Xu Zhang1,2, Fahu Chen3,4. 1. Alpine Paleoecology and Human Adaption Group (ALPHA), State Key Laboratory of Tibetan Plateau Earth System, Resources and Environment (TPESRE), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China. xu.zhang@itpcas.ac.cn. 2. Key Laboratory of Western China's Environmental Systems (Ministry of Education), College of Earth and Environmental Science, Lanzhou University, Lanzhou, China. xu.zhang@itpcas.ac.cn. 3. Alpine Paleoecology and Human Adaption Group (ALPHA), State Key Laboratory of Tibetan Plateau Earth System, Resources and Environment (TPESRE), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China. 4. Key Laboratory of Western China's Environmental Systems (Ministry of Education), College of Earth and Environmental Science, Lanzhou University, Lanzhou, China.