The Hongqian-Chepaizi

Karamay-Baikouquan

and Wuerhe-Xiazijiefaultzones faulted zones

developed at the northwestern margin of the Junggar Basin

are considered to be key controls on the development of hydrocarbon reservoirs in the area.However

the timing and span of the fault zones' evolution

and their characteristics are still under intensive debate.Our purpose here is to determine the structure attributes of the northwestern margin of Junggar Basin based on analysis of regional tectonic setting as well as previous studies.The result shows that West Junggar is dominated by NE-trending strike-slip fault systems caused by the Paleozoic-Cenozoic tectonic evolution of the basin.Three main stages of NE-trending strike-slip fault systems have been distinguished.The first stage is the Late Carboniferous sinistral strike slip fault belt that resulted in the emplacement of the Baijiantan and Darbut ophiolitic belts.The following second stage is the dextral strike-slip fault system that was expressed by the development of the Late Permian-Mid-late Triassic Karamay-Baikouquan and Wuerhe-Xiazijie dextral strike-slip fault belts.These two fault belts were resulted from the Late Permian-Triassic counterclockwise rotation of the Junggar Plate and the West Junggar relative to the western part of the Chingiz Range.The faulted noses

blocks and en echelon anticlines derived from the relevant thrust faulting and folding may account for the development of main structural traps in the West Junggar.The third stage is characterized by the development of the Cenozoic Darbut sinistral strike-slip fault

resulting in limited deformation confined in the north margin of the Basin.In field analyses

this younger imprint shall be distinguished from the Mesozoic strike-slip faults.