青海唐古拉沱沱河地区晚更新世河流阶地沉积特征及意义

Sedimentary characteristic and geological significance of Late Pleistocene river terrace in Tuotuohe area, Qinghai province

青海沱沱河地区水系密布、河网交织,沿主干水系河流阶地发育。对沱沱河沿岸不同地段河流阶地进行物质成分及古植物孢粉进行研究,确定了自63.1 kaB.P.(ESR)以来的晚更新世草本植物与木本植物两个古植被演化阶段,相应气候由温凉较干向温和较湿转变。详细的测年(TL、ESR)数据显示,位于基座阶地之上的阶地堆积物为晚更新世97.78 KaB.P.以来堆积而成,推断长江水系在研究区的形成与外泄地质时期为晚更新世早期。

The Tuotuo River, Tanggula, Qinghai has a large drainage density with anastomosing stream pattern, many river terrace developed along the trunk drainage. According to the research of the material composition and paleo - plant sporopollen in different plat river terrace coastwise the Tuotuo River, it makes sure the two evolutionary stages of herbaceous vegetation and woody plant since 63.1 ka B.P. （ESR） in Late Pleistocene epoch, the corresponding climate changed from warm and cool dry to the mild and wet. The detail dating （TL, ESR） data show that the terrace deposits above base terrace were formed since 97.78 ka B.P. in Late Pleistocene epoch, this paper propose that the forming and leak of Yangtze River drainage in the study area is in the Early Late Pleistocene epoch.