| Northern Slope of Tazhong area locates in the north of Tazhong uplift,and in the vicinity of Manjiaer sag,which has been proved to be an important oil/gas exploration area.This article based on the 3D fine seismic interpretation of the study area and equilibrium profile of each main fault,as well as the seismic attribute to study the strike-slip fault characteristic,including the fault combination,profile pattern and fault evolution.The study has revealed that the fault mainly strike NE and NEE,and Shunnan area exists a small scale of NW-striking strike-slip fault.NE and NEE strike-slip faults turn out to be simple steep flower structure or composite flower structure,and its vertical fault throw is small.The lower transpressive positive flower structure composed of reverse faults and the upper transtensive negative flower structure composed of normal faults were spatially overlaid.The main fault zone of the strike-slip fault extends far away in the surface,which appeared to be reciprocal and ganged in the deep and en-echelon in the shallow.Through stress field simulation and equilibrium profiles,it was known that the strike-slip fault mainly experienced four tectonic movement period: Early Caledonian act,Middle Caledonian act III,Early Hercynian and Late Hercynian.Based on regional structural background,it is known that transpressive stress originated from Altun gradually decreased westward in Middle Caledonian act III.In this stage,lots of reverse fault formed and controlled the structural feature of Tazhong uplift to be convergent in the east and divergent in the west.In the formation process of reverse faults,there developed large amount of strike-slip faults perpendicular to its strike so as to accommodate the displacement diversity among reverse faults.In Early Hercynian,the strike-slip fault turned form transpressive deformation to transtensive deformation under the regional extensive background. |
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