THE E W TRENDING STRIKE SLIP FAULT SYSTEM IN XINGLONG, HEBEI

The Xinglong area, Hebei province, is tectonically located in the central sector of the Yanshan orogenic belt. A conjugate structure formed by intersection of the E W and NE structures is widely developed in the area. Study suggests that the E W trending principal strike slip fault displays a dextral step pattern （P fault）, while the NE trending subsidiary structure is composed of en echelon folds and branching faults in the north block and subsidiary faults in the south block. The chief deformation in the Yanshanian platform fold belt resulted from dextral strike slip of the Shangyi Pingquan fault and Miyun Hongshankou fault during the Jurassic, and the shear zone between them generally resembles a large scale S C structure or plane ramp structure. The ancient basement fault in the area not only controlled the Middle Late Proterozoic sedimentation and magmatism, but also played an important role in the occurrence of the mode of Mesozoic tectonic deformation. The formation of the principal strike slip fault was directly related to the rejuvenation of the ancient basement fault.