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Geoscience ›› 2021, Vol. 35 ›› Issue (06): 1797-1808.DOI: 10.19657/j.geoscience.1000-8527.2021.188

• Petroleum Geology • Previous Articles     Next Articles

Formation Mechanism of the Conjugate Strike-slip Faults in Tabei Uplift

HUANG Shaoying1(), SONG Xingguo2,3, LUO Caiming1, NENG Yuan4, MA Xiaodan1, QI Jiafu2,3, CHEN Shi2,3()   

  1. 1. Research Institute of Petroleum Exploration and Development, PetroChina Tarim Oilfield Company, Korla,Xinjiang 841000, China
    2. State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China
    3. College of Geosciences, China University of Petroleum, Beijing 102249, China
    4. China University of Petroleum (Beijing) at Karamay, Karamay,Xinjiang 834000, China
  • Received:2021-03-16 Revised:2021-07-15 Online:2021-12-10 Published:2022-02-14
  • Contact: CHEN Shi

Abstract:

Two sets of permeable X-type strike-slip faults (NNE- and NNW-trending) intersecting at a small angle (40°) are developed in the Tabei uplift of the Tarim basin. Based on the interpreted 3D seismic data in the Harahartang area of northern Tarim Basin, we studied the geometric distribution characteristics and profile deformation characteristics of strike-slip faults (focusing on the RP6 and HA13 faults), and analyzed and compared the differences of deformation and development characteristics of NNW-trending and NNE-trending faults. Based on the gravity and magnetic data from the basin and the activity characteristics of the surrounding orogenic belt, the development mechanism and evolution of the small-angle X-type strike-slip fault in Tabei uplift were analyzed. The study shows that the strike-slip fault in Tabei uplift has clear vertical delamination deformation characteristics, comprising three structural layers: (lower) Sinian-Middle Cambrian (below TH3 interface), (middle) Upper Cambrian-Middle Ordovician (TH3-TO3t interface), and (upper) Upper Ordovician-Carboniferous (TO3t-TP interface). The fault was generally in a transpressive setting in the lower and middle structural layers, and developed most of the positive flower structures. In contrast, negative flower structures and normal faults were mainly developed in the upper structural layer, which was in a transtensional setting as a whole. Comparing the two fault sets, the NNW-trending ones are highly active, and there are distinctive fault characteristics in each structural layer, together with strong vertical connectivity, and the development of pre-existing basement faults. Meanwhile, the NE-trending faults are mainly developed in the middle structural layer, but unclear in the lower and upper structural layers. Activity analysis shows that the formation and evolution of faults are multistage, and that the strike-slip faulting had undergone three major phases in the late Middle Cambrian, Middle-Late Ordovician and Silurian-Carboniferous. Formation of the X-type strike-slip faults in Tabei uplift was controlled by the NNW-trending basement faults and weak zones. Strike-slip faults are developed preferentially in NNW-trending basement faults or structural weakness zones, and the angle between the basement faults and the main compressive stress direction is less than 45 °-Φ/2. Development of NNE-trending faults was restricted by the pre-existing NNW-trending faults, and finally the X-type faults intersecting at small angles were formed.

Key words: Tabei uplift, conjugate strike-slip faults, layered and multistage deformation, formation mechanism

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