Deformation of the Northwestern Junggar Basin (Che-Guai Region, Northwest China) and Implications for Hydrocarbon Accumulation

The Che-Guai region is located in the most strongly deformed area of the northwestern Junggar Basin (northwest China) and its deformation history is key to understanding the tectonic evolution of West Junggar and its associated hydrocarbon accumulation. However, the presence of complex multiphase structures makes it difficult to unravel the deformation history. In this study, we present comprehensive seismic and well log data, combined with geological observations from sedimentary and volcanic rocks, to reveal the structural deformation of the northwestern Junggar Basin. Based on our results, four zones of concentrated deformation are identified: (1) the Ke-Bai Fault Zone, (2) the Hongshanzui transition zone, (3) the Zhongguai uplifted zone, and (4) the Hong-Che Fault Zone. Based on the interpretation of seismic profiles, we suggest that Paleozoic strata were affected mainly by thrust faults, whereas Triassic and Jurassic strata of the Zhongguai uplifted zone were affected by strike-slip faults. Deformation in Cretaceous and Cenozoic strata is associated mainly with normal faults. Based on our results, the following tectonic history is proposed. The first stage involved initial basin formation during the Permian under the influence of northwestward subduction of the Junggar Ocean crust. The second stage, during the Triassic and Jurassic, involved transpressional deformation related to movement along the Darbute Fault. The third stage, during the Cretaceous and Cenozoic, involved moderate extensional deformation triggered by collision between the Indian and Eurasian plates. In the context of this tectonic history, hydrocarbon accumulation is proposed to be linked to fault terraces of the Hong-Che and Ke-Bai Fault Zones and the uplift of the Zhongguai Uplift.