Li Shijie, Li Shude
According to the first investigation of Quaternary glacial and lake history to the Hoh Xil region located in the interior of Qinghai-Xizang (Tibet) Plateau, it is obvious that the development and evolution of Quaternary glaciers is not only coincident with other places of the Qinghai-Xizang Plateau due to the co-control of the global climate changes and the uplift process of the plateau throughout the period of Quaternary, but also exists the distinctive regional features. During the Pleistocene, three glaciations had occurred in huge mountains of the Tanggula and Kunlun, but in the lower mountains in the centre part of the region only had taken place two or one glaciation in the later time. The developing scale and extent of glaciers were mainly limited in the high mountain areas and in the form of valley glacier, piedmont glacier and ice cap. No ice sheet existed during the Quaternary.With the intermittent uplift of the plateau in the Quaternary, the evolution of glaciation shows a pattern that the glacial scale and glaciated area of each individual glaciation from early to late Pleistocene changed from small to large, to small again. The main reason probably is that the height of most mountains was not enough to develop the large scale glaciers in the early time, and the favourable elevation of the plateau in the middle Pleistocene caused a strong plateau monsoon and south asia monsoon which brought about rich precipitation over the area. And later, its lofty elevation played a role of the barrier to obstruct water vapour into the interior of the plateau, leading to dry climate. On the other hand, lakes in the Hoh Xil area had experienced a historical process from the outflow drainage systems to the closed lake basins during the late Middle Pleistocene, which is related to the divergence movement of fault block formed by the neotectonic movement, and also affected by the drier climate.
