Characteristics of the central segment of Shunbei 5 strike-slip fault zone in Tarim Basin and its geological significance

The Shunbei 5 fault zone is known so far as the longest intracratonic strike-slip fault zone in Shunbei area and its surroundings, Tarim Basin. With a length of 270 km identified by both 2D and 3D seismic data, the Shunbei 5 fault zone is characterized by a long fault trace running through the Tabei uplift, Shuntuoguole low uplift and Tazhong uplift. Based on the overall change of fault strike, the Shunbei 5 fault zone can be divided into three segments: the northern segment (trending approximately NW20°), the central segment (trending nearly NS, i. e. NE10°) and the southern segment (trending approximately NE20°). The main faulting of the central segment (the part trending NE10°) of the Shunbei5 fault zone occurred in the 3rd episode of the middle stage of the Caledonian and the Late Caledonian, when the deep ridge-like structures and medium-deep grabens were formed under transpressional and extensional stress regimes, respectively. The shallow en echelon normal faults in the central segment of Shunbei 5 fault zone controlled the formation of reservoir space of fracture-cavity type in the Silurian clastic strata (namely sandstone and mudstone intervals). The fractured zones were developed in an asymmetric pattern in the hanging wall and footwall of the en echelon normal faults. The measured displacements of the northern and central segments of the Shunbei 5 fault zone are characterized by "longer at both ends and shorter in the center". Furthermore, the northern and central segments also remarkably differ in both geometries and kinematics, suggesting that Shunbei 5 fault zone was formed through the linking of various faults developed in different fault systems in early tectonic evolution. © 2019, OIL & GAS GEOLOGY Editorial Board. All right reserved.