STUDY ON DIFFERENTIAL UPLIFT OF THE NORTH EDGE OF TIBETAN PLATEAU DURING THE LATE CENOZOIC

The differential uplift of Tibetan Plateau is a very important topic in the study of Tibetan Plateau concerning the process of its uplift and formation mechanism. This paper primarily studies the characteristics of the uplift difference of the north edge of Tibetan Plateau during the Late Cenozoic. The results of the study show that the uplift difference is obvious in the north edge of Tibetan Plateau. The average denudation rate of the mountain system of the west-Kunlun, Altyn and Qilian has experienced the changes with the characteristics of four ladders, of valley-peak-valley-peak-valley and of two ladders respectively, since 23. 7 Ma BP. Before 3. 6 Ma BP the uplift difference of the north edge of Tibetan Plateau presented the east-high and west-low feature. During the period of the Tibetan Movement (3. 6-1. 7 Ma) the uplift difference presented the west-high and east-low feature. Since 0. 6 Ma BP the uplift difference has appeared strong in the west, weak in the middle and less strong in the east. Since 1. 7 Ma the average strain of the tectonic shortening by the squeezing action in the north mountain system of the Tibetan Plateau are 38% in the west Kunlun fold belt, 8% in the Altyn fold belt, 15% in the Qilian fold belt respectively. These characters are similar to that of the uplift difference in the altitude during the same period of time.