Study On The Strike-Slip Faults System And Its Formation Mechanism In The Tazhong Uplift,Tarim Basin

The Tazhong uplift is located in the middle part of the Tarim Basin which is one of the key areas for oil and gas exploration in the Tarim Basin.Based on the interpretation of the high-quality 3D seismic data in the Tazhong uplift,the geometric features of the strike-slip fault in the Tazhong uplift,the active period of the fault,the tectonic evolution process,and the formation mechanism of the fault are studied.Studies have shown that more than ten north-east strike-slip faults develop in the Tazhong uplift,with distinct geometric and structural features in different layers.The Cambrian is dominated by upright faults and appears as linear faults in the plane.The Upper Ordovician faults develop positive flower structures.The plane is dominated by linear structures,with branch faults on both sides of the main displacement zone;faults in the Silurian-Devonian system develop negative flower structures,and on the plane the faults are NW trending and display right-stepping en-echelon arrangements distributed along the main displacement zone.The evolutionary stages of strike-slip faults are divided into three periods.The initial development time was middle Cambrian,the second activity time was later than the sedimentation period of the santamu formation,and the third activity time was Silurian-Devonian.Due to the local transpression stress in the middle Cambrian tower,the basement weak zone broke and formed a series of short-extension strike-slip faults.The subduction of the ancient Kunlun Ocean at the southern margin of the Tarim plate in the Late Ordovician intensified,the Tazhong area was strongly uplifted by strong compressive stress from the southwest.At this time,the pre-existing weak zones of the basement subjected to strong compressive stress and fractured.The compressive stress generated by the Alginian subduction acts on the study area from the southeast edge of the Tazhong area,acts obliquely on the basement weak zone,causing the basement fault to generate left lateral shear movements,the early strike-slip fault reactivated to form the extended strike-slip fault.The Altun tectonic domain on the southeastern edge of the Tarim basin experienced strong orogeny in the Silurian-Middle Devonian period,and the southern Tianshan in the northern edge of the basin developed a back-arc basin in the Silurian-early Carboniferous,the study area was in a tectonic setting of transtension.Under the tectonic environment,the Tazhong uplift strike-slip fault is active again,the faults are NW trending and display right-stepping en-echelon arrangements distributed along the main displacement zone formed in the Silurian-Devonian system.