Tibet forcing of mid-Pleistocene synchronous enhancement of East Asian winter and summer monsoons revealed by Chinese loess record |
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Authors: | Wenxia Han Xiaomin Fang André Berger |
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Institution: | 1. Key Lab of Salt Lake Resources and Chemistry, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, 810008, China;2. Institute of Tibet Plateau Research, Chinese Academy of Sciences, Beijing 100085, China;3. Université Catholique de Louvain, Institut d''Astronomie et de Géophysique G. Lemaître and Center for Earth and Climate Research, 2 Chemin du Cyclotron, B-1348 Louvain-la-Neuve, Belgium |
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Abstract: | The mid-Pleistocene transition (MPT) of the global climate system, marked by a shift of previously dominant 41-ka cycles to lately dominant 100-ka cycles roughly in the mid-Pleistocene, is one of the fundamental enigma in the Quaternary climate evolution. The process and origin of the MPT remain of persistent interest and conjecture. Here we present high-resolution astronomically tuned magnetic susceptibility (MS) and grain‐size records from a complete loess–paleosol sequence at Chaona on the central Chinese Loess Plateau. These two proxies are well-known sensitive indicators to the East Asian summer and winter monsoons, respectively. The records reveal a remarkable two-step simultaneous enhancement of the East Asian summer and winter monsoons at 0.9 Ma and 0.64 Ma, respectively, accompanied with an onset of a clear 100-ka cycle at 0.9 Ma and of a final, predominant 100-ka cycle starting at 0.64 Ma. The mid-Pleistocene stepwise rapid uplift of the Tibetan Plateau could be the mechanism driving the simultaneous enhancement of East Asian summer and winter monsoons and the shift of the periodicities during the MPT by complex positive feedbacks. |
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