Differential Activity Of Intraplate Fault In The Late Paleozoic In The Hangjinqi Area Of The Ordos Basin

The Hangjinqi Fault Zone(HFZ)is located in the northern Ordos Basin,covered by2 D + 3D seismic data,which provides the possibility for transforming the fracture geometry anatomy and kinematics inside the tectonic belt;The intersection of the block and the active tectonic zone(the northern edge of North China Craton(NCC))is one of the ideal samples for studying the relationship between intraplate deformation and plate edge activity.Based on seismic data interpretation,3D seismic time slicing,fault growth index and displacement distance profile analysis,and interpretation of gravity and magnetic data,this paper analyzes the fault differential deformation characteristics,regional tectonic evolution,and its relationship with the NCC in the Hangjinqi area of the Ordos Basin.The research on the coupling relationship of the northern margin activities and other aspects finally reached the following conclusions: The NE-direction segment(east section of the Poerjianghaizi Fault)formed earlier;the end of the fault overlapped with the near-EW-direction segment(west section of the Portjianghaizi Fault),resulting in increased local displacement and hard-connection;the EW direction The Sanyanjing Fault was formed in the Late Carboniferous,and has undergone the evolution process of fault segmentation,lateral expansion and connection.As accommodation fault,Wulanjilinmiao Fault has relatively weak activity and local reversal.The 3D seismic area in the Hangjinqi area is mainly composed of three groups of basement faults: east-west basement faults,north-south basement faults,and north-west basement faults;their structures The deformation factors are controlled by: the reversal of the pre-existing controlled depression,the location of the pre-existing geological body,the SinoSingapore Proterozoic thick layer rift subsidence,and the activation of the main basement fault.The Wulanjilinmiao Fault and J134 fault are in the basement as a fault zone,and the shallow basement Wulanjilinmiao Fault and the SN-strike-basement Fault leave traces of mutual cutting in different stages of strike-slip.The formation and evolution of the HFZ are mainly controlled by pre-existing structures(including basement faults,preexisting faults and geological bodies);the EW basement faults control the regional structural pattern,and the north-westward basement faults cause differential deformation of the secondary fault zones,which are controlled by pre-existing faults and geological bodies.The development of small concealed faults;the change of stratum thickness and the analysis of the intensity of fault activity are consistent with the tectonic events of the NCC,which are the main driving stress for the differential deformation of intra-plate faults.