CP Climate of the Past CP Clim. Past 1814-9332 Copernicus Publications Göttingen, Germany 10.5194/cp-9-1863-2013 Late Cenozoic continuous aridification in the western Qaidam Basin: evidence from sporopollen records Miao Y. F. 1 Fang X. M. 2 Wu F. L. 2 Cai M. T. 2 Song C. H. 3 Meng Q. Q. 3 Xu L. 4 Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Institute, Chinese Academy of Sciences, Lanzhou, 730000, China Key Laboratory of Continental Collision and Plateau Uplift, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100085, China School of Earth Science, Lanzhou University, Lanzhou, 730000, China Qinghai Petroleum Sub-corporation of Petro China Company Limited, Dunhuang, 736202, China 09 08 2013 9 4 1863 1877 Copyright: © 2013 Y. F. Miao et al. 2013 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://cp.copernicus.org/articles/9/1863/2013/cp-9-1863-2013.html The full text article is available as a PDF file from https://cp.copernicus.org/articles/9/1863/2013/cp-9-1863-2013.pdf

Cenozoic climate changes in inner Asia provide a basis for understanding linkages between global cooling, the Tibetan Plateau uplift, and possibly the development of the East Asian monsoon. Based on a compilation of palynological results from the western Qaidam Basin, this study reconstructed a 15-million-year (Ma) record of changing vegetation and paleoclimates spanning the middle Miocene to present (comprising two series: ~ 18–5 Ma and ~ 3.1–0 Ma, respectively). The thermophilic percentages were highest between 18 and 14 Ma, and decreased after 14 Ma, closely corresponding to the Middle Miocene Climatic Optimum (MMCO) between 18 and 14 Ma and the following global climatic cooling between 14 and 5 Ma. At the same time, decreases in the xerophytic and coniferous taxa percentages, and the increasing logarithmic ratio of non-arboreal pollen to arboreal pollen (ln (NAP/AP)), reveal the continuous aridification across both the basin and surrounding mountains. Between ~ 3.1 and 0 Ma, the percentages of the thermophilic, xerophytic and coniferous pollen as well as the ln (NAP/AP) imply further cooling and drying in this region since 3.1 Ma. We argue that these vegetation and climate patterns during the late Cenozoic western Qaidam Basin are primarily a result of the global cooling, with the Tibetan Plateau uplift and East Asian summer monsoon having contributions of lesser importance.

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