全新世青藏高原东部西南季风的演变

EVOLUTION OF SOUTHWEST MONSOON IN THE EASTERN PART OF QINGHAI-TIBET PLATEAU DURING HOLOCENE

本研究报道一组新的西南季风代用指标,即泥炭中单一种属植物———木里苔草残体纤维素和泥炭混合植物残体纤维素的δ13C时间序列,所记录的青藏高原东部全新世气候变化。两记录表明,该区全新世的下限年龄约11200aBP(14C年龄约9900aBP);从约11200aBP起该区迅速进入湿暖的全新世阶段,季风活动迅速增强;在约10800～5500aBP期间,季风总体保持在强盛状态,但其间有4次突然减弱,气候变干冷;约从5500aBP起季风活动在波动中逐渐减弱,其中有4次减弱最明显。所有这8次气候的突然变化都与北大西洋浮冰事件一一对应。这种密切的相关关系表明,西南季风强度的波动可能是对全球变化,特别是对海洋热盐环流引起的地球南北方气候波动的所谓"跷跷板效应"的响应。

The δ^(13)C time series of the mono-species plant, carex mulieensis cellulose and mixed plant cellulose, selected from the Hongyuan peat bog has been considered as a sensitive proxy indicator for the strength of Indian Ocean summer monsoon. It is clearly shown that the lower age limit of Holocene of this region is 11200aB.P. (^(14)C age 9900 a B.P.). The monsoon activity became strong from 11200 a B.P. and the climate of this region became humid and warm. There are 8 abrupt variation events of the monsoon, strongly corresponding to the 8 ice-rafted debris events occurring in the North Atlantic Ocean during the same period. Evidence from this project indicates that teleconnection between Indian Ocean summer monsoon and North Atlantic climate is present not only in the last glacial period, but also in the Holocene, which may be linked to abrupt reorganization of the ocean thermohaline circulation, changing temperature and moisture gradient over southern subtropical Indian Ocean.