All ICDP Publications with Abstracts
From parent-sysfolder "Publications" + 2 folder-levels deep
2494.
Initial Results From the Oman Drilling Project Multi-Borehole Observatory: Petrogenesis and Ongoing Alteration of Mantle Peridotite in the Weathering Horizon
Journal of Geophysical Research: Solid Earth,
126
(12)
e2021JB022729
2021
2493.
Iron Mineralogy and Sediment Color in a 100 m Drill Core From Lake Towuti, Indonesia Reflect Catchment and Diagenetic Conditions
Geochemistry, Geophysics, Geosystems,
22
(8)
2021
ISSN: 15252027
Publisher: John Wiley and Sons Inc
Keywords:▾
Greater Sunda Islands; Lake Towuti; Malili Lakes; South Sulawesi; Sulawesi; Sunda Isles; Catchments; Chemical analysis; Cluster analysis; Crystallinity; Drills; Infill drilling; Iron oxides; Lakes; Nanocrystalline materials; Runoff; Sedimentary rocks; Sedimentology; Sediments; Serpentine; Drainage patterns; Environmental conditions; Lacustrine systems; Redox sensitives; Sedimentary environment; Sedimentary systems; Visible/near infrared; Water rock interactions; diagenesis; iron oxide; lacustrine deposit; mineralogy; sediment chemistry; sediment core; sedimentation; Core drilling
Abstract: ▾ Iron is the most abundant redox-sensitive element on the Earth's surface, and the oxidation state, mineral host, and crystallinity of Fe-rich phases in sedimentary systems can record details of water-rock interactions and environmental conditions. However, we lack a complete understanding of how these Fe-rich materials are created, maintained, and oxidized or reduced in sedimentary environments, particularly those with mafic sources. The catchment of Lake Towuti, Indonesia, is known to contain a wide range of abundant crystalline Fe oxide, and the lake has a long sedimentary history. Here, we study a ∼100 m long drill core from the lake to understand patterns of sedimentation and how young iron-rich sediments are affected by diagenesis through geologic time. We use visible/near infrared and Mössbauer spectroscopy, X-ray diffraction, bulk chemistry measurements, and statistical cluster analysis to characterize the core sediment. We find that the core sediment can be divided into three statistically different zones dominated by Mg serpentine, Al clay minerals, and Fe2+ carbonate, respectively. The entire core is rich in nanophase Fe, and elemental correlations and Fe mineralogy vary between these zones. The nanophase Fe is highly complex with both ferrous and ferric components, and contributes to, but does not dictate, variations in sediment color. We propose that the distinctive zones are the result of structural basin changes (notably river capture and shifting drainage patterns), and diagenetic overprinting caused by deep burial of reactive Fe. This complex record has implications for disentangling depositional and diagenetic trends in other mafic lacustrine systems. © 2021. American Geophysical Union. All Rights Reserved.
2492.
Labyrinth patterns in Magadi (Kenya) cherts: Evidence for early formation from siliceous gels
Geology,
49
(9)
1137 – 1142
2021
ISSN: 00917613
Publisher: Geological Society of America
DOI:10.1130/G48774.1
Keywords:▾
Kajiado; Kenya; Lake Magadi; Binary alloys; Field emission microscopes; Infill drilling; Lakes; Phase interfaces; Scanning electron microscopy; Silica; Silica gel; Thorium alloys; Thorium metallography; Uranium alloys; Uranium metallography; Air liquid interfaces; Analog systems; Drilling projects; Field emission scanning electron microscopy; Geochemical conditions; Microfossils; Synsedimentary; Thin section; Archean; chert; depositional environment; microfossil; paleolimnology; petrography; precipitation (chemistry); silica; Gels
Abstract: ▾ Sedimentary cherts, with well-preserved microfossils, are known from the Archean to the present, yet their origins remain poorly understood. Lake Magadi, Kenya, has been used as a modern analog system for understanding the origins of nonbiogenic chert. We present evidence for synsedimentary formation of Magadi cherts directly from siliceous gels. Petrographic thin-section analysis and field-emission scanning electron microscopy of cherts from cores drilled in Lake Magadi during the Hominin Sites and Paleolakes Drilling Project in 2014 led to the discovery of two-dimensional branching “labyrinth patterns” in chert, which are a type of fractal “squeeze” pattern formed at air-liquid interfaces. Labyrinth patterns preserved in chert from Lake Magadi cores indicate invasion of air along planes in dewatering gels. These patterns support the precipitation of silica gels in the saline-alkaline Lake Magadi system and syndepositional drying of gels in contact with air as part of chert formation. Recognizing cherts as syndepositional has been critical for our use of them for U-Th dating. Identification of labyrinth patterns in ancient cherts can provide a better understanding of paleoenvironmental and geochemical conditions in the past © 2021 Geological Society of America. For permission to copy, contact editing@geosociety.org.
2491.
Land-sea correlations in the Eastern Mediterranean region over the past c. 800 kyr based on macro- and cryptotephras from ODP Site 964 (Ionian Basin)
Quaternary Science Reviews,
255
2021
ISSN: 02773791
Publisher: Elsevier Ltd
Keywords:▾
Balkans; Catania [Sicily]; Central Macedonia; Cyclades; Etna; Greece; Italy; Lake Ohrid; Lipari Islands; Messina [Sicily]; Pantelleria; Santorin; Santorini [Southern Aegean]; Serrai [Central Macedonia]; Sicily; Southern Aegean; Tenaghi Philippon; Trapani; Lakes; Trace elements; Volcanoes; Climate variability; Eastern Mediterranean; Land-sea correlations; Major and trace elements; Marine isotope stages; Middle Pleistocene; Ocean drilling programs; South Aegean volcanic arc; Campanian; marine record; Mediterranean environment; Ocean Drilling Program; proxy climate record; tephra; tephrochronology; volcanic eruption; volcanic glass; volcanic island; Climate models
Abstract: ▾ Direct correlations between terrestrial and marine climate-proxy records are essential in order to determine potential lead/lag relationships in the response of the terrestrial and marine realms to climate forcing. In the Eastern Mediterranean region, such land-sea correlations have not yet been established beyond c. 200 ka. To explore the potential of tephra layers for Late and Middle Pleistocene land-sea correlations in the Eastern Mediterranean region, we have revisited yet unconfirmed tephra layers previously reported from Ocean Drilling Program (ODP) Site 964 (Ionian Basin) for the past c. 800 kyr in order to identify their origin and examine potential terrestrial counterparts. Using major- and trace-element glass analyses, we confirmed the presence of seven visible tephra layers with ages from 623 to 38 ka. These tephra layers represent known tephra isochrons from Italian volcanic centers (Y-5, Y-7, X-6, and V-0) and three yet unknown eruptions from Etna (623 ka), the Campanian Volcanic Zone (CVZ; 238 ka), and Pantelleria (238 ka). Because the majority of the previously reported tephra layers from ODP Site 964 were identified as clastic layers of non-volcanic origin, cryptotephra analyses were carried out for cores spanning Marine Isotope Stages (MIS) 13 to 9 (500–320 ka). This effort yielded 19 cryptotephra layers originating from Santorini volcano, the CVZ, possibly Roccamonfina volcano, and an undefined source in either the Aeolian Islands or the South Aegean Volcanic Arc. Two tephra layers are correlated with potential equivalents from terrestrial archives on the Italian and Balkan Peninsulas, including tephra isochrons SC5/A7/OH-DP-1966 (c. 493 ka; Mercure basin, Acerno basin, and Lake Ohrid) and TP09–65.95 (c. 359 ka; Tenaghi Philippon) that represent an unknown eruption of Roccamonfina and the Cape Therma 1 eruption of Santorini, respectively. Direct linking of the marine record from ODP Site 964 with the terrestrial records from Tenaghi Philippon, Lake Ohrid, and the Acerno basin via tephra tie points allowed us to circumvent shortcomings of the individual age models, and to obtain a comprehensive picture of climate variability in the greater Eastern Mediterranean region for the MIS 13–9 interval. © 2021 Elsevier Ltd
2490.
Hydrogen Production from Alteration of Chicxulub Crater Impact Breccias: Potential Energy Source for a Subsurface Microbial Ecosystem
Astrobiology,
21
(12)
1547-1564
2021
Abstract: ▾ A sulfate-reducing population of thermophiles grew in porous, permeable niches within glass-bearing impact breccias of the Chicxulub impact crater. The microbial community grew in an impact-generated hydrothermal system that vented on the seafloor several hundred meters beneath the sea surface. Potential electron donors for that metabolism are hydrocarbons, although a strong C-isotope signature of that source does not exist. Model calculations explored here suggest that alteration of glass within the impact breccias may have produced H2 in sufficient quantities for population growth as the hydrothermal system cooled through thermophilic temperatures, although it is sensitive to the oxidation state of iron in the melt rock prior to hydrothermal alteration and the secondary mineral assemblage. At high water-to-rock ratios and temperatures below 45°C, H2 yields are insufficient to maintain a population of hydrogenotrophic sulfate-reducing bacteria, but yields double with a higher proportion of ferrous iron between 45 and 65°C. The most reduced rocks (i.e., highest proportion of ferrous iron) that are allowed to form andradite, which is observed in core samples, produce copious amounts of H2 in the temperature window for thermophiles and hyperthermophiles. Mixtures of melt rock and carbonate, which is observed in breccia matrices, produce somewhat less H2, and the onset of massive H2 production is shifted to higher temperatures (i.e., lower W/R). © Copyright 2021, Mary Ann Liebert, Inc., publishers 2021.
2489.
Late Pliocene to early Pleistocene climate dynamics in western North America based on a new pollen record from paleo-Lake Idaho
Palaeobiodiversity and Palaeoenvironments,
101
(1)
177-195
2021
ISSN: 18671594
Publisher: Springer Science and Business Media Deutschland GmbH
Keywords:▾
climate effect; climate variation; drilling; glaciation; ice sheet; Neogene; palynology; Pliocene-Pleistocene boundary; proxy climate record; vegetation dynamics, Idaho; North America; Pacific Ocean; Snake River Plain; United States, Coniferophyta
Abstract: ▾ Marked by the expansion of ice sheets in the high latitudes, the intensification of Northern Hemisphere glaciation across the Plio/Pleistocene transition at ~ 2.7 Ma represents a critical interval of late Neogene climate evolution. To date, the characteristics of climate change in North America during that time and its imprint on vegetation has remained poorly constrained because of the lack of continuous, highly resolved terrestrial records. We here assess the vegetation dynamics in northwestern North America during the late Pliocene and early Pleistocene (c. 2.8–2.4 Ma) based on a pollen record from a lacustrine sequence from paleo-Lake Idaho, western Snake River Plain (USA) that has been retrieved within the framework of an International Continental Drilling Program (ICDP) coring campaign. Our data indicate a sensitive response of forest ecosystems to glacial/interglacial variability paced by orbital obliquity across the study interval, and also highlight a distinct expansion of steppic elements that likely occurs during the first strong glacial of the Pleistocene, i.e. Marine Isotope Stage 100. The pollen data document a major forest biome change at ~ 2.6 Ma that is marked by the replacement of conifer-dominated forests by open mixed forests. Quantitative pollen-based climate estimates suggest that this forest reorganisation was associated with an increase in precipitation from the late Pliocene to the early Pleistocene. We attribute this shift to an enhanced moisture transport from the subarctic Pacific Ocean to North America, confirming the hypothesis that ocean-circulation changes were instrumental in the intensification of Northern Hemisphere glaciation. © 2021, The Author(s).
2488.
Lithospheric extension in response to subduction of the Paleo-Pacific Plate: Insights from Early Jurassic intraplate volcanic rocks in the Sk2 Borehole, Songliao Basin, NE China
Lithos,
380-381
2021
ISSN: 00244937
Publisher: Elsevier B.V.
Keywords:▾
borehole; deformation mechanism; extensional tectonics; intraplate process; Jurassic; lithospheric structure; Pacific plate; paleogeography; plate tectonics; subduction zone; tectonic evolution; tectonic setting; volcanic rock, China; Mongol-Okhotsk Fold Belt; Songliao Basin
Abstract: ▾ Subduction of the Paleo-Pacific and Mongol–Okhotsk oceanic plates is widely believed to have caused extensive Mesozoic magmatism and lithospheric deformation in East Asia. However, it remains unclear how the two tectonic domains affected NE China, and whether a boundary exists between them, because the Songnen Block in central NE China is covered by sedimentary rocks and the related mafic magmatism has been rarely discovered. Here we report a suite of Early Jurassic (ca. 175 Ma) mafic volcanic rocks (including basalt and basaltic andesite) from the Sk2 Borehole, Songliao Basin, NE China. The Sk2 mafic rocks are characterized by high Th/U, Zr/Y and Ti/Y ratios, and their geochemical signatures are consistent with formation in a back-arc extensional setting, rather than an arc setting. The rocks show depleted zircon εHf(t) and whole-rock εNd(t) values, which are comparable to mafic rocks located on the east of the Songliao Basin. This suggests that they both have a depleted mantle source, unlike the mafic rocks on the west of the Songliao Basin with relatively enriched Nd and Hf isotopes. Early–Middle Jurassic mafic rocks are distributed in the Erguna Block, >500 km to the west from the Sk2 Borehole, whereas coeval mafic rocks are widely distributed in the nearby eastern Heilongjiang and Jilin provinces. These intraplate-like mafic rocks and the Early Jurassic bimodal rocks within the Lesser Xing'an and Zhangguangcai ranges likely formed in response to lithospheric extension that was triggered by subduction of the Paleo-Pacific Plate. The Early Jurassic mafic rocks directly underlie the oldest sedimentary rocks (the Huoshiling Formation) in the Songliao Basin, which suggests that basin formation was probably initiated by lithospheric extension. © 2020 Elsevier B.V.
2487.
Low-temperature hydrogen formation during aqueous alteration of serpentinized peridotite in the Samail ophiolite
Journal of Geophysical Research: Solid Earth,
126
(6)
e2021JB021981
2021
2486.
Magnetostratigraphy of the Hominin Sites and Paleolakes Drilling Project (HSPDP) Baringo-Tugen Hills-Barsemoi core (Kenya)
Palaeogeography, Palaeoclimatology, Palaeoecology,
570
2021
ISSN: 00310182
Publisher: Elsevier B.V.
Keywords:▾
Baringo; Kenya; Tugen Hills; Vertebrata; chronostratigraphy; demagnetization; environmental change; fossil record; hominid; human evolution; magnetostratigraphy; paleohydrology; paleomagnetism; titanomagnetite
Abstract: ▾ The principal objective of the Hominin Sites and Paleolakes Drilling project (HSPDP) is to study the relationship between climate and environmental change and the implications on human evolution in eastern Africa. For this purpose, HSPDP has recovered a 228 m core in the Chemeron Formation of the Baringo Basin (Kenya). The Chemeron Formation spans approximately 3.7 Myr, from around 1.6 to 5.3 Ma, and has yielded many vertebrate fossils, including fossil hominins. The magnetostratigraphy of the Baringo core contributes to the chronological framework. A total of 567 individual paleomagnetic samples were collected from 543 levels at regular intervals throughout the core and 264 were processed using thermal and alternative field stepwise demagnetizations. In most samples, distinct Low-Temperature (LT; 20–150 °C) and High-Temperature (HT; 150–550 °C) Characteristic Remanent Magnetization (ChRM) could be determined. Typical demagnetization behaviors and some rock magnetic experiments suggest titanomagnetite acts as the main carrier of the HT ChRM with pervasive secondary overprints in normal polarity expressed by the LT component. Normal and reversed polarities were identified based on the secondary overprints LT ChRM directions, either parallel or antiparallel to the HT ChRM directions respectively. Our study identified four paleomagnetic reversals interpreted as the Matuyama-Gauss, Gauss-Kaena, Kaena-Gauss and the Gauss-Mammoth transitions. These boundaries provide chronostratigraphic tie-points that can be combined with those derived from 40Ar/39Ar dating of tuffs (Deino et al., 2020) and together indicate that the HSPDP Baringo core has an age range of ~3.3 Ma to ~2.6 Ma. The consistent paleomagnetic and radioisotopic age constraints are incorporated into a Bayesian age model of the core (Deino et al., 2020). © 2021 Elsevier B.V.
2485.
Directional drilling technology takes lead with focus on deep earth anddeep sea exploration—Review of science and technology innovation by Institute of Exploration Techniques，CAGS during the 13th Five‑Year Plan and an outlook to the 14th Five‑Year Plan (in Chinese with English abstract);[定向钻井技术引领 聚焦深地深海探测——勘探技术所“十三五”科技创新回顾及“十四五”业务展望]
Drilling Engineering,
48
(01)
7-14
2021
2484.
Magnetostratigraphy of the Triassic Moenkopi Formation From the Continuous Cores Recovered in Colorado Plateau Coring Project Phase 1 (CPCP-1), Petrified Forest National Park, Arizona, USA: Correlation of the Early to Middle Triassic Strata and Biota in Colorado Plateau and Its Environs
Journal of Geophysical Research: Solid Earth,
126
(9)
2021
ISSN: 21699313
Publisher: John Wiley and Sons Inc
Keywords:▾
Anisian; biostratigraphy; demagnetization; fossil assemblage; lithostratigraphy; magnetostratigraphy; vertebrate, Arizona; China; Colorado Plateau; Petrified Forest National Park; United States, Vertebrata
Abstract: ▾ The Colorado Plateau Coring Project Phase 1 (CPCP-1) acquired three continuous drill cores from Petrified Forest National Park (PFNP), Arizona, U.S.A., two of which (CPCP-PFNP13-1A and CPCP-PFNP13-2B) intersected the Upper Triassic Chinle Formation, Lower(?)-Middle Triassic Moenkopi Formation (MF) and Permian Coconino Sandstone. We examined both cores to construct a high-resolution magnetostratigraphy of MF strata, and progressive demagnetization data yield well-defined, interpretable paleomagnetic results. Each lithostratigraphic member of the MF (Wupatki, Moqui, and Holbrook members) contains authigenic and detrital hematite as the dominant magnetic carrier with distinguishing rock magnetic characteristics. Magnetostratigraphy of MF strata in both CPCP-1 cores consists of six normal and six reverse polarity magnetozones, from the youngest to the oldest, MF1n to MF6r. Recent single-crystal chemical abrasion–thermal ionization mass spectrometry (CA-TIMS) U-Pb data from a sample in magnetozone MF1n yield a latest Anisian/earliest Ladinian (241.38 ± 0.43 Ma) age. Correlation of the CA-TIMS-calibrated magnetostratigraphy with the astronomically tuned polarity timescale for the Middle Triassic deep-marine Guandao (GD) section of South China ties the magnetozone MF1n with GD8 and MF6r with GD2r, and implies that the MF spans, at most, the earliest Anisian (Aegean) to latest Anisian (Illyrian)/earliest Ladinian stages (ca. 246.8 to 241.5 Ma). This age estimate for the MF suggests that the timespan of the regional, pre-Norian disconformity is about 17 Ma, which demonstrates that MF vertebrate fossil assemblages in east-central Arizona are millions of years (minimally 3–4 Ma) younger than previously suggested and are all Anisian in age, with no indications of substantial hiatuses in the MF section. © 2021. American Geophysical Union. All Rights Reserved.
2483.
Hydrometeorological analysis and forecasting of a 3 d flash-flood-Triggering desert rainstorm
Natural Hazards and Earth System Sciences,
21
(3)
917 – 939
2021
2482.
Insight Into Hartoušov Mofette, Czech Republic: Tales by the Fluids
Frontiers in Earth Science,
9
2021
ISSN: 22966463
Publisher: Frontiers Media S.A.
Keywords:▾
Cheb Basin; Czech Republic; Karlovarsky; Atmospheric movements; Boreholes; Chemical analysis; Earthquakes; Inert gases; Isotopes; Solubility; Atmospheric contributions; Chemical compositions; Chemical concentrations; CO2 concentration; Crustal earthquakes; Isotope compositions; Monitoring stations; Sampling campaigns; carbon; carbon dioxide; carbon flux; concentration (composition); degassing; helium; isotopic composition; magma; mantle structure; solubility; Carbon dioxide
Abstract: ▾ The Cheb Basin (Czech Republic) is characterized by emanations of magma-derived gases and repeated occurrences of mid-crustal earthquake swarms with small to intermediate magnitudes (ML < 4.5). Associated intense mantle degassing occurs at the Hartoušov Mofette, a representative site for the Cheb Basin. Here, we performed 14 sampling campaigns between June 2019 and March 2020. Gas samples of fluids ascending in two boreholes (F1, ∼28 m depth and F2, ∼108 m depth) and from a nearby natural mofette were analyzed for their chemical (CO2, N2, O2, Ar, He, CH4, and H2) and isotope compositions (noble gases and CO2). CO2 concentrations were above 99.1% in most samples, while O2 and N2 were below 0.6%. He ranged from 19 to 34 μmol/mol and CH4 was mostly below 12 μmol/mol. Isotope compositions of helium and carbon in CO2 ranged from 5.39 to 5.86 RA and from −2.4 to −1.3 ‰ versus VPDB, respectively. Solubility differences of the investigated gases resulted in fluctuations of their chemical compositions. These differences were accompanied by observed changes of gas fluxes in the field and at the monitoring station for F1. Variations in solubilities and fluxes also impacted the chemical concentration of the gases and the δ13C values that were also likely influenced by Fischer-Tropsch type reactions. The combination of (a) the Bernard ratio, (b) CH4/3He distributions, (c) P-T conditions, (d) heat flow, and (e) the sedimentary regime led to the hypothesis that CH4 may be of mixed biogenic and volcanic/geothermal origin with a noticeable atmospheric contribution. The drilling of a third borehole (F3) with a depth of ∼238 m in August 2019 has been crucial for providing insights into the complex system of Hartoušov Mofette. © Copyright © 2021 Daskalopoulou, Woith, Zimmer, Niedermann, Barth, Frank, Vieth-Hillebrand, Vlček, Bağ and Bauz.
2481.
Hydroclimate changes in eastern Africa over the past 200,000 years may have influenced early human dispersal
Communications Earth and Environment,
2
(1)
2021
2480.
Fine-grained gravity flow deposits and their depositional processes: A case study from the Cretaceous Nenjiang Formation, Songliao Basin, NE China
Geological Journal,
56
(3)
1496-1509
2021
ISSN: 00721050
Publisher: John Wiley and Sons Ltd
DOI:10.1002/gj.4017
Keywords:▾
borehole; Cretaceous; debris flow; gravity flow; hydrocarbon reservoir; lacustrine deposit; lithofacies; mudstone; reservoir characterization; shale; source rock, China; Songliao Basin
Abstract: ▾ The Songliao Basin in NE China is a large rift basin filled with Cretaceous terrestrial sediments. Lacustrine mudstones of the Nenjiang Formation form an important source rock in the Cretaceous Songliao Basin. These shales are commonly thought to have been deposited in deep, quiet, and anoxic environments. Samples obtained from the core of the SK-2 scientific borehole provide critical insights to understand the hydrodynamic and hydroclimatic environments, which are, however, different from the traditional views regarding the deposition of these rocks. By following a mudstone description guide, five different mudstone lithofacies (LF) transported and deposited by muddy hyperpycnal flows and muddy debris flows were recognized. They are laminated fine mudstone (LF1), laminated medium mudstone (LF2), and laminated coarse mudstone (LF3) showing pairs of inverse grading (Ha) and normal grading (Hb) under the microscope, graded coarse mudstone (LF4) and massive coarse mudstone (LF5). We found that mudstones of the First Member of the Nenjiang Formation are dominated by siliciclastic detritus and argillaceous components and show frequent variations in grain size. Because large-scale sub-lacustrine channels travelling long distance (>80 km) were widely distributed in the Songliao palaeolake during the deposition of the Nenjiang Formation, fluctuations in mudstone grain size might have been caused by velocity fluctuations in flows. Sedimentary structures and textures preserved in mudstones of the First Member of the Nenjiang Formation indicate that the majority of these lithofacies were accumulated by muddy hyperpycnal flows and muddy debris flows. Therefore, a depositional model dominantly influenced by muddy hyperpycnal flows and debris flows is proposed. This work not only provides a new view for the depositional process of mudstones of the Songliao Basin, NE China, but also give insights to understand lacustrine palaeoenvironment and terrestrial palaeoclimate. © 2020 John Wiley & Sons Ltd
2479.
Drivers of phytoplankton community structure change with ecosystem ontogeny during the Quaternary
Quaternary Science Reviews,
265
2021
2478.
Hydration Imaging Spectroscopy Dataset for Oman Drilling Project Holes GT1A, GT2A, and GT3A
2477.
Enhancing gas production from Class II hydrate deposits through depressurization combined with low-frequency electric heating under dual horizontal wells
Energy,
233
2021
ISSN: 03605442
Publisher: Elsevier Ltd
Keywords:▾
Dissociation; Electric heating; Energy efficiency; Gas hydrates; Horizontal wells; Hydration, Class II; Depressurizations; Electrical heating; Energy; Energy recovery; Gas productions; Hydrate deposit; Lower frequencies; Thermal stimulation; Water zone, Deposits, energy efficiency; gas hydrate; gas production; numerical model; optimization; permafrost; simulation
Abstract: ▾ Class II hydrate deposits are characterized by a mobile water zone (WZ) underneath the hydrate-bearing layer (HBL) and are encountered in permafrost and deep-sea sediments. In this work, an efficient method of depressurization combining low-frequency electric heating under dual horizontal wells is proposed to exploit Class II hydrate deposits, in which two parallel horizontal wells are arranged in the HBL and the WZ. Based on the geological parameters in the Mallik deposit, the energy recovery behaviors are studied through a numerical simulation approach. Electric heating significantly improves hydrate dissociation and gas production compared with the depressurization method. However, gas production lags electric heating for a long time, and the energy efficiency ratio decreases with time in the later stage. To address these shortcomings, two additional electric heating schemes are designed and optimized. The results show that the additional wellbore heating at the beginning of production accelerates the dissociation of hydrates near the production well, thus greatly reducing the lag time. When electric heating is terminated after the 800th day, the cumulative gas production is reduced by 9.1%, but the energy efficiency ratio is improved as high as 48.71, which confirms the great potential of the proposed method. © 2021 Elsevier Ltd
2476.
Environmental changes during MIS6-3 in the Basin of Mexico: A record of fire, lake productivity history and vegetation
Journal of South American Earth Sciences,
109
2021
ISSN: 08959811
Publisher: Elsevier Ltd
Keywords:▾
environmental change; fire history; glacial-interglacial cycle; paleoenvironment; palynology; reconstruction; vegetation dynamics, Lake Chalco; Mexico [North America]
Abstract: ▾ The responses of lake productivity, vegetation, and fire events in the Basin of Mexico to orbital changes from late MIS 6 to MIS 3 (146–35 ka) have been studied based on geochemical (Ti, TIC, TOC, C/N), charcoal (CHAR) and pollen data of the sediment core CHA08 from Lake Chalco. The paleoenvironmental reconstruction identifies the MIS 6 as a wetter period with episodes of dry conditions, low forest cover and low fire activity. A sudden change from wetter to dry environments with low to high forest cover and fire activity episodes characterized the end of the MIS 6 (132–130 ka) coincident with high spring insolation. Variations in vegetation composition, with a tendency towards higher forest cover, fire-activity, runoff, and organic matter availability, are recorded during the MIS 5, MIS 4, and MIS 3. However, a reduction in the fire-activity was recorded for the cold and dry MIS 4. Spectral analysis based on the titanium concentration record of Lake Chalco suggests a precessional forcing on runoff variations. We explored the impact of the Intertropical Convergence Zone latitudinal migrations which have been related to the summer insolation at 65° N by comparing runoff data with other sedimentary records from North and Central America. Our results highlight the sensitivity of the high altitude tropical basin to climate variations. © 2021 Elsevier Ltd
2475.
Erratum to “Chronostratigraphy of the Baringo-Tugen-Barsemoi (HSPDP-BTB13-1A) core – 40Ar/39Ar dating, magnetostratigraphy, tephrostratigraphy, sequence stratigraphy and Bayesian age modeling” [PALAEO, Volume 532(2019), 109258] (Palaeogeography, Palaeoclimatology, Palaeoecology (2019) 532, (S0031018218310496), (10.1016/j.palaeo.2019.109258))
Palaeogeography, Palaeoclimatology, Palaeoecology,
571
2021
ISSN: 00310182
Publisher: Elsevier B.V.
Abstract: ▾ The Publisher regrets that this article is an accidental duplication of an article that has already been published in, https://doi.org/10.1016/j.palaeo.2019.109519. The duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal. © 2019 Elsevier B.V.
2474.
Exotic rock block from the Koshava gypsum mine, Northwest Bulgaria: Petrography, geochemistry, mineralogy and melting phenomena
Geologica Balcanica,
50
(1)
45-65
2021
Abstract: ▾ The described exotic rock block (60×80×13-15 cm) was found at 290 m depth in a lower.middle Badenian gypsum layer in the Koshava mine, NW Bulgaria, near the Danube River. It is greyish-black, granular, with layered structure and layers composed of α-quartz rosettes covered with organic matter (kerogen-like type with high contents of Ge, Mo and B), wood relicts with chalcedony replacement, and porous lenses with compact accumulation of organic matter. The block is coated with quartz crust, up to 2 cm thick, with regmaglypt-like forms, also replaced by quartz. Aside from the surface, melting phenomena were also observed inside the quartz rosettes and especially in the wood relicts and porous lenses. The melted drops are actually crystallized chalcedony. The organic matter accumulations contain Si-organic zoned micrometre-sized spherules. Fe silicides were found in the organic matter of all parts of the block, in which hapkeite was determined by X-ray analysis. Other detected minerals include graphite, cristobalite, coesite, skeletal and framboidal pyrite, moassanite, magnetite, suessite, sphalerite and minerals formed in the gypsum lagoon (gypsum, celestine, barite, calcite, halite and clays). The geological position of the block in the gypsum without any other sediments, the extensive melting phenomena with melted spherules, crushed quartz, its enrichment in 18O isotope and the presence of coesite suggest that it is shock ejecta, in certain aspects resembling the large Muong Nong-type tektites, but its characteristics could be the basis for distinguishing it as a new tektite type. The fact that it was found in a gypsum layer of early.middle Badenian age points to its probable association with the Ries-Steinheim impact event, despite the long distance between them (~1100 km). © 2021 Geological Institute â€Strashimir Dimitrovâ€, Bulgarian Academy of Sciences.
2473.
Exploring the Past Biosphere of Chew Bahir/Southern Ethiopia: Cross-Species Hybridization Capture of Ancient Sedimentary DNA from a Deep Drill Core
Frontiers in Earth Science,
9
2021
ISSN: 22966463
Publisher: Frontiers Media S.A.
Keywords:▾
Ethiopia; Bacteria (microorganisms); Chlorophyta; Eukaryota; Gastropoda; Hexapoda; archaeological evidence; biosphere; core analysis; DNA; hominid; human settlement; hybridization; irradiation; paleoclimate; paleoecology; paleoenvironment; paleolimnology; reconstruction; timescale; tropical environment; ultraviolet radiation
Abstract: ▾ Eastern Africa has been a prime target for scientific drilling because it is rich in key paleoanthropological sites as well as in paleolakes, containing valuable paleoclimatic information on evolutionary time scales. The Hominin Sites and Paleolakes Drilling Project (HSPDP) explores these paleolakes with the aim of reconstructing environmental conditions around critical episodes of hominin evolution. Identification of biological taxa based on their sedimentary ancient DNA (sedaDNA) traces can contribute to understand past ecological and climatological conditions of the living environment of our ancestors. However, sedaDNA recovery from tropical environments is challenging because high temperatures, UV irradiation, and desiccation result in highly degraded DNA. Consequently, most of the DNA fragments in tropical sediments are too short for PCR amplification. We analyzed sedaDNA in the upper 70 m of the composite sediment core of the HSPDP drill site at Chew Bahir for eukaryotic remnants. We first tested shotgun high throughput sequencing which leads to metagenomes dominated by bacterial DNA of the deep biosphere, while only a small fraction was derived from eukaryotic, and thus probably ancient, DNA. Subsequently, we performed cross-species hybridization capture of sedaDNA to enrich ancient DNA (aDNA) from eukaryotic remnants for paleoenvironmental analysis, using established barcoding genes (cox1 and rbcL for animals and plants, respectively) from 199 species that may have had relatives in the past biosphere at Chew Bahir. Metagenomes yielded after hybridization capture are richer in reads with similarity to cox1 and rbcL in comparison to metagenomes without prior hybridization capture. Taxonomic assignments of the reads from these hybridization capture metagenomes also yielded larger fractions of the eukaryotic domain. For reads assigned to cox1, inferred wet periods were associated with high inferred relative abundances of putative limnic organisms (gastropods, green algae), while inferred dry periods showed increased relative abundances for insects. These findings indicate that cross-species hybridization capture can be an effective approach to enhance the information content of sedaDNA in order to explore biosphere changes associated with past environmental conditions, enabling such analyses even under tropical conditions. © Copyright © 2021 Krueger, Foerster, Trauth, Hofreiter and Tiedemann.
2472.
Effects of alteration and cracks on the seismic velocity structure of oceanic lithosphere inferred from ultrasonic measurements of mafic and ultramafic samples collected by the Oman Drilling Project
Journal of Geophysical Research: Solid Earth,
126
(11)
e2021JB021923
2021
2471.
Geochemical Profiles Across the Listvenite-Metamorphic Transition in the Basal Megathrust of the Semail Ophiolite: Results From Drilling at OmanDP Hole BT1B
Journal of Geophysical Research: Solid Earth,
126
(12)
e2021JB022733
2021
ISSN: 21699313
Publisher: Wiley Online Library
Keywords:▾
drilling; metasediment; ophiolite; peridotite; petrogenesis; petrography; serpentinite; serpentinization, Oman
Abstract: ▾ The transition from the Semail ophiolite mantle to the underlying metamorphic sole was drilled at ICDP OmanDP Hole BT1B. We analyzed the bulk major, volatile and trace element compositions of the mantle-derived listvenite series and metamorphic rocks, with the aim to constrain chemical transfers associated with peridotite carbonation along the ophiolite basal thrust. The listvenite series comprise variously carbonated serpentinites and (fuchsite-bearing) listvenites. They have high CO2 (up to 43 wt.%) and variable H2O (0–12 wt.%). Yet, they have compositions close to that of the basal banded peridotites for most major and lithophile trace elements, with fuchsite-bearing listvenites overlapping in composition with amphibole-bearing basal lherzolites (e.g., Al2O3 = 0.1–2.2 wt.%; Yb = 0.05–1 x CI-chondrite). The protolith of the listvenite series was likely similar in structure and composition to serpentinized banded peridotites which immediately overlie the metamorphic sole elsewhere in Oman. The listvenite series are enriched in fluid mobile elements (FME) compared to Semail peridotites (up to ∼103–104 x Primitive Mantle), with concentrations similar to the underthrusted metabasalts and/or metasediments for Cs, Sr and Ca and sometimes even higher for Pb, Li, As, and Sb (e.g., Li up to 130 μg/g; As up to 170 μg/g). We also observe a decoupling between Sr-Ca enrichments and other FME, indicating interactions with several batches of deep CO2-rich fluids transported along the basal thrust. These results suggest that peridotite carbonation could represent one of the major trap-and-release mechanisms for carbon, water and FME along convergent margins. © 2021. American Geophysical Union. All Rights Reserved.
2470.
Geospatial management and analysis of microstructural data from san andreas fault observatory at depth (Safod) core samples
ISPRS International Journal of Geo-Information,
10
(5)
2021
ISSN: 22209964
Publisher: MDPI AG
Abstract: ▾ Core samples obtained from scientific drilling could provide large volumes of direct mi-crostructural and compositional data, but generating results via the traditional treatment of such data is often time-consuming and inefficient. Unifying microstructural data within a spatially referenced Geographic Information System (GIS) environment provides an opportunity to readily locate, visual-ize, correlate, and apply remote sensing techniques to the data. Using 26 core billet samples from the San Andreas Fault Observatory at Depth (SAFOD), this study developed GIS-based procedures for: 1. Spatially referenced visualization and storage of various microstructural data from core billets; 2. 3D modeling of billets and thin section positions within each billet, which serve as a digital record after irreversible fragmentation of the physical billets; and 3. Vector feature creation and unsuper-vised classification of a multi-generation calcite vein network from cathodluminescence (CL) imagery. Building on existing work which is predominantly limited to the 2D space of single thin sections, our results indicate that a GIS can facilitate spatial treatment of data even at centimeter to nanometer scales, but also revealed challenges involving intensive 3D representations and complex matrix transformations required to create geographically translated forms of the within-billet coordinate systems, which are suggested for consideration in future studies. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.