Abstract:Tectonic movements have occurred frequently in the middle section of west Sichuan depression since the late Triassic, including the Indosinian movement, the Anxian movement, the Yanshan movement and the Himalaya movement. They are mainly caused by compressive stresses, leading to many unconformity surfaces. In this paper, considering these movements and the unconformity surfaces, the main unconformity surfaces are identified in the region, their denuded amounts are calculated, and the geological significance of the distribution of the denuded amounts is analyzed. Based on Vitrinite reflectance distribution characteristics and seismic reflection profile , it is shown that three of the tectonic movements are closely related with hydrocarbon accumulation of the mesozoic era in the region, that is, the late Indosinian movement, the Anxian movement and the Himalaya movement. According to the data availabe and due to the restrictions of the denudation recovery methods, the Vitrinite reflectance-depth method, the combined Vitrinite reflectance-depth and reference layer thickness method, and the sonic velocity analysis method are chosen to recover the denuded amount caused by the three movements, respectively. The calculation results of the denuded amounts show that the regional structural strength center has migrated from north to south since the late Triassic era; the Himalaya movement is the strongest of the movements and is mainly responsible to the current tectonic pattern; the main structural traps have been formed before hydrocarbon migration and accumulation; and the hydrocarbon accumulation action has ceased after the Himalayan movement.