Fold structure pattern in southwestern Qaidam Basin

Based on the studies of tectonic profile and deformation history,the structures in the southwestern Qaidam Basin have been divided into 5 categories according to their genetic mechanisms: thrust fold structure,fault-propagation fold structure,detachment fold structure,diapiric structure(mud diapir structure) and composite fold structure.The thrust fold structure distributes in the Kunbei fault-uprising belt,mainly characterized by the involving of basement into severely-uprising unilaterally extruding asymmetrical fold.The fault-propagation fold structure locates in the Gasi-Zhahaquan fault-fold belt,mainly characterized by the involving of basement into unilaterally extruding fault-propagation asymmetrical fold.The detachment fold structure locates in the Yingxiongling detachment fold belt and the central depression as well as the shallow layer of the Gasi-Zhahaquan fault-fold belt,mainly characterized by detachment fold which is approximately symmetrical in middle-shallow layer.The diapiric structure(mud diapir structure) is characterized by the upwarp of plastic mudstone and usually distributes in the east of the central depression and the Yingxiongling detachment fold belt.The composite fold structure is composed of the trust-propagation and the detachment fold structures.