All ICDP Publications with Abstracts
From parent-sysfolder "Publications" + 2 folder-levels deep
2044.
Real-time earthquake monitoring during the second phase of the deep fault drilling project, Alpine fault, New Zealand
Seismological Research Letters,
88
(6)
1443-1454
2017
ISSN: 08950695
Publisher: Seismological Society of America
Keywords:▾
Drills; Faulting; Geophysics; Open source software; Open systems; Rock drilling; Software engineering, Drilling operation; Earthquake monitoring; In-situ measurement; International team; Postgraduate students; Science activities; Scientific drilling; Seismic monitoring, Earthquakes, drilling; earthquake magnitude; earthquake swarm; fault; seismicity, Alpine Fault Zone; New Zealand; South Island; West Coast [South Island]; Whataroa
Abstract: ▾ 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. © 2017 by the Seismological Society of America.
2043.
Seafloor Response to Large Volcanic Activity and Geohazard Implications in Naples Bay, Southern Italy
Offshore Site Investigation Geotechnics 8th International Conference Proceeding
265-275
2017
Abstract: ▾ In this study, marine geophysical investigations were utilized to recognize, compare and classify seafloor features related to volcanic activity in the Naples Bay, southern Italy. The dataset includes swath bathymetry, side-scan sonar records, as well as single-channel and multichannel reflection seismics. Ground truth was provided by detailed analysis of gravity cores. By integrating these data, large portions of the seafloor were mapped, providing important information for geohazard assessment.
2042.
Redox variations in Mauna Kea lavas, the oxygen fugacity of the Hawaiian plume, and the role of volcanic gases in Earth’s oxygenation
Proceedings of the National Academy of Sciences of the United States of America,
114
(34)
8997-9002
2017
ISSN: 00278424
Publisher: National Academy of Sciences
Abstract: ▾ The behavior of C, H, and S in the solid Earth depends on their oxidation states, which are related to oxygen fugacity (fO2). Volcanic degassing is a source of these elements to Earth’s surface; therefore, variations in mantle fO2 may influence the fO2 at Earth’s surface. However, degassing can impact magmatic fO2 before or during eruption, potentially obscuring relationships between the fO2 of the solid Earth and of emitted gases and their impact on surface fO2. We show that low-pressure degassing resulted in reduction of the fO2 of Mauna Kea magmas by more than an order of magnitude. The least degassed magmas from Mauna Kea are more oxidized than midocean ridge basalt (MORB) magmas, suggesting that the upper mantle sources of Hawaiian magmas have higher fO2 than MORB sources. One explanation for this difference is recycling of material from the oxidized surface to the deep mantle, which is then returned to the surface as a component of buoyant plumes. It has been proposed that a decreasing pressure of volcanic eruptions led to the oxygenation of the atmosphere. Extension of our findings via modeling of degassing trends suggests that a decrease in eruption pressure would not produce this effect. If degassing of basalts were responsible for the rise in oxygen, it requires that Archean magmas had at least two orders of magnitude lower fO2 than modern magmas. Estimates of fO2 of Archean magmas are not this low, arguing for alternative explanations for the oxygenation of the atmosphere. © 2017, National Academy of Sciences. All rights reserved.
2041.
Relationships between lake-level changes and water and salt budgets in the Dead Sea during extreme aridities in the Eastern Mediterranean
Earth and Planetary Science Letters,
464211-226
2017
ISSN: 0012821X
Publisher: Elsevier B.V.
Keywords:▾
Brines; Budget control; Climate change; Climate models; Drops; Drought; Flood control; Isotopes; Lakes; Sea level; Sodium chloride; Stratigraphy; Water, Annual precipitation; Climatic conditions; Dead sea; Eastern Mediterranean; Interglacial; Lake levels; Marine isotope stages; Sedimentation rates, Chloride minerals, aridity; drought; extreme event; halite; interglacial; lake level; marine isotope stage; paleoclimate; Quaternary; salt; water budget, Dead Sea; Mediterranean Region
Abstract: ▾ Thick halite intervals recovered by the Dead Sea Deep Drilling Project cores show evidence for severely arid climatic conditions in the eastern Mediterranean during the last three interglacials. In particular, the core interval corresponding to the peak of the last interglacial (Marine Isotope Stage 5e or MIS 5e) contains ∼30 m of salt over 85 m of core length, making this the driest known period in that region during the late Quaternary. This study reconstructs Dead Sea lake levels during the salt deposition intervals, based on water and salt budgets derived from the Dead Sea brine composition and the amount of salt in the core. Modern water and salt budgets indicate that halite precipitates only during declining lake levels, while the amount of dissolved Na+ and Cl− accumulates during wetter intervals. Based on the compositions of Dead Sea brines from pore waters and halite fluid inclusions, we estimate that ∼12–16 cm of halite precipitated per meter of lake-level drop. During periods of halite precipitation, the Mg2+ concentration increases and the Na+/Cl− ratio decreases in the lake. Our calculations indicate major lake-level drops of ∼170 m from lake levels of 320 and 310 m below sea level (mbsl) down to lake levels of ∼490 and ∼480 mbsl, during MIS 5e and the Holocene, respectively. These lake levels are much lower than typical interglacial lake levels of around 400 mbsl. These lake-level drops occurred as a result of major decreases in average fresh water runoff, to ∼40% of the modern value (pre-1964, before major fresh water diversions), reflecting severe droughts during which annual precipitation in Jerusalem was lower than 350 mm/y, compared to ∼600 mm/y today. Nevertheless, even during salt intervals, the changes in halite facies and the occurrence of alternating periods of halite and detritus in the Dead Sea core stratigraphy reflect fluctuations between drier and wetter conditions around our estimated average. The halite intervals include periods that are richer and poorer in halite, indicating (based on the sedimentation rate) that severe dry conditions with water availability as low as ∼20% of the present day, continued for periods of decades to centuries, and fluctuated with wetter conditions that spanned centuries to millennia when water availability was ∼50–100% of the present day. These conclusions have potential implications for the coming decades, as climate models predict greater aridity in the region. © 2017 Elsevier B.V.
2040.
Repeating Marmara Sea earthquakes: Indication for fault creep
Geophysical Journal International,
210
(1)
332-339
2017
ISSN: 0956540X
Publisher: Oxford University Press
Keywords:▾
Creep; Faulting; Geophysics; Hazards; Locks (fasteners); Nucleation; Seismic response; Seismology; Transform faults, Earthquake hazard; Metropolitan regions; North Anatolian Fault Zone; Northwestern Turkey; Nucleation points; Rupture propagation; Selection criteria; Waveform cross correlation, Earthquakes, active fault; creep; earthquake catalogue; earthquake magnitude; earthquake rupture; fault zone; seismic hazard; seismicity; transform fault, Marmara [Turkey]; Sea of Marmara; Turkey
Abstract: ▾ Discriminating between a creeping and a locked status of active faults is of central relevance to characterize potential rupture scenarios of future earthquakes and the associated seismic hazard for nearby population centres. In this respect, highly similar earthquakes that repeatedly activate the same patch of an active fault portion are an important diagnostic tool to identify and possibly even quantify the amount of fault creep. Here, we present a refined hypocentre catalogue for the Marmara region in northwestern Turkey, where a magnitude M up to 7.4 earthquake is expected in the near future. Based on waveform cross-correlation for selected spatial seismicity clusters, we identify two magnitude M ~ 2.8 repeater pairs. These repeaters were identified as being indicative of fault creep based on the selection criteria applied to the waveforms. They are located below the western part of the Marmara section of the North Anatolian Fault Zone and are the largest reported repeaters for the larger Marmara region. While the eastern portion of the Marmara seismic gap has been identified to be locked, only sparse information on the deformation status has been reported for its western part. Our findings indicate that the western Marmara section deforms aseismically to a substantial extent, which reduces the probability for this region to host a nucleation point for the pending Marmara earthquake. This is of relevance, since a nucleation of the Marmara event in the west and subsequent eastward rupture propagation towards the Istanbul metropolitan region would result in a substantially higher seismic hazard and resulting risk than if the earthquake would nucleate in the east and thus propagate westward away from the population centre Istanbul. © The Authors 2017.
2039.
Report on the ICDP workshop DIVE (Drilling the Ivrea-Verbano zonE)
Scientific Drilling,
2347 – 56
2017
ISSN: 18168957
Publisher: Copernicus GmbH
Keywords:▾
Chemical operations; Continental crusts; Drilling operation; Physicochemical property; Scientific objectives; Space and time; Technical aspects; Technical details; Transition zones; Earth (planet)
Abstract: ▾ The Ivrea-Verbano Zone is the most complete, time-integrated crust-upper mantle archive in the world. It is a unique target for assembling data on the deep crust and the Moho transition zone and testing several hypotheses of formation, evolution, and modification of the continental crust through space and time across the Earth. The ICDP workshop Drilling the Ivrea-Verbano zonE (DIVE), held in Baveno, Italy, from 1 to 5 May 2017, focused on the scientific objectives and the technical aspects of drilling and sampling in the Ivrea- Verbano Zone at depth. A total of 47 participants from 9 countries with a wide variety of scientific and/or drilling expertise attended the meeting. Discussion on the proposed targets sharpened the main research lines and led to working groups and the necessary technical details to compile the full drilling proposal. The participants of the workshop concluded that four drilling operations in the Val Sesia and Val d'Ossola crustal sections represent the scientifically most promising solution to achieve the major goals within DIVE to unravel the physico-chemical properties and architecture of the lower continental crust towards the crust-mantle (Moho) transition zone. © Author(s) 2017.
2038.
Rock strength measurements on Archaean basement granitoids recovered from scientific drilling in the active Koyna seismogenic zone, western India
Tectonophysics,
712-713182-192
2017
ISSN: 00401951
Publisher: Elsevier B.V.
Keywords:▾
Buildings; Deformation; Granite; Infill drilling; Seismographs; Stress-strain curves, Failure criteria; Granitoids; India; Rock strength; Scientific drilling; Seismic zones, Earthquakes, Archean; basement rock; drilling; failure mechanism; granitoid; rock mechanics; seismic zone; seismicity; strength; stress-strain relationship
Abstract: ▾ Reservoir triggered earthquakes have been occurring in the Koyna area, western India for the past five decades. Triaxial tests carried out on 181 core samples of Archaean granitoids underlying the Deccan Traps provide valuable constraints on rock strength properties in the Koyna seismogenic zone for the first time. The data include measurements on granite gneiss, granite, migmatitic gneiss and mylonitised granite gneiss obtained from boreholes KBH-3, KBH-4A, KBH-5 and KBH-7 located in the western and eastern margins of the seismic zone. Salient results are as follows. (i) Increase of rock strength with increasing confining pressure allow determination of the linearized failure envelopes from which the cohesive strength and angle of internal friction are calculated. (ii) Variable differential stresses at different depths are the manifestations of deformation partitioning in close association of fault zone(s) or localized fracture zones. (iii) Fractures controlled by naturally developed weak planes such as cleavage and fabric directly affect the rock strength properties, but the majority of failure planes developed during triaxial tests is not consistent with the orientations of pre-existing weak planes. The failure planes may, therefore, represent other planes of weakness induced by ongoing seismic activity. (iv) Stress-strain curves confirm that axial deformation is controlled by the varying intensity of pre-existing shear in the granitoids, viz., mylonite, granite gneiss and migmatitic gneiss. (v) Frequent occurrences of low magnitude earthquakes may be attributed to low and variable rock strength of the granitoids, which, in turn, is modified by successive seismic events. © 2017 Elsevier B.V.
2037.
Prediction of the bottom hole geotemperature, formation pressure and formation fracture pressure of the Continental Scientific Drilling of Cretaceous Songliao Basin (SK2)
Earth Science Frontiers,
24
(1)
257 – 264
2017
ISSN: 10052321
Publisher: Science Frontiers editorial department
Keywords:▾
Forecasting; Geology; Petroleum prospecting; Bottom hole; Bottom hole temperatures; Continental scientific drillings; Cretaceous; Formation pressure; Scientific achievements; Songliao basin; Xujiaweizi Fault Depression; Fracture
Abstract: ▾ The designed depth of SK2 is 6400 m, which is the deepest scientific drilling in the East Asia. Previous studies shows that the Xujiaweizi Fault Depression is located in the high geotemperature area. However the high geotemperature and possible abnormal pressure are the main challenges for continental scientific drilling. Based on a great deal of geological and geophysical data including regional geological survey, petroleum exploration and exploitation and scientific achievements in the Songliao Basin, we predicted the bottom hole temperature, formation pressure and formation fracture pressure of target strata of SK2. According to the relationship between depth and present geotemperatures, geothermal gradients, we predicted the bottom hole geotemperature of SK2 probably range from 238.83℃ to 265.11℃. According to the relationship between depth and formation pressures, and calculated results using DrillWorks, we estimated the formation pressure of Yingcheng Formation, Shahezi Formation and Huoshiling Formation to the bottom of the hole in the range of 30.54-37.72 MPa, 33.22-59.52 MPa, 59.52-67.18 MPa, respectively; and the formation fracture pressure range from 52.35 MPa to 58.62 MPa, from 61.88 MPa to 105.68 MPa, from 104.57 MPa to 118.03 MPa, respectively. © 2017, Editorial Office of Earth Science Frontiers. All right reserved.
2036.
Preservation and significance of extracellular DNA in ferruginous sediments from Lake Towuti, Indonesia
Frontiers in Microbiology,
8
(JUL)
2017
ISSN: 1664302X
Publisher: Frontiers Media S.A.
Keywords:▾
cell DNA; RNA 16S; Acidobacteria; Actinobacteria; Alphaproteobacteria; Article; cell count; Chloroflexi; controlled study; cytolysis; Deltaproteobacteria; DNA base composition; DNA extraction; DNA sequence; high throughput sequencing; hydrothermal vent species; Nitrospirae; nonhuman; phylogenetic tree; phylogeny; Planctomycetes; polymerase chain reaction; population abundance; preservation; sediment; Thaumarchaeota; Thermoplasmatales; Verrucomicrobia
Abstract: ▾ Extracellular DNA is ubiquitous in soil and sediment and constitutes a dominant fraction of environmental DNA in aquatic systems. In theory, extracellular DNA is composed of genomic elements persisting at different degrees of preservation produced by processes occurring on land, in the water column and sediment. Extracellular DNA can be taken up as a nutrient source, excreted or degraded by microorganisms, or adsorbed onto mineral matrices, thus potentially preserving information from past environments. To test whether extracellular DNA records lacustrine conditions, we sequentially extracted extracellular and intracellular DNA from anoxic sediments of ferruginous Lake Towuti, Indonesia. We applied 16S rRNA gene Illumina sequencing on both fractions to discriminate exogenous from endogenous sources of extracellular DNA in the sediment. Environmental sequences exclusively found as extracellular DNA in the sediment originated from multiple sources. For instance, Actinobacteria, Verrucomicrobia, and Acidobacteria derived from soils in the catchment. Limited primary productivity in the water column resulted in few sequences of Cyanobacteria in the oxic photic zone, whereas stratification of the water body mainly led to secondary production by aerobic and anaerobic heterotrophs. Chloroflexi and Planctomycetes, the main degraders of sinking organic matter and planktonic sequences at the water-sediment interface, were preferentially preserved during the initial phase of burial. To trace endogenous sources of extracellular DNA, we used relative abundances of taxa in the intracellular DNA to define which microbial populations grow, decline or persist at low density with sediment depth. Cell lysis became an important additional source of extracellular DNA, gradually covering previous genetic assemblages as other microbial genera became more abundant with depth. The use of extracellular DNA as nutrient by active microorganisms led to selective removal of sequences with lowest GC contents. We conclude that extracellular DNA preserved in shallow lacustrine sediments reflects the initial environmental context, but is gradually modified and thereby shifts from its stratigraphic context. Discrimination of exogenous and endogenous sources of extracellular DNA allows simultaneously addressing in-lake and post-depositional processes. In deeper sediments, the accumulation of resting stages and sequences from cell lysis would require stringent extraction and specific primers if ancient DNA is targeted. © 2017 Vuillemin, Horn, Alawi, Henny, Wagner, Crowe and Kallmeyer.
2035.
Lithology and stratigraphic interfaces prediction of the Continental Scientific Drilling Project of Cretaceous Songliao Basin (SK2)
Earth Science Frontiers,
24
(1)
242 – 256
2017
ISSN: 10052321
Publisher: Science Frontiers editorial department
Keywords:▾
Buildings; Lithology; Metamorphic rocks; Sedimentology; Stratigraphy; Well drilling; Continental scientific drillings; Denglouku formations; Low-grade metamorphism; Scientific drilling; Shahezi formations; Songliao basin; Stratigraphic columns; Stratigraphic interfaces; Sedimentary rocks
Abstract: ▾ The simulated stratigraphic column of SK2 is the main reference for the whole scientific drilling process bases on the experience of SK1. First of all, the depth of the main formation boundaries was predicted according to structural maps, seismic profiles and adjacent wells. Secondly, we predicted the detail lithology of each member or formation, based on regional stratigraphic-lithologic characteristics, geophysical data, and well Songshen3 and other adjacent wells. Finally, the designed coring horizon, contents, oil, gas and water bearing layers, probable drilling failures etc. were integrated into the comprehensive simulated stratigraphic column of SK2. The depth of the main formation boundaries of SK2 is predicted as below: the top of the 2nd member of Nenjiang Formation (T06) is 950 m, the top of Yaojia Formation (T1) is 1245 m, the top of Quantou Formation (T2) is 1680 m, the top of Denglouku Formation (T3) is 2530 m, the top of Yingcheng Formation (T4) is 2965 m, the top of Shahezi Formation (T4-1) is 3320 m, the top of Huoshiling Formation (T4-2) is 5670 m, and the top of basement (T5) is 6240 m. The lithology of main target strata of SK2 are predicted as follows. Yingcheng Formation can be divided into two parts, and the upper part consists mostly of coarse sand, conglomerate, and glutinite, with mudstone as interlayers, and massive tuff, andesite-basalt and rhyolite, dominated in the lower part. The Shahezi Formation is composed mostly of dark mudstone, with sand, siltstone, silty mudstone, and coal streak as interlayers. The lithology of Huoshiling Formation possibly corresponds to regional stratigraphic-lithologic characteristics, and the upper part is mainly composed of tuff, mudstone, and dacite and andesite, while the lower part consists mostly of dark mudstone, with fine-siltstone and coal streak as interlayers. The basement probably composed of conglomerate and permian-carboniferous “metamorphic rock”, which are probably very high diagenesis or very low-grade metamorphism sedimentary rocks. © 2017, Editorial Office of Earth Science Frontiers. All right reserved.
2034.
Porewater salinity reveals past lake-level changes in Lake Van, the Earth's largest soda lake
Scientific Reports,
7
(1)
2017
ISSN: 20452322
Publisher: Nature Publishing Group
Abstract: ▾ In closed-basin lakes, sediment porewater salinity can potentially be used as a conservative tracer to reconstruct past fluctuations in lake level. However, until now, porewater salinity profiles did not allow quantitative estimates of past lake-level changes because, in contrast to the oceans, significant salinity changes (e.g., local concentration minima and maxima) had never been observed in lacustrine sediments. Here we show that the salinity measured in the sediment pore water of Lake Van (Turkey) allows straightforward reconstruction of two major transgressions and a major regression that occurred during the last 250 ka. We observed strong changes in the vertical salinity profiles of the pore water of the uppermost 100 m of the sediments in Lake Van. As the salinity balance of Lake Van is almost at steady-state, these salinity changes indicate major lake-level changes in the past. In line with previous studies on lake terraces and with seismic and sedimentological surveys, we identify two major transgressions of up to +105 m with respect to the current lake level at about 135 ka BP and 248 ka BP starting at the onset of the two previous interglacials (MIS5e and MIS7), and a major regression of about-200 m at about 30 ka BP during the last ice age. © 2017 The Author(s).
2033.
New constraints on the Paleoarchean meteorite bombardment of the Earth – Geochemistry and Re-Os isotope signatures of spherule layers in the BARB5 ICDP drill core from the Barberton Greenstone Belt, South Africa
Geochimica et Cosmochimica Acta,
211322 – 340
2017
ISSN: 00167037
Publisher: Elsevier Ltd
Keywords:▾
Australia; Barberton Greenstone Belt; Pilbara Block; Western Australia; Archean; Earth; geochemistry; impact; meteorite; Ocean Drilling Program; remobilization; rhenium-osmium dating; siderophile element; spherule
Abstract: ▾ Archean spherule layers, resulting from impacts by large extraterrestrial objects, to date represent the only remnants of the early meteorite, asteroid, and comet bombardment of the Earth. Only few Archean impact debris layers have been documented, all of them embedded in the 3.23–3.47 billion year old successions of the Barberton Greenstone Belt (BGB) in South Africa and the Pilbara Craton in Western Australia. Some of them might be correlated with each other. Given the scarcity of Archean spherule deposits, four spherule layer intersections from the recently recovered BARB5 drill core from the central Barberton Greenstone Belt, analyzed in this study, provide an opportunity to gain new insight into the early terrestrial impact bombardment. Despite being hydrothermally overprinted, siderophile element abundance signatures of spherule-rich samples from the BARB5 drill core, at least in part, retained a meteoritic fingerprint. The impact hypothesis for the generation of the BARB5 spherule layers is supported by correlations between the abundances of moderately (Cr, Co, Ni) and highly siderophile (Re, Os, Ir, Pt, Ru and Pd) elements, whose peak concentrations and interelement ratios are within the range of those for chondrites. Rhenium-Osmium isotope evidence further support the impact hypothesis. Collectively, this study provides evidence for extraterrestrial admixtures ranging between ∼40 and up to 100% to three of the four analyzed BARB5 spherule layers, and a scenario for their genesis involving (i) impact of a chondritic bolide into a sedimentary target, (ii) varying admixtures of meteoritic components to target materials, (iii) spherule formation via condensation in an impact vapor plume, (iv) transportation of the spherules and sedimentation under submarine conditions, followed by (v) moderate post-impact remobilization of transition metals and highly siderophile elements. © 2017 Elsevier Ltd
2032.
Source and magmatic evolution inferred from geochemical and Sr-O-isotope data on hybrid lavas of Arso, the last eruption at Ischia island (Italy; 1302 AD)
Journal of Volcanology and Geothermal Research,
3311 – 15
2017
ISSN: 03770273
Publisher: Elsevier B.V.
Keywords:▾
Campania [Italy]; Ischia; Italy; Napoli [Campania]; Geochemistry; Isotopes; Minerals; Rock products; Volcanic rocks; Volcanoes; Crustal contamination; Ischia island; Magmatic plumbing system; Mingling/mixing; Stable isotopes; crustal contamination; igneous geochemistry; lava; magmatism; mixing; oxygen isotope; point source; source rock; stable isotope; strontium isotope; volcanic eruption; volcanology; Strontium compounds
Abstract: ▾ Geochemical and isotopic (87Sr/86Sr and 18O/16O) data have been acquired on whole rock and separated mineral samples from volcanic products of the 1302 AD Arso eruption, Ischia volcanic island (Gulf of Naples, Southern Italy), to investigate magmatic processes. Our results highlight petrographic and isotopic disequilibria between phenocrysts and their host rocks. Similar disequilibria are observed also for more mafic volcanic rocks from Ischia and in the Phlegraean Volcanic District in general. Moreover, 87Sr/86Sr and 18O/16O values suggest mixing between chemically and isotopically distinct batches of magma, and crystals cargo from an earlier magmatic phase. The radiogenic Sr isotope composition suggests that the mantle source was enriched by subduction-derived sediments. Furthermore, magmas extruded during the Arso eruption were affected by crustal contamination as suggested by high oxygen isotope ratios. Assimilation and fractional crystallization modelling of the Sr-O isotope compositions indicates that not more than ~ 7% of granodioritic rocks from the continental crust have been assimilated by a mantle-derived mafic magma. Hence the recent volcanic activity of Ischia has been fed by distinct batches of magma, variably contaminated by continental crust, that mixed during their ascent towards the surface and remobilized phenocrysts left from earlier magmatic phases. © 2016 Elsevier B.V.
2031.
Logan medallist 4. Large-scale impact and earth history
Geoscience Canada,
44
(1)
1-26
2017
Abstract: ▾ The current record of large-scale impact on Earth consists of close to 200 impact structures and some 30 impact events recorded in the stratigraphic record, only some of which are related to known structures. It is a preservation sample of a much larger production population, with the impact rate on Earth being higher than that of the moon. This is due to the Earth’s larger physical and gravitational cross-sections, with respect to asteroidal and cometary bodies entering the inner solar system. While terrestrial impact structures have been studied as the only source of ground-truth data on impact as a planetary process, it is becoming increasingly acknowledged that large-scale impact has had its effects on the geologic history of the Earth, itself. As extremely high energy events, impacts redistribute, disrupt and reprocess target lithologies, resulting in topographic, structural and thermal anomalies in the upper crust. This has resulted in many impact structures being the source of natural resources, including some worldclass examples, such as gold and uranium at Vredefort, South Africa, Ni-Cu-PGE sulphides at Sudbury, Canada and hydrocarbons from the Campeche Bank, Mexico. Large-scale impact also has the potential to disrupt the terrestrial biosphere. The most devastating known example is the evidence for the role of impact in the Cretaceous-Paleocene (K-Pg) mass extinction event and the formation of the Chicxulub structure, Mexico. It also likely had a role in other, less dramatic, climatic excursions, such as the Paleocene-Eocene-Thermal Maximum (PETM) event. The impact rate was much higher in early Earth history and, while based on reasoned speculation, it is argued that the early surface of the Hadean Earth was replete with massive impact melt pools, in place of the large multiring basins that formed on the lower gravity moon in the same time-period. These melt pools would differentiate to form more felsic upper lithologies and, thus, are a potential source for Hadean-aged zircons, without invoking more modern geodynamic scenarios. The Earth-moon system is unique in the inner solar system and currently the best working hypothesis for its origin is a planetary-scale impact with the proto-Earth, after core formation at ca. 4.43 Ga. Future large-scale impact is a low probability event but with high consequences and has the potential to create a natural disaster of proportions unequalled by other geologic processes and threaten the extended future of human civilization, itself. © 2017 GAC/AGC®.
2030.
Magmatic systems of large continental igneous provinces
Geoscience Frontiers,
8
(4)
621--640
2017
2029.
Magnetic mineralogical variability along Deccan trap basalt borehole (KBH07), Koyna deep continental drilling program, western Maharashtra, India
Journal of the Geological Society of India,
90
(6)
769-775
2017
ISSN: 00167622
Publisher: Geological Society of India
Keywords:▾
basalt; borehole; Deccan Traps; deep drilling; magnetic mineral; mineralogy, India; Koyna; Maharashtra
Abstract: ▾ A 1248 m long core (KBH 07, 17°18′07″ N; 73°47′28.2″E, 960m above msl) drilled up to basement in the Deccan traps from Koyna region was sampled at ∼10m interval for magnetic mineralogical studies.Analysis of routine rock magnetic parameters (mass specific magnetic susceptibility: χlf, frequency dependence of susceptibility: χfd, susceptibility of anhysteretic remanance: χARM, saturation isothermal remanance: SIRM, remanance coercivty: B(0)CR, SoftIRM, HardIRM, S-Ratio, SIRM/χlf, χARM/χlf) and density (σ, gm/cc) depicted significant higher order temporal variation. The χlf varies between 13 and 309 x 10-8m3/kg and is independent of density variation. The χARM, B(0)CR and S-Ratios indicate majority of SD-PSD ferrimagnets with episodes of MD ferrimagnetic concentration and few hard coercivity components. The giant plagioclase lath bearing (GPB) horizons show highest variability of ferrimagnetic concentration marked by anomalous peaks. Overall the variability of rock magnetic parameters independent of lava flow units suggest that the changeover in magnetic mineral concentration, composition and domain size occur at major episodes in magma composition (e.g., primary source, crustal contamination and fractional crystallization). The studied parameters are therefore examined to mark intervals of (i) magma compositional changes, (ii) zones of oxidative conditions and (iii) rapid/slow cooling intervals demanding detailed petrologic studies. We identified one I order trend, four II order cycles and eight III order cycles for the purpose of correlation. Notable peak in χlf at 650–700m, the changeover in rock magnetic parameters at ∼930 m and ∼280 m can facilitate marker intervals while several higher order variations can be adopted for high resolution correlation to other boreholes in the region. The complex variation in rock magnetic parameters independent of flow units reflect temporal magnitudes of compositional variability, cooling and emplacement history that needs detailed petro-mineralogical attempts; and the present data is useful for high order inter-core correlations under the deep drilling program. © 2017, Geological Society of India.
2028.
Magnetic records from the Nenjiang Formation of core SK-1s and their implications
Earth Science Frontiers,
24
(1)
143 – 153
2017
ISSN: 10052321
Publisher: Science Frontiers editorial department
Keywords:▾
Lithology; Magnetic susceptibility; Magnetite; Remanence; Sedimentology; Detrital provenance; Lake level fluctuations; Nenjiang Formation; Reductive diagenesis; Rock magnetism; Songke-1 south core (SK-1s); Magnetism
Abstract: ▾ Rock magnetic records have been achieved from the Nenjiang Formation of the Songke-1 south core (SK-1s) in the Songliao Basin (972.46-1060.24 m). According to the magnetic records, this sequence is divided into three sections, termed A (972.46-979 m), B (979-1025 m) and C (1025-1060.24 m), respectively. Magnetic susceptibility (MS) and remanence of section A are both controlled by magnetite; while MS of sections B and C is controlled by paramagnetic minerals and their remanence is mainly carried by magnetite. Among the three sections, the concentration of magnetite of section A is the most and that of section B is the least; while the magnetite particles of section A are the coarsest and those of section C are the finest. The magnetic records of the Nenjiang Formation from SK-1s has deciphered the information of the uplift of the basin and the paleoclimatic changes of this area, although reductive diagenesis plays an effect on the sediments of sections B and C and thus produces the A/B boundary. On the one hand, the fluctuation of the magnetic parameters have recorded the periodical paleoclimatic changes. On the other hand, the abrupt variation of the magnetic parameters at the B/C boundary may be related to the alteration of detrital provenances resulting from the uplift of the eastern basin, from south-north to east-west. © 2017, Editorial Office of Earth Science Frontiers. All right reserved.
2027.
Microbiological and geochemical survey of Co2-dominated mofette and mineral waters of the Cheb Basin, Czech Republic
Frontiers in Microbiology,
8
(DEC)
2017
ISSN: 1664302X
Publisher: Frontiers Media S.A.
Keywords:▾
carbon dioxide; helium; hydrogen; iron; mineral water; organic carbon; Actinobacteria; aquatic environment; Article; chromatography by stationary phase; controlled study; correlation analysis; Czech Republic; earthquake; electrical conductivity parameters; environmental factor; freshwater environment; geochemical analysis; hypoxia; isotope analysis; limit of quantitation; mass spectrometry; microbial community; microbiology; multivariate analysis; nonhuman; Proteobacteria; reverse transcription polymerase chain reaction; sequence analysis; soil analysis
Abstract: ▾ The Cheb Basin (NW Bohemia, Czech Republic) is a shallow, neogene intracontinental basin. It is a non-volcanic region which features frequent earthquake swarms and large-scale diffuse degassing of mantle-derived CO2 at the surface that occurs in the form of CO2-rich mineral springs and wet and dry mofettes. So far, the influence of CO2 degassing onto the microbial communities has been studied for soil environments, but not for aquatic systems. We hypothesized, that deep-trenching CO2 conduits interconnect the subsurface with the surface. This admixture of deep thermal fluids should be reflected in geochemical parameters and in the microbial community compositions. In the present study four mineral water springs and two wet mofettes were investigated through an interdisciplinary survey. The waters were acidic and differed in terms of organic carbon and anion/cation concentrations. Element geochemical and isotope analyses of fluid components were used to verify the origin of the fluids. Prokaryotic communities were characterized through quantitative PCR and Illumina 16S rRNA gene sequencing. Putative chemolithotrophic, anaerobic and microaerophilic organisms connected to sulfur (e.g., Sulfuricurvum, Sulfurimonas) and iron (e.g., Gallionella, Sideroxydans) cycling shaped the core community. Additionally, CO2-influenced waters form an ecosystem containing many taxa that are usually found in marine or terrestrial subsurface ecosystems. Multivariate statistics highlighted the influence of environmental parameters such as pH, Fe2+ concentration and conductivity on species distribution. The hydrochemical and microbiological survey introduces a new perspective on mofettes. Our results support that mofettes are either analogs or rather windows into the deep biosphere and furthermore enable access to deeply buried paleo-sediments. © 2017 Krauze, Kämpf, Horn, Liu, Voropaev, Wagner and Alawi.
2026.
North Atlantic controlled depositional cycles in MIS 5e layered sediments from the deep Dead Sea basin
Quaternary Research (United States),
87
(1)
168-179
2017
ISSN: 00335894
Publisher: Cambridge University Press
Keywords:▾
Atmospheric pressure; Chloride minerals; Gypsum; Hydrology; Seawater; Sodium chloride; Statistical mechanics; Watersheds, Dead sea; ICDP core; Interglacial; Laminated sediments; Levant; North Atlantic oscillations; Paleoclimates; Solar cycle, Oceanography, deposition; drilling; halite; Last Glacial; Last Interglacial; marine isotope stage; North Atlantic Oscillation; paleoclimate; periodicity; sedimentary sequence; solar cycle, Atlantic Ocean; Atlantic Ocean (North); Dead Sea; Levant; Mediterranean Region
Abstract: ▾ The drilled Inter-Continental Drilling Project core at the deeps of the Dead Sea reveals thick sequences of halite deposits from the last interglacial period, reflecting prevailing arid conditions in the lake's watershed. Here, we examine sequences of intercalating evaporates (halite or gypsum) and fine-detritus laminae and apply petrographic, micro-X-ray fluorescence, and statistical tools to establish in high-temporal resolution the hydroclimatic controls on the sedimentation in the last interglacial Dead Sea. The time series of the thickness of the best-recovered core sections of the layered halite, detritus, and gypsum reveals periodicities of ~11, 7-8, and 4-5 yr, pointing to a North Atlantic control and possibly solar influence on the hydrology of the Dead Sea watershed during the regionally arid period of the last interglacial period. Similar periodicities were detected in the last glacial and modern sedimentary sequences of the Dead Sea and other archives of the central Levant, indicating a persistent impact of the solar cycles on regional hydrology, possibly through the effects of the North Atlantic Oscillation. © University of Washington. Published by Cambridge University Press, 2017.
2025.
Pore structure characterization of the Cretaceous Quantou Formation: Results from microresistivity imaging logs in the second scientific drilling borehole (SK-2 east borehole) Songliao basin, northeast China
Journal of Petroleum Science and Engineering,
159915-926
2017
ISSN: 09204105
Publisher: Elsevier B.V.
Keywords:▾
Boring; Geophysics; Geothermal fields; Geothermal logging; Lithology; Pore structure; Porosity; Sedimentology; Spectrum analysis; Structural geology, Clastic strata; Continental scientific drillings; Imaging log; Long term observations; Petrophysical properties; Pore structure characterizations; Sedimentary environment; Songliao basin, Well logging, borehole logging; clastic rock; drilling; environmental change; lithology; paleoclimate; porosity, China; Songliao Basin
Abstract: ▾ As the main borehole of the China Cretaceous Continental Scientific Drilling Project, the SK-2 east borehole was drilled to obtain in-situ multi-information of geophysics and investigate the paleoclimatic and environmental changes. A study based on continuous geophysical logs facilitates achievement of scientific goals, such as the establishment of the typical petrophysical properties for Songliao basin and other similar basins, analysis of sedimentary environment, resource exploration, geothermal system research, and long-term observation and fluid experiments on deep strata. Both conventional logs and microresistivity imaging logs of the Cretaceous Quantou formation have been acquired. Porosity spectra from microresistivity imaging logs are obtained by using the Archie equation. Based on analysis of porosity spectrum features, we divide the porosity spectra of K1q in the SK-2 east borehole into twelve configurations according to the location and combination of peaks to characterize different pore structure. The porosity spectra of K1q in the SK-2 east borehole are dominated by unimodal distribution indicating more primary porosity. Five layers dominated by unimodal distribution are considered for performing long-term observations and fluid experiments on aspects of depth, thickness or petrophysical properties. By comparing spectrum features, porosity spectrum can be used to reflect the heterogeneity and analyze the pore structure of clastic strata. Layered strata will produce complicated porosity spectra as secondary porosity will. It is better to combine porosity spectra with microresistivity image to study secondary porosity. The decline of the porosity heterogeneity in the SK-2 east borehole is demonstrated by two parameters, φvk and W from porosity spectra, which can indicate the sedimentary environment. Moreover, porosity spectra in clastic strata is favorable for determining lithology and sedimentary environment when combined with microresistivity images. © 2017 Elsevier B.V.
2024.
Nucleation process of magnitude 2 repeating earthquakes on the San Andreas Fault predicted by rate-and-state fault models with SAFOD drill core data
Geophysical Research Letters,
44
(1)
162-173
2017
ISSN: 00948276
Publisher: Blackwell Publishing Ltd
Keywords:▾
Core drilling; Drills; Faulting; Friction; Geophysics; Laboratories; Nucleation; Numerical models; Phase meters; Plates (structural components); Slip forming; Stick-slip; Strike-slip faults; Tectonics; Tribology, Earthquake nucleation; Friction parameters; Frictional interface; Physics-based modeling; Rate and state friction; Repeating earthquake; Slow rupture front; Two-phase nucleation, Earthquakes, active fault; earthquake hypocenter; earthquake magnitude; earthquake rupture; experimental study; fault zone; friction; laboratory method; nucleation; numerical model; San Andreas Fault
Abstract: ▾ Recent laboratory shear-slip experiments conducted on a nominally flat frictional interface reported the intriguing details of a two-phase nucleation of stick-slip motion that precedes the dynamic rupture propagation. This behavior was subsequently reproduced by a physics-based model incorporating laboratory-derived rate-and-state friction laws. However, applying the laboratory and theoretical results to the nucleation of crustal earthquakes remains challenging due to poorly constrained physical and friction properties of fault zone rocks at seismogenic depths. Here we apply the same physics-based model to simulate the nucleation process of crustal earthquakes using unique data acquired during the San Andreas Fault Observatory at Depth (SAFOD) experiment and new and existing measurements of friction properties of SAFOD drill core samples. Using this well-constrained model, we predict what the nucleation phase will look like for magnitude ∼2 repeating earthquakes on segments of the San Andreas Fault at a 2.8 km depth. We find that despite up to 3 orders of magnitude difference in the physical and friction parameters and stress conditions, the behavior of the modeled nucleation is qualitatively similar to that of laboratory earthquakes, with the nucleation consisting of two distinct phases. Our results further suggest that precursory slow slip associated with the earthquake nucleation phase may be observable in the hours before the occurrence of the magnitude ∼2 earthquakes by strain measurements close (a few hundred meters) to the hypocenter, in a position reached by the existing borehole. ©2016. American Geophysical Union. All Rights Reserved.
2023.
Overview of Neotropical-Caribbean freshwater ostracode fauna (Crustacea, Ostracoda): identifying areas of endemism and assessing biogeographical affinities
Hydrobiologia,
786
(1)
5 – 21
2017
ISSN: 00188158
Publisher: Springer International Publishing
Keywords:▾
Crustacea; Ostracoda
Abstract: ▾ Freshwater ostracodes from the Neotropical-Caribbean region are potentially excellent tools for evolutionary and paleoenvironmental studies but their use is limited, because integrated data in taxonomy, environmental, and geographical preferences of the species at large scale remain unknown. A total of 118 species were recorded in the Neotropical-Caribbean region based on existing literature and results from fieldwork. About 74% of the species are restricted to the region and most of them show limited distributional areas as a consequence of environmental heterogeneity. Based on Parsimony Analysis of Endemicity, five areas of endemism were identified: (1) southern Florida, (2) southern Mexico-northern Central America, (3) Cuba, (4) Lesser Antilles, and (5) northern Venezuela-Aruba-Curacao-Trinidad. The conservation status of these areas was revised and lake ecosystems with endemic taxa were proposed to be included in environmental protection initiatives. Biogeographical analysis showed a strong differentiation between the ostracode faunas of the Neotropical-Caribbean region and the Neotropical-Neogen region. Few exchanges of species were attributed to ecological and geographical barriers such as volcanism and irregular orography. Faunal affinities within the Neotropical-Caribbean region indicated closer relationship between southern Mexico, southern Florida and the Antilles suggesting a common biogeographical history. Middle Central America and Chiapas-Guatemala highlands were discriminated as isolated regions. © 2016, Springer International Publishing Switzerland.
2022.
Paleointensity From Subaerial Basaltic Glasses From the Second Hawaii Scientific Drilling Project (HSDP2) Core and Implications for Possible Bias in Data From Lava Flow Interiors
Journal of Geophysical Research: Solid Earth,
122
(11)
8664 – 8674
2017
ISSN: 21699313
Publisher: Blackwell Publishing Ltd
Keywords:▾
Hawaii [United States]; United States; basalt; drilling; glass; lava flow
Abstract: ▾ In this study, we collected samples from subaerial basaltic glassy margins from the second Hawaii Scientific Drilling Project (HSDP2) core. We employed the rigorous “IZZI” method during the paleointensity experiment combined with the stringent “CCRIT” criteria for data selection to obtain 21 robust paleointensity estimates recorded by glassy margins from 20 lava flows. We compared our new results to published paleointensities from the interiors of the lava flows from HSDP2 and found that our data are systematically lower than those from the interiors of the same lava flows. The reasons for the discrepancy in intensity are still unclear, but one possibility that could not be absolutely excluded is the effect of cooling rate on the more slowly cooled lava flow interiors. Although our new data from the glassy margins are lower than those from the lava flow interiors, they are still overall higher than the expected field of the study site calculated from a geocentric axial dipole model with an ancient average field of 42 ZAm2, either because of a long-term local anomaly of the field in Hawaii or an insufficient age distribution of our new data (e.g., missing the time period with low field intensities). ©2017. American Geophysical Union. All Rights Reserved.
2021.
Periodic 1.5 ka climate variations during MIS 2 in the belt of Southern Hemispheric westerlies
Quaternary Research (United States),
88
(1)
110 – 120
2017
Keywords:▾
Argentina; Patagonia; Greenhouse effect; Lakes; Magnetic susceptibility; Dansgaard-oeschger events; Frequency Analysis; Laguna potrok aike; Lake sediments; PASADO; Patagonia; climate variation; frequency analysis; lacustrine deposit; marine isotope stage; paleoclimate; Southern Hemisphere; westerly; Sediments
Abstract: ▾ Lacustrine sediments retrieved from Laguna Potrok Aike in the framework of the Potrok Aike Maar Lake Sediment Archive Drilling Project (PASADO) offer the possibility to investigate climate variations of the past ~51 cal ka BP in Southern Hemispheric midlatitudes, Argentinean Patagonia. This study focuses on short-term cyclicities in the Ca and magnetic susceptibility data sets between 51 and 15 cal ka BP. The record yields a climate pattern with a periodicity of 1.5 ka during Marine Oxygen Isotope Stage 2 (MIS 2) detected in the Southern Hemisphere from 31 to 17 cal ka BP for the first time. MIS 2 is known for constantly cold temperatures, whereas prominent climate variations paced by a 1.5 ka periodicity occurred during MIS 3. Our study documents that minor latitudinal oscillations of the Southern Hemispheric westerlies and the polar easterlies with a 1.5 ka periodicity also took place during MIS 2. However, we assume that because of a major northward displacement of the Southern Hemispheric westerlies, these oscillations did not sufficiently affect the zone of Circumpolar Deep Waters and an increased greenhouse effect by upwelling of CO2-rich deep waters did not occur. This mechanism illustrates why prominent climate events fail to appear during MIS 2. Copyright © University of Washington. Published by Cambridge University Press, 2017.
2020.
Permeability and seismic velocity and their anisotropy across the Alpine Fault, New Zealand: An insight from laboratory measurements on core from the Deep Fault Drilling Project phase 1 (DFDP-1)
Journal of Geophysical Research: Solid Earth,
122
(8)
6160-6179
2017
ISSN: 21699313
Publisher: Blackwell Publishing Ltd
Keywords:▾
deep drilling; elastic property; fault zone; hydraulic property; laboratory method; permeability; seismic anisotropy; seismic velocity, Alpine Fault Zone; New Zealand; South Island
Abstract: ▾ The Alpine Fault, a transpressional plate boundary between the Australian and Pacific plates, is known to rupture quasiperiodically with large magnitude earthquakes (Mw ~8). The hydraulic and elastic properties of fault zones are thought to vary over the seismic cycle, influencing the nature and style of earthquake rupture and associated processes. We present a suite of laboratory permeability and P (Vp) and S (Vs) wave velocity measurements performed on fault lithologies recovered during the first phase of the Deep Fault Drilling Project (DFDP-1), which sampled principal slip zone (PSZ) gouges, cataclasites, and fractured ultramylonites, with all recovered lithologies overprinted by abundant secondary mineralization, recording enhanced fluid-rock interaction. Core material was tested in three orthogonal directions, orientated relative to the down-core axis and, when present, foliation. Measurements were conducted with pore pressure (H2O) held at 5 MPa over an effective pressure (Peff) range of 5–105 MPa. Permeabilities and seismic velocities decrease with proximity to the PSZ with permeabilities ranging from 10−17 to 10−21 m2 and Vp and Vs ranging from 4400 to 5900 m/s in the ultramylonites/cataclasites and 3900 to 4200 m/s at the PSZ. In comparison with intact country rock protoliths, the highly variable cataclastic structures and secondary phyllosilicates and carbonates have resulted in an overall reduction in permeability and seismic wave velocity, as well as a reduction in anisotropy within the fault core. These results concur with other similar studies on other mature, tectonic faults in their interseismic period. ©2017. The Authors.