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Late Ordovician Mass Extinction: earth, fire and ice

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National Science Review 2024年第1期11卷 51-65页

作者： David A.T.Harper Palaeoecosystems Group Department of Earth SciencesDurham University

The Late Ordovician Mass Extinction was the earliest of the ‘big’ five extinction events and the earliest to affect the trajectory of metazoan life. Two phases have been identified near the start of the Hirnantian period and in the middle. It was a massive taxonomic extinction, a weak phylogenetic extinction and a relatively benign ecological extinction. A rapid cooling, triggering a major ice age that reduced the temperature of surface waters, prompted a drop in sea level of some 100 m and introduced toxic bottom waters onto the shelves. These symptoms of more fundamental planetary processes have been associated with a range of factors with an underlying driver identified as volcanicity. Volcanic eruptions, and other products, may have extended back in time to at least the Sandbian and early Katian, suggesting the extinctions were more protracted and influential than hitherto documented.

关键词： Ordovician LOME paleoecology palaeobiogeography biotas

Analysis of ancient mass extinction recoveries in marine environments: generating strategies for managing outcomes of the current mass extinction

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National Science Review 2024年第1期11卷 8-10页

作者： David J.Bottjer Department of earth sciences University of Southern California

The defining feature of a mass extinction and its associated recovery is the global amount of extinction that occurred[1]. However, there is finer-scale detail to the story, as seen in the ongoing modern mass extinction(the sixth mass extinction), which exhibits variable effects among marine ecosystems and environments, and hence geographic areas [1].

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Two thin middle-crust low-velocity zones imaged in the Chuan-Dian region of southeastern Tibetan Plateau and their tectonic implications

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Science China earth sciences 2024年第5期67卷 1675-1686页

作者： Long LI Xin WANG Guangbing HOU Yuan LING Yinshuang AI Key Laboratory of earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of earth and Planetary sciences University of Chinese Academy of SciencesBeijing 100049China Innovation Academy for earth Science Chinese Academy of SciencesBeijing 100029China

Intracrustal low-velocity zones(LVZs)indicate a mechanically weak crust and are widely observed in the southeast margin of the Tibetan ***,their spatial distributions and formation mechanisms remain *** investigate their distribution and detailed morphology of the LVZs in the southeastern Tibetan Plateau,here we used teleseismic events and continuous waveform data recorded by 40 broadband seismic stations newly deployed in the Sichuan-Yunnan region from December 2018 to October 2020.A total of 12,924 high-quality P-wave receiver functions and 5–40 s fundamental Rayleigh surface wave phase velocity dispersion curves from ambient noise cross-correlation functions were *** Swave velocity model at a depth interval of 0–100 km in the study area was inverted by using the trans-dimensional Markov chain Monte Carlo strategy to jointly invert the complementary data of the receiver function waveform and Rayleigh surface wave phase velocity *** results show that there are two separate LVZs(~3.5 km/s)surrounding the rigid Daliangshan subblock at crustal depths of approximately 30–40 km,providing new constraints on the geometry of the LVZs in our study *** two LVZs obtained in this study may represent the middle crustal flow channels,through which the material in the center of the Tibetan Plateau extrudes to its southeast *** by the rigid Sichuan Basin and the spindle-like Daliangshan subblock,the material continues to flow southward through the mechanically weak middle crustal channels surrounding the Daliangshan *** addition,the existence of thin LVZs in the middle crust plays an important role in understanding the decoupling between the upper and lower crust in the study *** also provides new constraint on the complex tectonic deformation process of the southeastern margin of the Tibetan Plateau caused by the collision and compression of the Indian and the Eurasian plates.

关键词： Southeastern Tibetan Plateau Joint inversion Intracrustal low-velocity zone Mid-crustal channel flow

Origin of the Yueguang gold deposit in Xinhua, Hunan Province, South China: insights from fl uid inclusion and hydrogen–oxygen stable isotope analysis

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Acta Geochimica 2024年第2期43卷 235-254页

作者： Hongxin Fan Qiang Wang Yulong Yang Yao Tang Hao Zou College of earth sciences Chengdu University of TechnologyChengdu 610059China College of earth sciences Jilin UniversityJilin 130061China

The Yueguang gold deposit is located in Fengjia,Xinhua County,Hunan Province,South *** represents a recently discovered small-scale gold deposit situated in the southwestern region of the Jiangnan Orogenic Belt,west of the Baimashan granitic *** order to discern the characteristics of the ore-formingﬂuids,the underlying mineralization processes,and establish a foundation for the origin of the Yueguang gold depositﬂuid inclusion micro-thermometry,as well as quartz hydrogen and oxygen isotope analysis,have been carried out on samples obtained from various stages of *** hydrothermal miner-alization stages within the Yueguang gold deposit can be categorized into three stages:(i)the barren,pre-ore quartz-pyrite stage(Stage Ⅰ),the quartz-pyrite-gold stage(Stage Ⅱ),and the post-ore quartz-carbonate stage(Stage Ⅲ),with the second stage being the main mineralization ***ﬂuid inclusions identiﬁed in samples from the main min-eralization stage can predominantly be described with the NaCl–H_(2)O and CO_(2)–NaCl–H_(2)O *** inclusions display homogenization temperatures ranging from 158.8 to 334.9℃,and theﬂuid salinity ranges from 0.3%to 4.0%(wt.%NaCl equiv.).Laser Raman spectroscopy analysis of individual inclusions further reveals the presence of gas-phases such as CO_(2),CH_(4),and N_(2).Isotopic analysis indicatesδ^(18)Oﬂuid values ranging from 3.95 to 6.7‰ and δDH_(2)O values ranging from-71.9 to-55.7‰.These results indi-cate that the ore-formingﬂuid of the Yueguang gold deposit belongs to metamorphic hydrothermalﬂuids of middle-low temperature and low *** the process of ore formation,gold is transported in the form of Au(HS)2-complexes,with gold deposition being driven byﬂuid ***,the Yueguang gold deposit is categorized as an orogenic gold deposit dominated by metamorphic hydrother-malﬂ*** may become a new target for gold exploration in the Baimashan region,central Hunan Province.

关键词： Hunan province Yueguang gold deposit Fluid inclusions Hydrogen–oxygen isotopes Laser Raman Fluid immiscibility Orogenic gold deposit

Identifying flow regime in the aquifer of fractured rock system in Germi Chai Basin,Iran

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Journal of Mountain Science 2024年第2期21卷 574-589页

作者： VAEZIHIR Abdorreza SEPEHRIPOUR Ali TABARMAYEH Mehri Department of earth sciences University of TabrizTabriz ***Iran

Considering the importance of fractured rock aquifers in the hydrogeologic process,this research aimed to analyze the flow regime,internal degree of karstification,and estimate storage volume in fractured rock aquifers of the Germi Chai Basin in northwest Iran,which is attributed to its active tectonics,erosion,and the lithological *** the geological setting,the hypothesis is that this basin is characterized by a high degree of karstification and diffuse or intermediate flow regime leading to variation in discharge flow *** hydrodynamic and hadrochemical analysis was conducted on 9 well distributed springs across the basin from 2019 to *** maximum flow rate in most of the springs appeared in the early wet season despite their different levels of fluctuations on the monthly discharge time *** the spring recession curve form revealed an aquifer containing multiple micro-regimes withαrecession coefficients and a degree of karstification ranging between 0.001 to 0.06 and 0.55 to 2.61,*** findings indicated a dominant diffuse and intermediate flow system resulting from the development of a high density of fractures in this *** electrical conductivity of the spring changes inversely proportional to the change in flow discharge,indicating the reasonable hydrological response of the aquifer to rainfall *** analysis revealed that the delay time of spring discharge after rainfall events mostly varies between 10 to 30 *** total dynamic storage volume of the spring for a given period(2019-2020)was estimated to be approximately 1324 million cubic meters reflecting the long-term drainage potential and high perdurability of dynamic *** the maximum and minimum ratio revealed that the springs recharging system in Germi Chai Basin comes under the slow aquifers *** finding provides valuable insight into the hydrogeological properties of fractured rock aquifers contributing to effective w

关键词： Fractured rock aquifer Hydrodynamic and hadrochemical analysis Germi Chai Basin Recession coefficient

Provenance of the Lower Jurassic pyroclastic sediments in the Zigui Basin:Implication for crustal thickening in the eastern Qinling orogenic belt

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Science China earth sciences 2024年第1期67卷 196-207页

作者： Rong CHAI Jianghai YANG Yuansheng DU Chengshan WANG School of earth sciences and Resources China University of Geosciences(Beijing)Beijing 100023China School of earth sciences China University of Geosciences(Wuhan)Wuhan 430074China Chinese Academy of Geological sciences Beijing 100037China

The Late Triassic witnessed significant collisional orogenic events in the Qinling orogenic belt,accompanied by magma underplating and tectonic *** processes potentially resulted in substantial crustal thickening and uplift of the Qinling ***,due to the absence of igneous rock records from this period in the eastern section of the Qinling orogen,the changes in crustal thickness during this orogenic process have not been thoroughly investigated.A series of foreland basins emerged during the Early Mesozoic to the south of the East Qinling orogenic *** basins have preserved clastic sedimentary rocks derived from the uplift and erosion of the orogenic *** sedimentary records serve as crucial records to reconstruct the evolutionary history of the Qinling *** further clarify the collisional orogenic process of the Qinling orogenic belt,this study conducted in situ volcanic lithic fragment geochemistry,detrital zircon U-Pb chronology and trace element composition analysis on the sandstones of the Lower Jurassic Tongzhuyuan Formation in the Zigui *** results suggest that the sandstones,which exhibit a significant abundance of volcanic lithic fragments,has a characteristic detrital zircon age group of 250–200 Ma,indicating a major provenance from the Triassic volcanic *** with regional correlation and paleocurrent analysis,the detrital zircon U-Pb age data show that the source area of volcanic rocks should be in the Qinling orogenic belt to the north of the *** interpretation is further supported by the Triassic granitic rocks exposed in the western part of the orogenic belt,representing the magmatism during the Triassic collisional orogenesis in the Qinling *** on the co-varying relationships between present-day crust thickness with the chemical compositions of granite rocks and zircons,the La/Yb ratio of volcanic lithic fragments in the Tongzhuyuan Formation and the Eu/Eu*ratio of detrital zircon

关键词： Qinling orogenic belt Zigui Basin Late Triassic Detrital zircons Crustal thickening

Numerical evaluations on the fluid production in the in-situ conversion of continental shale oil reservoirs

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Petroleum Science 2024年第04期21卷 2485-2501页

作者： Zhao-Bin Zhang Maryelin Josefina Brice?o Montilla Shou-Ding Li Xiao Li Jian-Peng Xing Yan-Zhi Hu Key Laboratory of Shale Gas and Geoengineering Institute of Geology and Geophysics Chinese Academy of Sciences Institute of earth sciences Chinese Academy of Sciences College of earth and Planetary sciences University of Chinese Academy of Sciences Institute of Energy Peking University

In-situ conversion presents a promising technique for exploiting continental oil shale formations,characterized by highly fractured organic-rich rock. A 3D in-situ conversion model, which incorporates a discrete fracture network, is developed using a self-developed thermal-flow-chemical(TFC) *** of the model elucidates the in-situ conversion process in three stages and defines the transformation of fluids into three distinct outcomes according to their end stages. The findings indicate that kerogen decomposition increases fluid pressure, activating fractures and subsequently enhancing permeability. A comprehensive analysis of activated fracture permeability and heating power reveals four distinct production modes, highlighting that increasing heating power correlates with higher cumulative fluid production. Activated fractures, with heightened permeability, facilitate the mobility of heavy oil toward production wells but hinder its cracking, thereby limiting light hydrocarbon ***, energy efficiency research demonstrates the feasibility of the in-situ conversion in terms of energy utilization, especially when considering the surplus energy from high-fluctuation energy sources such as wind and solar power to provide heating.

关键词： In-situ conversion Continental shale oil Natural fracture network TFC model

The great catastrophe: causes of the Permo-Triassic marine mass extinction

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National Science Review 2024年第1期11卷 37-50页

作者： Paul B.Wignall David P.G.Bond School of earth & Environment University of Leeds School of Environmental sciences University of Hull

The marine losses during the Permo-Triassic mass extinction were the worst ever experienced. All groups were badly affected, especially amongst the benthos(e.g. brachiopods, corals, bryozoans, foraminifers,ostracods). Planktonic populations underwent a fundamental change with eukaryotic algae being replaced by nitrogen-fixing bacteria, green-sulphur bacteria, sulphate-reducing bacteria and prasinophytes. Detailed studies of boundary sections, especially those in South China, have resolved the crisis to a ～55 kyr interval straddling the Permo-Triassic boundary. Many of the losses occur at the beginning and end of this interval painting a picture of a two-phase extinction. Improved knowledge of the extinction has been supported by numerous geochemical studies that allow diverse proposed extinction mechanisms to be studied. A transition from oxygenated to anoxic-euxinic conditions is seen in most sections globally, although the intensity and timing shows regional variability. Decreased ocean ventilation coincides with rapidly rising temperatures and many extinction scenarios attribute the losses to both anoxia and high *** kill mechanisms include ocean acidification for which there is conflicting support from geochemical proxies and, even less likely, siltation(burial under a massive influx of terrigenous sediment) which lacks substantive sedimentological evidence. The ultimate driver of the catastrophic changes at the end of the Permian was likely Siberian Trap eruptions and their associated carbon dioxide emissions with consequences such as warming, ocean stagnation and acidification. Volcanic winter episodes stemming from Siberian volcanism have also been linked to the crisis, but the short-term nature of these episodes(

关键词： ocean anoxia ocean acidification siltation productivity collapse volcanic winter

Circum-Indian Holocene sea-level database:A repository of distinct relative sea-level plots across the Indian Peninsula

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Journal of Palaeogeography 2024年第1期13卷 1-17页

作者： Shradha Menon Pankaj Khanna Santanu Banerjee REEFS Lab Department of Earth SciencesIIT GandhinagarPalajGandhinagarGujarat382355India Department of earth sciences IIT BombayPowaiMumbai400076India

The Indian Peninsula is one of the most well-studied regions for Holocene sea-level fluctuations in the world, however, standardized relative sea-level datasets are missing. This study provides an archive of sealevel indicators(n = 162, 20 locations) along the western and the eastern sides of the peninsula, that have been used to develop Relative Sea Level(RSL) plots. Each dated sea-level indicator is recalibrated for its elevation based on tidal and tectonic correction, as well as age with reservoir correction, and have been separated into six zones based on coastal geomorphology and number of datasets. The database spans throughout the Holocene and covers sea-level depth/elevations from-45 m to +5 m from mean sea-level(MSL). Approximately 90 % of the dataset range from 8 ka to the present day. The first transgression is highly variable and identified between 8.5-8 ka BP in Gujarat(Zone 1), ~ 5.5 ka BP in Maharashtra(Zone 2), between 8 and 7 ka BP in Tamil Nadu(Zone 4) and between 8 and 7.5 ka BP in the Bengal coasts(Zone 6). No transgression above present sea-level is observed along Andhra Pradesh(Zone 5)(no data for Kerala-Zone 3).Further, Zones 1, 2, 4 and 6 show a strong uplift component(tectonic), whereas Zone 5 exhibits subsidence during the Holocene(Zone 3-insufficient data). Based on these findings, and given the region's coastal topography and tidal components, Zones 6 and 1 will likely undergo the largest coastal inundation, followed by Zones 5, 4, 2, and 3. These insights are critical in planning future coastal inundation measures across the Indian Peninsula.

关键词： Indian ocean Terraces Relative sea level curve Holocene Arabian sea Bay of Bengal