GEOLOGICAL CHARACTERISTICS AND STRUCTURAL EVOLUTION OF MESO-CENOZOIC CONTINENTAL BASINS IN GUANGXI

Meso-Cenozoic continental basins in Guangxi developed by inheriting lndosinian basement folds.Eastern Guangxi belongs to the domain of the Cathaysian structural system,where NE trending basins such as the Shiwan- dashan basin are relatively developed.Western Guangxi lies Where the Youjiang structural system is exposed,along which the Bose basin and other ones controlled by NW-trending fractures are distributed.“V”-shaped basins such as the Nanning basin in central Guangxi are just located in a transitional zone between the two directions mentioned above. The structural framework of continental basins in Guangxi resulted from subduction of the Pacific plate and the Indian plate towards the Chinese mainland and their collision.In the in dosinian time,the plate motion was compressive in nature.The Yanshanian crust was in a state of relative relaxation,and some basins in eastern Guangxi were tensional in Jurassic to Cretaceous time.In the Himalayan time,the stresses generated by the plate motion were mainly tensional in the east and compressive in tile west.At that time Cenozoic basins formed by high-angle tensional fracturing were scattered sporadically in eastern Guangxi,while in the west NW-trending frac- turing activity occurred as a result of compression and controlled some compresso-shear basins.The intersection and crosscutting of the NE and NW sets of fractures and the Meso-Cenozoic continental basins controlled by them formed the modern structural-geomorphological framework with the“X” type as the main part in Guangxi.