RECENT PROGRESS OF GEOGRAPHICAL STUDIES ON THE QINGHAI-XIZANG PLATEAU
Zheng Du Li Bingyuan (Institute of Geology, Chinese Academy of Sciences, Beijing)
Based on the research results of geographical studies of the Qinghai-Xizang Plateau in the last two decades, the main progress of studies on the paleogeographical evolution, natural environment and its regional differentiation, as well as environmental problems are dealt with in the present paper. The altitude of the Plateau surface remained generally at a mean elevation of 1000 m asl until the occurence of intense uplifting between the end of Pliocene and beginning of Early Pleistocene, A total uplifting magnitude of 3500m, with differentiations in space and stages, has been attained over most parts of the Plateau since Quaternary. The intense uplifting of the Plateau has given rise to enormous changes of the natural environment since Late Cenozoic, such as the evolution of lakes and drainage systems, the Quaternary glaciation, the paleogeographical evolution in the Holocene and the influence of uplifting of the plateau on natural environments and processes. Characterized by the most outstanding features of natural environment the Qinghai-Xizang Plateau differs to a great extent from the Eastern Monsoon Realm and the Northwest Arid Realm in China. According to comparative studies of the altitudinal belt, two systems of the structure-type of the altitudinal belt may be identified: the monsoonal and the continental. From a point of view of three dimensional zonation, the spatial differentiations of the Plateau are explained and a tentative scheme of physico-geographical regionalization has been proposed. A number of gee-ecological phenomena, such as the vapour channel, dry valley and the cold-arid core area are discussed in the present paper.