All ICDP Publications with Abstracts
From parent-sysfolder "Publications" + 2 folder-levels deep
2694.
Pyroclastic deposition in the Cretaceous Shahezi Formation (Well SK-2) Songliao Basin, China: Implications for tectonics and volcanism
Geological Journal,
57
(6)
2346-2364
2022
ISSN: 00721050
Publisher: John Wiley and Sons Ltd
DOI:10.1002/gj.4414
Keywords:▾
Cretaceous; graben; lithofacies; provenance; pyroclastic deposit; tectonics; transtension; Triassic; volcanism; weathering, China; Songliao Basin
Abstract: ▾ Well SK-2 is located in the Songliao Basin. Core samples from this well indicate that the Early Cretaceous Shahezi Formation has a length of 2,359.01 m and is in direct contact with the basin basement of the Middle Triassic, missing the Huoshiling Formation. This paper is focused on the lowest sequence 1 (S1, at the bottom of the Shahezi Formation, interval of 5,450.72–5,695.00 m, a length of 244.28 m) of the Cretaceous basin fills. It was found that the volcanic components contributed important parts in the sequence of basin fills, and the start of the rifting resulted from the combination of regional extensional tectonics and volcanism. Based on the centimetre-scale description of the continuous core samples, we propose a model to delineate the interaction between tectonics, volcanism, and pyroclastic deposition. The study shows the tectonic-volcanism in the earliest rifting stages and its control on sedimentary filling. These results also have common sense for the initial rifting process of a continental half-graben basin. Sequence 1 of the Shahezi Formation in well SK-2 shows a typical volcanic- sedimentary sequence. During the lowstand stage, the weathering-depositional system was controlled by extension; during the transgressive and highstand stages, the transitional weathering-depositional system and the mixed volcanic and weathering depositional system were controlled by transtension. © 2022 John Wiley & Sons Ltd.
2693.
Resolving impact volatilization and condensation from target rock mixing and hydrothermal overprinting within the Chicxulub impact structure
Geoscience Frontiers,
13
(5)
2022
Abstract: ▾ This work presents isotopic data for the non-traditional isotope systems Fe, Cu, and Zn on a set of Chicxulub impactites and target lithologies with the aim of better documenting the dynamic processes taking place during hypervelocity impact events, as well as those affecting impact structures during the post-impact phase. The focus lies on material from the recent IODP-ICDP Expedition 364 Hole M0077A drill core obtained from the offshore Chicxulub peak ring. Two ejecta blanket samples from the UNAM 5 and 7 cores were used to compare the crater lithologies with those outside of the impact structure. The datasets of bulk Fe, Cu, and Zn isotope ratios are coupled with petrographic observations and bulk major and trace element compositions to disentangle equilibrium isotope fractionation effects from kinetic processes. The observed Fe and Cu isotopic signatures, with δ56/54Fe ranging from −0.95‰ to 0.58‰ and δ65/63Cu from −0.73‰ to 0.14‰, mostly reflect felsic, mafic, and carbonate target lithology mixing and secondary sulfide mineral formation, the latter associated to the extensive and long-lived (>105 years) hydrothermal system within Chicxulub structure. On the other hand, the stable Zn isotope ratios provide evidence for volatility-governed isotopic fractionation. The heavier Zn isotopic compositions observed for the uppermost part of the impactite sequence and a metamorphic clast (δ66/64Zn of up to 0.80‰ and 0.87‰, respectively) relative to most basement lithologies and impact melt rock units indicate partial vaporization of Zn, comparable to what has been observed for Cretaceous-Paleogene boundary layer sediments around the world, as well as for tektites from various strewn fields. In contrast to previous work, our data indicate that an isotopically light Zn reservoir (δ66/64Zn down to −0.49‰), of which the existence has previously been suggested based on mass balance considerations, may reside within the upper impact melt rock (UIM) unit. This observation is restricted to a few UIM samples only and cannot be extended to other target or impact melt rock units. Light isotopic signatures of moderately volatile elements in tektites and microtektites have previously been linked to (back-)condensation under distinct kinetic regimes. Although some of the signatures observed may have been partially overprinted during post-impact processes, our bulk data confirm impact volatilization and condensation of Zn, which may be even more pronounced at the microscale, with variable degrees of mixing between isotopically distinct reservoirs, not only at proximal to distal ejecta sites, but also within the lithologies associated with the Chicxulub impact crater. © 2022 China University of Geosciences (Beijing) and Peking University
2692.
Quaternary environmental changes in central Chukotka (NE Russia) inferred from the Lake El'gygytgyn pollen records
Journal of Quaternary Science,
37
(5)
915-927
2022
ISSN: 02678179
Publisher: John Wiley and Sons Ltd
DOI:10.1002/jqs.3408
Keywords:▾
albedo; environmental change; glacial-interglacial cycle; ice; Milankovitch cycle; Pleistocene; pollen; snow; vegetation, Chukchi; Elgygytgyn Lake; Russian Federation
Abstract: ▾ The 3.6-Myr sedimentary record of Lake El'gygytgyn is crucial for understanding the response of the sensitive ecosystems in the Arctic to Quaternary climate variations at orbital timescales. In this study, we synthesize previously published pollen records and biome reconstructions and perform pollen diversity analysis of the deep-drilling core ICDP 5011-1 from Lake El'gygytgyn for periods during the Early Pleistocene (MIS 82 – MIS 79), Early–Middle Pleistocene (MIS 31 – MIS 18) and late Middle Pleistocene (MIS 7e – MIS 6f). The results indicate that the predominance of herb tundra in the regional vegetation was most characteristic during glacials/stadials. Interglacials, in contrast, can be distinguished by the expansion of shrub communities mainly composed of birch, alder and willow. The expansion of forest biomes in the region was influenced by peaks in obliquity values, which led to increases in daylight length, which was essential for plant growth in high latitudes. An apparent long-term decreasing trend in the tree and shrub population, accompanied by a reduction in floristic richness, was induced by stepwise cooling and drying since the Mid-Pleistocene Transition (MPT), which is linked to the modulation of extended global ice volume during the MPT via strong snow- and ice-albedo feedback effects. © 2022 John Wiley & Sons, Ltd.
2691.
Reconstructing the Environmental Context of Human Origins in Eastern Africa Through Scientific Drilling
Annual Review of Earth and Planetary Sciences,
50451 – 476
2022
2690.
Reconstructing the Environmental Context of Human Origins in Eastern Africa Through Scientific Drilling
Annual Review of Earth and Planetary Sciences,
50451 – 476
2022
ISSN: 00846597
Publisher: Annual Reviews Inc.
Keywords:▾
Africa; Core drilling; Drills; Infill drilling; Sedimentary rocks; Stratigraphy; Continental scientific drillings; Drill core; East African Rift; Eastern Africa; Environmental contexts; High resolution; Hominins; Human evolution; Late Neogene; Paleoclimates; environmental change; environmental history; human evolution; Neogene; paleoclimate; Pleistocene; Lakes
Abstract: ▾ Paleoanthropologists have long speculated about the role of environmental change in shaping human evolution in Africa. In recent years, drill cores of late Neogene lacustrine sedimentary rocks have yielded valuable high-resolution records of climatic and ecosystem change. Eastern African Rift sediments (primarily lake beds) provide an extraordinary range of data in close proximity to important fossil hominin and archaeological sites, allowing critical study of hypotheses that connect environmental history and hominin evolution. We review recent drill-core studies spanning the Plio-Pleistocene boundary (an interval of hominin diversification, including the earliest members of our genus Homo and the oldest stone tools), and the Mid-Upper Pleistocene (spanning the origin of Homo sapiens in Africa and our early technological and dispersal history). Proposed drilling of Africa's oldest lakes promises to extend such records back to the late Miocene. squf High-resolution paleoenvironmental records are critical for understanding external drivers of human evolution. squf African lake basin drill cores play a critical role in enhancing hominin paleoenvironmental records given their continuity and proximity to key paleoanthropological sites. squf The oldest African lakes have the potential to reveal a comprehensive paleoenvironmental context for the entire late Neogene history of hominin evolution. © 2022 by Annual Reviews. All rights reserved.
2689.
Reduced plate motion controlled timing of Early Jurassic Karoo-Ferrar
large igneous province volcanism
SCIENCE ADVANCES,
8
2022
2688.
Research and application of high−temperature drilling fluid designed for the continental scientific drilling project of Songliao Basin, China
Energy Sources, Part A: Recovery, Utilization and Environmental Effects,
44
(1)
2075-2087
2022
ISSN: 15567036
Publisher: Taylor and Francis Ltd.
Keywords:▾
Additives; Bentonite; Drilling fluids; Infill drilling; Thermodynamic stability, Bottom hole temperatures; Continental scientific drillings; Drilling fluid systems; High temperature resistance; High temperature stability; Research and application; Rheological behaviour; Songliao basin, Core drilling
Abstract: ▾ Well Songke−2 is the main hole of the Continental Scientific Drilling Project of Songliao Basin, China, and its bottom hole temperature is estimated to exceed 240°C in the fourth spud at the well depth of 5800 m. To ensure that the drilling fluid could meet the demand of high temperature resistance, different components, including clay, filtration reducers and anti−collapse additives, of the high–temperature drilling fluid system were optimized through thermal stability tests. Comprehensive test results suggested that the optimal bentonite content to be 4% (w/v). Compared with other materials of the same type, polymer filtration reducers SO−1 and HLW−1, as well as sulfonation additive LOCKSEAL were demonstrated to have stronger resistance to high temperature. The proposed high temperature drilling fluid formula exhibited good thermal stability, rheological behaviour, anti−contamination capacity and shale inhibition property. Finally, a great success of the formula was practically obtained in the field application during the following−up core drilling project. © 2022 Taylor & Francis Group, LLC.
2687.
Research progress of absorption and attenuation mechanism and petrophysical theory for gas hydrate reservoir [天然气水合物储层吸收衰减机制及岩石物理理论研究进展]
Shiyou Diqiu Wuli Kantan/Oil Geophysical Prospecting,
57
(4)
992-1008
2022
ISSN: 10007210
Publisher: Science Press
Keywords:▾
Gas hydrates; Gases; Hydration; Microstructure; Petroleum prospecting; Petrophysics; Seismology, Attenuation characteristics; Bottom simulating reflection; Exploration technologies; Gas hydrate reservoir; Hydrate saturation; Petrophysical; Petrophysics; Quantitative interpretation; Reflection characteristics; Seismic attenuation, Seismic waves
Abstract: ▾ The bottom simulating reflection (BSR) characteristics of reflected seismic waves are an important sign of gas hydrate. Although they can indicate the bottom of hydrate, they can hardly be used for quantitative interpretation of hydrate content. The rapid development of the gas hydrate exploration technology in recent years results in an understanding that the "blank" zone of seismic amplitude above BSR, directly related to the absorption and attenuation of seismic waves, can be used as an indicator of gas hydrate distribution and quantification. This paper reviews the seismic wave absorption and attenuation characteristics of various hydrate exploration areas around the world (the Mallik permafrost area in Canada, the Nankai Trough in Japan, the Makran accretionary wedge in the Arabian Sea, the Gulf of Mexico, and the Shenhu area in the South China Sea) and artificial hydrate-bearing rock samples. The results show that for different hydrate exploration areas, hydrate-bearing samples, and data used, seismic waves show different attenuation characteristics. Then, the possible attenuation mechanisms and related petrophysical theories are summarized for hydrate reservoirs, mainly including global flow attenuation (the Leclaire model), squirt flow (the improved Leclaire model, the hydrate effective grain (HEG) model for submicron hydrate particle squirt, or the hydrate-bearing effective sediment (HBES) model for micron flow squirt), skeleton friction attenuation (the improved Leclaire model). At present, the main problem is that although the hydrate-bearing strata in many areas demonstrate obvious absorption and attenuation characteristics, the relationships of absorption and attenuation variation with hydrate saturation remain unknown due to the varied hydrate formation conditions and geological environments and different occurrence states of hydrate in sediments of different areas. In addition, the frequency band ranges of the current measured observation data and those petrophysical experiments test are limited, so the characteristics of attenuation variation with frequency are not fully reflected. Therefore, petrophysical experimental studies need to be further conducted, and available data from actual exploration areas and the making and experimental measurement results of artificial cores shall be well utilized, thereby studying the additional effect of the microstructure of the hydrate reservoir on the attenuation mechanism in depth. After the reasons of seismic wave attenuation in hydrate reservoirs are clarified, a quantitative seismic interpretation method for hydrate saturation can be developed. © 2022, Editorial Department OIL GEOPHYSICAL PROSPECTING. All right reserved.
2686.
Revisiting the Milankovitch Theory from the Perspective of the 405 ka Long Eccentricity Cycle; [从40万年长偏心率周期看米兰科维奇理论]
Diqiu Kexue - Zhongguo Dizhi Daxue Xuebao/Earth Science - Journal of China University of Geosciences,
47
(10)
3543 – 3568
2022
2685.
Spectroscopic study of terrestrial analogues to support rover missions to Mars – A Raman-centred review
Analytica Chimica Acta,
1209
2022
2684.
Rhodothermus bifroesti sp. nov., a thermophilic bacterium isolated from the basaltic subsurface of the volcanic island Surtsey
International Journal of Systematic and Evolutionary Microbiology,
72
(1)
005214
2022
2683.
Search for a meteoritic component within the impact melt rocks of the Chicxulub impact structure peak ring, Mexico
Geochimica et Cosmochimica Acta,
32374-101
2022
Abstract: ▾ Constraining the degree of preservation of a meteoritic signature within an impact structure provides vital insights in the complex pathways and processes that occur during and after an impact cratering event, providing information on the fate of the projectile. The IODP-ICDP Expedition 364 drilling recovered a ∼829 m continuous core (M0077A) of impactites and basement rocks within the ∼200-km diameter Chicxulub impact structure peak ring. No highly siderophile element (HSE) data have been reported for any of the impact melt rocks of this drill core to date. Previous work has shown that most Chicxulub impactites contain less than 0.1% of a chondritic component. Only few impact melt rock samples in previous drill cores recovered from the Chicxulub might contain such a signal. Therefore, we analyzed impact melt rock and suevite samples, as well as pre-impact lithologies of the Chicxulub peak ring, with a focus on the HSE concentrations and Re–Os isotopic compositions. Similar to the concentrations of the other major and trace elements, those of the moderately siderophile elements (Cr, Co, Ni) of impact melt rock samples primarily reflect mixing between a mafic (dolerite) and felsic (granite) components, with the incorporation of carbonate material in the upper impact melt rock unit (from 715.60 to 747.02 meters below seafloor). The HSE concentrations of the impact melt rocks and suevites are generally low (<39 ppt Ir, <96 ppt Os, <149 ppt Pt), comparable to the values of the average upper continental crust, yet three impact melt rock samples exhibit an enrichment in Os (125–410 ppt) and two of them also in Ir (250–324 ppt) by one order of magnitude relative to the other investigated samples. The 187Os/188Os ratios of the impact melt rocks are highly variable, ranging from 0.18 to 2.09, probably reflecting heterogenous target rock contributions to the impact melt rocks. The significant amount of mafic dolerite (mainly ∼20–60% and up to 80–90%), which is less radiogenic (187Os/188Os ratio of 0.17), within the impact melt rocks makes an unambiguous identification of an extraterrestrial admixture challenging. Granite samples have unusually low 187Os/188Os ratios (0.16 on average), while impact melt rocks and suevites broadly follow a mixing trend between upper continental crust and chondritic/mantle material. Only one of the investigated samples of the upper impact melt rock unit could also be interpreted in terms of a highly diluted (∼0.01–0.05%) meteoritic component. Importantly, the impact melt rocks and pre-impact lithologies were affected by post-impact hydrothermal alteration processes, probably remobilizing Re and Os. The mafic contribution, explaining the least radiogenic 187Os/188Os values, is rather likely. The low amount of meteoritic material preserved within impactites of the Chicxulub impact structure may result from a combination of the assumed steeply-inclined trajectory of the Chicxulub impactor (enhanced vaporization, and incorporation of projectile material within the expansion plume), the impact velocity, and the volatile-rich target lithologies. © 2022 The Author(s)
2682.
Sediment provenance and silicic volcano-tectonic evolution of the northern East African Rift System from U/Pb and (U-Th)/He laser ablation double dating of detrital zircons
Earth and Planetary Science Letters,
580
2022
ISSN: 0012821X
Publisher: Elsevier B.V.
Keywords:▾
East African Rift; Clay alteration; Core drilling; Drills; Infill drilling; Sedimentary rocks; Sedimentology; Single crystals; Tectonics; Volcanic rocks; Volcanoes; Zircon; Detrital zircon; Double dating; Drill core; East African Rift; Hydrothermal alterations; Laser ablation double dating; Lasers ablations; Rift systems; Sediment provenance; Tectonic evolution; dating method; detrital deposit; helium isotope; hydrothermal alteration; provenance; sediment analysis; tectonic evolution; uranium series dating; uranium-lead dating; zircon; Laser ablation
Abstract: ▾ Detrital zircons from two major rift basins within the East African Rift System (EARS) provide a means to evaluate not only sediment provenance and landscape dynamics in sedimentary basins, but also the timing of the silicic volcano-tectonic evolution of the rift system. We sampled from drill cores collected by the Hominin Sites and Paleolakes Drilling Project (HSPDP) in Ethiopia and Kenya to study the detrital mineral records of the Northern Awash (NA; 3.3–2.9 Ma) and West Turkana (WTK; 1.9–1.4 Ma) drill cores. We performed (U-Th)/He and U/Pb analyses on detrital zircons using single crystal laser ablation double dating (LADD) techniques. Analyses of four NA samples yielded zircon 206Pb/238U dates younger than ∼45 Ma, consistent with derivation from silicic volcanic rocks associated with EARS activity. Most of these samples lack zircon 206Pb/238U dates from ∼22–13 Ma, due to a decrease in silicic volcanism and a watershed configuration limiting delivery of silicic source materials to the sample site. NA zircon 206Pb/238U dates imply a sedimentary source from the western Afar margin, with a transition to more localized sediment reworking within the Afar Depression after a major regional tectonic reorganization and formation of a disconformity at ∼2.9 Ma. The WTK sample yielded many zircons with Cenozoic 206Pb/238U dates similar to those from the NA core, but the WTK sample also sources a small population of Neoproterozoic zircons associated with rocks from the Mozambique Belt and reworked sedimentary deposits. Despite being recorders of predominantly silicic activity, the detrital zircon U/Pb dates from both drill sites track the established timing of major volcanic phases in the EARS. A subset of zircons from both sites has concordant 206Pb/238U and (U-Th)/He dates, indicating a short duration between zircon crystallization and eruption of the host volcanic rock, but the majority of zircon (U-Th)/He dates are significantly younger than the 206Pb/238U dates for the same zircon. Some (U-Th)/He dates are even younger than the depositional age of the sedimentary sample from which it was collected. The observed spread in zircon (U-Th)/He dates likely reflects partial resetting associated with late mafic volcanism and/or hydrothermal activity within this dynamic rift environment. © 2022 Elsevier B.V.
2681.
SediRate-Fischer plots as a tool to illustrate relative sea-level and lake-level changes in subaqueous terrigenous deposits
Sedimentology,
69
(5)
2080 – 2098
2022
ISSN: 00370746
Publisher: John Wiley and Sons Inc
Keywords:▾
Andalucia; China; Guadalquivir Basin; Songliao Basin; Spain; Lakes; Lithology; Sea level; Fischer plot; Guadalquivir basin; Lake level changes; Lake levels; Orbital tuning; Relative sea level; Run test; Sedimentary cycles; Sedimentary rate; Songliao basin; facies; lake level; lithology; sea level change; terrigenous deposit; Sedimentology
Abstract: ▾ For more extensive and efficient sea-level and lake-level reconstructions and correlations in siliciclastic systems, this paper presents a new tool called SediRate-Fischer plot (SR-Fischer plot). In SR-Fischer plots, the linear-corrected sedimentary rate of each terrigenous sedimentary cycle is plotted from the top of the previous cycle to the top of the current cycle. This process is repeated cycle by cycle, constructing curves of cumulative departure from mean sedimentary rate (CDMR). Based on the assumption that relative sea-level and lake-level changes may control sedimentary rates of subaqueous terrigenous sediments within basins, the CDMR could change inversely with relative sea or lake level. Thus, this tool could be interpreted as an indicator of relative sea-level and lake-level changes in terrigenous successions. SediRate-Fischer plots can be obtained from either lithological or proxy cycles formed by sea-level and lake-level changes in the case of availability of orbitally tuned data. The SR-Fischer plots constructed based on different materials are compared with other methods in two cases, as follows: first for the lacustrine Mingshui Formation of the Songliao Basin in China; and second for the deep-marine Arcillas de Gibraleón Formation of the Guadalquivir Basin in Spain. The SR-Fischer plots of the Mingshui Formation exhibit low and high CDMR values for shallow-lake intervals and lakeshore intervals, respectively, and vary inversely with the lake-level curves derived from changes in sedimentary facies. For the Arcillas de Gibraleón Formation, the CDMR values illustrated by the SR-Fischer plots exhibit opposite variations with sea-level curves indicated by dinocyst/pollen ratios. The negative Z-scores derived from runs tests indicate that these SR-Fischer plots are not randomly stacked and are minimally influenced by different cycle-splitting strategies. Thus, the results of comparison with other methods and runs tests demonstrate the validity of this method. Nonetheless, the other allogenic inflows (tectonics and climates) may limit interpretations of SR-Fischer plots. © 2022 International Association of Sedimentologists.
2680.
Sensitivity of the West Antarctic Ice Sheet to+ 2° C (SWAIS 2C)
Scientific Drilling,
30101--112
2022
2679.
Ship-board determination of whole-rock (ultra-)trace element concentrations by laser ablation-inductively coupled plasma mass spectrometry analysis of pressed powder pellets aboard the D/V Chikyu
Scientific Drilling,
3075-99
2022
ISSN: 18168957
Publisher: Copernicus GmbH
Keywords:▾
Exploratory geochemistry; Fluorescence spectroscopy; Inductively coupled plasma; Inductively coupled plasma mass spectrometry; Infill drilling; Laser ablation; Pelletizing; Petrology; Preferred numbers; Rare earths; Rocks; Stratigraphy, Crust mantle; Drilling projects; Laser-ablation inductively-coupled plasma mass spectrometry; Mass spectrometry analysis; New approaches; Oceanic crust; Pressed powder pellets; Trace elements concentration; Traces elements; Ultratraces, Trace elements
Abstract: ▾ The Oman Drilling Project (OmanDP), performed under the International Continental Scientific Drilling Program (ICDP), is an international scientific research project that undertook drilling at a range of sites in the Semail ophiolite (Oman) to collect core samples spanning the stratigraphy of the ophiolite, from the upper oceanic crust down to the basal thrust. The cores were logged to International Ocean Discovery Program (IODP) standards aboard the D/V Chikyu. During ChikyuOman2018 Leg 3 (July-August 2018), participants described cores from the crust-mantle transition (CM) sites. The main rock types recovered at these sites were gabbros, dunites and harzburgites, rocks typically forming the base of the oceanic crust and the shallow mantle beneath present-day spreading centres. In addition to the core description, selected samples were analysed by X-ray fluorescence spectrometry (XRF) for their chemical compositions, including major, minor and some trace elements. To complement these standard procedures, we developed new approaches to measure ultra-trace element concentrations using a procedure adapted from previous works to prepare fine-grained pressed powder pellets coupled with laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis using instrumentation aboard the D/V Chikyu. First, three (ultra)mafic reference materials were investigated to test and validate our procedure (BHVO-2, BIR-1a and JP-1), and then the procedure was applied to a selection of gabbro and dunite samples from the CM cores to explore the limitations of the method in its current stage of development. The obtained results are in good agreement with preferred values for the reference materials and with subsequent solution replicate analyses of the same samples performed in shore-based laboratories following Leg 3 for the CM samples. We describe this procedure for the determination of 37 minor and (ultra-)trace elements (transition elements and Ga, Li and Large-Ion Lithophile Elements (LILE), Rare Earth Elements (REE), High-Field-Strength Elements (HFSE), U, Th, and Pb) in mafic and ultramafic rocks. The presented method has the major advantage that it allows the determination at sea of the (ultra-)trace element concentrations in a "dry", safe way, without using acid reagents. Our new approach could be extended for other elements of interest and/or be improved to be adapted to other rock materials during future ocean drilling operations aboard the D/V Chikyu and other platforms. © 2022 Mathieu Rospabé et al.
2678.
Koyna, India: A very prominent site of artificial water reservoir-triggered seismicity
Journal of Earth System Science,
131
(1)
2022
ISSN: 23474327
Publisher: Springer
Keywords:▾
borehole geophysics; earthquake event; human activity; laboratory method; reservoir; seismicity, India; Koyna Dam; Maharashtra
Abstract: ▾ Abstract: Anthropogenic activities such as gold and coal mining, oil and gas production, filling of artificial water reservoirs, harnessing of geothermal energy, etc., have induced/triggered earthquakes. Koyna dam, located in the Deccan volcanic province of India, was impounded in 1962, and soon after tremors were reported from the vicinity of Koyna dam. The largest triggered earthquake of magnitude (M) 6.3 occurred on 10 December 1967. The triggered earthquakes have continued until now and the region has experienced 22 events of an M~5, over 200 events of an M~4 and several thousand smaller events. The reservoir-triggered seismicity has continued until 2021, which is unique. Some of the early investigations, leading to drilling of a 3 km deep pilot borehole at Koyna for near-field studies of earthquakes, and a few recent results are summarised in this paper. Research highlights: Koyna, located near the west coast of India, in the Deccan volcanic province is one of the most prominent sites of artificial water reservoir-triggered seismicity (RTS). Triggered earthquakes started soon after the impoundment of Shivaji Sagar lake created by Koyna dam in 1962 and have continued until now.Unlike other RTS sites where triggered earthquakes did not continue for long, Koyna is still active, and it is estimated that RTS may continue for another one to two decades.Detailed field work and analyses of earthquake data demonstrated that Koyna is a very suitable site for near-field studies of earthquakes: an observation that is much needed to validate earthquake genesis models.International Continental Drilling Programme sponsored workshops and participation of experts from all over the world helped in deciding to dig a 3 km deep pilot borehole. The borehole was completed in June 2017.Recent research studies further demonstrated that the Koyna region is under critical stress.Studies under progress would help in designing the proposed ~7 km deep borehole laboratory. © 2022, Indian Academy of Sciences.
2677.
Stress State in the Source Region of Mw2.2 Earthquake in a Deep Gold Mine in South Africa Determined from Borehole Cores
Pure and Applied Geophysics,
179
(5)
1679-1700
2022
ISSN: 00334553
Publisher: Birkhauser
Keywords:▾
Deformation; Earthquakes; Faulting; Gold mines; Infill drilling, Deep mine in south africa; Deep-mines; Deformation analysis; Deformation rate analyse; Deformation rate analysis; Diametrical core deformation analyse; Drilling intersecting a seismogenic fault; Earthquake source; Seismogenic faults; Source region; South Africa; Stress in earthquake source region, Boreholes, aftershock; borehole stability; deformation mechanism; drilling; earthquake event; earthquake magnitude; gabbro; gold mine, South Africa
Abstract: ▾ In December 2007, an Mw2.2 earthquake occurred in a gabbroic dike at 3.3 km depth in a deep gold mine in South Africa. The fore- and aftershock activity was analyzed in an effort to understand the preparation and generation processes of earthquakes; these findings have already been published. The present paper focuses on the stress state in the source region of the mainshock. A 90-m-long borehole across the mainshock fault was drilled ~ 1.5 years after the mainshock and logged by an optical televiewer. The fault can be identified by severe damage to the borehole wall at the point where the borehole intersected the aftershock cluster. Except for a 10-m section in the hanging wall of the fault, borehole cores were fully recovered. Borehole breakout (BO) and core disking (CD) were found to occur. Two stress measurement techniques [Deformation Rate Analysis (DRA) and Diametrical Core Deformation Analysis (DCDA)] were applied to the borehole cores. By combining their results with occurrence criteria for BO and CD, the principal stress state in the source region of the mainshock was determined. The principal directions in the hanging wall of the fault were nearly identical to the virgin stress state, while it was significantly disturbed in the footwall. The vertical stresses were 106 MPa and 40 MPa in the hanging wall and footwall, respectively. The significant difference in the vertical stress between the two sides of the fault can be explained by the stress redistribution associated with a nonuniform slip on a nonplanar fault. © 2022, The Author(s).
2676.
Intensified microbial sulfate reduction in the deep Dead Sea during the early Holocene Mediterranean sapropel 1 deposition
Geobiology,
20
(4)
518-532
2022
ISSN: 14724677
Publisher: John Wiley and Sons Inc
Keywords:▾
biomarker; cyanobacterium; Holocene; isotopic composition; lipid; microbial activity; phytoplankton; reduction; sapropel; stable isotope; sulfate, Dead Sea; Mediterranean Sea, benzopyran derivative; sapropel; sulfate; water, chemistry; ecosystem; humic substance; lake; sediment, Benzopyrans; Ecosystem; Geologic Sediments; Humic Substances; Lakes; Sulfates; Water
Abstract: ▾ The hypersaline Dead Sea and its sediments are natural laboratories for studying extremophile microorganism habitat response to environmental change. In modern times, increased freshwater runoff to the lake surface waters resulted in stratification and dilution of the upper water column followed by microbial blooms. However, whether these events facilitated a microbial response in the deep lake and sediments is obscure. Here we investigate archived evidence of microbial processes and changing regional hydroclimate conditions by reconstructing deep Dead Sea chemical compositions from pore fluid major ion concentration and stable S, O, and C isotopes, together with lipid biomarkers preserved in the hypersaline deep Dead Sea ICDP-drilled core sediments dating to the early Holocene (ca. 10,000 years BP). Following a significant negative lake water balance resulting in salt layer deposits at the start of the Holocene, there was a general period of positive net water balance at 9500–8300 years BP. The pore fluid isotopic composition of sulfate exhibit evidence of intensified microbial sulfate reduction, where both (Formula presented.) and (Formula presented.) of sulfate show a sharp increase from estimated base values of 15.0‰ and 13.9‰ to 40.2‰ and 20.4‰, respectively, and a (Formula presented.) vs. (Formula presented.) slope of 0.26. The presence of the n-C17 alkane biomarker in the sediments suggests an increase of cyanobacteria or phytoplankton contribution to the bulk organic matter that reached the deepest parts of the Dead Sea. Although hydrologically disconnected, both the Mediterranean Sea and the Dead Sea microbial ecosystems responded to increased freshwater runoff during the early Holocene, with the former depositing the organic-rich sapropel 1 layer due to anoxic water column conditions. In the Dead Sea prolonged positive net water balance facilitated primary production and algal blooms in the upper waters and intensified microbial sulfate reduction in the hypolimnion and/or at the sediment–brine interface. © 2022 The Authors. Geobiology published by John Wiley & Sons Ltd.
2675.
Biomarker proxy records of Arctic climate change during the Mid-Pleistocene transition from Lake El'gygytgyn (Far East Russia)
Climate of the Past,
18
(3)
559-577
2022
ISSN: 18149324
Publisher: Copernicus GmbH
Keywords:▾
biomarker; climate change; glacial-interglacial cycle; Pleistocene; vegetation cover; warming, Chukchi; Elgygytgyn Lake; Russian Federation
Abstract: ▾ The Mid-Pleistocene Transition (MPT) is a widely recognized global climate shift occurring between approximately 1250 and 700ka. At this time, Earth's climate underwent a major transition from dominant 40kyr glacial-interglacial cycles to quasi-100kyr cycles. The cause of the MPT remains a puzzling aspect of Pleistocene climate. Presently, there are few, if any, continuous MPT records from the Arctic, yet understanding the role and response of the high latitudes to the MPT is required to better evaluate the causes of this climatic shift. Here, we present new continental biomarker records of temperature and vegetation spanning 1142 to 752ka from Lake El'gygytgyn (Far East Russia). We reconstruct warm-season temperature variations across the MPT based on branched glycerol dialkyl glycerol tetraethers (brGDGTs). The new Arctic temperature record does not display an overall cooling trend during the MPT but does exhibit strong glacial-interglacial cyclicity. Spectral analysis demonstrates persistent obliquity and precession pacing over the study interval and reveals substantial sub-orbital temperature variations at 1/4900ka during the first "skipped"interglacial. Interestingly, Marine Isotope Stage (MIS) 31, which is widely recognized as a particularly warm interglacial, does not exhibit exceptional warmth in the Lake El'gygytgyn brGDGT record. Instead, we find that MIS 29, 27, and 21 were as warm or warmer than MIS 31. In particular, MIS 21 (1/4870 to 820ka) stands out as an especially warm and long interglacial in the continental Arctic while MIS 25 is a notably cold interglacial. Throughout the MPT, Lake El'gygytgyn pollen data exhibit a long-term drying trend, with a shift to an increasingly open landscape noted after around 900ka (Zhao et al., 2018), which is also reflected in our higher plant leaf wax (n-alkane) distributions. Although the mechanisms driving the MPT remain a matter of debate, our new climate records from the continental Arctic exhibit some similarities to changes noted around the North Pacific region. Overall, the new organic geochemical data from Lake El'gygytgyn contribute to expanding our knowledge of the high-latitude response to the MPT. © 2022 Kurt R. Lindberg et al.
2674.
Application of SPAC Method to Survey Deep Geothermal Water Storage Structures in SK-2; [基于SPAC法探测松科二井深层地热储水构造]
Acta Geoscientica Sinica,
43
(6)
909 – 916
2022
ISSN: 10063021
Publisher: Science Press
Abstract: ▾ As a method for acquiring the velocity structure of underground strata and hidden structural faults, microtremor surveying is very popular for shallow exploration in cities and villages because of its advantages of no active source, convenient survey process, and strong anti-interference ability. To explore the deep geothermal resource potential of the northern Songliao Basin in greater detail, the subsurface fine velocity structure within the burial depth range from the Nenjiang Formation to the Denglouku Formation at the bottom of the depression was obtained by using the micro motion detection method in and around Songke Well No. 2 (SK-2) south of Anda City, Heilongjiang Province. Based on the spatial autocorrelation method (SPAC), the S-wave dispersion curve was extracted from the vertical component of the micro motion signal and transformed into the apparent S-wave velocity curve. Finally, through interpolation and smooth calculation, a two-dimensional underground S-wave velocity structure section spanning 9 km and reaching 4000 m beneath the surface was obtained. Analysis of the micro motion profile revealed that the subsurface S-wave velocity generally shows a trend of high velocity in the west and low velocity in the east. There are three obvious low-speed anomaly zones with depths ranging from 1400 m to 2800-100 m in the west, 2300 m in the east, and 3700 m to the east of well SK-2-indicating that there are likely faults or hidden fault structures at these locations. By combining these data with the stratigraphic data, the Quantou and Denglouku Formations were determined as the main units in this depth range, and the lithology is mostly interbedded sandstone and mudstone. These are suitable units for hydrothermal storage. The study shows that the lateral low-velocity anomaly of the surface wave results can be used as a basis of discrimination for identifying deep geothermal water storage structures and can provide direction for further clean energy investigation in this area. © 2022, Science Press. All right reserved.
2673.
Archaeal lipids reveal climate-driven changes in microbial ecology at Lake El'gygytgyn (Far East Russia) during the Plio-Pleistocene
Journal of Quaternary Science,
37
(5)
900-914
2022
ISSN: 02678179
Publisher: John Wiley and Sons Ltd
DOI:10.1002/jqs.3347
Keywords:▾
biogeochemistry; biomarker; climate variation; isoprenoid; lacustrine environment; lake water; lipid; microbial ecology; paleoclimate; paleoenvironment; permafrost; Pliocene; Pliocene-Pleistocene boundary; proxy climate record; timescale, Chukchi; Elgygytgyn Lake; Russian Federation
Abstract: ▾ Isoprenoid glycerol dialkyl glycerol tetraethers (iGDGTs) are commonly preserved molecular biomarkers of archaea whose distributions can be used to reconstruct past temperature, and possibly, methane and nitrogen cycling. To date, iGDGT systematics have not been widely investigated in Arctic lacustrine environments. Here, we analyze iGDGTs in sediments of Lake El'gygytgyn, located in the Russian Arctic, to reconstruct the paleoenvironmental conditions from the Pliocene to today using TEX86 and other indices. The TEX86-inferred temperature history shows a long-term warming trend, in stark contrast to other Arctic records and other proxies from Lake El'gygytgyn, suggesting that non-temperature factors obfuscate the use of TEX86 at this site. Other GDGT-based indices including the BIT Index, ΔRing Index, Methane Index and the GDGT-0/crenarchaeol ratio suggest that TEX86 is strongly influenced by archaeal community changes. The most significant community shifts are observed c. 2.4 Ma and record an increase in Euryarchaeota production and/or a decrease in Thaumarchaeota production, which was driven by the establishment of permafrost and perennial lake ice during the early Pleistocene. Overall, this study demonstrates an important interpretative framework for iGDGTs in lacustrine systems and describes variations in Arctic climate and lake biogeochemistry over timescales of thousands to millions of years. © 2021 John Wiley & Sons, Ltd.
2672.
Artificial Water Reservoir-Triggered Seismicity (RTS): Most Prominent Anthropogenic Seismicity
Surveys in Geophysics,
43
(2)
619-659
2022
ISSN: 01693298
Publisher: Springer Science and Business Media B.V.
Keywords:▾
Boreholes; Diffusion in liquids; Earthquakes; Faulting; Induced Seismicity; Petroleum reservoir engineering; Pore pressure; Stresses, Anthropogenics; Artificial water; Coal-mining; Deep boreholes; Drilling projects; Geological conditions; High water; Permeability; Reservoir-triggered seismicity; Water reservoir level, Abstracting, diffusion; earthquake magnitude; environmental stress; fault zone; permeability; pore pressure; seismicity, India; Koyna; Maharashtra
Abstract: ▾ Abstract: Under certain suitable geological conditions, anthropogenic seismicity due to gold/coal mining, geothermal and natural gas/oil production, filling of artificial water reservoirs, and high-pressure fluid injection has been reported globally. The reservoir-triggered seismicity (RTS) is most prominent, having been reported from hundreds of with at least five sites where earthquakes exceeding M 6 occurred, claiming human lives and destruction of properties. The most important correlate for RTS to occur is the height of water column in the reservoir. Certain common characteristics of the RTS sequences have been identified, which discriminate them from normal earthquake sequences. Factors influencing RTS include the highest water levels reached in the reservoir, duration of the retention of high-water levels and rate of loading/unloading. The mechanism of RTS is reviewed. The absence of knowledge of physical properties of rocks and fluids in the fault zone does not permit us to comprehend the RTS mechanism. Koyna, India, is found to be a very suitable site for such investigations as the earthquakes have been occurring in a small region of 20 × 30 km, at shallow depths (mostly within 8 km), with no other seismic source in the vicinity, and the region being accessible for all kinds of observation and investigations. The suitability of Koyna for setting up of a deep borehole laboratory was discussed during International Continental Drilling Program (ICDP) workshop in 2011 and accepted. Suggestions were made for some additional scientific works, which were completed during 2011–2014. The second ICDP workshop in 2014 approved of going ahead. A 3-km-deep Pilot Borehole has been completed in the vicinity of Donachiwada fault that hosted the main 10 December 1967 M 6.3 earthquake and several earthquakes of M ~ 5. The investigations being carried out are providing the necessary input to set up the proposed ~ 7-km-deep borehole laboratory. In this article, an overview of RTS globally and at Koyna, India, specifically is focused. Article Highlights: Global review of the reservoir-triggered seismicity (RTS) sitesFactors influencing RTS, their common characteristics and mechanismContinued seismicity at Koyna, India, and near-field studies © 2021, The Author(s), under exclusive licence to Springer Nature B.V.
2671.
Benthic-Pelagic state changes in the primary trophic level of an ancient tropical lake
Palaeogeography, Palaeoclimatology, Palaeoecology,
594
2022
ISSN: 00310182
Publisher: Elsevier B.V.
Keywords:▾
Greater Sunda Islands; Lake Towuti; Malili Lakes; South Sulawesi; Sulawesi; Sunda Isles; benthic-pelagic coupling; plankton; primary production; sediment chemistry; trophic level
Abstract: ▾ Many large, ancient lakes support primarily planktonic-driven food webs. In contrast, the lowest trophic levels of the Malili Lakes of Sulawesi Island, Indonesia are dominated by benthic diatom communities composed mainly of endemic species. Centric diatoms are not observed in the current diatom assemblage and pennate pelagic species are rare. Using two deep drill-cores from Lake Towuti, we investigated whether the lake has always been dominated by benthic primary production. Despite the ultra-oligotrophic conditions observed in the lake today, we observed state changes characterized by productive planktonic communities and less productive, benthic-dominated diatom assemblages. Two periods of planktonic production, each lasting approximately 50 kyr, were dominated by a complex mixture of Aulacoseira spp., with valve densities >1.0 × 109 valves/g with a maximum biovolume of 3.5 × 1012 μm3/g. A similar planktonic assemblage was observed at much lower abundances (<107valves/g) in the deeper sediments (>1 Ma), during the earliest stages of lake formation. Two periods of increased benthic primary production of approximately ~11 kyr in duration, originating from the littoral zone of the lake, were also observed, one between the two planktonic phases and one above the last planktonic maxima. The benthic periods were dominated by Cymbopleura spp., with valve densities of approximately 2.0 × 108 valves/g and a maximum biovolume of 1.2 × 1011 μm3/g. Nonmetric multidimensional scaling analysis of sediment chemistry revealed that the benthic and pelagic states clustered with distinct chemical environments. The benthic phases were associated with well-mixed conditions in the lake whereas the planktonic phases were related to rapidly reoccurring water column mixing followed by intense stratification that generate nutrient recycling events. We conclude that lake mixing and nutrient cycling regimes regulated, in part, the switch between benthic and pelagic states in Lake Towuti. © 2022
2670.
Big volcano science: needs and perspectives
Bulletin of Volcanology,
84
(3)
2022
ISSN: 02588900
Publisher: Springer Science and Business Media Deutschland GmbH
Keywords:▾
magma; volcano; volcanology
Abstract: ▾ Volcano science has been deeply developing during last decades, from a branch of descriptive natural sciences to a highly multi-disciplinary, technologically advanced, quantitative sector of the geosciences. While the progress has been continuous and substantial, the volcanological community still lacks big scientific endeavors comparable in size and objectives to many that characterize other scientific fields. Examples include large infrastructures such as the LHC in Geneva for sub-atomic particle physics or the Hubble telescope for astrophysics, as well as deeply coordinated, highly funded, decadal projects such as the Human Genome Project for life sciences. Here we argue that a similar big science approach will increasingly concern volcano science, and briefly describe three examples of developments in volcanology requiring such an approach, and that we believe will characterize the current decade (2020–2030): the Krafla Magma Testbed initiative; the development of a Global Volcano Simulator; and the emerging relevance of big data in volcano science. © 2022, The Author(s).