A Late-Eocene palynological record from the Hoh Xil Basin,northern Tibetan Plateau,and its implications for stratigraphic age,paleoclimate and paleoelevation |
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| Institution: | 1. Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Institute, Chinese Academy of Sciences, Lanzhou 730000, China;2. Key Laboratory of Continental Collision and Plateau Uplift, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100010, China;3. CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China;4. State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi''an 710075, China;5. Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China;6. Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, P.O. Box 9825, Beijing 100029, China;1. Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, P.O. Box 9825, Beijing 100029, China;2. CAS Center for Excellence in Tibetan Plateau Earth Sciences;3. Department of Geology, The University of Leicester, Leicester LE1 7RH, UK;1. State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China;2. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China;3. Key Laboratory of Marginal Sea Geology, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China;1. Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, P.O. Box 9825, Beijing 100029, China;2. College of Resources and Environment Science, Hebei Normal University, Shijiazhuang, China;3. Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, China;4. Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130012, China;5. Xiamen Seismological Survey and Research Center, Xiamen, China;6. National Meteorological Information Center, Beijing 100081, China;1. Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;2. CAS Center for Excellence in Tibetan Plateau Earth Sciences;3. State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China;1. CAS Center for Excellence in Tibetan Plateau Earth Sciences, Key Laboratory of Continental Collision and Plateau Uplift, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China;2. School of Earth Sciences, Key Laboratory of Western China''s Mineral Resources of Gansu Province, Lanzhou University, Lanzhou 730000, China;3. University of Chinese Academy of Sciences, Beijing 100049, China |
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| Abstract: | The Hoh Xil Basin, lying in the central Tibetan Plateau, is key to understanding the Cenozoic tectonics, paleoelevation and paleoclimate changes that have occurred in the Tibetan Plateau since the collision of the Indian and Asian tectonic plates. However, the stratigraphic age and paleoelevation indicated by the sediments of the Hoh Xil Basin remain hotly debated. Here we report on one palynological record from the TTH-C section, extracted from the Yaxicuo Group (the stratigraphic unit between the Fenghuoshan and Wudaoliang groups), and analyze its implications for stratigraphic age, paleoclimate and paleoelevation in the Hoh Xil Basin. The record shows that palynological taxa are mainly dominated by xerophytic Ephedripites, Nitrariadites (Nitrariapollis) and Chenopodipollis, with few ferns and conifers. Rich morphologies correspond well with those in the Xia Ganchaigou Formation (Fm) of the Qaidam Basin to the north. Palynological percentages are well correlated with the middle member of the Xia Ganchaigou Fm in the Qaidam Basin as well as the lower member of the Mahalagou Fm in the Xining Basin to the northeast. The ages of the middle member of the Xia Ganchaigou and lower member of the Mahalagou Fms from these two basins are both identical to the Bartonian Stage (~ 40–37 Ma) of the Late Eocene, according to their respective high-resolution magnetostratigraphic dating. This means that the age of the Yaxicuo Group at least covers the Bartonian Stage. Besides the Qaidam and Xining basins, the palynological assemblages of the TTH-C section are also similar to those of three other sites (the Jiuquan, Tu-ha and Hetao basins), indicating similarly arid climates dominated by a northwestern Chinese subtropical high, and a relatively low paleoelevation in the Hoh Xil Basin (mostly < 2000 m a.s.l.) in the Late Eocene. |
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