YANSHANIAN STRUCTURAL DEFORMATION AND DYNAMICS OF THE XUEFENGSHAN INTRACONTINENTAL TECTONIC SYSTEM

This paper deals with the geometry and temporal-spatial evolution of the Yanshanian faults and folds in the Xuefengshan intracontinental tectonic system. The results show that the structural pattern of the west of the Xuefengshan Mountain is obviously controlled by the blocking effect and the boundary faults between different structural units play a significant role in controlling structural styles. In general, there are two-stages of Yanshanian folding in this region. The early-stage fold extends in NE-NNE,and the late-stage fold in SN-NNE directions. Under the stress of SE-NW shortening, the Xuefengshan Precambrian basement lifted up vertically along some thrusts and escaped laterally along some strike-slip faults in a plane view. Separated by the Huaihua-Xinhuang fault, the south part of the Xuefengshan Precambrian basement escaped southwestward. Compared the subduction of the paleo-Pacific plate in the Yanshanian period with the Yanshanian deformation of the Xuefengshan intracontinental tectonic system, we can find that the northwestward and westward subduction of the paleo-Pacific plate possibly controlled the two stages of Yanshanian folding and thrusting in this region.