A high-resolution environmental change record since 19 cal ka BP in Pumoyum Co, southern Tibet  

作　　者：LU XinMiao ZHU LiPing NISHIMURA Mitsugu MORITA Yoshimune WATANABE Takahiro NAKAMURA Toshio WANG Yong 

机构地区：[1]Key Laboratory of Tibetan Environment Changes and Land Surce Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085, China [2]School of Marine Scinece and Technology, Tokai University, Shizuoka 424-8610, Japan [3]Botanical Garden, Okayama University of Science, Okayama 700-0005, Japan [4]Graduate School of Science, Tohoku University, Sendai 980-8578, Japan [5]Centre for Chronological Research, Nagoya University, Nagoya 464-8602, Japan [6]Graduate University of Chinese Academy of Sciences, Beijing 100049, China

出　　处：《Chinese Science Bulletin》2011年第27期2931-2940,共10页

基　　金：supported by the National Natural Science Foundation of China (40871099 and 40810166);the Knowledge Innovation Key Program of the Chinese Academy of Sciences (KZCX2-YW-146 and KZCX2-EW-113);the Special Pilot Research of the Chinese Academy of Sciences (XDA05120301)

摘　　要：A 380-cm-long sediment core was acquired from the deep water area of Pumoyum Co, southern Tibet. Twenty-five plant residue samples were selected, and organic carbon stable isotopes were obtained using the AMS 14 C chronological method. The 14 C age and carbon reservoir effect were calibrated with surface sedimentation rate measurements using 210 Pb dating. Results showed that the core sediment deposited over 19 cal ka BP. Based on a multi-proxy analysis of TOC and IC contents, grain size and pollen assemblage data, the palaeoclimatic evolution of Pumoyum Co was reconstructed since the last glacial. Pumoyum Co was a shallow lake prior to 16.2 cal ka BP; although the glacier around the lake began to melt due to increasing temperatures, climate was still cold and dry. In the interval of 16.2-11.8 cal ka BP, the sedimentary environment fluctuated drastically and frequently. Two cold-events occurred at 14.2 and 11.8 cal ka BP, and these may correspond to the Older Dryas and the Younger Dryas events, respectively. After 11.8 cal ka BP, Pumoyun Co developed into the deep lake as it is now. The lake water temperature was relatively lower at that time because of influx of cold water from glacial meltwater entering the lake. As a result, the multi-proxy indicators showed no sign of warm conditions. Comparisons between the sedimentary record of Pumoyum Co with that of other lakes of the same age in southern Tibet indicate a warmer climate following the last deglaciation influenced the southeastern Tibetan Plateau. These results imply that the southwest Asian monsoon gradually became stronger since the deglaciation during its expansion to the inner plateau. The glacial-supplied water of the lake responded sensitively to cold-events. The entire southern Tibet region was dominantly influenced climatically by the southwest Asian monsoon during the Holocene.A 380-cm-long sediment core was acquired from the deep water area of Pumoyum Co, southern Tibet. Twenty-five plant residue samples were selected, and organic carbon stable isotopes were obtained using the AMS 14 C chronological method. The 14 C age and carbon reservoir effect were calibrated with surface sedimentation rate measurements using 210 Pb dating. Results showed that the core sediment deposited over 19 cal ka BP. Based on a multi-proxy analysis of TOC and IC contents, grain size and pollen assemblage data, the palaeoclimatic evolution of Pumoyum Co was reconstructed since the last glacial. Pumoyum Co was a shallow lake prior to 16.2 cal ka BP; although the glacier around the lake began to melt due to increasing temperatures, climate was still cold and dry. In the interval of 16.2-11.8 cal ka BP, the sedimentary environment fluctuated drastically and frequently. Two cold-events occurred at 14.2 and 11.8 cal ka BP, and these may correspond to the Older Dryas and the Younger Dryas events, respectively. After 11.8 cal ka BP, Pumoyun Co developed into the deep lake as it is now. The lake water temperature was relatively lower at that time because of influx of cold water from glacial meltwater entering the lake. As a result, the multi-proxy indicators showed no sign of warm conditions. Comparisons between the sedimentary record of Pumoyum Co with that of other lakes of the same age in southern Tibet indicate a warmer climate following the last deglaciation influenced the southeastern Tibetan Plateau. These results imply that the southwest Asian monsoon gradually became stronger since the deglaciation during its expansion to the inner plateau. The glacial-supplied water of the lake responded sensitively to cold-events. The entire southern Tibet region was dominantly influenced climatically by the southwest Asian monsoon during the Holocene.

关 键 词：西藏南部 环境变化 CAL BP 合作 高分辨率 青藏高原东南部 古气候演变 

分 类 号：P512.2[天文地球—地质学]