New insights on Late Quaternary Asian palaeomonsoon variability and the timing of the Last Glacial Maximum in southwestern China |
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| Authors: | Charlotte G Cook Richard T Jones Peter G Langdon Melanie J Leng Enlou Zhang |
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| Institution: | 1. Graduate School of Science and Engineering, Tokai University, 3-20-1 Orido, Shimizu, Shizuoka 424-0902, Japan;2. Department of Applied Science, Okayama University of Science, 1-1 Ridai-cho, Okayama 700-0005, Japan;3. Graduate School of Science, Tohoku University, 6-3 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8578, Japan;4. Center for Chronological Research, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8601, Japan;5. Institute of Tibetan Plateau Research, Chinese Academy of Sciences, No. 18 Shuangqing Road, Haidian District, Beijing 100085, China;6. National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba 305-8506, Japan;1. MOE Key Laboratory of Western China''s Environmental Systems, Collaborative Innovation Centre for Arid Environments and Climate Change, Lanzhou University, Lanzhou 73000, China;2. Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, China;3. College of Tourism & Geography Science, Yunnan Normal University, Kunming 650500, China |
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| Abstract: | A ～6.35 m core (06SD) was retrieved from Lake Shudu, Yunnan Province, China. The sediments spanning the period ～22.6–10.5 kcal. yr BP (6.35–1.44 m) were analysed using a combination of variables including pollen, charcoal, particle size, magnetic susceptibility and loss-on-ignition. The resulting palaeorecord provides a high-resolution reconstruction of Late Pleistocene to Early Holocene climatic and environmental changes in southwestern China. Our findings indicate that from c. 22.6 to 17.7 kcal. yr BP, vegetation assemblages were primarily aligned to sparse xerophytic grassland/tundra or cold-tolerant boreal Pinus forest, indicating that climatic conditions in southwestern China were cold and dry. However, from c. 17.7 to 17.4 kcal. yr BP, the Lake Shudu record is punctuated by marked environmental changes. These include the establishment of denser vegetation cover, a marked expansion of boreal Pinus forest and enhanced hydrological activity in the catchment over centennial timescales, perhaps suggesting that stepwise variations in the Asian Monsoon were triggering fundamental environmental changes over sub-millennial timescales. Thereafter, the pollen record captures a period of environmental instability reflected in fluctuations across all of the variables, which persists until c. 17.1 kcal. yr BP. After c. 17.1 kcal. yr BP, the expansion of steppe vegetation cover and cold–cool mixed forest consisting of mesophilous vegetation such as Tsuga and Picea, thermophilous trees including Ulmus and deciduous Quercus inferred from the Lake Shudu pollen record point to the establishment of warmer, wetter and perhaps more seasonal conditions associated with a strengthening Asian Summer Monsoon during the shift from Pleistocene to Holocene climatic conditions. |
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