气候变化领域集成服务门户(CCPortal): Expanded lacustrine sedimentation in the Qaidam Basin on the northern Tibetan Plateau: Manifestation of climatic wetting during the Oligocene icehouse

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DOI	10.1016/j.epsl.2021.116935
	Expanded lacustrine sedimentation in the Qaidam Basin on the northern Tibetan Plateau: Manifestation of climatic wetting during the Oligocene icehouse
	Wu M.; Zhuang G.; Hou M.; Liu Z.
发表日期	2021
ISSN	0012821X
卷号	565
英文摘要	The Qaidam Basin in the core area of arid Inner Asia has been considered undergoing continuous aridification over the Cenozoic. However, the Qaidam Basin is marked with expanded lacustrine sedimentation during the Oligocene, which contrasts with the fluvial or deltaic facies stratigraphically below (Eocene) and above (Miocene-present). The Oligocene lacustrine expansion challenges the idea of persistent aridification. To solve the conundrum, we reconstruct a long-term compound-specific hydrogen isotope (δ2H) record from sedimentary leaf wax n-alkanes to evaluate the paleoclimatic context before, during, and after the Oligocene lacustrine expansion. The δ2H results reveal three shifts at ca. 40 Ma, 34 Ma, and 24 Ma. The leaf wax δ2H values range from −176.8‰ to −166.7‰ from 51 to 40 Ma, followed by an abrupt increase of 23.9‰ at 40 Ma. We interpret this rapid increase as enhanced aridification due to the coeval retreat of the Paratethys Sea from the region. At 34 Ma, the δ2H plunges across the Eocene-Oligocene transition (EOT). Post-EOT δ2H values are the lowest, vary with high amplitude from −187.1‰ to −153.2‰, and are associated with the lacustrine facies expansion, indicating a wetter climate. By compiling the regional isotopic proxy studies, we observe the contrasting patterns in paleohydrology conditions since the EOT: the relaxation of aridity in the westerlies region versus the enhanced aridification in the East Asian summer monsoon region. We interpret that the west-east contrasting patterns represent the different climatic responses to global cooling: wetting in the west as a result of the enhanced moisture transport via westerlies replacing the subtropical high, and drying in the east due to the reduction in moisture content associated with weakening East Asian summer monsoon. Wetting in Inner Asia is synchronous with cooling in the ocean (North Atlantic) and on land (Xining Basin). Since 24 Ma, δ2H increases in response to warming during the latest Oligocene to the early Miocene when the subtropical high re-occupied Inner Asia, causing the aridity. This study reveals a dynamic climate in Inner Asia with different mechanisms responding to global change. © 2021 Elsevier B.V.
关键词	compound specific hydrogen isotope East Asian summer monsoon Inner Asia Qaidam Basin westerlies
英文关键词	Climatology; Expansion; Isotopes; Moisture; Paraffins; Wetting; Aridification; Compound specific hydrogen isotope; Core area; East Asian summer monsoon; Inner asia; Lacustrine sedimentations; Northern Tibetan plateaux; Oligocene; Qaidam basin; Westerly; Atmospheric thermodynamics; aridification; hydrogen isotope; lacustrine deposit; monsoon; Oligocene; paleoclimate; sedimentation; westerly; wetting; China; Qaidam Basin; Qinghai; Qinghai-Xizang Plateau
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203341
作者单位	Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA 70810, United States; Department of Earth Sciences, The University of Hong Kong, Hong Kong, Hong Kong
推荐引用方式 GB/T 7714	Wu M.,Zhuang G.,Hou M.,et al. Expanded lacustrine sedimentation in the Qaidam Basin on the northern Tibetan Plateau: Manifestation of climatic wetting during the Oligocene icehouse[J],2021,565.
APA	Wu M.,Zhuang G.,Hou M.,&Liu Z..(2021).Expanded lacustrine sedimentation in the Qaidam Basin on the northern Tibetan Plateau: Manifestation of climatic wetting during the Oligocene icehouse.Earth and Planetary Science Letters,565.
MLA	Wu M.,et al."Expanded lacustrine sedimentation in the Qaidam Basin on the northern Tibetan Plateau: Manifestation of climatic wetting during the Oligocene icehouse".Earth and Planetary Science Letters 565(2021).