The study area, located in the middle part of Altyn slope zone in the Qaidam Basin, spans three structural units including Qaidam Basin, Altyn fault and Suoerkuli Basin. The Altyn slope zone generally characterized with an approximately southdip ramp is a curved surface varying in threedimension, and the trend of its envelope surface is almost consistent with that of the Altyn fault. The Altyn slope zone consists of nearEWtrending anticlines associated with the Altyn fault, which gradually converge towards the fault. In the foreland of the Altyn Mts, the slope zone is characterized with a series of oblique nose structures, presenting a regular change of wide and gentle alternate uplift and depression. In most parts, it presents as the forelimb of the largescale anticline resulted from the thrusting of stackingtype duplex structure to south from north. Based on the growth strata of the forelimb, the formation of Altyn fault began at the deposition of the upper member of the Xiaganchaigou Formation (38Ma), the fault has been active until now. The active intensity of the fault was weak during the deposition period from the upper member of the Xiaganchaigou Formation to the upper Shangyoushashan Formation (38~8.1Ma), and became strong since the deposition of Shizigou Formation (8.1Ma).