All ICDP Publications with Abstracts
From parent-sysfolder "Publications" + 2 folder-levels deep
2719.
Major sulfur cycle perturbations in the Panthalassic Ocean across the
Pliensbachian-Toarcian boundary and the Toarcian Oceanic Anoxic Event
GLOBAL AND PLANETARY CHANGE,
215
2022
Keywords:▾
Early Toarcian; Panthalassic Ocean; Sulfur cycle; Pyrite sulfur isotope;
Local sedimentary environment
2718.
Measurements of the inclination of the SE-03 Borehole on Surtsey Volcano
Surtsey research,
15121-126
2022
2717.
Microbial biosignature preservation in carbonated serpentine from the Samail Ophiolite, Oman
Communications Earth and Environment,
3
(1)
2022
2716.
Mid-latitude precipitation in East Asia influenced by a fluctuating greenhouse climate during the latest Cretaceous through the earliest Paleogene
Global and Planetary Change,
216
2022
ISSN: 09218181
Publisher: Elsevier B.V.
Keywords:▾
China; Songliao Basin; Carbon dioxide; Greenhouses; Cretaceous; East Asia; Greenhouse climates; Late cretaceous; Mean annual precipitation; Midlatitudes; Palaeosols; Paleogene; Songliao basin; Time records; air mass; carbon dioxide; concentration (composition); cooling; Cretaceous; hydrological cycle; low pressure system; Northern Hemisphere; paleosol; precipitation (climatology); proxy climate record; warming; Weathering
Abstract: ▾ Deep-time records from greenhouse climate periods (e.g., the Late Cretaceous) provide a reference point for understanding how high atmospheric CO2 concentrations influence precipitation in the mid-latitude Northern Hemisphere (e.g., East Asia). In this study, we quantitatively reconstruct mean annual precipitation (MAP) in East Asia during the latest Cretaceous through the earliest Paleogene (~76–65.5 Ma), based on a well-studied paleosol sequence from the Sifangtai and Mingshui Formations from the SK-1n scientific borehole in the Songliao Basin, northeastern China. We use several proxies, including sedimentary-based observational proxies (e.g., depth to the calcic horizon, DTC) and elemental geochemistry proxies in the paleosol B horizon (e.g., the chemical index of alteration minus potassium, CIA-K; the calcium‑magnesium weathering index, CALMAG), which show the consistency with weathering proxies and previously published isotopic records. Changes in the MAP are associated with warming and cooling events. In the warciaming period (e.g., at ~69.5–68.5 Ma), an increase in the land-sea thermal contrast led to an expanded, enhanced, poleward-shifted thermal low-pressure system over the East Asian continent, which triggered an enhanced hydrological cycle and increasing MAP in the Songliao Basin. During the cooling period (e.g., at ~72.5–69.5 Ma and ~68.5–66.5 Ma), weakened East Asian monsoon and strengthened equatorward-shifted westerlies allowed for colder and arid air masses to encroach upon the Songliao Basin, which led to decreased MAP. Changes in MAP across the K-Pg boundary coincide with climate fluctuations and catastrophic geological events. Furthermore, our work compares three warming intervals in deep-time (middle Maastrichtian, late Maastrichtian and earliest Paleogene) with Shared Socio-economic Pathway scenarios used by the IPCC for the end of the 21st century, and indicates MAP increases in East Asia with ongoing anthropogenic CO2 emissions. © 2022 Elsevier B.V.
2715.
Molecular hydrogen from organic sources in the deep Songliao Basin, P.R. China
International Journal of Hydrogen Energy,
47
(38)
16750-16774
2022
ISSN: 03603199
Publisher: Elsevier Ltd
Keywords:▾
Hydrogen storage; Kinetic theory; Molecular physics, Aromatization and cracking; Hydrogen trapping; Hydrogen trapping and storage; Kinetic models; Molecular hydrogen; Natural maturity series; Natural organic hydrogen; Natural organics; Organic sources; Songliao basin, Mass spectrometry
Abstract: ▾ Free hydrogen detected in the Songke-2 well (Songliao Basin, China) has a strong crustal contribution. Here we evaluate whether the source could be the organic matter in Lower Cretaceous coals and shales, and extend our findings regionally. We could establish the rapid growth of aromatic ring systems, forming hydrogen, methane and pyrobitumen, using high resolution mass spectrometry. Molecular hydrogen is generated after late hydrocarbon gas generation is complete, concluding at Rr = 5.0%. The kinetic parameters of molecular hydrogen formation were constructed by subtracting the hydrogen associated with hydrocarbon formation from the total hydrogen, as measured by extensive open system pyrolysis experiments. This new insight was achieved using a CH4–H2 stoichiometric balance. Generalised calculations indicate that the yield per unit rock volume closely resembles that of economic shale gas in the Barnett Shale, though storage in organic matrices is unlikely in this depositional setting. While the prolific generation of hydrogen from organic sources appears to be a reality in the Songliao basin, the free H2 in the Songke-2 mudstream coming from this source must most likely have migrated into the basement rocks mainly from lateral equivalents of the Shahezi rather than from the drilled section itself. © 2022 Hydrogen Energy Publications LLC
2714.
Present situation and prospect of drilling and completion of 10000 meter scientific ultra deep wells (in Chinese with English abstract);[万米科学超深井钻完井现状与展望]
Science & Technology Review,
40
(13)
27-35
2022
2713.
Sulfate (re-) cycling in the oceanic crust: Effects of seawater-rock interaction, sulfur reduction and temperature on the abundance and isotope composition of anhydrite
Geochimica et Cosmochimica Acta,
31765--90
2022
2712.
Prospects of gas production from the vertically heterogeneous hydrate reservoirs through depressurization in the Mallik site of Canada
Energy Reports,
82273-2287
2022
ISSN: 23524847
Publisher: Elsevier Ltd
Keywords:▾
Dissociation; Energy resources; Gases; Hydration; Methane; Natural gas; Natural gas deposits; Petroleum reservoir engineering; Petroleum reservoirs; Submarine geology, Depressurizations; Gas productions; Heterogeneous; Mallik site; Methane gas; Natural gas hydrates; Natural gas-hydrates; Production efficiency; Production performance; Reservoir models, Gas hydrates
Abstract: ▾ Natural gas hydrate (NGH) is a clean and efficient energy resource with extensive distribution in the permafrost regions and marine sediments. A few short-term production tests focusing on reservoir depressurization have been conducted in recent years. However, the long-term production performance and the transient evolution characteristics of reservoir properties are not well known. In this work, a more realistic hydrate-reservoir model that considers the heterogeneity of permeability, porosity and hydrate saturation is constructed, according to the available geological data at the Mallik site. The model is validated by reproducing the field depressurization test. The main purposes of this work are to evaluate the long-term gas production performance and to analyze the unique multiphase flow behaviors from the validated geologically descriptive hydrate-reservoir model. The results indicate that the long-term gas production through depressurization from hydrate reservoirs at the Mallik site is technically feasible, but the gas production efficiency is generally modest. The hydrate dissociation front in HBS is strongly affected by the reservoir heterogeneity and shows a unique dissociation front. The vertically heterogeneous HBS is beneficial for depressurization production compared to the massive hydrate reservoirs. Furthermore, the vertically heterogeneous hydrate-reservoir with low permeability of clay-layer can effectively block methane gas diffusion in the vertical direction. These emphasize that constructing realistic reservoir models is very important to accurately predict the hydrate production performance. At the end of 1-year depressurization, a total of 1.80 × 106 ST m3 of methane gas can be produced from the validated hydrate-reservoir, while which is far from the commercial value. In addition, reducing the production pressure in the wellbore is beneficial for increasing gas production volume, but is not conducive to improving the hydrate production efficiency at the Mallik site. © 2022 The Author(s)
2711.
Transformation of low-molecular-weight organic acids by microbial endoliths in subsurface mafic and ultramafic igneous rock
Environmental Microbiology
2022
2710.
Syn-rift to post-rift tectonic transition and drainage reorganization in continental rifting basins: Detrital zircon analysis from the Songliao Basin, NE China
Geoscience Frontiers,
13
(3)
2022
2709.
Terrestrial heat flow and its geodynamic implications in the northern Songliao Basin, Northeast China
Geophysical Journal International,
229
(2)
962-983
2022
ISSN: 0956540X
Publisher: Oxford University Press
Keywords:▾
Geodynamics; Geothermal energy; Infill drilling; Petroleum prospecting; Sedimentology; Structural geology, Asia; Composition and structure of the continental crust; Dynamics of lithosphere and mantles; Heat generation and transports; Heat-flow; Lithospheric; Northeast China; Sedimentary basin process; Songliao basin, Heat transfer, continental crust; crustal structure; geodynamics; heat flow; heat transfer; lithosphere; mantle; sedimentary basin, China; Songliao Basin
Abstract: ▾ Heat flow data are essential for understanding lithospheric dynamics. As a petroliferous basin, a large number of boreholes have been drilled during hydrocarbon exploration and production in the northern part of Songliao Basin, Northeast China. Meanwhile, the data on crustal structures, core samples and formation temperatures have been accumulated, which provide an opportunity for understanding the thermal state of the basin. Based on the temperature data from both Drilling Stem Test and continuous steady-state logging profiles, together with the systematic analysis of the thermal properties of rock samples, we present a new heat flow map of the northern Songliao Basin with significantly increased number of heat flow sites. The northern Songliao Basin is characterized by relatively high geothermal gradients and high heat flow for sedimentary basins. The heat flow values range from 44.4 to 95.0 mW m-2 with an average of 67.2 ± 12.8 mW m-2, and the geothermal gradients range from 21 to 59 °C km-1 with an overall average of 41.7 °C km-1. Heat production from sedimentary covers accounts for about 4.5 mW m-2 at the site of Well SK-2. Furthermore, based on the crustal structures revealed by previous seismic studies, lithospheric thermal structures are analysed and compared among different structural units of the basin. A thinned thermal lithosphere with a thickness of ∼65 km is found beneath the Central downwarp and the Southeast uplift in which a large part of the heat flow is mantle derived. The Western Slope exhibits a moderate heat flow value and a thicker thermal lithosphere with thickness greater than 110 km. From the perspective of the geothermal state of the lithosphere, the regional geodynamics related to the Mesozoic lithosphere stretching and the subduction of the Pacific Plate are discussed. © 2021 The Author(s).
2708.
The Chicxulub impact and its environmental consequences
NATURE REVIEWS EARTH & ENVIRONMENT,
3
(5)
338-354
2022
Abstract: ▾ The extinction of the dinosaurs and around three-quarters of all living species was almost certainly caused by a large asteroid impact 66 million years ago. Seismic data acquired across the impact site in Mexico have provided spectacular images of the approximately 200-kilometre-wide Chicxulub impact structure. In this Review, we show how studying the impact site at Chicxulub has advanced our understanding of formation of large craters and the environmental and palaeontological consequences of this impact. The Chicxulub crater’s asymmetric shape and size suggest an oblique impact and an impact energy of about 1023 joules, information that is important for quantifying the climatic effects of the impact. Several thousand gigatonnes of asteroidal and target material were ejected at velocities exceeding 5 kilometres per second, forming a fast-moving cloud that transported dust, soot and sulfate aerosols around the Earth within hours. These impact ejecta and soot from global wildfires blocked sunlight and caused global cooling, thus explaining the severity and abruptness of the mass extinction. However, it remains uncertain whether this impact winter lasted for many months or for more than a decade. Further combined palaeontological and proxy studies of expanded Cretaceous–Palaeogene transitions should further constrain the climatic response and the precise cause and selectivity of the extinction. © 2022, Springer Nature Limited.
2707.
The Effect of Correlated Permeability on Fluid-Induced Seismicity
Geophysical Research Letters,
49
(4)
2022
2706.
The post-Caledonian thermo-tectonic evolution of Fennoscandia
Gondwana Research,
107201--234
2022
ISSN: 1342-937XKeywords:▾
Exhumation, AFTA, Craton, Missing section, Peneplain
Abstract: ▾ The evolution of Fennoscandia following the early Devonian collapse of the Caledonian mountains is a matter of debate, due largely to the scarcity of post-Caledonian cover rocks. The preserved geological record therefore provides only partial documentation of the geological evolution. A more complete understanding is obtained by also considering evidence of rocks that were formerly present but have since been removed. We report apatite fission track data and associated thermal history constraints in 331 samples of Precambrian basement, younger sedimentary cover, Paleozoic and Mesozoic igneous rocks from outcrops and boreholes (up to 6 km depth) across Fennoscandia, which define thirteen phases of cooling (each representing kilometre-scale exhumation) over the last 1100 Myr. Key post-Caledonian episodes began in the intervals 311–307 Ma (late Carboniferous), 245–244 Ma (Middle Triassic), 170–167 Ma (Middle Jurassic), 102–92 Ma (mid-Cretaceous) and 23–21 Ma (early Miocene). These episodes, varying in magnitude, are recognised across Fennoscandia, and their effects are documented in the stratigraphic record and as prominent regional peneplains. The results define a history involving repeated episodes of regional burial and exhumation. Major offsets in Mesozoic paleotemperatures over short distances define kilometre-scale differential vertical displacements, emphasising the tectonic nature of the history. Results from Finland record the same events recognised in Norway and Sweden (though less pronounced), and are not consistent with long-term cratonic stability. The lack of preserved Phanerozoic sedimentary cover in Finland is interpreted to be due to complete removal during multiple episodes of denudation. In southern Norway and Sweden, early Miocene exhumation led to creation of a peneplain, which in Pliocene times was uplifted and dissected, producing the modern landscape. Post-Caledonian exhumation episodes defined here are broadly synchronous with similar events in Greenland, the British Isles and North America. Far-field transmission of plate-tectonic stress and/or mantle processes may explain the vertical movements described here.
2705.
Thermal History of Lithosphere Formed Beneath Fast Spreading Ridges: Constraints From the Mantle Transition Zone of the East Pacific Rise at Hess Deep and Oman Drilling Project, Wadi Zeeb, Samail Ophiolite
Journal of Geophysical Research: Solid Earth,
127
(1)
e2021JB022696
2022
ISSN: 21699313
Publisher: Wiley Online Library
Keywords:▾
gabbro; hydrothermal alteration; mantle source; ophiolite; seafloor spreading; temperature anomaly; thermometry; trace element, East Pacific Rise; Hess Deep; Pacific Ocean
Abstract: ▾ We investigate the cooling histories of peridotites and gabbros from localities that expose oceanic lithosphere formed beneath two fast seafloor spreading centers: Hess Deep as recovered from IODP Expedition 345 and ODP Leg 147, and the Oman Ophiolite as sampled by the Oman Drilling Project, ICDP Expedition 5057 (OmanDP). At these locations, relict crust-mantle transition zones are directly sampled, enabling characterization of the thermal history of the crust-mantle transition, and by inference, the depth extent of hydrothermal circulation beneath spreading centers. We measured major and trace element abundances in crustal gabbros and mantle peridotites from Hess Deep and OmanDP, and applied major and trace element-based thermometers. Geospeedometric interpretation of the temperatures suggests similar cooling histories at both locations; cooling rates ranged from 0.02 to 2.6 °C/y from peak temperatures up to 1,350°C. The rates are consistent on either side of the paleo-Moho (i.e., in the crust and mantle). Models for conductive cooling of the lower oceanic crust predict rates more than two orders of magnitude slower at the crust-mantle transition zone, while thermal models that invoke deep and efficient hydrothermal circulation throughout the entire crustal section predict rates consistent with our observations. We infer that hydrothermal cooling extended to or near the petrologic Moho beneath the East Pacific Rise and the OmanDP paleo-spreading center, consistent with the Sheeted Sills model for crustal accretion. Comparison with previously published rates recalculated using the methods we employed suggests the oceanic lower crust is cooled hydrothermally in some places and by conduction at others. © 2021. American Geophysical Union. All Rights Reserved.
2704.
Triprojectacites in the Songliao Basin, Northeast China: Systematics, biostratigraphy and evolution
Cretaceous Research,
135
2022
2703.
Study of fluid circulation through the chicxulub crater using Rock-Eval pyrolysis and fluid inclusions
Applied Geochemistry,
137
2022
Abstract: ▾ The aim of the study is to evaluate fluids circulation through the Chicxulub crater, and to determine the composition of hydrothermal fluids after the impact. Rock-Eval pyrolysis and fluid inclusion micro-thermometry analyses were performed. The technique has been routinely used for about fifteen years and has become a standard tool for hydrocarbon exploration. Rock-Eval pyrolysis reveals the distribution of organic and mineral carbon affected by the impact and later affected by hydrothermal activity. All measured inclusions are primary and were found in basement samples only. Both the fluid inclusions data and Rock-Eval pyrolysis show that composition and temperature of the fluids changed as the fluids migrated though crater rocks. An evolution of temperatures occurs (vertical, horizontal, or both), from the surface and from the center of the crater; this spatial evolution is consistent with model of Abramov and Kring, showing a thermal evolution of temperature with depth in the crater as well as its influence on the hydrothermal system. Post-impact fluid circulation modifies the temperature distribution. © 2022 Elsevier Ltd
2702.
Vegetation history of a Mexican Neotropical basin from the late MIS 6 to early MIS 3: The pollen record of Lake Chalco
Quaternary Science Reviews,
297
2022
ISSN: 02773791
Publisher: Elsevier Ltd
Keywords:▾
Forestry; Glacial geology; Lakes; Saline water; Tropics; Vegetation, Basin of mexico; Dry condition; Last glacial; Marine isotopic stages; Me-xico; Millennial-scale variability; Penultimate interglacial; Plant diversity; Pollen analysis; Vegetation dynamics, Climate change, climate change; climate variation; coniferous forest; glacial-interglacial cycle; Last Glacial; late glacial; marine isotope stage; Neotropical Region; palynology; reconstruction; vegetation dynamics; vegetation history, Arctic; Atlantic Ocean; Cariaco Basin; Caribbean Sea; Greenland; Lake Chalco; Mexico [North America]; Valley of Mexico
Abstract: ▾ A new detailed pollen record of the penultimate glacial–interglacial–glacial cycle corresponding to the late marine isotopic stages (MISs) 6–3 (146–35 ka ago) has been obtained from Lake Chalco, in the Basin of Mexico. This record provides an insight into vegetation dynamics and climate variability at the northern limit of the American tropics. The pollen record displays a high temporal resolution with a mean sampling interval of ∼230 years. The changes in plant composition were reconstructed by pollen analysis and differences in plant composition between distinct periods were established. The wettest cold stage, indicated by a combination of diverse open vegetation and mesophytic taxa correlates with the penultimate late glacial MIS 6 (146–130 ka), when Lake Chalco was a deep freshwater lake. The penultimate interglacial MIS 5e (126.5–123.6 ka) shows a dominance of Pinus forests, with tropical taxa suggesting warmer than present conditions; environmental proxies indicate drier conditions and that the lake transitioned into a saline water body. Open communities and Pinus and Quercus forests with mesophytic taxa and, during the stadial periods, MIS 5 d, 5c, and 5 b (125–90 ka), with tropical taxa, characterize the record of interstadials. Pinus-dominated forests characterize the landscape during MIS 5a. MIS 5c to MIS 3 showed lower and variable evenness and palynological richness, along with an increase in fire activity. During MIS 4 and 3, a trend towards drier conditions was also recorded with enhanced carbonate precipitation and proxies indicating saline conditions. Tree-line changes in response to climate change and taxa migration were documented. A comparison with long records from the Greenland ice cores, the marine Cariaco Basin and insolation parameters revealed that the pollen data and the Pinus pollen accumulation rates evidence the response of the vegetation to glacial and interglacial changes and to millennial-scale variability. Wetter conditions were inferred to exist during the Greenland interstadials, while drier conditions persisted during Heinrich events. © 2022 Elsevier Ltd
2701.
Volcanic tremor associated with the Surtsey eruption of 1963–1967
Jökull,
7221-34
2022
2700.
[English]
The remanent magnetisation recorded in the Chesapeake Bay impact crater, Virginia
Volume 2145
,
In Chatthong B., Buranachai C., Kalasuwan P., Rakkapao S., Putson C., Soonthornthum B., Aukkaravittayapun S.,
Editor
Publisher
IOP Publishing Ltd
2022
Division of Physical Science, Faculty of Science, Prince of Songkla University, Songkhla, Hat Yai, 90110, Thailand; Department of Geophysics, Stanford University, Stanford, CA 94305, United States; Department of Earth and Planetary Science, Rutgers University, Piscataway, NJ 08854, United StatesKeywords:▾
Rocks, Chesapeake Bay; High pressure; Impact craters; Impact events; Impact heating; Natural remanent magnetization; Planetary bodies; Recrystallisation; Remanent magnetization; Virginia, Magnetization
2699.
Drilling Overdeepened Alpine Valleys (ICDP-DOVE): Age, extent and environmental impact of Alpine glaciations
EGU General Assembly Conference Abstracts
,
Page EGU22--3165
2022
2698.
How was the Bushveld Complex assembled? A search for cryptic layering in ICDP drillcores from the Main Zone
EGU General Assembly Conference Abstracts
,
Page EGU22--8339
2022
2697.
Intensive peatland wildfires during the Aptian–Albian oceanic anoxic event 1b: Evidence from borehole SK-2 in the Songliao Basin, NE China
Journal of Palaeogeography,
11
(3)
448-467
2022
ISSN: 20953836
Publisher: Elsevier B.V.
Abstract: ▾ The Cretaceous has been considered a “high-fire” world accompanied by widespread by-products of combustion in the rock record. The mid-Cretaceous oceanic anoxic event 1b (OAE1b) is marked by one of the major perturbations in the global carbon cycle characterized by deposition of organic-rich sediments in both marine and terrestrial settings. However, our understanding is still limited on changes in wildfire activity during OAE1b period. Here, we carried out a comprehensive analysis, including organic carbon isotope (δ13Corg), total organic carbon (TOC), coal petrology, trace elements, and pyrolytic polycyclic aromatic hydrocarbons (pyroPAHs), of coal seams of the middle Aptian to early Albian Shahezi Formation from borehole SK-2 in Songliao Basin, Northeast China. Two negative δ13Corg excursions in the Shahezi Formation can be corresponded with the 113/Jacob and Kilian sub-events of OAE1b. Moreover, the intensive peatland wildfires have been identified during the sub-event periods of OAE1b based on the co-occurrence of high abundance of charcoal and pyroPAHs at that time. In addition, Sr/Ba, Sr/Cu and Sr/Rb ratios demonstrate that enhanced peatland wildfires were controlled by dryer climate conditions owing to episodic northward migration of arid zones in East Asia related with rising global temperature during the sub-events of OAE1b. The climate-driven extensive wildfire activity in the mid-latitude terrestrial ecosystems can be a contributing factor for OAE1b through the increased flux of nutrients fuelling primary producers in the lake and marine environments and leading to more speculative anoxia to allow the deposition of organic-rich sediments. Our results provide essential understanding of the importance of wildfires in driving mechanism of oceanic anoxic events (OAEs) in Earth's history. © 2022 The Author(s)
2696.
Subaqueous event deposits response to regional neotectonics: Case studies of the Dead Sea Basin and the Qaidam Basin
Quaternary Sciences,
42
(3)
617-636
2022
ISSN: 10017410
Publisher: Science Press (China)
Abstract: ▾ Sharp changes in lithology and increases in grain size and sedimentation rate of sedimentary sequences from tectonically active basins are often used to indicate regional neotectonic activity. However, these conventional methods have been challenged by others who argue that the sedimentary evidence used to infer tectonism could be climatically induced. Therefore, some form of independent evidence or sedimentary criteria are required to discriminate between these two alternatives. Seismites, sedimentary structures preserved in lacustrine or marine stratigraphic sequences caused by seismic shaking, are reliable indicators of regional neotectonic activity. Lacustrine/Marine paleoseismology, an emerging cross-field, can extend the record of strong earthquakes and deepen the understanding of fault zone activity by studying seismites preserved in subaqueous sedimentary sequences. In this paper, we use the Dead Sea Basin and Qaidam Basin as examples to understand regional neotectonic activity from the perspective of subaqueous paleoseismology. The Dead Sea Basin is the deepest and largest continental tectonic structure in the world. A 457 m deep core(ICDP Core 5017-1)was recovered from the Dead Sea depocenter(31°30′29″N, 35°28′16″E) during 2010~2011. The bottom of the core was dated back to 220 ka. In situ folded layers and intraclast breccia layer in the core are identified as earthquake indicators, based on their resemblance to the lake outcrop observations of seismites that are known to be earthquake-induced. Based on the Kelvin-Helmholtz instability, we model the ground acceleration needed to produce each seismite by using the physical properties of the Dead Sea deposits. We invert acceleration for earthquake magnitude by considering regional earthquake ground motion attenuation, fault geometry, and other constraints. Based on the magnitude constraints, we develop a 220 ka-long record of MW ≥7 earthquakes. The record comprises 151 MW ≥7 events. The record shows a clustered earthquake recurrence pattern and a group-fault temporal clustering model, and reveals an unexpectedly high seismicity rate on a slow-slipping plate boundary. The Qaidam Basin is the largest topographic depression on the Tibetan Plateau that was formed by the ongoing India-Asia collision. The northeastward growth of the Tibetan Plateau formed a series of sub-parallel NW-SE-trending folds over a distance of ca. 300 km in the western Qaidam Basin. A 723 m deep core was drilled in the basin on the crest of one such fold, the Jianshan Anticline(38°21′9.46″N, 92°16′24.72″E) during 2010~2011. In this study, we focus on the upper 260 m of the core. Paleomagnetic dating constrains the age of the studied core interval to ca. 3.6~1.6 Ma. Sedimentological analysis reveals micro-faults, soft-sediment deformation, slumps, and detachment surfaces preserved in the core interval, which we interpret as paleoearthquake indicators. We recover a 2-Ma seismite sequence comprising 164 MW ≥5 events. The seismite sequence is relatively more complete during 3.6~2.7 Ma, which comprises 126 events and five seismite clusters. This suggests that the rate of tectonic strain accommodated by the folds/thrusts in the region varies in time and thus reveals episodic local deformation. During the clusters, regional deformation is concentrated more in the fold-and-thrust system than along regional major strike-slip faults. © 2022, Science Press (China). All rights reserved.
2695.
Stratigraphic record reveals contrasting roles of overflows and underflows over glacial cycles in a hypersaline lake (Dead Sea)
Earth and Planetary Science Letters,
594
2022
ISSN: 0012821X
Publisher: Elsevier B.V.
Keywords:▾
Climate change; Deposits; Floods; Glacial geology; Orbits; Sediment transport; Stratigraphy, Dead sea; Flash-floods; Flood plumes; Flow process; Geological record; Hypersaline lakes; Sediment density flows; Sediment transport process; Turbidite; Underflows, Lakes, climate change; density; flash flood; geological record; hypersaline environment; lake level; plume; salinity; sediment transport; stratigraphy; turbidite, Dead Sea
Abstract: ▾ In lakes and oceans, links between modern sediment density flow processes and deposits preserved in long-term geological records are poorly understood. Consequently, it is unclear whether, and if so how, long-term climate changes affect the magnitude/frequency of sediment density flows. One approach to answering this question is to analyze a comprehensive geological record that comprises deposits that can be reliably linked to modern sediment flow processes. To address this question, we investigated the unique ICDP Core 5017-1 from the Dead Sea (the largest and deepest hypersaline lake on the Earth) depocenter covering MIS 7-1. Based on an understanding of modern sediment density flow processes in the lake, we link homogeneous muds in the core to overflows (surface flood plumes, ρflow<ρwater), and link graded turbidites and debrites to underflows (ρflow>ρwater). Our dataset reveals (1) overflows are more prominent during interglacials, while underflows are more prominent during glacials; (2) orbital-scale climate changes affected the flow magnitude/frequency via changing salinity and density profile of lake brine, lake-level, and source materials. © 2022 The Author(s)