A NW-trending Karatau strike-slip fault system develops in the South Turgay Basin, which presents as horsetail-shaped fault assemblage in plane, and controls the four-graben-three-horst structure of the Aryskum Depression. Based on the detailed 3D seismic interpretation, displacement-distance curve and structural evolution profile analysis, a systematic study on the structural characteristics and fault genesis mechanism in the depression was carried out. The result shows that there are large numbers of strike-slip faults associated secondary elements in Karatau fault system, which include R fracture, P fracture, T fracture and R′ fracture. These faults are pre-existing faults in the Meso-Cenozoic basins, which control the structure and fault distributions of the half-graben. Vertically, the structural evolution of the depression can be divided into three stages, which include the Early-Middle Jurassic oblique extension stage, the Late Jurassic compression reverse stage and the Cretaceous-Cenozoic extensional slip stage. The Aryskum half-graben is consist of three major and one secondary structural units during the early and middle Jurassic oblique extension stage. Three types of anticline structures developed in the Late Jurassic compression reverse stage: broad anticline, traction anticline and sharp anticline. Tractional anticline along the fault distribution was formed during the Cretaceous-Cenozoic right-lateral shear-slip stage.
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