通过分析达里湖沉积剖面的粒度和元素组成,结合OSL年代序列,探讨了17.8-6.8 ka BP期间达里湖的水文环境变化。在17.8 ka BP,该剖面由冲洪积相转为湖相沉积,标志着达里湖水位显著升高,这是末次盛冰期结束后气温回升山地冰雪融水增多所导致的;但是,在13.5-13.1 ka BP和12.2-11.8 ka BP,湖水位明显下降,这大致对应着两次仙女木事件时的冷干气候;在11.8-6.8 ka BP湖泊水位再次升高,并于7.6-6.8 ka BP达到最高,这是进入全新世后东亚夏季风增强带来的较多降水所造成的。
英文摘要:
Based on investigating of OSL chronology and environmental proxies including grain size and elemental composition of a sedimentary section,history and changing mechanisms of the hydrological environment in Dali Lake during17.8-6.8 ka BP had been discussed. The results show that: in 17.8 ka BP,the sedimentary section had changed from alluvial-proluvial to lacustrinetype,marking an obvious rise of the lake level,which was caused by the increasing input of snow /ice melt water after the termination of the Last Glacial Maximum. However, the lake level showed dramatically fluctuation during the last deglaciation,which had been dropped obviously in 13.5-13.1 ka BP and 12.2-11.8 ka BP respectively,corresponding to relativelydry and cold climate during the two Dryas Events. In 11.8-6.8 ka BP,the lake level rose again and reached the highest lake level during 7.6-6.8 ka BP,probably resulting from the increasing of East Asian summer monsoon precipitation after entering the Holocene.