Mesozoic strike-slip fault system at the margin of the Junggar Basin, NW China
Ming Zhu, Zeliang Liang, Xin Wang, Renfu Wang, Yangli Yu, Lixin Xiao, Lingyun Wei
Abstract
The Junggar Basin in Northwest China is covered by thick sediments, causing challenges in recognizing buried structures. Seismic reflection and drilling data from petroleum exploration provide essential data for the study of subsurface structures. In this study, we focus on the Mesozoic structural characteristics and tectonic evolution along the margins of the Junggar Basin by using 2D and 3D seismic reflection, drilling data, and surface geology. Our results demonstrate that a unified dextral strike-slip fault system developed along the marginal area around the Junggar Basin. The structural style is characterized by both transpressional structures, such as positive flower structures, en echelon folds, restraining bends, and fan-shaped and horsetail fractures at the fault tip, and transtensional structures, including releasing bends, pull-apart basins (fault basins), and positive inverted structures. We further interpret that except for the southern margin of the Junggar Basin, the current structural pattern of the basin margin was mainly formed in the pre-Cretaceous, which was covered by Cretaceous and Cenozoic strata. Based on the timing and style of deformation, we propose that the vertical-axis counterclockwise rotation of the Junggar Basin during the Mesozoic caused right-lateral strike-slip faulting along the basin margin. Cenozoic reactivation of these structures has been localized in the southern margin of the Junggar Basin under the far-field influence of the India-Asia collision.