Millennial-scale climate change since the last glaciation recorded by grain sizes of loess deposits on the northeastern Tibetan Plateau  

作　　者：Lü Lianqing FANG Xiaomin LU Huayu HAN Yongxiang YANG Shengli LI Jijun AN Zhisheng 

机构地区：[1]State Key Laboratory of Loess and Quaternary Geology. Institute of Earth Environment. Chinese Academy of Sciences, Xi'an 7l0054, China [2]MOE National Laboratory of Western China's Unvironmental Systems & Department of Geography, Lanzhou University, Lanzhou 730000,China [3]Institute of Arid Meteorology. China Meteorological Administration, Lanzhou 730020, China

出　　处：《Chinese Science Bulletin》2004年第11期1157-1164,共8页

摘　　要：Whether climatic changes in high latitudes of the Northern Hemisphere since the last glaciation have effects on the Tibetan Plateau monsoon, and the variation characteristics of the Plateau monsoon itself are still not solved but of great significance. The 22-m high-resolution Ioess-paleosol sequence in the Hezuo Basin on the northeastern Tibetan Plateau demonstrates that the Plateau winter monsoon experienced a millennial variation similar to high latitude Northern Hemisphere, with cold events clearly correlated with Heinrich events but less for the warm events (Dansgarrd-Oeschger events). It may indicate that the climate system at high latitudes in the Northern Hemisphere had played an important role in both the Plateau monsoon and the high-level westerlies. On 10^4 year scale, there are two distinct anomalous changes, which are not found in the records from high latitude northern hemisphere, revealed by the loess grain size in the Hezuo Basin. One is that there was a considerable grain size increase at -36 kaBP, suggesting an abrupt enhancement of the Plateau winter monsoon at that time; the other is that, during 43--36 kaBP, the grain size decreased distinctly, indicating a notable weakening of the Plateau winter monsoon around that period. Both of the two anomalies suggest that the Tibetan climate may have been controlled by some other factors, besides the high latitude climatic changes in the Northern Hemisphere.Whether climatic changes in high latitudes of the Northern Hemisphere since the last glaciation have ef-fects on the Tibetan Plateau monsoon, and the variation characteristics of the Plateau monsoon itself are still not solved but of great significance. The 22-m high-resolution loess-paleosol sequence in the Hezuo Basin on the northeast-ern Tibetan Plateau demonstrates that the Plateau winter monsoon experienced a millennial variation similar to high latitude Northern Hemisphere, with cold events clearly cor-related with Heinrich events but less for the warm events (Dansgarrd-Oeschger events). It may indicate that the cli-mate system at high latitudes in the Northern Hemisphere had played an important role in both the Plateau monsoon and the high-level westerlies. On 104 year scale, there are two distinct anomalous changes, which are not found in the re-cords from high latitude northern hemisphere, revealed by the loess grain size in the Hezuo Basin. One is that there was a considerable grain size increase at ~36 kaBP, suggesting an abrupt enhancement of the Plateau winter monsoon at that time; the other is that, during 43—36 kaBP, the grain size decreased distinctly, indicating a notable weakening of the Plateau winter monsoon around that period. Both of the two anomalies suggest that the Tibetan climate may have been controlled by some other factors, besides the high latitude climatic changes in the Northern Hemisphere.

关 键 词：青藏高原东北部 黄土沉积 千年气候变化 冰川作用 季风 颗粒大小 冰芯记录 

分 类 号：P532[天文地球—古生物学与地层学]