Differential Characteristics and Evolution of Conjugate Strike Slip Faults in the Halahatang Area,Northern Tarim Basin
Non-classical X-type conjugate strike-slip faults are observed in the Halahatang Oilfield,which have obvious differ-ences in zoning,stratification,segmentation and evolution characteristics,constraining oil and gas exploration and exploitation.Based on the 3 400 km2 seismic data,this paper describes the stratification and segmentation characteristics of two strike-slip faults in NE direction and NW direction,and analyzes the differential evolution characteristics and mechanism.The results show that 1)from north to south,fault maturity and extensibility become weaker,and stress perturbation by NE-striking faults increased;from deep to shallow layers,the disturbance effect of NW-trending faults on NE-trending faults became weaker;deformation degree and maturity decreases upward in NW-striking faults,but increases in NE-striking faults.2)Strike-slip fault underwent multiple evolution stages in Halahatang Area,which can be divided into Middle Ordovician conjugate fault formation stage,Carboniferous-Permian transtensional strike-slip fault reactivation stage,and Meso-Cenozoic transtensional strike-slip fault reactivation stage.The NE-and NW-striking faults had differential fault evolution process.3)Mechanism of fault formation and reactivation changes during the evolution process.The strike-slip fault system during the Middle Ordovi-cian is controlled by the superimposed deformation of pure shear and simple shear,and were also controlled by stress field,pre-existing structure and regional strata thickness.The reduction of stress from north to south and the change of associated stress field resultes in the difference of fault styles in the south and north.
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