Oil & Gas Geology ›› 2022, Vol. 43 ›› Issue (1): 118-131.doi: 10.11743/ogg20220110

• Petroleum Geology • Previous Articles     Next Articles

Three-layer structure model of strike-slip faults in the Tazhong Uplift and its formation mechanism

Caiming Luo1(), Xinxin Liang2,3, Shaoying Huang1, Yuan Neng2,3, Wei Zhang1, Shi Chen2,3(), Shujuan Cao1   

  1. 1.Petroleum Exploration and Development Research Institute of Tarim Oilfield Company,PetroChina,Korla,Xinjiang 841000,China
    2.State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum (Beijing),Beijing 102249,China
    3.College of Geosciences,China University of Petroleum (Beijing),Beijing 102249,China
  • Received:2020-12-11 Revised:2021-12-03 Online:2022-02-01 Published:2022-01-28
  • Contact: Shi Chen E-mail:luocm?tlm@petrochina.com;chenshi4714@163.com

Abstract:

The Tazhong uplift located in the central uplift zone of Tarim Basin, is one of the key oil and gas plays in the Tarim Basin. A detailed interpretation of high-quality 3D seismic data, is applied to study the geometry characteristics of the strike-slip faults on both plane and sectional views, active periods of faulting and its formation mechanism in the Tazhong Uplift. Seismological data show that activity of most strike-slip faults in Tazhong uplift finalized before the Carboniferous, and only a few still kept active after the Carboniferous. The strike-slip faults cut through the strata from the basement to the Silurian and Devonian systems with vertical fault planes, which are obviously different from each other in geometry as in a three-layer structure. The fault planes in the deep Middle and Lower Cambrian feature linear distribution, with the strata on both sides of the fault arching. Multiple branch faults are developed on the top surface of carbonate rock after the strike-slip faults growing upward into the Upper Cambrian and Ordovician, as shown in a positive flower-like structure on sectional view, and by a diagonal fault pattern on plane view. While the strike-slip faults in the shallow Upper Ordovician, Silurian and Devonian systems commonly appear as a negative flower-like structure on sectional view, and as NW-trending en-echelon faults on plane view, specific to this layer. These three-layer faults are superimposed vertically in a complex spatial pattern. The evolution of strike-slip faults in the Tazhong Uplift is divided into three stages, that is, the Middle Cambrian when a structural inversion event led to the development of small-scale strike-slip faults under transpressional stress; the Late Ordovician when the strike-slip faults got reactivated to form a positive flower-like structure; and the Silurian and Devonian during which the strike-slip faults kept active. The development of the strike-slip faults in the Tazhong Uplift can be attributed to the control of peripheral tectonic environment and evolution under the local transpressional stress in the Middle Cambrian, the transpressional setting in the Late Ordovician, Silurian and Devonian.

Key words: three-layer structure model, layered deformation, staged activity, formation mechanism, strike-slip fault, Tazhong Uplift, Tarim Basin

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