Mesozoic multistage structural deformation along the Ke‐Bai fault zone in the north‐west Junggar Basin, NW China

Abstract

The Junggar Basin is one of the main oil basins in Northwest China, and the north‐west part of the basin is a significant petroleum exploration target. Mesozoic structural activity had an important influence on the present structural characteristics of the north‐west Junggar Basin. In this paper, we discuss the tectonic evolution of the Junggar Basin by studying the structural characteristics of the Ke‐Bai Fault. Our results suggest that the Ke‐Bai Fault has obvious strike‐slip characteristics and that it is an important basin‐controlling fault that has controlled the tectonic evolution of the north‐west Junggar Basin. The Junggar Basin was a rift basin in the Early Permian, but it experienced a tectonic reversal during the Middle Permian to the Triassic. The Ke‐Bai Fault changed from a normal fault into a thrust fault from the Early Permian to the Triassic. During the Jurassic, dextral strike‐slip structures developed along the Ke‐Bai Fault, horsetail splay faults developed in its north segment, and there is evidence that it was under WNW–ESE compression. The dextral strike‐slip faulting of the Ke‐Bai Fault is consistent with tectonic movement along the Kelameili, Sangequan, Wu‐Xia, Hong‐Che, and North Tianshan fault systems in the Junggar Basin. We therefore infer that counterclockwise rotation occurred in the Junggar Basin in the Jurassic.