ON THE INDOSINAN MOVEMENT ON THE QINGHAI-XIZANG （TIBET） PLATEAU

According to an analysis and study of the data of regional geology, this paper discusses in detail the nature and age division of the Indosinian movement on the Qinghai-Tibet plateau and the evolutionary characteristics of the plateau. The age and sequence of various stages and episodes of the Indo-Sinian movement are shown as follows. The evolutionary characteristics of the Indosinian Qinghai-Tibet plateau are as follows: I. In the Hercynian, India and Cathaysia were subjected to extension and disintegration. From the continent to the center of the oceanic basin, there occurred successively continental fluvial-lacustrine formation→continental-margin plateau carbonate formation→continental rise or slope （miogeosyncline） flysch formation→abyssal siliceous volcanic rock （flysch） formation→ophiolitic m lange formation, which shows the feature of symmetrical spreading of the ocean （geosyncline）. 2. In the early Indosinian, the Qingling, Qilian and Kunlun sea basins first closed, in the middle Indosinian, the Bayan Har Sea closed and Cathesia aeereted up to the vicinity of the Nujiang River in the late Indosinian,the Tethyan Sea of Qinghai-Tibet further shrank, giving rise to asymmetricalclose-up of the ocean and unidirectional inversion of the geosyncline. 3, Qiang-tang, Tanggula, Qamdo and the "Sanjiang （Three-River）"region lying betweenthe Nujiang-Bangong Co and Jinshajiang fault belts were assembled by the In-dian and Cathesian land masses which have different natures.