All ICDP Publications with Abstracts
From parent-sysfolder "Publications" + 2 folder-levels deep
2469.
Globally distributed iridium layer preserved within the Chicxulub impact structure
Science Advances,
7
(9)
2021
Abstract: ▾ The Cretaceous-Paleogene (K-Pg) mass extinction is marked globally by elevated concentrations of iridium, emplaced by a hypervelocity impact event 66 million years ago. Here, we report new data from four independent laboratories that reveal a positive iridium anomaly within the peak-ring sequence of the Chicxulub impact structure, in drill core recovered by IODP-ICDP Expedition 364. The highest concentration of ultrafine meteoritic matter occurs in the post-impact sediments that cover the crater peak ring, just below the lowermost Danian pelagic limestone. Within years to decades after the impact event, this part of the Chicxulub impact basin returned to a relatively low-energy depositional environment, recording in unprecedented detail the recovery of life during the succeeding millennia. The iridium layer provides a key temporal horizon precisely linking Chicxulub to K-Pg boundary sections worldwide. Copyright © 2021 The Authors, some rights reserved.
2468.
High-resolution seismic reflection survey crossing the Insubric Line into the Ivrea-Verbano Zone: Novel approaches for interpreting the seismic response of steeply dipping structures
Tectonophysics,
816
2021
ISSN: 00401951
Publisher: Elsevier B.V.
Keywords:▾
Italy; Ivrea-Verbano Zone; Aspect ratio; Boreholes; Geological surveys; Infill drilling; Seismic prospecting; Seismic response; Well logging; Continental scientific drillings; Geostatistical estimation; High resolution seismic; Local heterogeneity; Quantitative interpretation; Seismic reflection data; Seismic reflection survey; Vertical structures; fault zone; geostatistics; hard rock; seismic reflection; seismic response; seismic survey; structural response; Seismic waves
Abstract: ▾ A high-resolution seismic reflection survey has been conducted across the Insubric Line from the Sesia Zone into the Ivrea-Verbano Zone (IVZ), where a remarkably complete cross-section of lower continental crust is exposed. The survey was carried out in preparation for the DIVE (Drilling the Ivrea-Verbano zonE) project, which was recently approved by the International Continental Scientific Drilling Program (ICDP). DIVE aims to gain new insights into the characteristics of the lower continental crust through targeted drilling, sampling, and borehole logging. A key borehole is planned near the Insubric Line at Balmuccia, where the deepest parts of the lower continental crust are exposed. As such, the primary objective of this seismic survey was to explore whether the sub-vertical structures prevailing at the surface can be expected to continue at depth or whether there are any indications for major flattening or fault-related offsets. Correspondingly, the acquisition and processing of the seismic reflection data were geared towards revealing weak backscattered events from local heterogeneities associated with the prevailing sub-vertical structural grain. The migrated sections, contain coherent backscattered events to a depth of ~1 km, which form numerous short lineaments that seem to align sub-vertically. To substantiate this observation, we have generated synthetic seismic reflection surveys for canonical models of sub-vertical structures associated with Gaussian- and binary-distributed heterogeneities. Both the observed and synthetic seismic data were then subjected to energy-based attribute analysis as well as geostatistical estimations of the structural aspect ratios and the associated dips. The results of these quantitative interpretation approaches are indicative of the overall consistency between the synthetic and the observed seismic data and, hence, support the original qualitative interpretation of the latter in that the sub-vertical structural grain evident at the surface seems to prevail throughout the imaged part of the upper crust. © 2021 The Authors
2467.
Highly siderophile element and Os isotope results from the structurally atypical Batin dunite in the Wadi Tayin massif of the Oman ophiolite
Journal of Geophysical Research: Solid Earth,
126
(10)
e2021JB021977
2021
ISSN: 21699313
Publisher: Wiley Online Library
Keywords:▾
dunite; mantle structure; ophiolite; osmium isotope; siderophile element
Abstract: ▾ Dunites in ophiolites form by pyroxene dissolution and olivine precipitation during melt-peridotite interaction. We present structural and geochemical data on peridotites from the Batin region (Wadi Tayin massif) of the Oman ophiolite, where an exceptionally large (∼9.5 km long) dunite body was sampled by the ICDP Oman Drilling Project (BA4A borehole). 900–1,200 m beneath the petrological Moho, this dunite is overlain by harzburgite hosting pyroxene-depleted and pyroxene-rich bands. Highly siderophile elements (HSEs) and Os isotopes, excellent tracers of melt flow through peridotites, were measured in dunites and interspersed harzburgites from BA4A borehole. The Batin dunite is structurally and chemically distinct from dunites from the Moho Transition Zone and basal section of the ophiolite, resembling instead sparse dunite veins in the main mantle section. Batin dunites have fairly uniform Os, Ir, and Ru abundances, but Pd and Pt contents increasing with depth. One deep dunite sample has initial 187Os/188Os more radiogenic than MORB. Though the limited number of data demands prudence, we suggest that the Batin dunite formed from a large pulse of radiogenic melts, whose flow was impeded ∼1,200 m below the Moho. As these melts ascended, they may have lost their radiogenic character and relative Pt and Pd enrichment through interaction with peridotites, which have much higher HSE contents than melts. Such interaction would also diminish the under-saturation in pyroxene of the melts, eliminating their capacity to sufficiently dissolve the pyroxene of the host harzburgite to form dunite, thus explaining the upper limit of the dunite at ∼900 m. © 2021. American Geophysical Union. All Rights Reserved.
2466.
Geochemical, biological, and clumped isotopologue evidence for substantial microbial methane production under carbon limitation in serpentinites of the Samail Ophiolite, Oman
Journal of Geophysical Research: Biogeosciences,
126
(10)
e2020JG006025
2021
2465.
Real-time gas monitoring at the Tekke Hamam geothermal field (Western Anatolia, Turkey): an assessment in relation to local seismicity
Natural Hazards,
104
(2)
1655-1678
2020
ISSN: 0921030X
Publisher: Springer Science and Business Media B.V.
Keywords:▾
concentration (composition); environmental monitoring; gas flow; geothermal system; mass spectrometry; mixing ratio; real time; seismic method; seismicity, Anatolia; Turkey
Abstract: ▾ This study presents the results of a real-time gas monitoring experiment conducted, via the use of a quadrupole mass spectrometer, in a mofette field within the Tekke Hamam geothermal site in western Anatolia (Turkey), a tectonically active region hosting several east–west trending grabens. The study is aimed to establish a baseline gas profile of the region. Within the framework of the experiment, gas compositions (CO2, N2, O2, H2, H2S, CH4, He, and Ar) and flow rate of a mofette were monitored during two observation periods: November 2007–January 2008 and April–July 2008. During the course of monitoring, the major gas component was CO2 with concentration changing around 96 volume percent. Other gases, from the most abundant to the least, were N2, CH4, O2, H2S, Ar, H2, and He. The study produced a short-term, baseline gas profile of the region with daily/diurnal variations and temporal gas fluctuations appearing as instant signals. Although the temporal gas fluctuations did not reach the anomaly level (variations staying within the mean ± 2σ), some of the variations in more than one parameter in the gas compositions (exceeding the mean ± 1σ), accompanied by changes in the diurnal gas pulses lasting for long durations, were correlated with the seismic events selected according to the adopted seismic event elimination criteria. The variations were mainly attributed to changing gas mixing ratios in relation to porosity/permeability modifications possibly related to seismicity. Studies involving the continuous monitoring of meteorological parameters are necessary to assign these variations to geogenic events. © 2020, Springer Nature B.V.
2464.
Preferred orientation distribution of shock-induced planar microstructures in quartz and feldspar
Meteoritics and Planetary Science,
55
(5)
1082-1092
2020
Abstract: ▾ Shocked quartz and feldspar grains commonly exhibit planar microstructures, such as planar fractures, planar deformation features, and possibly microtwins, which are considered to have formed by shock metamorphism. Their orientation and frequency are typically reported to be randomly distributed across a sample. The goal of this study is to investigate whether such microstructures are completely random within a given sample, or whether their orientation might also retain information on the direction of the local shock wave propagation. For this work, we selected samples of shatter cones, which were cut normal to the striated surface and the striation direction, from three impact structures (Keurusselkä, Finland, and Charlevoix and Manicouagan, Canada). These samples show different stages of pre-impact tectonic deformation. Additionally, we investigated several shocked granite samples, selected at different depths along the drill core recovered during the joint IODP-ICDP Chicxulub Expedition 364 (Mexico). In this case, thin sections were cut along two orthogonal directions, one parallel and one normal to the drill core axis. All the results refer to optical microscopy and universal-stage analyses performed on petrographic thin sections. Our results show that such shock-related microstructures do have a preferred orientation, but also that relating their orientation with the possible shock wave propagation is quite challenging and potentially impossible. This is largely due to the lack of dedicated experiments to provide a key to interpret the observed preferred orientation and to the lack of information on postimpact orientation modifications, especially in the case of the drill core samples. © 2020 The Authors. Meteoritics & Planetary Science published by Wiley Periodicals LLC on behalf of The Meteoritical Society (MET)
2463.
Probing the hydrothermal system of the chicxulub impact crater
Science Advances,
6
(22)
2020
Abstract: ▾ The ~180-km-diameter Chicxulub peak-ring crater and ~240-km multiring basin, produced by the impact that terminated the Cretaceous, is the largest remaining intact impact basin on Earth. International Ocean Discovery Program (IODP) and International Continental Scientific Drilling Program (ICDP) Expedition 364 drilled to a depth of 1335 m below the sea floor into the peak ring, providing a unique opportunity to study the thermal and chemical modification of Earth's crust caused by the impact. The recovered core shows the crater hosted a spatially extensive hydrothermal system that chemically and mineralogically modified ~1.4 × 105 km3 of Earth's crust, a volume more than nine times that of the Yellowstone Caldera system. Initially, high temperatures of 300° to 400°C and an independent geomagnetic polarity clock indicate the hydrothermal system was long lived, in excess of 106 years. © 2020 American Association for the Advancement of Science. All rights reserved.
2462.
Progress of Deep Geological Survey Project under the China Geological Survey
China Geology,
3
(1)
153 – 172
2020
2461.
Protracted Shearing at Midcrustal Conditions During Large-Scale Thrusting in the Scandinavian Caledonides
Tectonics,
39
(9)
e2020TC006267
2020
ISSN: 1944-9194Keywords:▾
U-Pb dating, Caledonides, electron backscatter diffraction, deformation mechanisms, petrochronology, thrusting, U-Pb dating
Abstract: ▾ During continental collision, large tracts of crust are mobilized along major shear zones. The metamorphic conditions at which these zones operate, the duration of thrusting, and the deformation processes that facilitated hundreds of km of tectonic transport are still unclear. In the Scandinavian Caledonides, the Lower Seve Nappe displays a main mylonitic foliation with thickness of 1 km. This foliation is overprinted by a brittle-to-ductile deformation pattern localized in C- and C′-type shear bands proximal to the tectonic contact with the underlying Särv Nappe. Thermobarometry of amphibolites and micaschists suggests a first high-pressure stage at 400–500°C and 1–1.3 GPa recorded in mineral relics. The main mylonitic foliation developed under epidote amphibolite facies conditions along the retrograde path from 600°C and 1 GPa to 500°C and 0.5 GPa. Age dating of synkinematic titanite grains in the amphibolites indicates that this mylonitic fabric formed at around 417 ± 9 Ma but older ages spanning 460–430 Ma could represent earlier stages of mylonitization. The shear bands developed at lower metamorphic conditions of 300–400°C and 0.3 GPa. In the micaschists, the recrystallized grain size of quartz decreases toward the shear bands. Monomineralic quartz layers are eventually dismembered to form polyphase aggregates deforming by dominant grain size sensitive creep accompanied by slip in muscovite and chlorite. Plagioclase zoning truncations suggest that the shear bands originated by fracturing followed by ductile deformation. The results suggest protracted and long-lasting shearing under amphibolite to greenschist facies conditions during the juxtaposition, stacking, and exhumation of the Lower Seve Nappe.
2460.
Quantification of gas hydrate saturation and morphology based on a generalized effective medium model
Marine and Petroleum Geology,
113
2020
ISSN: 02648172
Publisher: Elsevier Ltd
Keywords:▾
Cementing (shafts); Elastic waves; Filling; Gases; Hydration; Matrix algebra; Morphology; Nuclear magnetic logging; Radioactivity logging; Sediments; Software testing; Submarine geology, Effective medium model; Effective medium theories; Elastic wave velocity; Hydrate bearing sediments; Hydrate saturation; Integrated ocean drilling programs; Modified cementation theory; Nuclear magnetic resonance logs, Gas hydrates, cementation; elastic wave; gas hydrate; marine sediment; model validation; quantitative analysis; saturation; wave velocity, Alaska; Alaska Peninsula; Canada; Cascadia Margin; Mackenzie Delta; Northwest Territories; Pacific Ocean; United States
Abstract: ▾ Numerous models have been developed for prediction of gas hydrate saturation based on the microstructural relationship between gas hydrates and sediment grains. However, quantification of hydrate saturation and morphology from elastic properties has been hindered by failing to account for complex hydrate distributions. Here, we develop a generalized effective medium model by applying the modified Hashin-Shtrikman bounds to a newly developed cementation theory. This model is validated by experimental data for synthetic methane and tetrahydrofuran hydrates. Good comparison of model predictions with experimental measurements not only reveals its ability to merge the results of contact cementation theory and effective medium theory, but also indicates its feasibility for characterizing complex morphologies. Moreover, the results of inverting acoustic measurements quantitatively confirm that for synthetic samples in “excess-gas” condition gas hydrates mainly occur as a hybrid-cementing morphology with a low percentage of pore-filling morphology, whereas for pressure-core hydrate-bearing sediments in natural environments they exist as matrix-supporting and pore-filling morphologies with a very low percentage of hybrid-cementing morphology. The hydrate saturations estimated from sonic and density logs in several regions including northern Cascadia margin (Integrated Ocean Drilling Program Expedition 311, Hole U1326D and Hole U1327E), Alaska North Slope (Mount Elbert test well) and Mackenzie Delta (Mallik 5L-38), are comparable to the referenced hydrate saturations derived from core data and resistivity, and/or nuclear magnetic resonance log data, confirming validity and applicability of our model. Furthermore, our results indicate that ~8% hybrid-cementing, ~33% matrix-supporting and ~59% pore-filling hydrates may coexist in the fine-grained and clay-rich marine sediments on the northern Cascadia margin, whereas ~10% hybrid-cementing, ~54% matrix-supporting and ~36% pore-filling hydrates may coexist in the coarse-grained and sand-dominated terrestrial sediments of the Alaska North Slope and Mackenzie Delta. © 2019 The Authors
2459.
RADIOCARBON RESERVOIR AGES in the HOLOCENE DEAD SEA
Radiocarbon,
62
(5)
1453 – 1473
2020
2458.
Relationships between low-temperature fires, climate and vegetation during three late glacials and interglacials of the last 430 kyr in northeastern Siberia reconstructed from monosaccharide anhydrides in Lake El'gygytgyn sediments
Climate of the Past,
16
(2)
799-818
2020
ISSN: 18149324
Publisher: Copernicus GmbH
Keywords:▾
biomass burning; boreal forest; Boreal Kingdom; climate feedback; evergreen forest; fire; global change; interglacial; lacustrine deposit; late glacial; long-term change; low temperature; monosaccharide; paleoclimate; proxy climate record; reconstruction; vegetation history, Chukchi; Elgygytgyn Lake; Russian Federation; Russian Federation; Siberia, Bryophyta; Larix; Picea; Sphagnum
Abstract: ▾ Landscapes in high northern latitudes are assumed to be highly sensitive to future global change, but the rates and long-term trajectories of changes are rather uncertain. In the boreal zone, fires are an important factor in climate-vegetation interactions and biogeochemical cycles. Fire regimes are characterized by small, frequent, lowintensity fires within summergreen boreal forests dominated by larch, whereas evergreen boreal forests dominated by spruce and pine burn large areas less frequently but at higher intensities. Here, we explore the potential of the monosaccharide anhydrides (MA) levoglucosan, mannosan and galactosan to serve as proxies of low-intensity biomass burning in glacial-to-interglacial lake sediments from the high northern latitudes. We use sediments from Lake El'gygytgyn (cores PG 1351 and ICDP 5011-1), located in the far northeast of Russia, and study glacial and interglacial samples of the last 430 kyr (marine isotope stages 5e, 6, 7e, 8, 11c and 12) that had different climate and biome configurations. Combined with pollen and non-pollen palynomorph records from the same samples, we assess how far the modern relationships between fire, climate and vegetation persisted during the past, on orbital to centennial timescales. We find that MAs attached to particulates were well-preserved in up to 430 kyr old sediments with higher influxes from low-intensity biomass burning in interglacials compared to glacials. MA influxes significantly increase when summergreen boreal forest spreads closer to the lake, whereas they decrease when tundra-steppe environments and, especially, Sphagnum peatlands spread. This suggests that lowtemperature fires are a typical characteristic of Siberian larch forests also on long timescales. The results also suggest that low-intensity fires would be reduced by vegetation shifts towards very dry environments due to reduced biomass availability, as well as by shifts towards peatlands, which limits fuel dryness. In addition, we observed very low MA ratios, which we interpret as high contributions of galactosan and mannosan from biomass sources other than those currently monitored, such as the moss-lichen mats in the understorey of the summergreen boreal forest. Overall, sedimentary MAs can provide a powerful proxy for fire regime reconstructions and extend our knowledge of long-term natural fire-climate-vegetation feedbacks in the high northern latitudes. © Author(s) 2020.
2457.
Recognition of Milankovitch cycles in XRF core-scanning records of the Late Cretaceous Nenjiang Formation from the Songliao Basin (northeastern China) and their paleoclimate implications
Journal of Asian Earth Sciences,
194
2020
ISSN: 13679120
Publisher: Elsevier Ltd
Keywords:▾
arid environment; climate variation; Cretaceous; deposition; humid environment; lacustrine deposit; Milankovitch cycle; paleoclimate; X-ray fluorescence, China; Songliao Basin
Abstract: ▾ Cretaceous terrestrial sedimentary records are crucial for our understanding of geological systems’ responses to past climate change under greenhouse condition. Numerous publications have documented that Milankovitch cycles were a dominant climate driver over multi-millennial timescales. However, most of these orbital signals were derived from marine records obtained during the Cenozoic geological period, whereas knowledge of Milankovitch cycles preserved in lacustrine sediments prior to the Cenozoic is limited due to the lack of a precise chronological framework, poor preservation rate of terrestrial sediments, limited records, and fewer experts in this research area. This paper reports high-resolution X-ray fluorescence (XRF) elemental records of K, Ti, Rb, Sr, Zr, Zr/Rb, Rb/Sr, and K/Ti from Member 1 (k2n1) and Member 2 (k2n2) of the Nenjiang Formation, which were obtained from a near-continuous SK-2 East (SK-2e) borehole drilled in the Songliao Basin (SB) of northeastern (NE) China. Variations of the elemental records reveal a humid-arid-humid-semiarid climatic evolution throughout the deposition of k2n1 and a humid-arid-humid-arid climatic variation throughout the deposition of k2n2. In this context, K2n1 experienced a relatively longer humid period and more pronounced climatic fluctuation than K2n2. A method of average spectral misfit (ASM) was adopted to successfully identify two optimal sedimentation rates of 6.577 and 8.369 cm/ka for K2n1 and K2n2, respectively. Based on these two sedimentation rates, nearly all significant Milankovitch cycles preserved in the Rb/Sr record were recognized. It is suggested that westerly wind was the main climatic driving factor of climate evolution in the SB under the forcing of Milankovitch cycles. The collectively regulation of obliquity and precession increased the seasonal contrasts during humid periods in the Nenjiang Formation and thereby amplified the paleomonsoon effect, thus bringing more moisture towards the SB and lead to enhanced rainfall. © 2019 Elsevier Ltd
2456.
Reconstructing East African monsoon variability from grain-size distributions: End-member modeling and source attribution of diatom-rich sediments from Lake Chala
Quaternary Science Reviews,
247
2020
ISSN: 02773791
Publisher: Elsevier Ltd
Keywords:▾
Bourgogne-Franche-Comte; France; Horn of Africa; Jura [Bourgogne-Franche-Comte]; Kilimanjaro [Kilimanjaro (RGA)]; Kilimanjaro [Tanzania]; Lake Chalain; Tanzania; Bacillariophyta; Nitzschia; Atmospheric thermodynamics; Atmospheric turbulence; Catchments; Climate change; Dust; Glacial geology; Grain size and shape; Lakes; Runoff; Size distribution; Amorphous organic matters; Grain size distribution; Intertropical convergence zone; Lacustrine sedimentations; Lacustrine sediments; Lake level fluctuations; Northern Hemispheres; Small-scale atmospheric turbulence; crater lake; diatom; environmental change; eolian deposit; grain size; lacustrine deposit; Last Glacial Maximum; paleoenvironment; proxy climate record; sedimentation; Sediments
Abstract: ▾ Grain-size analysis and end-member modeling of the clastic fraction of the 25-kyr sediment sequence from Lake Chala, a meromictic crater lake on the lower east slope of Mt. Kilimanjaro, reveal crucial aspects of climate-driven environmental change in equatorial East Africa since the Last Glacial Maximum. The finely laminated sediments of Lake Chala contain only up to 40% of clastic components, the rest are mainly diatom frustules and amorphous organic matter. Measured grain-size distributions were split into six statistically meaningful end members, of which four could be linked to a distinct source and transport mechanism of clastic mineral input: fine aeolian dust from distal sources (EM1), fine catchment runoff (EM2), coarser aeolian dust from proximal sources (EM5) and coarse erosive material from the upper crater slopes (EM6). The two other end members (EM3 and EM4) represented frustules of the two most common diatom taxa in Lake Chala, Afrocymbella barkeri and Nitzschia fabiennejansseniana, which had (partly) survived sample pre-treatment. Temporal variation in normalized abundance of the two dust-derived end members are valuable proxies for past changes in monsoon circulation over equatorial East Africa. During Northern Hemisphere cold periods (e.g., Last Glacial Maximum and Younger Dryas) the Inter-Tropical Convergence Zone shifted southward, enhancing northeasterly monsoon winds in the Lake Chala area and increasing advection of fine dust from the dry Horn of Africa region. Simultaneously, more modest continental heating reduced the prevalence of small-scale atmospheric turbulence, and thus the occurrence of dust devils, resulting in reduced influx of coarse dust from drylands nearby. Conversely, abrupt intensification of the southeasterly monsoon at the onset of the Holocene is recorded by an abrupt increase in the amount of coarse dust delivered to Lake Chala. Temporal variation in the end members representing catchment run-off (EM2) and erosion (EM6) mainly reflect changes in lacustrine sedimentation dynamics associated with major lake-level fluctuation, as evidenced by other paleoenvironmental proxies. Overall this study shows that subdivision of the clastic fraction of lacustrine sediments into statistically robust grain-size end members can provide multiple independent and quantitative proxies which help constrain reconstructions of a region's multi-faceted climate history. © 2020 The Authors
2455.
Report on ICDP Deep Dust workshops: Probing continental climate of the late Paleozoic icehouse-greenhouse transition and beyond
Scientific Drilling,
2893-112
2020
ISSN: 18168957
Publisher: Copernicus GmbH
Keywords:▾
Biospherics; Geothermal energy; Greenhouses; Induced Seismicity; Site selection; Stratigraphy; Warehouses, Broader impacts; Continental climate; High resolution; Late Paleozoic; Paleoenvironments; Planetary science; Reference points; Research questions, Dust
Abstract: ▾ Chamberlin and Salisbury's assessment of the Permian a century ago captured the essence of the period: it is an interval of extremes yet one sufficiently recent to have affected a biosphere with near-modern complexity. The events of the Permian - the orogenic episodes, massive biospheric turnovers, both icehouse and greenhouse antitheses, and Mars-analog lithofacies - boggle the imagination and present us with great opportunities to explore Earth system behavior. The ICDP-funded workshops dubbed "Deep Dust," held in Oklahoma (USA) in March 2019 (67 participants from nine countries) and Paris (France) in January 2020 (33 participants from eight countries), focused on clarifying the scientific drivers and key sites for coring continuous sections of Permian continental (loess, lacustrine, and associated) strata that preserve high-resolution records. Combined, the two workshops hosted a total of 91 participants representing 14 countries, with broad expertise. Discussions at Deep Dust 1.0 (USA) focused on the primary research questions of paleoclimate, paleoenvironments, and paleoecology of icehouse collapse and the run-up to the Great Dying and both the modern and Permian deep microbial biosphere. Auxiliary science topics included tectonics, induced seismicity, geothermal energy, and planetary science. Deep Dust 1.0 also addressed site selection as well as scientific approaches, logistical challenges, and broader impacts and included a mid-workshop field trip to view the Permian of Oklahoma. Deep Dust 2.0 focused specifically on honing the European target. The Anadarko Basin (Oklahoma) and Paris Basin (France) represent the most promising initial targets to capture complete or near-complete stratigraphic coverage through continental successions that serve as reference points for western and eastern equatorial Pangaea. © 2020 Copernicus GmbH. All rights reserved.
2454.
Scientific drilling workshop on the Weihe Basin Drilling Project (WBDP): Cenozoic tectonic-monsoon interactions
Scientific Drilling,
2863-73
2020
ISSN: 18168957
Publisher: Copernicus GmbH
Keywords:▾
Atmospheric thermodynamics; Sedimentology; Tectonics, Chinese Academy of Sciences; Chinese Loess Plateau; Continental scientific drillings; Different boundary condition; Environmental change; Scientific collaboration; Scientific objectives; Workshop participants, Infill drilling
Abstract: ▾ The Weihe Basin, enclosed by the Chinese Loess Plateau to the north and the Qinling Mountains to the south, is an outstanding, world-class continental site for obtaining high-resolution multi-proxy records that reflect environmental changes spanning most of the Cenozoic. Previous geophysical and sedimentary studies indicate that the basin hosts 6000-8000 m thick fluvial-lacustrine sedimentary successions spanning the Eocene to Holocene. This sedimentary record provides an excellent and unique archive to decipher long-term tectonic-climate interactions related to the uplift of the Tibetan Plateau, the onset/evolution of the Asian monsoon, and the development of the biogeography of East Asia. Owing to its location at the interface of the opposing westerly and Asian monsoon circulation systems, the Weihe Basin also holds enormous promise for providing a record of changes in these circulation systems in response to very different boundary conditions since the Eocene. To develop an international scientific drilling programme in the Weihe Basin, the Institute of Earth Environment, Chinese Academy of Sciences, organized a dedicated workshop with 55 participants from eight countries. The workshop was held in Xi'an, China, from 15 to 18 October 2019. Workshop participants conceived the key scientific objectives of the envisaged Weihe Basin Drilling Project (WBDP) and discussed technical and logistical aspects as well as the scope of the scientific collaboration in preparation for a full drilling proposal for submission to the International Continental Scientific Drilling Program (ICDP). Workshop participants mutually agreed to design a two-phase scientific drilling programme that will in a first phase target the upper 3000 m and in a second phase the entire up to 7500 m thick sedimentary infill of the basin. For the purpose of the 7500 m deep borehole, the world's only drill rig for ultra-deep scientific drilling on land, Crust 1, which previously recovered the entire continental Cretaceous sediments in the Songliao Basin, will be deployed in the WBDP. © 2020 Copernicus GmbH. All rights reserved.
2453.
Revised chronology of the ICDP Dead Sea deep drill core relates drier-wetter-drier climate cycles to insolation over the past 220 kyr
Quaternary Science Reviews,
244
2020
ISSN: 02773791
Publisher: Elsevier Ltd
Keywords:▾
Carbonate minerals; Caves; Driers (materials); Glacial geology; Incident solar radiation; Infill drilling; Isotopes; Lakes; Sedimentology, Climate condition; Eastern Mediterranean; Gypsum precipitation; Heinrich Events; Marine isotope stages; Northern Hemispheres; Oxygen isotopes; Sedimentary facies, Core drilling, aragonite; chronology; climate conditions; climate cycle; Deep Sea Drilling Project; hydrometeorology; insolation; marine isotope stage; Northern Hemisphere; watershed; wetting-drying cycle, Atlantic Ocean; Atlantic Ocean (North); Dead Sea; Mediterranean Sea; Mediterranean Sea (East)
Abstract: ▾ The Dead Sea Deep Drilling Project drilled 456 meters into the deepest floor of the Dead Sea and recovered a record of the past ∼220 kyr of the Levant hydroclimate history, that is, Marine Isotope Stages 1–7, including the last three interglacials and the last two glacials. We present an updated chronology of the core from DSDDP Hole 5017-1-A, from the Dead Sea's deepest basin, that refines our previous chronology (Torfstein et al. 2015) based on new information. The updated chronology uses the following approaches: (1) radiocarbon ages of Kitagawa et al. (2017); (2) correlation of specific layers in the core with U–Th-dated sediments on the Dead Sea margin, particularly during the interval of glacial Lake Lisan (MIS 2,3,4); (3) tuning of the δ18O data of DSDDP core aragonite to the U–Th dated oxygen isotopes of regional cave speleothems; and (4) tuning of the DSDDP aragonite δ18O data to summer insolation curves when the cave δ18O chronology is less clear. The updated chronology reveals a strong relationship between the sedimentary facies comprising the core and Northern Hemisphere summer insolation variations. It shows that sequences of sediments marking drier/wetter/drier climate conditions in the lake's watershed (e.g., salt/muds/salt, respectively) appear across the flank/peak/flank segments of several summer insolation peaks. In particular, the transition from drier to wetter sedimentary facies during mid-latitude insolation peaks coincides with the intervals of sapropel conditions in the Mediterranean, reflecting enhanced Nile flow due to intense African monsoonal conditions, and marking the impact of the tropical precession cycles on Eastern Mediterranean hydroclimate. This pattern was lost during MIS 2,3,4, when mostly sequences of primary aragonite are punctuated by gypsum precipitation during Heinrich events, marking the strong impact of the North Atlantic on the last glacial Levant hydroclimate. © 2020 Elsevier Ltd
2452.
Scientific drilling workshop on the Weihe Basin Drilling Project (WBDP): Cenozoic tectonic-monsoon interactions
Scientific Drilling,
2863-73
2020
ISSN: 18168957
Publisher: Copernicus GmbH
Keywords:▾
Atmospheric thermodynamics; Sedimentology; Tectonics, Chinese Academy of Sciences; Chinese Loess Plateau; Continental scientific drillings; Different boundary condition; Environmental change; Scientific collaboration; Scientific objectives; Workshop participants, Infill drilling
Abstract: ▾ The Weihe Basin, enclosed by the Chinese Loess Plateau to the north and the Qinling Mountains to the south, is an outstanding, world-class continental site for obtaining high-resolution multi-proxy records that reflect environmental changes spanning most of the Cenozoic. Previous geophysical and sedimentary studies indicate that the basin hosts 6000-8000 m thick fluvial-lacustrine sedimentary successions spanning the Eocene to Holocene. This sedimentary record provides an excellent and unique archive to decipher long-term tectonic-climate interactions related to the uplift of the Tibetan Plateau, the onset/evolution of the Asian monsoon, and the development of the biogeography of East Asia. Owing to its location at the interface of the opposing westerly and Asian monsoon circulation systems, the Weihe Basin also holds enormous promise for providing a record of changes in these circulation systems in response to very different boundary conditions since the Eocene. To develop an international scientific drilling programme in the Weihe Basin, the Institute of Earth Environment, Chinese Academy of Sciences, organized a dedicated workshop with 55 participants from eight countries. The workshop was held in Xi'an, China, from 15 to 18 October 2019. Workshop participants conceived the key scientific objectives of the envisaged Weihe Basin Drilling Project (WBDP) and discussed technical and logistical aspects as well as the scope of the scientific collaboration in preparation for a full drilling proposal for submission to the International Continental Scientific Drilling Program (ICDP). Workshop participants mutually agreed to design a two-phase scientific drilling programme that will in a first phase target the upper 3000 m and in a second phase the entire up to 7500 m thick sedimentary infill of the basin. For the purpose of the 7500 m deep borehole, the world's only drill rig for ultra-deep scientific drilling on land, Crust 1, which previously recovered the entire continental Cretaceous sediments in the Songliao Basin, will be deployed in the WBDP. © 2020 Copernicus GmbH. All rights reserved.
2451.
Potential mobilizable Fe from secondary phases of differentially altered subsurface basaltic rock– a sequential extraction study on ICDP site Hawaii
Applied Geochemistry,
121
2020
ISSN: 08832927
Publisher: Elsevier Ltd
Keywords:▾
Basalt; Budget control; Chemical bonds; Core drilling; Extraction; Infill drilling; Positive ions; Seawater; Silica; Submarines; Surface waters; Volcanoes; Weathering, Chemical bondings; Controlling parameters; Scientific drilling; Secondary phasis; Sequential extraction; Sequential extraction procedure; Specific surface area (SSA); Volcanic ocean island, Iron compounds, adsorption; basalt; chemical bonding; mobilization; seawater; sequential extraction; silica; surface water; volcanic island, Hawaii
Abstract: ▾ The potential for the mobilization of Fe from secondary phases within subsurface basaltic rocks of the Hawaii Scientific Drilling Project Phase2 (HSDP2) drill core was investigated to elucidate the possible contribution of volcanic islands to the Fe budget of nearby ocean surface waters. Rock specific parameters governing Fe mobilization, such as Fe redox state, specific surface area (SSA), and connected porosity were determined. A four-step sequential extraction procedure using solutions with increasing strength of the extractants was applied to characterize different states of chemical bonding of Fe in secondary phases of the basaltic rocks, a controlling parameter for its release to oceanic water. The sequential extraction results were then used as a measure for the reactivity of secondary Fe-bearing phases and the mobilizable Fe from these rocks. Basaltic rocks with different degrees of weathering showed elevated Fe(III) contents up to 58% total Fe as Fe(III), compared to 11–18% in fresh basalts. SSAs increased with depth, with maximum values of 70 m2/g observed for hyaloclastites. Both parameters depended mainly on the alteration state of the basalt, which was more strongly affected by the fluid chemistry (freshwater ↔ seawater) than by the age of the rocks. The sequential extractions revealed the presence of highly reactive secondary Fe-bearing phases in submarine rocks exposed to seawater whereas observations for rocks altered in freshwater point to better crystallized phases with lower mobilizable Fe contents. In seawater, aging of secondary Fe-bearing phases was most probably suppressed by the adsorption of silica and multivalent anions. Comparing different types of rock, hyaloclastites and pillow basalts showed the highest mobilizable Fe with up to 19% and 16%, respectively, of the total Fe of the bulk rock. The potential for high amounts of mobilizable Fe from basaltic rocks altered under seawater dominated conditions suggests that the submarine part of volcanic ocean islands represent an underestimated source of Fe supply to ocean surface waters. © 2020 Elsevier Ltd
2450.
Precise maturity assessment over a broad dynamic range using polycyclic and heterocyclic aromatic compounds
Organic Geochemistry,
148
2020
ISSN: 01466380
Publisher: Elsevier Ltd
Keywords:▾
Aromatic compounds; Deposits; Mass spectrometry; Shale, Coefficient of correlation; Fourier transform ion cyclotron resonance mass spectrometry; Heterocyclic aromatic compounds; Lacustrine deposits; Maturity assessments; Maturity parameters; Thermally induced; Vitrinite reflectance, Aromatization, catagenesis; chemical alteration; cracking (chemistry); maturation; molecular analysis; PAH; precision; thermal maturity, China; Germany; Songliao Basin, Posidonia
Abstract: ▾ The construction and reliable application of maturation indices is extremely important in deep Earth exploration, yet predicting levels of maturation on a molecular level, especially at overmature stages, is still a major challenge. Here, we report robust, broad ranging and precise maturity parameters that were developed using a continuous core of thermally overmature lacustrine deposits (Shahezi Fm.) from the deep Songke-2 Well (SK-2), Songliao Basin, China, augmented by shallow cores of lower maturity marine deposits (Posidonia Shale) from the Hils Syncline, Germany. The novel indices presented here are based on the general process of thermally-induced cyclization, aromatization and aliphatic chain cracking of hundreds to thousands of compounds during maturation. The newly developed parameters, with an extremely broad dynamic range extending from catagenesis and into metagenesis (vitrinite reflectances (Ro) range from 0.9% to 2.2%), are based on polycyclic and heterocyclic aromatic compounds measured using Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS). The high coefficient of correlations between the new maturity parameters with Ro and Tmax demonstrate their utility for assessing precisely the thermal maturity of overmature shales. © 2020 Elsevier Ltd
2449.
Monitoring crustal CO2 flow: Methods and their applications to the mofettes in West Bohemia
Solid Earth,
11
(3)
983 – 998
2020
ISSN: 18699510
Publisher: Copernicus GmbH
Keywords:▾
Bohemia; Czech Republic; Boreholes; Carbon dioxide; Degassing; Earthquakes; Flow measurement; Flow of gases; Gases; Mineral springs; Bubble fractions; Continuous monitoring; Earthquake swarms; Environmental conditions; Field conditions; Long term monitoring; Nonlinear dependence; Pressure differences; carbon dioxide; coseismic process; crustal structure; degassing; discharge; earthquake hypocenter; earthquake swarm; flow velocity; gas flow; monitoring; Flow rate
Abstract: ▾ Monitoring of CO2 degassing in seismoactive areas allows the study of correlations of gas release and seismic activity. Reliable continuous monitoring of the gas flow rate in rough field conditions requires robust methods capable of measuring gas flow at different types of gas outlets such as wet mofettes, mineral springs, and boreholes. In this paper we focus on the methods and results of the long-term monitoring of CO2 degassing in the West Bohemia/Vogtland region in central Europe, which is typified by the occurrence of earthquake swarms and discharge of carbon dioxide of magmatic origin. Besides direct flow measurement using flowmeters, we introduce a novel indirect technique based on quantifying the gas bubble contents in a water column, which is capable of functioning in severe environmental conditions. The method calculates the mean bubble fraction in a water-gas mixture from the pressure difference along a fixed depth interval in a water column. Laboratory tests indicate the nonlinear dependence of the bubble fraction on the flow rate, which is confirmed by empirical models found in the chemical and nuclear engineering literature. Application of the method in a pilot borehole shows a high correlation between the bubble fraction and measured gas flow rate. This was specifically the case for two coseismic anomalies in 2008 and 2014, when the flow rate rose during a seismic swarm to a multitude of the preseismic level for several months and was followed by a long-term flow rate decline. However, three more seismic swarms occurring in the same fault zone were not associated with any significant CO2 flow anomaly.We surmise that this could be related to the slightly farther distance of the hypocenters of these swarms compared to the two ones which caused the coseismic CO2 flow rise. Further long-term CO2- flow monitoring is required to verify the mutual influence of CO2 degassing and seismic activity in the area. © 2020 Cambridge University Press. All rights reserved.
2448.
Pore characteristics of lacustrine shale oil reservoir in the Cretaceous Qingshankou Formation of the Songliao Basin, NE China
Energies,
13
(8)
2020
ISSN: 19961073
Publisher: MDPI AG
Keywords:▾
Enamels; Field emission microscopes; Fractal dimension; Gas adsorption; Petroleum reservoir engineering; Petroleum reservoirs; Pore structure; Scanning electron microscopy; Shale oil, Correlation analysis; Correlation matrix; Field emission scanning electron microscopy; Fractal analysis; Multi-dimensional scaling; Nitrogen adsorption; Organic-rich shales; Pore characteristics, Nanopores
Abstract: ▾ Shale oil is hosted in nanopores of organic-rich shales, so pore characteristics are significant for shale oil accumulation. Here we analyzed pore characteristics of 39 lacustrine shale samples of the Late Cretaceous Qingshankou Formation (K2qn) in the Songliao Basin, which is one of the main shale oil resource basins in China, using field emission-scanning electron microscopy (FE-SEM), and low-pressure nitrogen adsorption. We accomplished fractal analysis, correlation analysis using correlation matrix and multidimensional scaling (MDS), and prediction of fractal dimensions, which is the first time to predict pore fractal dimensions of shales. Interparticle pores are highly developed in K2qn. These shales have mesoporous nature and slit-shaped pores. Compared with the second and third members (K2qn2,3), the first member of the Qingshankou Formation (K2qn1) has a larger average pore diameter, much smaller surface area, fewer micropores, simpler pore structure and surface indicated by smaller fractal dimensions. In terms of pore characteristics, K2qn1 is better than K2qn2,3 as a shale oil reservoir. When compared with marine Bakken Formation shales, lacustrine shales of the Qingshankou Formation have similar complexity of pore structure, but much rougher pore surface. This research can lead to an improved understanding of the pore system of lacustrine shales. © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
2447.
Non-reactive and reactive experiments to determine the electrical conductivities of aqueous geothermal solutions up to supercritical conditions
Journal of Volcanology and Geothermal Research,
391
2020
2446.
Seismic attribute analysis of Chicxulub impact crater
Acta Geophysica,
68
(3)
627-640
2020
Abstract: ▾ Chicxulub crater formed ~ 66 Ma ago by an asteroid impact on the Yucatan platform in the southern Gulf of Mexico. The crater has a ~ 200 km rim diameter and has been covered by carbonate sediments up to ~ 1.1 km thick in the central zone. Previous studies have identified the structure and major crater units through geophysical models from seismic reflection and potential field data, classified as the central uplift, terrace zone, outer and inner ring fault zones and impactite deposits. Impact produced a deep excavation cavity, with fragmentation and ejection of large volumes of crustal target rocks. Understanding the pre-existing structures, impact-induced deformation and post-impact processes requires high-resolution images of the crater and target zone. For this study, we use complex trace attributes of instantaneous phase, frequency, envelope amplitude and similarity, in an E-W seismic reflection profile crossing the crater in the marine sector. Geophysical logs and borehole lithological columns from the on-land drilling projects are used to constrain the petrophysical analysis. Seismic attributes aid to characterize the radial fault zones and physical property contrasts, revealing asymmetries in the crater structure. The reflector packages in the post-impact sediments and target Cretaceous sequence are identified in the frequency and phase attributes. The bottom crater reflectors, with the basal sediments filling the crater floor topography, are enhanced with the envelope amplitude attribute. A set of high-amplitude reflectors is shown in the similarity attribute, in which the reflector geometry is delineated on the target carbonate sequence. The offsets in the high-amplitude reflectors between the eastern and western sectors are possibly associated to target pre-impact asymmetries, impact deformation and effects of central crater collapse. © 2020, Institute of Geophysics, Polish Academy of Sciences & Polish Academy of Sciences.
2445.
Multi-Level Gas Monitoring: A New Approach in Earthquake Research
Frontiers in Earth Science,
8
2020
ISSN: 22966463
Publisher: Frontiers Media S.A.
Keywords:▾
Carbon dioxide; Earthquakes; Gas detectors; Geochemistry; Earthquake research; Environmental change; Gas monitoring systems; Geochemical properties; High sampling rates; Magmatic process; Temporal variation; Vertical profile; carbon dioxide; crustal structure; degassing; drilling; earthquake mechanism; earthquake swarm; fluid flow; fluid pressure; geochemistry; geophysics; hydrocarbon reservoir; monitoring; radon; Flow of fluids
Abstract: ▾ Fluid anomalies were often considered as possible precursors before earthquakes. However, fluid properties at the surface can change for a variety of reasons, including environmental changes near the surface, the response of the superficial fluid system to loads associated with the mechanical nucleation of earthquake fractures, or as a result of transients in fluid flow from the depths. A key problem is to understand the origin of the anomaly and to distinguish between different causes. We present a new approach to monitor geochemical and geophysical fluid properties along a vertical profile in a set of drillings from a depth of a few hundred meters to the surface. This setup can provide hints on the origin of temporal variations, as the migration direction and speed of properties can be measured. In addition, potential admixtures of fluids from a deep crustal or mantle origin with meteoric fluids can be better quantified. A prototype of a multi-level gas monitoring system comprising flow and pressure probes, as well as monitoring of fluid-geochemical properties and stable isotopes is being implemented in a mofette field with massive CO2 (up to 97 tons per day) degassing. The mofette is believed a gas emission site where CO2 ascends through crustal-scale conduits from as deep as the upper mantle, and may therefore provide a natural window to ongoing magmatic processes at mantle depth. Fluids from three adjacent boreholes—30, 70, and 230 m deep—will be continuously monitored at high sampling rates. © Copyright © 2020 Woith, Daskalopoulou, Zimmer, Fischer, Vlček, Trubač, Rosberg, Vylita and Dahm.