Cenozoic fault systems and their genetic analysis in central area of the Huanghua Depression
He Shu1, Yang Qiao2, Qi Jiafu2, Wang Jiading1
1. State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi’ an 710069; 2. Key Laboratory for Hydrocarbon Accumulation Mechanism, Ministry of Education, China University of Petroleum, Beijing 102249
Fault was a major structure in the Cenozoic Huanghua Depression and an important affect factor for hydrocarbon accumulation.The faults in central area of the Huanghua Depression could be divided into six systems and the interaction among these systems was analyzed in this paper.Every fault system had a major fault at least,which combined the sub-order faults developing in hanging wall or foot wall in various forms.The group features of the faults in section and plane showed the Cenozoic kinematic characters of the fault systems.The mechanism of the fault system in the Cenozoic Huanghua Depression was discussed based on study of the fault groups,structural modes,tectonic backgrounds,boundary directions,the interaction of faults,fault displacement and the history of development of some major faults.The results showed that the regional setting of the fault system was controlled by the extension stress field,so the major faults were parallel to the extensional boundaries.Furthermore,it was proved that the extension tectonics was coupled with the strike-slip structure,which resulted in change of the direction of some faults or suddenly breaking of some faults.The kinematic relation between each fault subsystem and within a fault system showed that the Huanghua Depression was controlled by two dynamic systems:the NW-SE extension caused by mantle heating action,and right-lateral strike-slipping caused by the deep fracture zones.