Tectonic deformation mechanism of the fault zone in the northwest margin of Junggar Basin: Based on physical experimental simulation

The development of marginal fault systems, exemplified by Hongche (Hongshanzui, Chepai), Kebai (Karamay, Baikouquan), and Wuxia (Wuerhe, Xiazijie) in the northwest margin of Junggar Basin, is a pivotal factor influencing the developmental characteristics of Carboniferous-Triassic strata and governing hydrocarbon accumulation. The nature and formation mechanism of the fault zone in the northwest margin of Junggar Basin have been extensively discussed within the earth science community. Building upon regional geological context and previous research findings, a physical sandbox experiment was conducted to simulate the tectonic deformation mechanism within the fault zone at northwestern Junggar Basin. The experimental outcomes reveal that the Wuxia and Kebai fault zones are primarily controlled by a west-dipping main fault with a symmetrically distributed subsidiary faults on both sides. Conversely, the Hongche fault zone is predominantly governed by two main faults exhibiting an en echelon distribution pattern with an approximately symmetrical flower-like structure. Through forward physical simulation, it can be inferred that Early Carboniferous to Late Triassic evolution at the northwest margin of Junggar Basin can be divided into two stages: residual ocean basin subduction stage followed by right-lateral strike-slip stage. The development of Carboniferous-Triassic stratigraphic traps in this region may be attributed to thrust faults and folds forming fault noses, fault blocks, and aligned anticlines. These associated structural traps serve as key factors for hydrocarbon accumulation at the northwest margin of Junggar Basin.