Folds in the Qiangtang basin, northern Tibet

Abstract：There are several structural layers in the Qiangtang basin owing to multi-stage tectonic movements, and these structural layers show different features of deformation. Some small and tight overturned folds are developed in the Triassic structural layers, and large broad anticlines and synclines or compound anticlines and synclines occur in the Jurassic structural layers. Compared with the above, Cretaceous-Neogene structural layers mostly occur in synclinal cores or anticlinal limbs, forming very broad folds. Folds are mainly of E-W trend, and from older to younger folds formed by different structural layers change from tight to broad and show the features of continuous and progressive superimposed deformation. All these show that amalgamation and compression of plates during different periods were the main forcing of the deformation. In addition, basal faults and basal uplift-depression controlled and affected the distribution and deformation of the folds to a certain extent.