Study On The Characteritic Of Structual Evolution In Western Zhenwu Fault Zone

Using well logs, well drilling and lots of seismic data, combing the new theories such as structural geometry, kinology and dynamics, this paper analyses the structural form,evolution history and formation mechanism thoroughly of the research area by the method of tectonic evolution sections, fault throw and structural physical simulation.Zhenwu fault zone is southern boundary fault of Gaoyou depression in Subei basin.Complex fracture system are formed in the research area after many structural movements.It is of high value to clarify the feature of fracture and evolution process.The faults in the study area can be classified into four categories, among which Zhen-1 fault belongs to the first grade and zhen-2 fault belongs to the second. A series of faults between zhen-1 fault and zhen-2 fault, cutting through Fu-ning formation, are almost third grade and dominant faults in the Zhenwu fault zone with the absence of Zhen-1 fault and Zhen-2 fault. The fourth graded faults with north-south strike are in smaller scale between third graded faults, whose formation closely related with differential uplifting-subsidence movement.It is concluded from the result of the physical simulation experiment in Western Zhenwu fault zone that the shape of the major fault has an important influence on secondary faults. It is concluded from the results of experiment in Huangjuenan area that the research area is made up of east-west faults in early Funing period because of extensional stress, which constitutes the basic structural frame of step-fault zone, and develops almost south-north small faults due to extensional stress and differential uplifting-subsidence movement in the late stage of Funing period.Based on tectonic evolution sections, fault throw and structural physical simulation, the tectonic history of Western Zhenwu fault zone is subdivided into three phases:â‘ The development of Step-fault zone with the characters that the faults with north-east and east-west strike are weak in south while strong in north to the early Funing period;â‘¡The participation of faults with north-south strike caused by differential subsidence in the late Funing period;â‘¢The stable settlement of Step-fault zone reformed by Zhen-2 Fault after Dainan period.