800KaB．P．来西藏“一江两河”中游地区的气候与西南季风变化

THE CLIMATE AND SOUTHWEST MONSOON CHANGE IN THE MIDDLE "ONE RIVER TWO TRIBUTARIES" BASIN, TIBET SINCE 0. 80 MA B. P.

西藏“一江两河”中游地区风成地层沉积时代、沉积相和磁化率等研究结果表明，早在８００ＫａＢ．Ｐ．前西南季风就已存在，受全球气候波动和青藏高原隆起的影响，其盛行衰变与东南季风具有较好的一致性，主要表现为本区地层所记录的气候变化信息不如东南季风区详细；而且西南季风因高原屏障作用给本区带来的降水愈来愈少，气候明显地向干冷化发展。

Based on the depositional age, sedimentary facies and susceptibility. This poper deals with the climate and southwest mosoon change in middle Yarlung Zangbo River Basin in Tibet, which lies in the temperate and semi-arid, monsoonal areas in Qinghai-Xoing Plateau. The result indithat the southwest mosoon circulstion had been existent before 0. 80 Ma B. P., and climatic change in this area coincides with that in eastern China and global changes. But there is difference between them. It shows mainly that the climate had been becoming cold-dry in this area since 518 ka B. P. due to glacial/interglacial climatic fluctuations and Qinghai-Xizang Plateau uplift.