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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 reconstruction.Geochemical 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 paleoclimate.In 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 Hemisphere.The 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 climate.The 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 isotopes.The 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 periods.The rapid increase in pCO_(2)concentration leads to an increase in temperature,precipitation,and surface runoff,exhibiting strong chemical weathering.The 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 MAP.In contrast,MAPc was more sensitive to the climate during low precipitation periods(precipitation<1000 mm,Jijuntun,and Xiloutian Forma-tions),with higher accuracy.To fully co

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 Peninsula.In 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 Formation.The 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 Antarctica.These taxa are characterized by lacking dental specializations usually associated with more abrasive diets like terminal forms of Uruguaytheriinae and Astrapotheriinae.Antarctodon appears to have thrived on the Antarctic continent during the Early eocene Climatic Optimum within the paleoclimatic context of a hot-house world.Unlike 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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Palaeogeographical development of two merging delta systems(eocene Shahejie Formation)in the Bohai Bay Basin,E China and implications for hydrocarbon exploration

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Journal of Palaeogeography 2023年第4期12卷 564-586页

作者： Ren-Chao Yang Yang Li Ai-Ping Fan A.J.Van Loon(Tom) Jin Li Zuo-Zhen Han Jie Chen Shandong Provincial Key Laboratory of Depositional Mineralization&Sedimentary Minerals Shandong University of Science and TechnologyQingdao 266590China Laboratory for Marine Mineral Resources Qingdao National Laboratory for Marine Science and TechnologyQingdao 266071China Department of Resource Science and Engineering Shandong Institute of Petroleum and Chemical TechnologyDongying 257061China

Two deltas developed simultaneously during the eocene on the eastern side of a large lake that existed in the Dongying Sub-basin,which forms part of the Bohai Bay Basin in eastern China.The rivers that built the deltas had different catchment areas,which resulted in sediments with different permeability and porosity,due to differences in sorting and mud content.Both deltas prograded,and mass flows that originated frequently on their fronts formed lobes that expanded laterally.This eventually led to merging of both deltas,a feature that has rarely been described from ancient deposits thus far.Core analysis and seismic reflection data show that the merging of the two deltas took place in nine phases,determined by phases of slower progradation or even temporary retrogradation in between.The alternation of sediments from both deltas and their eventual mixing makes the architecture of the merged deltas much more complex than that of'classical'single deltas.This affects the predictability of the spatial distribution of possible reservoir characteristics significantly,but detailed core analysis shows that the best hydrocarbon reservoirs consist of sand bodies formed in distributary channels on the delta plains,and of sandy turbidites formed in the deep-lacustrine environment in front of the merged deltas.

关键词： Delta development Merging deltas Palaeogeography Bohai Bay Basin Lacustrine environment eocene Hydrocarbon exploration

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Fertile Woodwardia from the middle eocene of South China and its implications for palaeogeography and palaeoclimate

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Plant Diversity 2022年第6期44卷 565-576页

作者： Han-Zhang Song Serge V.Naugolnykh Xin-Kai Wu Xiao-Yan Liu Jian-Hua Jin State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources School of Life SciencesSun Yat-sen UniversityGuangzhou 510275China Geological Institute of Russian Academy of Sciences Moscow119017Russia Contract Affiliation:Kazan Federal University Republic of TatarstanRussia School of Ecology Sun Yat-sen UniversityGuangzhou 510275China School of Geography South China Normal UniversityGuangzhou 510631China

The genus Woodwardia,which together with the genera Anchistea and Lorinseria comprise the subfamily Woodwardioideae of Blechnaceae,has a disjunct distribution across Central and North America,Europe and the temperate to tropical areas of Asia.Fossil records of Woodwardia occur throughout the Paleogene and Neogene of North America,Europe and Asia.However,well-preserved fertile pinna fossils of this genus have not yet been reported in South China.In this paper,a new species,W.changchangensis Naugolnykh et Song,sp.***.is described from the middle eocene of the Changchang Basin,Hainan Island,South China.Macromorphological and micromorphological features of the fertile pinna show a straight pinna rachis,alternate,subtriangular pinnules,acute pinnule apices,almost entire or slightly undulate pinnule margins,long-ovoid sori,stalked sporangia and spores with wing-like folds on the surface,which are characterised in detail.Overall,the present fossil is most similar to the extant species Woodwardia japonica,which mostly grows in warm and moist environments.The discovery of this new species from the Changchang Basin of Hainan Island indicates that this genus has been distributed in the low-latitude tropical regions of South China from as early as the middle eocene.Based on this find,and previous studies of other ferns from the same site,we infer that the climate of the Palaeo-Hainan landscape during deposition of the Changchang Formation was warm and humid,similar to conditions prevailing today across this region.

关键词： Woodwardia eocene Climate Hainan Island South China

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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 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 State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences University of Chinese Academy of Sciences Key Laboratory for Plant Diversity and Biogeography of East Asia Kunming Institute of Botany Chinese Academy of Sciences School of Geographical Sciences and Cabot Institute University of Bristol Faculty of Land Resource Engineering Kunming University of Science and Technology 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

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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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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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 particularly the larger benthic foraminifera att

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 paleo-climate 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℃, the mean annual range of temperature 12-12.6℃ 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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Latitudinal trends in genus richness of vascular plants in the eocene and Oligocene of North America

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Plant Diversity 2016年第3期38卷 133-141页

作者： AJ.Harris Cassondra Walker Justin R.Dee Michael W.Palmer Smithsonian Institution Department of BotanyNational Museum of Natural History Oklahoma State University Integrative Biology501 Life Sciences West Oklahoma State University Botany301 Physical Sciences Oklahoma State University Plant BiologyEcologyand Evolution301 Physical Sciences

The latitudinal richness gradient is a frequent topic of study on the modern landscape,but its history in deep time is much less well known.Here,we preliminarily evaluated the paleolatitudinal richness gradient of vascular plants for the eocene(56-33.9 million years ago) and Oligocene(33.9-23 million years ago) epochs of North America north of IVlexico using 201 fossil floras.We calculated the direction and shape of the gradient using quadratic regression to detect linear and curvilinear trends.We performed regressions for the eocene and Oligocene as well as for informal time intervals within the eocene:early,middle,and middle + late.We found that quadratic models better explain the data than linear models for both epochs as well as for the early eocene.A roughly linear trend in the middle and middle + late intervals may reflect limited sampling of high latitude floras for those times.The curvilinear relationship was weak for the eocene and the model showed a peak in richness at 45.5°N.The curvilinear relationship was much stronger for the Oligocene and the peak occurred at 48.5°N.In the eocene,the mid-latitude peak in richness may be explained by mean annual temperature,which was probably higher at some mid-latitudes than at lower ones.For the Oligocene,the peak in richness at midlatitudes may be explained by evolutionary diversification within the temperate zone or by increased aridity at low latitudes.We also assessed the latitudinal richness gradient of genera within modern floras in North America north of Mexico and we found a weak,curvilinear trend with a peak in richness at 31.5°N.Our results suggest that the latitudinal genus richness gradient of vascular plants in North America continued to develop into its modern structure following the Oligocene.

关键词： eocene Genus richness North America Oligocene Paleolatitude Vascular plants

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