Response of sedimentation to structural evolution in Biyang Sag

In this paper, the structural evolution and the responses of the basin filling, the sedimentary sequence, the sedimentary and subsidence centers to tectonic movement in Biyang Sag are summarized. The movement times of boundary faults are determined and the evolution history is restored based on the migration of sedimentary and subsidence centers. It is shown that the extension action of Yanshanian movement, the movement of boundary faults after Yanshanian movement and the deposition after Himalayan movement determine three basin filling sequences and structural sequence in Biyang Sag. Besides, sedimentary sequence is also controlled directly by the changes of accumulation space and sediment supply resulted from episode movement of faults. The studies on the changes of sedimentation and subsidence centers show that structural situation is unstable in He-2 member. The movements of the two boundary faults are all weakened greatly and the centers of sedimentation and subsidence superpose gradually in the southeast of Biyang Sag until No.1 sandstone group of He-2 member, the basin come really into atrophied rift and fault basin.