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Quantitative geochemical reconstruction of eocene paleoenvironment in Fushun Basin,northeast China

Acta Geochimica 2024年第3期43卷 571-587页

作者： Yuanji Li Pingchang Sun Qiang Zhang Junxian Wang Department of Safety Engineering Heilongjiang University of Science and TechnologyHarbin 150022China National Professional Center Lab of Safety Basic Research for Hydrocarbon Gas Pipeline Transportation Network Harbin 150022China College of Earth Sciences Jilin UniversityChangchun 130061JilinChina Beijing Research Institute of Uranium Geology Beijing 100029China

The quantitative estimation of key parameters of paleotemperature and paleoprecipitation is crucial for paleoclimate *** data from mod-ern sediments are highly consistent with climate data,and their relationship can provide an important reference for the quantitative reconstruction of the *** this study,detailed inorganic geochemical analysis was carried out using high-precision sampling of the Paleogene(LFD-1 well)Guchengzi,Jijuntun and Xiloutian Formations in the Fushun Basin located in the mid-latitudes of the Northern *** eocene Guchengzi Formation(54.51–47.8 Ma)and Jijuntun Formation(47.8–41.2 Ma)in the Fushun Basin were found to have been deposited under a humid *** lower(41.2–40.1 Ma)and upper(40.1–37.8 Ma)parts of the Xiloutian Formation were character-ized by semiarid and semihumid–semiarid climates,respec-tively,which is very similar to the paleoclimatic information reflected by organic carbon *** eocene Thermal Maximum 2(ETM2,~53.7 Ma),Early eocene Climatic Optimum(EECO,~53.1–46.5 Ma),eocene Thermal Maxi-mum 3(ETM 3,~52.8 Ma),and Middle eocene Climatic Optimum(MECO,~40.7–40.1 Ma)events significantly enhanced chemical weathering during these *** rapid increase in pCO_(2)concentration leads to an increase in temperature,precipitation,and surface runoff,exhibiting strong chemical *** mean annual temperature(MATa)and mean annual precipitation(MAPa,MAPb,and MAPc)were estimated using parameters,such as the corrosion index without potassium(CIA-K),CaO/Al_(2)O_(3),and(Na_(2)O+K_(2)O)/Al_(2)O_(3).Comparing MAPa,MAPb,and MAPc with the MAP estimated using pollen data,MAPa and MAPb were found to be more sensitive to the climate during high precipitation periods(precipitation>1000 mm,Guchengzi Formation),and the recovered average precipi-tation was similar to *** contrast,MAPc was more sensitive to the climate during low precipitation periods(precipitation<1000 mm,Jijuntun,and Xilouti

关键词： eocene Fushun Basin Major element Paleoclimate Geochemical reconstruction

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Contributions to the knowledge of Antarctodon sobrali(Mammalia:Astrapotheria)from the eocene of Antarctica

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Advances in Polar Science 2024年第1期35卷 48-62页

作者： Javier N.GELFO Consejo Nacional de Investigaciones Científicasy Técnicas(CONICET) Buenos Aires C1425FQBArgentina División Paleontología Vertebrados Museo de La PlataFacultad de Ciencias Naturales y Museo de La PlataUniversidad Nacional de La PlataLa Plata B1900FWAArgentina

The Astrapotheria constitutes one of the five orders of extinct South American native ungulates,with a fossil record that also extends to the eocene of the Antarctic *** contrast to the abundant specimens known for litoptern Sparnotheriodontidae and metatherians,astrapotheres are represented by scant remains assigned to the endemic Antarctodon sobrali and indeterminate astrapotheres,restricted to levels 35C_(u0)and 35n of the Cucullaea I Allomember of the La Meseta *** discovery of alower molar assignable to this species in the eocene levels of Seymour(Marambio)Island,enables a revision of the diagnosis and the homologies of the dental characters used to describe this taxon.A reanalysis of its phylogenetic relationships reveals the nearly simultaneous presence of basal astrapotheres in the early eocene of Itaboraí(Brazil),Patagonia,and West *** taxa are characterized by lacking dental specializations usually associated with more abrasive diets like terminal forms of Uruguaytheriinae and *** appears to have thrived on the Antarctic continent during the Early eocene Climatic Optimum within the paleoclimatic context of a hot-house *** present conditions in Antarctica where no terrestrial mammals inhabit,the early eocene climate was characterized by warmer temperatures and a biologically diverse environment rich in primary producers,dominated by Nothofagus forests,encompassing both deciduous and evergreen forests,which supported a diverse assemblage of continental vertebrates.

关键词： Astrapotheria Antarctodon eocene Seymour Island La Meseta Formation

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eocene foraminiferal biofacies in Kutch Basin(India) in context of palaeoclimate and palaeoecology

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Journal of Palaeogeography 2019年第3期8卷 209-224页

作者： Sonal Khanolkar Pratul Kumar Saraswati Department of Earth Sciences Indian Institute of Technology Bombay Mumbai 400076 India Department of Earth Sciences Indian Institute of Technology Kanpur Kanpur 208016 India

The eocene Epoch passed through multiple hyperthermal events and recorded highest temperatures in the Cenozoic. Very few studies from eocene palaeotropical sites have recorded changes in shallow marine foraminiferal assemblages. The present study investigates the foraminiferal biofacies of shallow marine successions from a palaeotropical site in western India (Kutch Basin) to understand the palaeoclimate and its impact on the ecology of foraminifera. The sections were biostratigraphically con strained using planktic and larger benthic foraminifera. Four biofacies are recognized by detrended correspondence analysis of the sample-wise distribution of foraminifera. Low diversity and dwarfed foraminifera characterize Bulimina-Chiloguembelino biofacies (SBZ5/6-SBZ10), corresponding to the interval of Paleocene-eocene Thermal Maxima (PETM) and eocene Thermal Maxima 2 (ETM 2). Rectilinear benthic foraminifera and biserial and triserial planktic foraminifera, typical of high runoff, upwelling or eutrophic conditions, are dominant taxa in this biofacies. The specialist taxa increased significantly in Asterigerina-Cibicides biofacies, corresponding to SBZ11 (Early eocene Climatic Optimum, EECO), and the environment became oligotrophic. The Jenkinsina-Brizalina biofacies (E12) is distinguished by foraminiferal assemblage ecologically like that of Bulimina-Chiloguembelina biofacies. It is characterized by high abundance of rectilinear benthic foraminifera and bloom of triserial planktic foraminifera, suggesting eutrophy and high runoff at the initiation of Middle eocene Climatic Optimum (MECO). The foraminifera were more diverse and abundant in Cibicides-Nonion biofacies. The highly diverse larger benthic foraminiferal assemblage in this biofacies, signify warm and clear-water oligotrophic sea that promoted the development of platform carbonate in Kutch Basin and other basins in western India. The EECO and MECO did not have an adverse impact on shallow marine foraminifera, and

关键词： Hyperthermal events Shallow marine Morphogroups Carbonate platform Stable isotopes eocene Kutch Basin

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eocene fossil Alseodaphne from Hainan Island of China and its paleoclimatic implications

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Science China Earth Sciences 2009年第10期52卷 1537-1542页

作者： LI JingZhao QIU Jue LIAO WenBo JIN JianHua School of Life Sciences Sun Yat-Sen UniversityGuangzhou 510275China

Alseodaphne changchangensis sp. nov. (Lauraceae), with a perfectly preserved fossil leaf, was found in the eocene Changchang Formation from the Changchang Basin of Hainan Island, China. This represents the earliest occurrence at the lowest latitude for the genus Alseodaphne, and offers important fossil evidence for further investigation of the origin and evolution of this genus and the paleoclimate of Hainan Island in the eocene. Based on leaf morphology and cuticle characteristics, our fossil specimen is closest to the living species A. hainanensis Merrill, which is distributed mainly in tropical lowland rain forests, tropical montane rain forests, and subtropical montane evergreen broad-leafed forests on Hainan Island, and also found on the Wanshan Islands of Zhuhai of Guangdong Province and in northern parts of Vietnam. In the above areas, the climate factors are similar, i.e., the mean annual temperature is 20–22.6°C, the mean annual range of temperature 12–12.6°C and the mean annual precipitation 1784–2500 mm. Based on the nearest living species analysis, we conclude that the climate of the Changchang Basin on Hainan Island during the eocene was close to that of the distribution areas of the living A. hainanensis.

关键词： Alseodaphne changchangensis sp. nov. A. hainanensis Merrill eocene Changchang Basin Hainan Island Lauraceae paleoclimate

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Clay mineralogy of an eocene fluvial-lacustrine sequence in Xining Basin, Northwest China, and its paleoclimatic implications

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Science China Earth Sciences 2019年第3期62卷 571-584页

作者： Bin HU Chunxia ZHANG Haibin WU Qingzhen HAO Zhengtang GUO Key Laboratory of Cenozoic Geology and Environment Institute of Geology and Geophysics Chinese Academy of Sciences Institution of Earth Science Chinese Academy of Science College of Earth Science and Engineering Shandong University of Science and Technology CAS Center for Excellence in Life and Paleoenvironment University of Chinese Academy of Sciences

The eocene was marked by significant cooling during which the global climate was transformed from greenhouse to icehouse conditions. Notable coeval events were the India-Asia collision and the retreat of the Paratethys Sea in Asia. The eocene section of the long and continuous sedimentary succession of the Xining Basin in Northwest China is characterized by red mudstones with intercalated gypsum and muddy-gypsiferous layers. In this study, we conducted a semi-quantitative analysis of the mineralogy of bulk samples and the clay fraction using X-ray diffraction, with the aim of characterizing the eocene climatic evolution of the northeastern margin of the Tibetan Plateau and inland Asia. We used a new pretreatment method to address the problem of extracting sufficient clay particles from the gypsum and gypsiferous layers. The bulk mineralogy is dominated by quartz, feldspar, calcite, gypsum and dolomite; and the clay mineralogy is dominated by illite, chlorite, and smectite(including irregular mixed-layer illite-smectite(I/S)). The variations of the clay mineral assemblages indicate the occurrence of alternations between warm humid conditions and hot dry conditions, with relatively high humidity during ～52–50,～41.5–39 and ～35–34 Ma. Comparison of the results with the timing of Tibetan Plateau uplift, transgressions and regressions of the Paratethys Sea, and the marine oxygen isotope record suggest that the eocene climatic evolution of the study region was driven fundamentally by global climate change.

关键词： eocene Xining Basin Clay minerals Paleoclimate

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Uplift, climate and biotic changes at the eocene-Oligocene transition in south-eastern Tibet

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National Science Review 2019年第3期6卷 495-504页

作者： Tao Su Robert A.Spicer Shi-Hu Li He Xu Jian Huang Sarah Sherlock Yong-Jiang Huang Shu-Feng Li Li Wang Lin-Bo Jia Wei-Yu-Dong Deng Jia Liu Cheng-Long Deng Shi-Tao Zhang Paul J.Valdes Zhe-Kun Zhou Key Laboratory of Tropical Forest Ecology Xishuangbanna Tropical Botanical Garden Chinese Academy of Sciences University of Chinese Academy of Sciences State Key Laboratory of Paleobiology and Stratigraphy Nanjing Institute of Geology and Paleontology Chinese Academy of Sciences School of Environment Earth and Ecosystem Sciences The Open UniversityMK7 6AA UK Guangdong Provincial Key Laboratory of Geodynamics and Geohazards School of Earth Sciences and Engineering Sun Yat-sen University Institute of Geology and Paleontology Linyi University Key Laboratory for Plant Diversity and Biogeography of East Asia Kunming Institute of Botany Chinese Academy of Sciences State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences Faculty of Land Resource Engineering Kunming University of Science and Technology School of Geographical Sciences and Cabot Institute University of Bristol

The uplift history of south-eastern Tibet is crucial to understanding processes driving the tectonic evolution of the Tibetan Plateau and surrounding areas. Underpinning existing palaeoaltimetric studies has been regional mapping based in large part on biostratigraphy that assumes a Neogene modernization of the highly diverse, but threatened, Asian biota. Here, with new radiometric dating and newly collected plant-fossil archives, we quantify the surface height of part of the south-eastern margin of Tibet in the latest eocene(～34 Ma) to be ～3 km and rising, possibly attaining its present elevation(3.9 km) in the early Oligocene. We also find that the eocene–Oligocene transition in south-eastern Tibet witnessed leaf-size diminution and a floral composition change from sub-tropical/warm temperate to cool temperate, likely reflective of both uplift and secular climate change, and that, by the latest eocene, floral modernization on Tibet had already taken place, implying modernization was deeply rooted in the Palaeogene.

关键词： biodiversity eocene Oligocene plant fossil Qinghai-Tibetan Plateau uplift

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Sedimentary and geochemical evidence of eocene climate change in the Xining Basin, northeastern Tibetan Plateau

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Science China Earth Sciences 2018年第9期61卷 1292-1305页

作者： Abu Sadat Md SAYEM Zhengtang GUO Haibin WU Chunxia ZHANG Fan YANG Guoqiao XIAO Zhilin HE Key Laboratory of Cenozoic Geology and Environment Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China University of Chinese Academy of Sciences Beijing 100049 China Department of Geological Sciences Jahangirnagar University Dhaka 1342 Bangladesh CAS Center for Excellence in Life and Paleoenvironment Bering 100044 China State Key Laboratory of Biogeology and Environmental Geology School of Earth Sciences China University of Geosciences Wuhan 430074 China

The northeastern Tibetan Plateau began to grow during the eocene and it is important to understand the climatic history of Asia during this period of so-called ‘doubthouse' conditions. However, despite major advances in the last few decades,the evolutionary history and possible mechanisms of eocene climate change in the northeastern Tibetan Plateau remain *** Xining Basin in the northeastern Tibetan Plateau contains a continuous sequence of Early to Late eocene non-marine sediments which provides the opportunity to resolve long-term climate changes during this period. In this study, we report the results of analyses of lithofacies, sediment color and geochemistry of bulk samples collected from the Xijigou section of the Xining Basin. An abrupt lithofacies change between the Early(~52–40 Ma) and Late eocene(~40–34 Ma) indicates a change in the depositional environment from a shallow lake to a playa lake in response to a significant climatic shift. During ~52–40 Ma,higher values of sediment redness(a*), redness/lightness(a*/L*) and higher modified Chemical Index of Weathering(CIW′)indicate a relatively warm and humid climate, while from ~40–34 Ma the lower values of a*, a*/L*and lower CIW′ imply subhumid to semi-arid climatic conditions. The paleoclimatic records indicate a long-term(~52–34 Ma) trend of decreasing chemical weathering, consistent with global climate change. An abrupt sharp excursion of the proxy records during ~42–40 Ma suggests a relatively brief warm interval, corresponding to the Middle eocene Climatic Optimum(MECO). We suggest that global cooling substantially reduced humidity in inner Asia, resulting in sub-humid to semi-arid climatic conditions after 40 Ma in the Xining Basin, which may have been responsible for the long-term trend of decreasing chemical weathering during the eocene.

关键词： eocene Climate change Sediment color Chemical index of weathering Xining Basin Tibetan Plateau

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Cyclocarya cf. paliurus （Batal.） Iljinskaja （Juglandaceae） from the Hunchun Formation （eocene）, Jilin Province, China

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Journal of Integrative Plant Biology 2005年第11期47卷 1281-1287页

作者： Tong-Xing SUN Albert G. ABLAEV Yu-Fei WANG Cheng-Sen LI Institute of Botany the Chinese Academy of Sciences Beijing 100093 China School of Life Sciences Laiyang Agricultural College Laiyang 265200 China Pacific Oceanological Institute Russian Academy of Sciences Vladivostok 600041 Russia Beijing Museum of Natural History Beijing 100050 China

The leaflet architecture of Cyclocarya cf. paliurus （Batal.） Iljinskaja from the Hunchun Formation （Middle eocene） shows similarity to that of modem C. paliurus （Batal.） Iljinskaja and the specimen is the oldest fossil record in Europe and Asia. The distributions of C. cf. paliurus and other fossil records, such as Glyptostrobus, Metasequoia, Nyssa, and Liquidambar, in Hunchun flora show that it would have been a warmer-temperature to subtropical climate in Hunchun District during the eocene period.

关键词： China Cyclocarya cf. paliurus eocene Juglandaceae.

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eocene magmatism(Maden Complex) in the Southeast Anatolian Orogenic Belt: Magma genesis and tectonic implications

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Geoscience Frontiers 2018年第6期9卷 1829-1847页

作者： Mehmet Ali Erturk Melahat Beyarslan Sun-Lin Chung Te-Hsien Lin Firat University Department of Geological Engineering Institute of Earth Sciences Academia Sinica Department of Geosciences National Taiwan University

The origin and geodynamic setting of the Maden Complex, which is situated in the Bitlis-Zagros Suture Zone in the Southeast Anatolian Orogenic Belt, is still controversial due to lack of systematic geological and geochemical data. Here we present new whole rock major-trace-rare earth element and Sre Nd isotope data from the Middle eocene volcanic rocks exposed in Maden Complex and discuss their origin in the light of new and old data. The volcanic lithologies are represented mainly by basalt and andesite, and minor dacite that vary from low-K tholeiitic, calc-alkaline, high-K calc-alkaline, and shoshonitic in composition. They exhibit enrichments in large ion lithophile and light rare earth elements, with depletions in high field strength elements. Basaltic rocks have uniform Sr and Nd isotope ratios with high εNd(t) values varying from t5.5 to t6.7, in contrast to, andesitic rocks are characterized by low εNd(t) values ranging from à1.6 to à10. These geochemical and isotopic characteristics indicate that two end-members, a subduction-related mantle source and a continental crust, were involved in the magma genesis. Considering all geological and geochemical data, we suggest that the eocene Maden magmatism occurred as a post-collisional product by asthenospheric upwelling owing to convective removal of the lithosphere during an extensional collapse of the Southeast Anatolian ranges.

关键词： Maden Complex eocene magmatism Southeast Turkey Asthenospheric upwelling

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Reconstructing early eocene(～55 Ma) paleogeographic boundary conditions for use in paleoclimate modelling

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Science China Earth Sciences 2019年第9期62卷 1416-1427页

作者： Zhilin HE Zhongshi ZHANG Zhengtang GUO Key Laboratory of Cenozoic Geology and Environment Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China University of Chinese Academy of Sciences Beijing 100049 China Department of Atmospheric Science School of Environmental Studies China University of Geosciences Wuhan 430074 China NORCE Norwegian Research Centre Bjerknes Centre for Climate Research Bergen 5007 Norway Nansen-Zhu International Research Centre Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China CAS Center for Excellence in Life and Paleoenvironment Beijing 100044 China

The early eocene is a period with very high atmospheric CO2 levels, which receives many interests from climate modelling aspects. To simulate the early eocene paleoclimate, a realistic reconstruction for land-sea distribution, paleotopography and paleobathymetry is the fundamental step. Here, we present global paleogeographic reconstructions for the early eocene(~55 Ma), based on integrated paleogeographic data set, the plate-tectonic reconstruction software(GPlates) and geographic information system software(ArcGIS). Comparing with previous paleogeographic reconstructions, we improve the reconstructions by incorporating many recent geologic data and data set, including:(1) Better representations of the Tethys Sea,some marginal or inland seas in the East and Southeast Asia, Atlantic and Arctic region, and the Drake Passage and Tasmanian Gateway;(2) integrated paleoelevation data of global high plateaus and mountains, especially the paleotopography of East Asia,and adopting the latest paleotopographic reconstruction data of the Antarctica;and(3) using the latest data set of oceanic crust paleo-age and oceanic sediment thickness to reconstruct the paleobathymetry.

关键词： Paleogeographic reconstruction Land-sea distribution Paleotopography Paleobathymetry Early eocene Paleoclimate modelling

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