Higher palaeoelevation in the Baoshan Basin:Implications for landscape evolution at the southeastern margin of the Tibetan Plateau

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外文摘要：Surface uplift at the southeastern margin of the Tibetan Plateau has been widely studied,but more palaeoaltimetry data are required to better understand the elevation history of this geologically complex region.In this study,fossil leaves of Abies(Pinaceae),a cool-temperate element,recovered from the latest Miocene-Pliocene Yangyi Formation of the southern Baoshan Basin,were used as a proxy to estimate the local palaeoelevation.Based on the regional modern altitude range(2100-4280 m)of the genus as well as regional temperature discrepancy(1.5 ℃)between the past and present,the palaeoelevation of the study area was calculated to be>2360 m above sea level as compared to 1670 m at present.Our result suggests that the southern Baoshan Basin experienced pronounced uplift prior to the time of fossil deposition,probably as a result of crustal shortening and thickening of the northern Baoshan Terrane during the Eocene-Oligocene.We infer that surface growth in areas south of the Dali Basin may have been greater than previously interpreted,and that a widespread plateau or plateau patches higher than 2000 m probably extended southwards into at least the Baoshan Basin by the latest Miocene-Pliocene.We also infer that the elevation of the southern Baoshan Basin has decreased by at least 690 m since then,in contrast to most other scenarios in which the elevation of the southeastern margin of the Tibetan Plateau has increased or remained close to modern levels since the late Miocene.The major cause of the inferred altitude decline is likely tectonic deformation.As a transtensional graben basin,the Baoshan Basin has experienced pull-apart and base-fall movement since the late Miocene,which would reduce the altitude of its southern part located on the hanging wall.Surface erosion associated with the increased summer rainfall might also have played a role especially in reducing the local relief,although its contribution can be limited.Our study provides one of the few palaeoelevation estimates from areas south of the Dali Basin and an example of past elevation loss at the southeastern margin of the Tibetan Plateau,thus shedding important light on the landscape evolution of this region.

外文关键词：

AbiesLapse ratePalaeoaltimetrySurface upliftTectonic movementTibetan plateau

作者：

Yong-Jiang Huang、Hao-Ran Zong、Shi-Tao Zhang、Arata Momohara、Jin-Jin Hu、Lin-Bo Jia、Yun-Heng Ji、Zhe-Kun Zhou

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作者单位：

Key Laboratory for Plant Diversity and Biogeography of East Asia,Kunming Institute of Botany,Chinese Academy of Sciences,Kunming 650201,Yunnan Province,China

College of Forestry,Shandong Agricultural University,Tai'an 271018,Shandong Province,China

Faculty of Land Resource Engineering,Kunming University of Science and Technology,Kunming 650093,Yunnan Province,China

Graduate School of Horticulture,Chiba University,Chiba 271-8510,Japan

Key Laboratory of Tropical Forest Ecology,Xishuangbanna Tropical Botanical Garden,Chinese Academy of Sciences,Mengla 666303,Yunnan Province,China

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基金：

National Natural Science Foundation of ChinaNational Natural Science Foundation of ChinaNatural Science Foundation of Yunnan ProvinceNatural Science Foundation of Yunnan ProvinceTen Thousand Talent Plans for Young Topnotch Talents of Yunnan ProvinceWest Light Foundation of the Chinese Academy of SciencesFoundation of the State Key Laboratory of Palaeobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology,CAS

项目编号：

4197202342272026202301AT070374202201AT070131YNWR-QNBJ-2019-261213106

出版年：

2024

DOI：

10.1016/j.jop.2024.05.004

古地理学报(英文版)

影响因子：0.186

ISSN：

年,卷(期)：2024.13(3)