for the suevite are 2900 –3700 m/s, 2.06 –2.37 g/cm3, and 20 –35%, respectively. The thin (25 m) impact melt rock unit below the suevite has velocity measurements of 3650 –4350 m/s, density measurements of 2.26 –2.37 g/cm3, and porosity measurements of 19 –22%. We associate the low velocity, low density, and high porosity of suevite and impact melt rock with rapid emplacement, hydrothermal alteration products, and observations of pore space, vugs, and vesicles. The uplifted granitic peak ring materials have values of 4000 –4200 m/s, 2.39 –2.44 g/cm3, and 8 –13% for velocity, density, and porosity, respectively; these values differ significantly from typical unaltered granite which has higher velocity and density, and lower porosity. The majority of Hole M0077A peak-ring velocity, density, and porosity measurements indicate considerable rock damage, and are consistent with numerical model predictions for peak-ring formation where the lithologies present within the peak ring represent some of the most shocked and damaged rocks in an impact basin. We integrate our results with previous seismic datasets to map the suevite near the borehole. We map suevite below the Paleogene sedimentary rock in the annular trough, on the peak ring, and in the central basin, implying that, post impact, suevite covered the entire floor of the impact basin. Suevite thickness is 100 –165 m on the top of the peak ring but 200 m in the central basin, suggesting that suevite flowed downslope from the collapsing central uplift during and after peak-ring formation, accumulating preferentially within the central basin. © 2018 Elsevier B.V.
cited By 46

Exploration of deep terrestrial subsurface microbiome in Late Cretaceous Deccan traps and underlying Archean basement, India - Dutta, A.; Dutta Gupta, S.; Gupta, A.; Sarkar, J.; Roy, S.; Mukherjee, A.; Sar, P. (Scientific Reports, 2018)
Scientific deep drilling at Koyna, western India provides a unique opportunity to explore microbial life within deep biosphere hosted by 65 Myr old Deccan basalt and Archaean granitic basement. Characteristic low organic carbon content, mafic/felsic nature but distinct trend in sulfate and nitrate concentrations demarcates the basaltic and granitic zones as distinct ecological habitats. Quantitative PCR indicates a depth independent distribution of microorganisms predominated by bacteria. Abundance of dsrB and mcrA genes are relatively higher (at least one order of magnitude) in basalt compared to granite. Bacterial communities are dominated by Alpha-, Beta-, Gammaproteobacteria, Actinobacteria and Firmicutes, whereas Euryarchaeota is the major archaeal group. Strong correlation among the abundance of autotrophic and heterotrophic taxa is noted. Bacteria known for nitrite, sulfur and hydrogen oxidation represent the autotrophs. Fermentative, nitrate/sulfate reducing and methane metabolising microorganisms represent the heterotrophs. Lack of shared operational taxonomic units and distinct clustering of major taxa indicate possible community isolation. Shotgun metagenomics corroborate that chemolithoautotrophic assimilation of carbon coupled with fermentation and anaerobic respiration drive this deep biosphere. This first report on the geomicrobiology of the subsurface of Deccan traps provides an unprecedented opportunity to understand microbial composition and function in the terrestrial, igneous rock-hosted, deep biosphere. © 2018, The Author(s).
cited By 33
Keywords: RNA 16S; biodiversity; biology; environmental microbiology; genetics; India; metagenome; metagenomics; microbiology; microflora; procedures; sediment; Biodiversity; Computational Biology; Environmental Microbiology; Geologic Sediments; India; Metagenome; Metagenomics; Microbiota; RNA; Ribosomal; 16S

Fluid Flux in Fractured Rock of the Alpine Fault Hanging-Wall Determined from Temperature Logs in the DFDP-2B Borehole, New Zealand - Janku-Capova, L.; Sutherland, R.; Townend, J.; Doan, M.-L.; Massiot, C.; Coussens, J.; C'el'erier, B. (Geochemistry, Geophysics, Geosystems, 2018)
Sixteen temperature logs were acquired during breaks in drilling of the 893m-deep DFDP-2B borehole, which is in the Alpine Fault hanging-wall. The logs record various states of temperature recovery after thermal disturbances induced by mud circulation. The long-wavelength temperature signal in each log was estimated using a sixth-order polynomial, and residual (reduced) temperature logs were analyzed by fitting discrete template wavelets defined by depth, amplitude, and width parameters. Almost two hundred wavelets are correlated between multiple logs. Anomalies generally have amplitudes <1°C, and downhole widths <20m. The largest amplitudes are found in the first day after mud circulation stops, but many anomalies persist with similar amplitude for up to 15 days. Our models show that thermal and hydraulic diffusive processes are dominant during the first few days of re-equilibration after mud circulation stops, and fluid advection of heat in the surrounding rock produces temperature anomalies that may persist for several weeks. Models indicate that the fluid flux normal to the borehole within fractured zones is of order 10−7 to 10−6 m s−1, which is 2 –3 orders of magnitude higher than the regional flux. Our approach could be applied more widely to boreholes, as it uses the thermal re-equilibration phase to derive useful information about the surrounding rock mass and its fluid flow regime. ©2018. American Geophysical Union. All Rights Reserved.
cited By 6
Keywords: Aquifers; Boreholes; Flow of fluids; Fracture; Groundwater; Groundwater resources; Hydrogeology; Mechanical permeability; Rocks; Diffusive process; geothermal; Orders of magnitude; Surrounding rock mass; Temperature anomaly; Temperature recovery; Temperature signal; Thermal disturbance; Thermal logging; aquifer; borehole logging; fluid flow; fractured medium; geothermal system; groundwater; hanging wall; hydrogeology; permeability; rock mechanics; temperature gradient; Alpine Fault Zone; New Zealand; South Island

Dietary versatility of Early Pleistocene hominins - L{udecke, Tina; Kullmer, Ottmar; Wacker, Ulrike; Sandrock, Oliver; Fiebig, Jens; Schrenk, Friedemann; Mulch, Andreas (Proceedings of the National Academy of Sciences of the United States of America, 2018)
New geochemical data from the Malawi Rift (Chiwondo Beds, Karonga Basin) fill a major spatial gap in our knowledge of hominin adaptations on a continental scale. Oxygen (δ 18 O), carbon (δ 13 C), and clumped (Δ 47 ) isotope data on paleosols, hominins, and selected fauna elucidate an unexpected diversity in the Pleistocene hominin diet in the various habitats of the East African Rift System (EARS). Food sources of early Homo and Paranthropus thriving in relatively cool and wet wooded savanna ecosystems along the western shore of paleolake Malawi contained a large fraction of C 3 plant material. Complementary water consumption reconstructions suggest that ca. 2.4 Ma, early Homo (Homo rudolfensis) and Paranthropus (Paranthropus boisei) remained rather stationary near freshwater sources along the lake margins. Time-equivalent Paranthropus aethiopicus from the Eastern Rift further north in the EARS consumed a higher fraction of C 4 resources, an adaptation that grew more pronounced with increasing openness of the savanna setting after 2 Ma, while Homo maintained a high versatility. However, southern African Paranthropus robustus had, similar to the Malawi Rift individuals, C 3 -dominated feeding strategies throughout the Early Pleistocene. Collectively, the stable isotope and faunal data presented here document that early Homo and Paranthropus were dietary opportunists and able to cope with a wide range of paleohabitats, which clearly demonstrates their high behavioral flexibility in the African Early Pleistocene. © 2018 National Academy of Sciences. All Rights Reserved.
Keywords: Adaptation; Physiological; Animals; Biological Evolution; Carbon Isotopes; Dental Enamel; Diet; Ecosystem; Environment; Feeding Behavior; Fossils; History; Ancient; Hominidae; carbon; adaptation; Article; C3 plant; diet; ecosystem; enamel; evolution; feeding behavior; fluid intake; fossil hominin; habitat; Homo rudolfensis; isotope analysis; Malawi; nonhuman; Paranthropus boisei; Pleistocene; priority journal; animal; chemistry; diet; environment; fossil; history; hominid; metabolism; physiology

Evolution of the Toarcian (Early Jurassic) carbon-cycle and global climatic controls on local sedimentary processes (Cardigan Bay Basin, UK) - Xu, Weimu; Ruhl, Micha; Jenkyns, Hugh C.; Huggett, Jennifer M.; Minisini, Daniel; Ullmann, Clemens V.; Riding, James B.; Weijers, Johan W.H.; Storm, Marisa S.; Percival, Lawrence M.E.; Idiz, Erdem F.; Tegelaar, Erik W.; et al. (Earth and Planetary Science Letters, 2018)
The late Early Jurassic Toarcian Stage represents the warmest interval of the Jurassic Period, with an abrupt rise in global temperatures of up to ∼7 °C in mid-latitudes at the onset of the early Toarcian Oceanic Anoxic Event (T-OAE; ∼183 Ma). The T-OAE, which has been extensively studied in marine and continental successions from both hemispheres, was marked by the widespread expansion of anoxic and euxinic waters, geographically extensive deposition of organic-rich black shales, and climatic and environmental perturbations. Climatic and environmental processes following the T-OAE are, however, poorly known, largely due to a lack of study of stratigraphically well-constrained and complete sedimentary archives. Here, we present integrated geochemical and physical proxy data (high-resolution carbon-isotope data (δ13C), bulk and molecular organic geochemistry, inorganic petrology, mineral characterisation, and major- and trace-element concentrations) from the biostratigraphically complete and expanded entire Toarcian succession in the Llanbedr (Mochras Farm) Borehole, Cardigan Bay Basin, Wales, UK. With these data, we (1) construct the first high-resolution biostratigraphically calibrated chemostratigraphic reference record for nearly the complete Toarcian Stage, (2) establish palaeoceanographic and depositional conditions in the Cardigan Bay Basin, (3) show that the T-OAE in the hemipelagic Cardigan Bay Basin was marked by the occurrence of gravity-flow deposits that were likely linked to globally enhanced sediment fluxes to continental margins and deeper marine (shelf) basins, and (4) explore how early Toarcian (tenuicostatum and serpentinum zones) siderite formation in the Cardigan Bay Basin may have been linked to low global oceanic sulphate concentrations and elevated supply of iron (Fe) from the hinterland, in response to climatically induced changes in hydrological cycling, global weathering rates and large-scale sulphide and evaporite deposition. © 2017 The Authors
Keywords: Cardigan Bay; United Kingdom; Wales; Carbon; Deposits; Geochemistry; Iron deposits; Iron ores; Isotopes; Sedimentology; Sulfur compounds; Trace elements; Weathering; Carbon isotope stratigraphy; Early Jurassic; Global weathering rates; Gravity flows; Oceanic anoxic events; siderite; biostratigraphy; carbon cycle; carbon isotope; deposition; depositional environment; evaporite; global climate; paleoceanography; paleotemperature; siderite; stratigraphy; sulfide; Toarcian; weathering; Stratigraphy

Evolution of atmospheric xenon and other noble gases inferred from Archean to Paleoproterozoic rocks - Avice, G.; Marty, B.; Burgess, R.; Hofmann, A.; Philippot, P.; Zahnle, K.; Zakharov, D. (Geochimica et Cosmochimica Acta, 2018)
We have analyzed ancient atmospheric gases trapped in fluid inclusions contained in minerals of Archean (3.3 Ga) to Paleozoic (404 Ma) rocks in an attempt to document the evolution of the elemental composition and isotopic signature of the atmosphere with time. Doing so, we aimed at understanding how physical and chemical processes acted over geological time to shape the modern atmosphere. Modern atmospheric xenon is enriched in heavy isotopes by 30 –40‰ u−1 relative to Solar or Chondritic xenon. Previous studies demonstrated that, 3.3 Ga ago, atmospheric xenon was isotopically fractionated (enriched in the light isotopes) relative to the modern atmosphere, by 12.9 ± 1.2 (1σ) ‰ u−1, whereas krypton was isotopically identical to modern atmospheric Kr. Details about the specific and progressive isotopic fractionation of Xe during the Archean, originally proposed by Pujol et al. (2011), are now well established by this work. Xe isotope fractionation has evolved from 21‰ u−1 at 3.5 Ga to 12.9‰ u−1 at 3.3 Ga. The current dataset provides some evidence for stabilization of the Xe fractionation between 3.3 and 2.7 Ga. However, further studies will be needed to confirm this observation. After 2.7 Ga, the composition kept evolving and reach the modern-like atmospheric Xe composition at around 2.1 Ga ago. Xenon may be the second atmospheric element, after sulfur, to show a secular isotope evolution during the Archean that ended shortly after the Archean-Proterozoic transition. Fractionation of xenon indicates that xenon escaped from Earth, probably as an ion, and that Xe escape stopped when the atmosphere became oxygen-rich. We speculate that the Xe escape was enabled by a vigorous hydrogen escape on the early anoxic Earth. Organic hazes, scavenging isotopically heavy Xe, could also have played a role in the evolution of atmospheric Xe. For 3.3 Ga-old samples, Ar-N2 correlations are consistent with a partial pressure of nitrogen (pN2) in the Archean atmosphere similar to, or lower than, the modern one, thus requiring other processes than a high pN2 to keep the Earth's surface warm despite a fainter Sun. The nitrogen isotope composition of the atmosphere at 3.3 Ga was already modern-like, attesting to inefficient nitrogen escape to space since that time. © 2018 The Authors
Keywords: Archean; atmospheric chemistry; fluid inclusion; isotopic composition; isotopic fractionation; nitrogen isotope; paleoatmosphere; Proterozoic; xenon

Evidence for cyclical fractional crystallization, recharge, and assimilation in basalts of the kimama drill core, central snake river plain, idaho: 5.5-million-years of petrogenesis in a mid-crustal sill complex - Potter, K.E.; Shervais, J.W.; Christiansen, E.H.; Vetter, S.K. (Frontiers in Earth Science, 2018)
Basalts erupted in the Snake River Plain of central Idaho and sampled in the Kimama drill core link eruptive processes to the construction of mafic intrusions over 5.5Ma. Cyclic variations in basalt composition reveal temporal chemical heterogeneity related to fractional crystallization and the assimilation of previously-intruded mafic sills. A range of compositional types are identified within 1,912m of continuous drill core: Snake River olivine tholeiite (SROT), low K SROT, high Fe-Ti, and evolved and high K-Fe lavas similar to those erupted at Craters of the Moon National Monument. Detailed lithologic and geophysical logs document 432 flow units comprising 183 distinct lava flows and 78 flowgroups. Each lava flowrepresents a single eruptive episode, while flow groups document chemically and temporally related flows that formed over extended periods of time. Temporal chemical variation demonstrates the importance of source heterogeneity and magma processing in basalt petrogenesis. Low-K SROT and high Fe-Ti basalts are genetically related to SROT as, respectively, hydrothermally-altered and fractionated daughters. Cyclic variations in the chemical composition of Kimama flow groups are apparent as 21 upward fractionation cycles, six recharge cycles, eight recharge-fractionation cycles, and five fractionation-recharge cycles. We propose that most Kimama basalt flows represent typical fractionation and recharge patterns, consistent with the repeated influx of primitive SROT parental magmas and extensive fractional crystallization coupled with varying degrees of assimilation of gabbroic to ferrodioritic sills at shallow to intermediate depths over short durations. Trace element models show that parental SROT basalts were generated by 5 –10% partial melting of enriched mantle at shallow depths above the garnet-spinel lherzolite transition. The distinctive evolved and high K-Fe lavas are rare. Found at four depths, 319, 1045, 1,078, and 1,189m, evolved and high K-Fe flows are compositionally unrelated to SROT magmas and represent highly fractionated basalt, probably accompanied by crustal assimilation. These evolved lavas may be sourced from the Craters of the Moon/Great Rift system to the northeast. The Kimama drill core is the longest record of geochemical variation in the central Snake River Plain and reinforces the concept of magma processing in a layered complex. © 2018 Potter, Shervais, Christiansen and Vetter.
cited By 14
Keywords: Basalt; Binary alloys; Drills; Infill drilling; Iron alloys; Moon; Olivine; Petrology; Rivers; Titanium alloys; Trace elements; Chemical compositions; Chemical heterogeneities; Drill core; Fractional crystallization; Geochemical variations; Mid-crustal sill complex; Snake river plains; Tholeiite; Core drilling; basalt; crystal structure; data assimilation; fractional crystallization; hydrothermal alteration; magma; petrogenesis; petrology; tholeiitic basalt; Idaho; Snake River Plain; United States

Evidence for carbon cycling in a large freshwater lake in the Balkans over the last 0.5 million years using the isotopic composition of bulk organic matter - Zanchetta, Giovanni; Baneschi, Ilaria; Francke, Alexander; Boschi, Chiara; Regattieri, Eleonora; Wagner, Bernd; Lacey, Jack H.; Leng, Melanie J.; Vogel, Hendrik; Sadori, Laura (Quaternary Science Reviews, 2018)
In the DEEP core from the Lake Ohrid ICDP drilling project, the carbon isotope composition of bulk organic matter (δ13CTOC) over the last 516 ka shows a negative correlation with total organic carbon (TOC) and total inorganic carbon (TIC). This relationship is marked by periods of lower δ13CTOC values corresponding to higher TIC and TOC. Along with TOC/TN, the correlation between δ13CTOC and δ13CTIC suggests that most of the organic matter in the core is from aquatic primary production within the lake. The combination of TOC, TIC, and δ13CTOC is able to disentangle long-term glacial/interglacial cycles and, to a lesser extent, millennial scale climate variability. Over the longer term, δ13CTOC shows modest variability, indicating that the δ13C of the dissolved inorganic carbon (DIC) pool is stabilised by the supply of karst spring water characterised by δ13CDIC influenced by the bedrock δ13C value, and the long residence time of the lake water and well mixed upper water column promoting equilibration with atmospheric CO2. However, comparison between arboreal pollen (AP%), TIC and TOC data indicates that the δ13CTOC signal is modulated by the leaching of soil CO2 through runoff and spring discharge, changes in primary productivity, and recycling of organic matter within the lake, all affecting δ13CDIC. Exceptionally low δ13CTOC during some interglacial periods (e.g. MIS7 and MIS9) possibly indicate rapid intensification of organic matter recycling and/or increasing stratification and enhanced methanogenesis, even if the latter process is not supported by the sedimentological data. © 2018 Elsevier Ltd
Keywords: Balkans; Lake Ohrid; Biogeochemistry; Biological materials; Carbon dioxide; Groundwater; Isotopes; Lakes; Paleolimnology; Recycling; Springs (components); Springs (water); Carbon isotope composition; Dissolved inorganic carbon; Europe; Lake Ohrid; Organic matter recycling; Pleistocene; Stable isotopes; Total inorganic carbon; carbon cycle; carbon isotope; freshwater environment; glacial-interglacial cycle; isotopic composition; karst; lacustrine environment; lake water; methanogenesis; paleolimnology; Pleistocene; primary production; spring water; stratification; Organic carbon

Evaluating Late Cretaceous OAEs and the influence of marine incursions on organic carbon burial in an expansive East Asian paleo-lake - Jones, M.M.; Ibarra, D.E.; Gao, Y.; Sageman, B.B.; Selby, D.; Chamberlain, C.P.; Graham, S.A. (Earth and Planetary Science Letters, 2018)
Expansive Late Cretaceous lacustrine deposits of East Asia offer unique stratigraphic records to better understand regional responses to global climate events, such as oceanic anoxic events (OAEs), and terrestrial organic carbon burial dynamics. This study presents bulk organic carbon isotopes (δ13Corg), elemental concentrations (XRF), and initial osmium ratios (187Os/188Os, Osi) from the Turonian –Coniacian Qingshankou Formation, a ∼5 Ma lacustrine mudstone succession in the Songliao Basin of northeast China. A notable δ13Corg excursion (∼+2.5‰) in organic carbon-lean Qingshankou Members 2 –3 correlates to OAE3 in the Western Interior Basin (WIB) of North America within temporal uncertainty of high-precision age models. Decreases in carbon isotopic fractionation (Δ13C) through OAE3 in the WIB and Songliao Basin, suggest that significantly elevated global rates of organic carbon burial drew down pCO2, likely cooling climate. Despite this, Osi chemostratigraphy demonstrates no major changes in global volcanism or weathering trends through OAE3. Identification of OAE3 in a lake system is consistent with lacustrine records of other OAEs (e.g., Toarcian OAE), and underscores that terrestrial environments were sensitive to climate perturbations associated with OAEs. Additionally, the relatively radiogenic Osi chemostratigraphy and XRF data confirm that the Qingshankou Formation was deposited in a non-marine setting. Organic carbon-rich intervals preserve no compelling Osi evidence for marine incursions, an existing hypothesis for generating Member 1's prolific petroleum source rocks. Based on our results, we present a model for water column stratification and source rock deposition independent of marine incursions, detailing dominant biogeochemical cycles and lacustrine organic carbon burial mechanisms. © 2017 Elsevier B.V.
cited By 36
Keywords: Biogeochemistry; Isotopes; Lakes; Petroleum geology; Stratigraphy; Weathering; Biogeochemical cycling; Chemostratigraphy; Oceanic Anoxic Event; Osmium isotopes; Paleoclimates; Songliao basin; Organic carbon; anoxic conditions; biogeochemical cycle; carbon isotope; chemostratigraphy; Cretaceous; lacustrine deposit; mudstone; organic carbon; osmium isotope; paleoclimate; paleoenvironment; China; Songliao Basin; Western Interior

Diatoms do radiate: evidence for a freshwater species flock - Stelbrink, Bj{orn; Jovanovska, Elena; Levkov, Zlatko; Ognjanova-Rumenova, Nadja; Wilke, Thomas; Albrecht, Christian (Journal of Evolutionary Biology, 2018)
Due to the ubiquity and high dispersal capacity of unicellular eukaryotes, their often extraordinary diversity found in isolated and long-lived ecosystems such as ancient lakes is typically attributed to multiple colonization events rather than to in situ speciation. However, respective evolutionary studies are very scarce and the often high number of species flocks in ancient lakes across multicellular taxa raises the question whether unicellular species, such as diatoms, may radiate as well. Here, we use an integrative approach that includes molecular data from benthic diatom species of the genus Aneumastus endemic to ancient Lake Ohrid, fossil data obtained from the sediment record of a recent deep-drilling project and biogeographical information to test if this group, indeed, constitutes a species flock. Molecular-clock and phylogenetic analyses indicate a young monophyletic group of several endemic species. Molecular, fossil and biogeographical data strongly suggest a rapid intralacustrine diversification, which was possibly triggered by the emergence of novel habitats. This finding is the first evidence for a species flock in diatoms and suggests that in situ speciation is also a relevant evolutionary process for unicellular eukaryotes in isolated ecosystems. © 2018 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2018 European Society For Evolutionary Biology
Keywords: Diatoms; Evolution; Molecular; Fossils; Fresh Water; Genetic Variation; Phylogeny; Time Factors; Lake Ohrid; Aneumastus; Bacillariophyta; Protista; fresh water; biogeography; colonization; diatom; endemic species; eukaryote; evolutionary biology; fossil record; freshwater environment; habitat type; molecular analysis; phylogenetics; sediment analysis; species flock; diatom; fossil; genetic variation; genetics; molecular evolution; phylogeny; physiology; time factor

Environmental change during MIS4 and MIS 3 opened corridors in the Horn of Africa for Homo sapiens expansion - Viehberg, Finn A.; Just, Janna; Dean, Jonathan R.; Wagner, Bernd; Franz, Sven Oliver; Klasen, Nicole; Kleinen, Thomas; Ludwig, Patrick; Asrat, Asfawossen; Lamb, Henry F.; Leng, Melanie J.; Rethemeyer, Janet; et al. (Quaternary Science Reviews, 2018)
Archaeological findings, numerical human dispersal models and genome analyses suggest several time windows in the past 200 kyr (thousands of years ago) when anatomically modern humans (AMH) dispersed out of Africa into the Levant and/or Arabia. From close to the key hominin site of Omo-Kibish, we provide near continuous proxy evidence for environmental changes in lake sediment cores from the Chew Bahir basin, south Ethiopia. The data show highly variable hydroclimate conditions from 116 to 66 kyr BP with rapid shifts from very wet to extreme aridity. The wet phases coincide with the timing of the North African Humid Periods during MIS5, as defined by Nile discharge records from the eastern Mediterranean. The subsequent record at Chew Bahir suggests stable regional hydrological setting between 58 and 32 kyr (MIS4 and 3), which facilitated the development of more habitable ecosystems, albeit in generally dry climatic conditions. This shift, from more to less variable hydroclimate, may help account for the timing of later dispersal events of AMH out of Africa. © 2018 The Authors
Keywords: Geology; Archaeological findings; Climatic conditions; Eastern Mediterranean; Environmental change; Genome analysis; Humid periods; Lake sediment cores; Rapid shifts; Natural sciences; anatomy; archaeology; aridity; climate conditions; dispersal; environmental change; horn; lacustrine deposit; marine isotope stage; sediment core; Arabian Sea; Ethiopia; Indian Ocean; Levantine Sea; Mediterranean Sea; Mediterranean Sea (East); Homo sapiens

Dynamics of microseismicity and its relationship with the active structures in the western Corinth Rift (Greece) - Duverger, C.; Lambotte, S.; Bernard, P.; Lyon-Caen, H.; Deschamps, A.; Nercessian, A. (Geophysical Journal International, 2018)
We analyse the complete earthquake archive of the western Corinth Rift using both crosscorrelations between pairs of event waveforms and accurate differential traveltimes observed at common stations, in order to identify small-scale fault structures at depth. The waveform database was generated by the dense Corinth Rift Laboratory network and includes about 205 000 events between 2000 and 2015. Half of them are accurately relocated using doubledifference techniques. The novelty of this relocated catalogue is the integration of the recent westernmost earthquakes due to the extension of the network in 2010 to the western extremity of the Corinth Rift and the consideration of the whole database over more than 15 yr. The total relocated seismicity exhibits well-defined clusters at the root of the main normal faults mainly between 5 and 10 km depth in the middle of the gulf and illuminates thin active structure planes dipping north about 20° under the northern coast. Some seismicity is observed in the footwall of the main active faults, along theWest and East Helike faults.We also built a multiplet database based on waveform similarity taking into account cross-correlation coefficients weighted by signal-to-noise ratios. Short-termmultiplets are concentrated in the middle of the gulf along the Kamarai fault system, in a 1-2 km thick layer at 6-8 km depth, interpreted as a highly fractured geological layer. They are often associated to slow seismic migration velocities occurring in this zone during strong swarm episodes and are thus likely to be triggered by pore pressure variations. On the other hand, most long-term and regular multiplets are located deeper (7- 10 km), under the northern coast, within a layer less than 0.3 km thick. They occur at the border of nearly planar structures with low seismicity rate, which we identify as fault planes, and they may be explained by aseismic slip on the fault surface around them. This supports the existence of an immature structure growing downdip towards the north at the base of the active geological layer, which possibly connects to the ductile middle crust around 15 km depth, as suggested by the occurrence of deeper events in the continuity of the 1995-fault plane. The different migration velocities (from 0.05 km d-1 to several km d-1) highlighted during the western 2014-swarms indicate that both pore pressure and creep diffusion are operating in the fault zone. The fast migrations observed in the Psathopyrgos fault zone, where a slow slip event was detected by dilatometers in 2002, compare with that for creeping faults. To the west, from spatial distribution of events, we show that the Rion-Patras fault connecting the western extremity of the Corinth Rift fault system to the Patras Rift, is dipping around 60° north-west with a rake angle of -115°. Finally, we identified two new areas within the central active zone which may correspond to large scale, locked asperities on active fault surfaces, similar in size to the main asperity broken during the 1995, MW 6.3, Aigion earthquake. © The Author(s) 2018.
Keywords: Corinth Rift; Greece; Ionian Sea; Mediterranean Sea; Database systems; Earthquakes; Pore pressure; Signal to noise ratio; Cross-correlation coefficient; Double-difference technique; Earthquake dynamics; Europe; Pressure variations; Seismicity and tectonics; Transient deformation; Waveform similarity; deformation; earthquake mechanism; normal fault; rift zone; seismic migration; seismicity; signal-to-noise ratio; tectonics; wave velocity; waveform analysis; Fault slips

Drilling-induced and logging-related features illustrated from IODP-ICDP Expedition 364 downhole logs and borehole imaging tools - Lofi, J.; Smith, D.; Delahunty, C.; Le Ber, E.; Brun, L.; Henry, G.; Paris, J.; Tikoo, S.; Zylberman, W.; Pezard, P.A.; C'el'erier, B.; Nixon, C.; et al. (Scientific Drilling, 2018)
Expedition 364 was a joint IODP and ICDP mission-specific platform (MSP) expedition to explore the Chicxulub impact crater buried below the surface of the Yucat'an continental shelf seafloor. In April and May 2016, this expedition drilled a single borehole at Site M0077 into the crater's peak ring. Excellent quality cores were recovered from 505 to 1335m below seafloor (m b.s.f.), and high-resolution open hole logs were acquired between the surface and total drill depth. Downhole logs are used to image the borehole wall, measure the physical properties of rocks that surround the borehole, and assess borehole quality during drilling and coring operations. When making geological interpretations of downhole logs, it is essential to be able to distinguish between features that are geological and those that are operation-related. During Expedition 364 some drilling-induced and logging-related features were observed and include the following: effects caused by the presence of casing and metal debris in the hole, logging-tool eccentering, drilling-induced corkscrew shape of the hole, possible re-magnetization of low-coercivity grains within sedimentary rocks, markings on the borehole wall, and drilling-induced changes in the borehole diameter and trajectory. © Author(s) 2018.
cited By 4

Diurnal Course of Evaporation From the Dead Sea in Summer: A Distinct Double Peak Induced by Solar Radiation and Night Sea Breeze - Lensky, N.G.; Lensky, I.M.; Peretz, A.; Gertman, I.; Tanny, J.; Assouline, S. (Water Resources Research, 2018)

Discrimination of Holocene tephra units in Lake Van using mineral magnetic analysis - Makaroğlu, {O.; Çağatay, M.N.; Nowaczyk, N.R.; Pesonen, L.J.; Orbay, N. (Quaternary International, 2018)
Detailed magnetic analysis of the four sediment cores from Lake Van, Eastern Turkey dating back to 9.4 cal ka BP were carried out for discriminating and correlating tephras and laminated sediments in four different cores. Six tephra units (T0, T1, T2, T3, T4 and T5) with distinct magnetic properties were identified in the cores. The tephra units are characterized by ferrimagnetic material, with a grain size in the pseudo single domain (PSD) range. There is no significant correlation between magnetic susceptibility peaks of the different tephra units except for the tephra T1 and T2. On the contrary ARM profiles show significant correlations as remanent magnetization indicators. The tephra units T1 and T2, have a higher magnetic susceptibility and a higher intensity of remanent magnetization, and finer grain size than the other tephra units. The results suggest that there is a clear difference between the magnetic properties of the different tephra units and the lake sediments. Our findings show that also differential deposition of volcanic material including magnetic mineral occurs during the transport with distance from the volcanic source. © 2018 Elsevier Ltd and INQUA
cited By 5
Keywords: geochemistry; Holocene; lacustrine deposit; magnetic mineral; magnetic susceptibility; remanent magnetization; sediment core; tephra; Lake Van; Turkey

Direct geometrical simulation of pore space evolution through hydrate dissociation in methane hydrate reservoirs - Mohammadmoradi, P.; Kantzas, A. (Marine and Petroleum Geology, 2018)
The identification of methane hydrate behavior in porous media is one of the most challenging yet rewarding pore-level visualization and simulation tasks. The hydrate morphology influences the physical characteristics of the host sediments as during the hydrate formation and dissociation processes the pore space and flow pathways constantly evolve. Here, a direct three-phase pore morphological simulation approach is proposed, verified and utilized to simulate hydrate deformities and predict fluid occupancies and absolute and effective permeabilities of hydrate-bearing geological formations. The proposed technique simulates capillary-dominant displacements by applying a set of geomaterial rules directly to the pixels of pore-level porous media images. The case studies are sandy microstructures generated based on the particle size distributions of the Mallik gas hydrate deposit. The fluid occupancy profiles, absolute permeability, and hydraulic tortuosity curves are comparable with the experimental datasets. The sensitivity analysis shows that although the gas relative permeability is less sensitive to the hydrate specifications, the porosity, grain size distribution, and hydrate content and occupancy remarkably influence the rock absolute permeability. © 2017 Elsevier Ltd
cited By 20
Keywords: Dissociation; Gas permeability; Grain size and shape; Hydration; Methane; Particle size; Porous materials; Sensitivity analysis; Size distribution; Absolute permeability; Effective permeability; Gas relative permeabilities; Geometrical simulations; Grain size distribution; Morphological simulation; Physical characteristics; Visualization and simulation; Gas hydrates; displacement; hydrocarbon reservoir; methane; microstructure; permeability; pore space; porous medium; sensitivity analysis

Dinosaur-killing asteroid impact made huge dead zones in oceans - Joel, L. (Eos, 2018)

Real‐Time Earthquake Monitoring during the Second Phase of the Deep Fault Drilling Project, Alpine Fault, New Zealand - Chamberlain, Calum J.; Boese, Carolin M.; Eccles, Jennifer D.; Savage, Martha K.; Baratin, Laura‐May; Townend, John; Gulley, Anton K.; Jacobs, Katrina M.; Benson, Adrian; Taylor‐Offord, Sam; Thurber, Clifford; Guo, Bin; et al. (Seismological Research Letters, 2017)
The Deep Fault Drilling Project (DFDP) is a multinational scientific drilling effort to study the evolution, structure, and seismogenesis of the Alpine fault, New Zealand, via in situ measurements of fault rock properties. The second phase of drilling (DFDP‐2), undertaken in the Whataroa Valley in late 2014, was intended to intersect the Alpine fault at a depth of around 1 km. In conjunction with the drilling and on‐site science activities, a real‐time seismic monitoring scheme and traffic‐light response protocol were established to detect, locate, and if necessary respond to seismicity within 30 km of the drill site. This network was operated around the clock between late August 2014 and early January 2015, and we detected and located 493 earthquakes of ML 0.6 –4.2. None of these earthquakes occurred within 3 km of the drill site, and nor did any of the seismicity detected require changes to drilling operations. The monitoring was undertaken using open‐source software operated by an international team of 16 seismologists (including eight postgraduate students) working in 7 institutions and 3 countries to provide rapid on‐ and off‐site manual checking and relocating of events. The team’s standard response time between detection and final location was less than 30 min under normal background seismicity conditions and up to 1 hr during swarm activity and for low‐priority, distant (≥30 km epicentrally from the drill site) earthquakes. This article documents the methodology, infrastructure, protocols, outcomes, and key lessons of this monitoring.

Rates and cycles of microbial sulfate reduction in the hyper-saline dead sea over the last 200 kyrs from sedimentary δ34 S and δ18 O(SO4) - Torfstein, A.; Turchyn, A.V. (Frontiers in Earth Science, 2017)
We report the δ34 S and δ18 O(SO4) measured in gypsum, pyrite, and elemental sulfur through a 456-m thick sediment core from the center of the Dead Sea, representing the last ∼200 kyrs, as well as from the exposed glacial outcrops of the Masada M1 section located on the margins of the modern Dead Sea. The results are used to explore and quantify the evolution of sulfur microbial metabolism in the Dead Sea and to reconstruct the lake’s water column configuration during the late Quaternary. Layers and laminae of primary gypsum, the main sulfur-bearing mineral in the sedimentary column, display the highest δ34 S and δ18 O(SO4) in the range of 13 –28 and 13 –30%, respectively. Within this group, gypsum layers deposited during interglacials display lower δ34 S and δ18 O(SO4) relative to those associated with glacial or deglacial stages. The reduced sulfur phases, including chromiumreducible sulfur, andsecondary gypsumcrystals are characterizedby extremely low δ34 S in the range of −27 to +7%. The δ18 O(SO4) of the secondary gypsum in the M1 outcrop ranges from 8 to 14%. The relationship between δ34 S and δ18 O(SO4) of primary gypsumsuggests that the rate of microbial sulfate reduction was lower during glacial relative to interglacial times. This suggests that the freshening of the lake during glacial wet intervals, and the subsequent rise in sulfate concentrations, slowed the rate of microbial metabolism. Alternatively, this could imply that sulfate-driven anaerobic methane oxidation, the dominant sulfur microbial metabolism today, is a feature of the hypersalinity in the modern Dead Sea. Sedimentary sulfides are quantitatively oxidized during epigenetic exposure, retaining the lower δ34 S signature; the δ18 O(SO4) of this secondary gypsum is controlled by oxygen atoms derived equally from atmospheric oxygen and from water, which is likely a unique feature in this hyperarid environment. © 2017 Torfstein and Turchyn.
cited By 6
Keywords: Glacial geology; Gypsum; Lakes; Metabolism; Oxidation; Oxygen; Paleolimnology; Pyrites; Sedimentology; Dead sea; Isotope fractionation; Sulfate reduction; Sulfates; Sulfide oxidation; Sulfur compounds; gypsum; outcrop; oxygen isotope; pyrite; sediment core; sulfate-reducing bacterium; sulfur; Dead Sea