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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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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

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 diversity.Given 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 rate.The hydrodynamic and hadrochemical analysis was conducted on 9 well distributed springs across the basin from 2019 to 2020.The 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 series.Analyzing 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,respectively.These findings indicated a dominant diffuse and intermediate flow system resulting from the development of a high density of fractures in this area.The electrical conductivity of the spring changes inversely proportional to the change in flow discharge,indicating the reasonable hydrological response of the aquifer to rainfall events.Hydrograph analysis revealed that the delay time of spring discharge after rainfall events mostly varies between 10 to 30 days.The 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 storage.Estimating the maximum and minimum ratio revealed that the springs recharging system in Germi Chai Basin comes under the slow aquifers category.This finding provides valuable insight into the hydrogeological properties of fractured rock aquifers contributing to effective water management strategy.

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

Mixed-layer water oscillations in tropical Pacific for ENSO cycle

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Science China earth sciences 2007年第12期50卷 1892-1908页

作者： ZHAO YongPing1,CHEN YongLi1,WANG Fan1 & WU AiMing2 1 Institute of oceanology,Chinese Academy of sciences,Qingdao 266071,China 2 department of earth & ocean sciences,University of British Columbia,Vancouver,BC,V6T 1Z4,Canada Institute of oceanology Chinese Academy of Sciences Qingdao China department of earth & ocean sciences University of British Columbia Vancouver Canada

The main modes of interannal variabilities of thermocline and sea surface wind stress in the tropical Pacific and their interactions are investigated,which show the following results.(1) The thermocline anomalies in the tropical Pacific have a zonal dipole pattern with 160°W as its axis and a meridional seesaw pattern with 6-8°N as its transverse axis.The meridional oscillation has a phase lag of about 90° to the zonal oscillation,both oscillations get together to form the El Ni?o/La Ni?a cycle,which be-haves as a mixed layer water oscillates anticlockwise within the tropical Pacific basin between equator and 12°N.(2) There are two main patterns of wind stress anomalies in the tropical Pacific,of which the first component caused by trade wind anomaly is characterized by the zonal wind stress anomalies and its corresponding divergences field in the equatorial Pacific,and the abnormal cross-equatorial flow wind stress and its corresponding divergence field,which has a sign opposite to that of the equatorial region,in the off-equator of the tropical North Pacific,and the second component represents the wind stress anomalies and corresponding divergences caused by the ITCZ anomaly.(3) The trade winds anomaly plays a decisive role in the strength and phase transition of the ENSO cycle,which results in the sea level tilting,provides an initial potential energy to the mixed layer water oscillation,and causes the opposite thermocline displacement between the west side and east side of the equator and also between the equator and 12°N of the North Pacific basin,therefore determines the amplitude and route for ENSO cycle.The ITCZ anomaly has some effects on the phase transition.(4) The thermal anomaly of the tropical western Pacific causes the wind stress anomaly and extends eastward along the equator accompanied with the mixed layer water oscillation in the equatorial Pacific,which causes the trade winds anomaly and produces the anomalous wind stress and the corresponding divergence in favor to conduce the oscillation,whi

关键词： tropical Pacific, thermocline and sea surface wind stress anomaly, ENSO cycle, mixed layer water oscillation

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

High-resolution tsunami hazard assessment for the Guangdong-Hong Kong-Macao Greater Bay Area based on a non-hydrostatic tsunami model

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Science China earth sciences 2024年第7期67卷 2326-2351页

作者： Yifan ZHU Chao AN Houyun YU Wei ZHANG Xiaofei CHEN Key Laboratory of Hydrodynamics(Ministry of Education) School of Ocean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China department of earth and Space sciences Southern University of Science and Technology Shenzhen 518055China

The Guangdong-Hong Kong-Macao Greater Bay Area(GBA)is threatened by potential tsunami hazards from the Littoral Fault Zone(LFZ)and the Manila subduction zone(MSZ),and may suffer huge damage because of its dense population,concentrated infrastructure,and low-lying coasts.Previous tsunami studies for the GBA made simple assumptions on the mechanisms of LFZ earthquakes,and used coarse bathymetry data in tsunami simulation,which limited the prediction of detailed tsunami hazard characteristics.In this paper,we develop a parallel dispersive tsunami model PCOMCOT to efficiently simulate dispersive,nonlinear,and breaking tsunami waves.We also construct large-scale and high-resolution bathymetry models for the GBA by correcting and integrating various data sources.Dynamic rupture simulation is performed for the LFZ to obtain a more reliable earthquake source model.We propose several representative earthquake scenarios for the LFZ and MSZ,and use PCOMCOT to calculate the resulting tsunami waves,currents,and inundation in the GBA.Our results indicate that if an M_(w)7.5 oblique-slip earthquake occurs in the LFZ off the Pearl River Estuary(PRE),the subsequent tsunami will primarily impact Hong Kong,causing maximum positive and negative waves of around 1 m and -2 m,respectively,along with slightly destructive currents(≥1.5 m/s).An M_(w)9.0 MSZ megathrust earthquake can lead to widespread inundation with>1 m depth on the outlying islands of Macao and in the urban areas of Hong Kong around the Victoria Harbour.Besides,it will also cause catastrophic tsunami currents along the narrow waterways in Hong Kong and Macao,and the spatial distribution of strong currents(≥3 m/s)shows a considerable discrepancy from the areas of serious inundation.Thus,more attention should be paid to the potential impacts of tsunami currents on the GBA.

关键词： Tsunami hazards Inundation Tsunami currents Non-hydrostatic model Guangdong-Hong Kong-Macao Greater Bay Area

Microfacies and diagenetic alteration in a semi-deep to deep lacustrine shale: The Yanchang Formation in the Ordos Basin, China

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Petroleum Science 2024年第3期21卷 1524-1538页

作者： Bin Bai Jing-Yue Hao Ling Fu Yu-Xi Liu Jian-Peng Wang Lan Wang Kevin G.Taylor Lin Ma PetroChina Research Institute of Petroleum Exploration and Development department of earth and Environmental sciences University of Manchester College of earth sciences Jilin University department of Chemical Engineering University of Manchester

The mineralogical development and diagenetic sequence of lacustrine shales in the Chang 7 Member of the Yanchang Formation in the Ordos Basin are detailed studied. A model of their depositional system and a diagenetic diagram are proposed in this study. Through detailed petrographic, mineralogical, and elemental analyses, four distinct shale types are identified: argillaceous shale, siliceous shale, calcareous shale, and carbonate, clay, and silt-bearing shale. The main diagenetic process in argillaceous shale is the transformation of illite to smectite, negatively impacting shale porosity. Siliceous shale undergoes carbonate cementation and quartz dissolution, contributing to increased porosity, particularly in mesopores.Calcareous shale experiences diagenesis characterised by carbonate formation and dissolution, with a prevalence of siderite. In carbonate, clay, and silt-bearing shale, the dissolution of K-feldspar contributes to illitization of kaolinite. Argillaceous shale, characterised by more clay minerals and lower mesopore volume, is identified as a potential hydrocarbon seal. Siliceous shale, with the highest pore volume and abundant inter-mineral pores, emerges as a promising shale oil reservoir. These findings contribute to a comprehensive understanding of shale properties, aiding in the prediction of shale oil exploration potential in the studied area.

关键词： Ordos Basin Yanchang Formation Chang 7 Member Diagenesis Microfacies

Hydrographic Characteristics and oceanic Heat Flux in the Upper Arctic ocean over the Alpha Ridge Observed by the DTOP Platform in 2018 and 2021

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Journal of ocean University of China 2024年第2期23卷 304-316页

作者： WANG Yongjun LI Tao College of oceanic and Atmospheric sciences Ocean University of ChinaQingdao 266100China Frontier Science Center for Deep ocean Multispheres and earth System(FDOMES) and Physical oceanography Laboratory Ocean University of ChinaQingdao 266100China Laoshan Laboratory Qingdao 266237China

In 2018 and 2021,the Drift-Towing ocean Profilers(DTOP)provided extensive temperature and salinity data on the upper 120m ocean through their drifts over the Alpha Ridge north of the Canada Basin.The thickness and temperature maximum of Alaska Coastal Water(ACW)ranged from 20m to 40m and-1.5℃to-0.8℃,respectively,and the salinity generally maintained from 30.2 to 32.5.Comparison with World ocean Atlas 2018’s climatology manifested a 40m-thick and warm ACW roughly ex-ceeding the temperature maximum by 0.4–0.5℃in June–August 2021.This anomalously warm ACW was highly related to the ex-pansion of the Beaufort Gyre in the negative Arctic Oscillation phase.During summer,the under-ice oceanic heat flux F_(w)^(OHF)was elevated,with a maximum value of above 25Wm^(-2).F_(w)^(OHF)was typically low in the freezing season,with an average value of 1.2Wm^(-2).The estimates of upward heat flux contributed by ACW to the sea ice bottom F_(w)^(OHF)were in the range of 3–4Wm^(-2)in June–August 2021,when ACW contained a heat content of more than 80MJm^(-2).The heat loss over this period was driven by a weak stratification upon the ACW layer associated with a surface mixed layer(SML)approaching the ACW core.After autumn,F_(w)^(OHF)was reduced(<2 Wm^(-2))except during rare events when it elevated F_(w)^(OHF)slightly.In addition,the intensive and widespread Ekman suction,which created a violent upwelling north of the Canada Basin,was largely responsible for the substantial cooling and thinning of the ACW layer in the summer of 2021.

关键词： Arctic ocean oceanic heat flux Alaska Coastal Water Alpha Ridge

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 temperatures.Other 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