Regional Geological and Tectonic Environment and Evolutionary Characteristics of the Yangbajing-Gedaxiang Basin,Tibet

Abstract

Gedaxiang Basin in Tibet is located in the south-eastern section of Gangdisi structural belt, with a typical geological and tectonic environment and a commonly developed tectonic pattern in plateau area. By studying the structural geological environment of Geda Township area and analyzing its internal geology, it can be seen that: (1) Six large-scale faults developed in the area control the basic geological and tectonic structure of the working area and affect the spatial structure of the area; The fault development direction is mainly north-south, mostly brittle faults at shallow surface level, and a few of them are east-west orientated. Most of the faults in the region are caused by the development of geological and tectonic activities in the Himalayan period, and the ones that developed later are the north-south oriented positive faults formed by the extension movement in the late Himalayan period. (2) There are three periods of tectonic environment evolution in the area of the evolutionary history, since Jurassic: the first period is the late Yanshan period, tectonic activity for the extrusion environment, the formation of north-south fold deformation under the compression environment; The second stage is early to middle mountain stage, which formed large scale EW-trending nappe structure and thrust fault, and the regional stress background is compressional environment. The third stage is the late Alpine stage, forming a series of tectonic systems of grabens and normal faults with SN strike, which were mainly formed by geological activities under the extensional system. The results of this study provide a reference for distinguishing the trace of geological rock group in the tectonic evolution of the Himalayan tectonic period.