All ICDP Publications with Abstracts
From parent-sysfolder "Publications" + 2 folder-levels deep
2244.
Characterization of Iron in Lake Towuti sediment
Chemical Geology,
51211 – 30
2019
ISSN: 00092541
Publisher: 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
Abstract: ▾ 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 Mössbauer 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.
2243.
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
Papers in Palaeontology,
5
(1)
47-81
2019
ISSN: 20562802
Publisher: Wiley-Blackwell Publishing Ltd
Abstract: ▾ 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
2242.
Chemical and noble gas isotope compositions of formation gases from a 3 km deep scientific borehole in the Koyna Seismogenic Zone, Western India
Geofluids,
2019
2019
ISSN: 14688115
Publisher: Hindawi Limited
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
Abstract: ▾ 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.
2241.
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
Quaternary Science Reviews,
215213 – 231
2019
ISSN: 02773791
Publisher: 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
Abstract: ▾ 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
2240.
Chronostratigraphy of the Baringo-Tugen-Barsemoi (HSPDP-BTB13-1A) core – 40Ar/39Ar dating, magnetostratigraphy, tephrostratigraphy, sequence stratigraphy and Bayesian age modeling
Palaeogeography, Palaeoclimatology, Palaeoecology,
532
2019
ISSN: 00310182
Publisher: 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
Abstract: ▾ 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.
2239.
Climatic and sea-level control of Jurassic (Pliensbachian) clay mineral sedimentation in the Cardigan Bay Basin, Llanbedr (Mochras Farm) borehole, Wales
Sedimentology,
66
(7)
2769 – 2783
2019
2238.
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]
Natural Gas Technology and Economy,
13
(01)
34-38+82
2019
2237.
3-D fluid channel location from noise tremors using matched field processing
Geophysical Journal International,
219
(3)
1550 – 1561
2019
ISSN: 0956540X
Publisher: Oxford University Press
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
Abstract: ▾ 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.
2236.
Climatic and tectonic controls on source-to-sink processes in the tropical, ultramafic catchment of Lake Towuti, Indonesia
Journal of Paleolimnology,
61
(3)
279 – 295
2019
ISSN: 09212728
Publisher: Springer Netherlands
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
Abstract: ▾ 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.
2235.
Constraints on aragonite precipitation in the Dead Sea from geochemical measurements of flood plumes
Quaternary Science Reviews,
221
2019
ISSN: 02773791
Publisher: Elsevier Ltd
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
Abstract: ▾ 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
2234.
Continuous measurement of stress-induced travel-time variations at SAFOD
Seismological Research Letters,
90
(1)
212-218
2019
ISSN: 08950695
Publisher: Seismological Society of America
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
Abstract: ▾ 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.
2233.
Contrasting rainfall-runoff characteristics of floods in desert and Mediterranean basins
Hydrology and Earth System Sciences,
23
(6)
2665 – 2678
2019
2232.
Crustal fracturing, unconformities, and barite deposition, 3.26–3.23 Ga, Barberton Greenstone Belt, South Africa
Precambrian Research,
32734 – 46
2019
2231.
Central Mediterranean explosive volcanism and tephrochronology during the last 630 ka based on the sediment record from Lake Ohrid
Quaternary Science Reviews,
226
2019
2230.
Bajocian transgressive-regressive sequences of the tecocoyunca group, southern Mexico, with maximum flooding surfaces marked by thalassinoides
Geological Quarterly,
63
(3)
449 – 459
2019
DOI:10.7306/gq.1480
2229.
Design of the subsurface observatory at Surtsey volcano, Iceland
Scientific Drilling,
2557-62
2019
ISSN: 18168957
Publisher: Copernicus GmbH
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
Abstract: ▾ 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.
2228.
A roadmap for amphibious drilling at the Campi Flegrei caldera: Insights from a MagellanPlus workshop
Scientific Drilling,
2629-46
2019
ISSN: 18168957
Publisher: Copernicus GmbH
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
Abstract: ▾ 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.
2227.
Mount Sedom salt diapir - Source for sulfate replenishment and gypsum supersaturation in the last glacial Dead Sea (Lake Lisan)
Quaternary Science Reviews,
221
2019
ISSN: 02773791
Publisher: Elsevier Ltd
Keywords:▾
Calcite; Calcium carbonate; Carbonate minerals; Chloride minerals; Dissolution; Drilling fluids; Glacial geology; Gypsum; Infill drilling; Isotopes; Lakes; Reservoirs (water); Saline water; Salt tectonics; Sodium chloride; Supersaturation, Dead sea; Hypersaline lakes; Last glacial; Last Glacial Maximum; Mt. Sedom diapir; Pore fluids; Solution density; Sulfate concentrations, Sulfur compounds, diapir; gypsum; isotopic analysis; Last Glacial; porewater; sulfate; supersaturation, Dead Sea; Israel; Mount Sedom; Southern District
Abstract: ▾ During the late Quaternary several hypersaline lakes occupied the tectonic depression of the Dead Sea Basin, depositing sequences of primary-evaporitic mineral phases: aragonite (CaCO3), gypsum (CaSO4·2H2O) and halite (NaCl). Aragonite and gypsum were the dominant primary mineral phases during the glacial periods and their formation required significant import of bicarbonate (HCO3 −) and sulfate (SO4 2−) ions to the lake. While bicarbonate was likely derived from dissolution of calcite in the watershed, the sources of sulfate remained elusive. Here we investigate and quantify the long-term sulfate reservoir changes in the deep waters (hypolimnion) of Lake Lisan (the last glacial Dead Sea) using concentrations and stable isotopes of sulfur in pore-fluids from the cores that were drilled at the lake floor (2010–11) by ICDP (International Continental Drilling Program). From ca. 117ka, pore-fluid sulfate concentrations increased and the brine attained supersaturation with respect to gypsum, peaking during the last glacial maximum (LGM; ca. 20ka). Stable isotopes of pore-fluid sulfate (δ34S and δ18O) are similar to the values found in bulk sulfate minerals from the nearby Mount Sedom salt diapir. We suggest that relatively diluted and cool paleo-epilimnion water facilitated dissolution of halite and anhydrite (CaSO4) of the Mt. Sedom salt diapir, resulting in a localized increase in solution density. Subsequently, this solution sank and mixed with saline hypolimnion water, simultaneously replenishing chloride, sodium and sulfate reservoirs, while diluting it with respect to other solutes. The mixing of the calcium-rich gypsum saturated hypolimnion and the sulfate-rich sinking brine from above resulted in gypsum supersaturation. © 2019 Elsevier Ltd
2226.
40Ar-39Ar step heating ages of North American tektites and of impact melt rock samples from the Chesapeake Bay impact structure
Geochimica et Cosmochimica Acta,
255289-308
2019
ISSN: 00167037
Publisher: Elsevier Ltd
Keywords:▾
argon-argon dating; Eocene-Oligocene boundary; geochronology; impact structure; magnetostratigraphy; melt; meteorite; paleomagnetism; tektite, Ascoli Piceno; Chesapeake Bay; Italy; Marche; Massignano; United States
Abstract: ▾ 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
2225.
40Ar-39Ar step heating ages of North American tektites and of impact melt rock samples from the Chesapeake Bay impact structure
Geochimica et Cosmochimica Acta,
255289-308
2019
ISSN: 00167037
Publisher: Elsevier Ltd
Keywords:▾
argon-argon dating; Eocene-Oligocene boundary; geochronology; impact structure; magnetostratigraphy; melt; meteorite; paleomagnetism; tektite, Ascoli Piceno; Chesapeake Bay; Italy; Marche; Massignano; United States
Abstract: ▾ 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
2224.
A discussion on deep-well combined drill string technology for ultra-deep drilling engineering [深井复合钻柱技术在特深科学钻探中的应用探讨]
Geology in China,
46
(5)
1200-1208
2019
ISSN: 10003657
Publisher: Science Press
Abstract: ▾ Deep-well combined drill string technology has become one of the most important scheme to solve the super-long drill string used for ultra-deep drilling project, which is related to equipment capacity, material property, drilling conditions and string mechanics. In this paper, the application and development of combined drill string technology in geological drilling are summarized systematically, the design scheme and its limitation length are discussed in detail on the basis of strength theory. The results show that the drilling mission with the depth of 13000m could not be finished by simply using pure steel combined drill string with the final borehole diameter being 216mm. By using drill string consisting of V150 steel drill pipe & titanium alloy drill pipe and S135 steel drill pipe & aluminum alloy drill pipe, the limitation depth and the weight of each combined drill string are respectively 13484m, 18783m and 360.5, 324.3t; in this way both of them own application reliability and advantage. These results have reference significance to the design and selection of deep-well combined drill string used for ultra-deep drilling project. © 2019 Editorial Board of Geology in China. All rights reserved.
2223.
A model for effective permeability in an unconsolidated hydrate reservoir
Journal of Natural Gas Science and Engineering,
72
2019
ISSN: 18755100
Publisher: Elsevier B.V.
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
Abstract: ▾ 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.
2222.
A new Dead Sea pollen record reveals the last glacial paleoenvironment of the southern Levant
Quaternary Science Reviews,
21498-116
2019
ISSN: 02773791
Publisher: Elsevier Ltd
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
Abstract: ▾ 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
2221.
A simplified MEV formulation to model extremes emerging from multiple nonstationary underlying processes
Advances in Water Resources,
127280 – 290
2019
2220.
Authigenic Mineral Texture in Submarine 1979 Basalt Drill Core, Surtsey Volcano, Iceland
Geochemistry, Geophysics, Geosystems,
20
(7)
3751-3773
2019
ISSN: 15252027
Publisher: Blackwell Publishing Ltd
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
Abstract: ▾ 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.