All ICDP Publications with Abstracts
From parent-sysfolder "Publications" + 2 folder-levels deep
2703.
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
2702.
Volcanic tremor associated with the Surtsey eruption of 1963–1967
Jökull,
7221-34
2022
2701.
[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
2700.
Drilling Overdeepened Alpine Valleys (ICDP-DOVE): Age, extent and environmental impact of Alpine glaciations
EGU General Assembly Conference Abstracts
,
Page EGU22--3165
2022
2699.
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
2698.
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)
2697.
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
2696.
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)
2695.
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.
2694.
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
2693.
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.
2692.
Reconstructing the Environmental Context of Human Origins in Eastern Africa Through Scientific Drilling
Annual Review of Earth and Planetary Sciences,
50451 – 476
2022
2691.
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.
2690.
Reduced plate motion controlled timing of Early Jurassic Karoo-Ferrar
large igneous province volcanism
SCIENCE ADVANCES,
8
2022
2689.
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.
2688.
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.
2687.
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
2686.
Spectroscopic study of terrestrial analogues to support rover missions to Mars – A Raman-centred review
Analytica Chimica Acta,
1209
2022
2685.
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
2684.
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)
2683.
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.
2682.
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.
2681.
Sensitivity of the West Antarctic Ice Sheet to+ 2° C (SWAIS 2C)
Scientific Drilling,
30101--112
2022
2680.
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.
2679.
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.