Abstract: The South Junggar Foreland Thrust Belt is located in northern Tian Shan piedmont, where multiple fold and thrust belts developed under the influence of strong compressional activity in the Late Cenozoic. Its deep structures as well as the impact of pre-Cenozoic paleo-structures on the present tectonic framework are still under debate due to structural complexity and lack of high quality seismic imaging data. In this paper, we select the Huoerguosi-Manasi-Tugulu fold and thrust belt—situated in the second row of the fold and thrust belt in the South Junggar Foreland Thrust Belt—as our study area. We used newly collected and processed seismic data and ground geological data to discover the deep structures. We also used sandbox modeling and balanced restoration method to explore the impact of the prototype basin in the Early Jurassic on the present tectonic framework. The results show that Lower Jurassic half-graben system, Middle-Upper Jurassic and Cretaceous structural wedge, and thrust belts in the Cenozoic layers developed in the Huoerguosi-Manasi-Tugulu fold and thrust belt. The normal faults developed in the Early Jurassic served as thrust ramps in the Late Cenozoic foreland thrust belts, and also controlled the development of structural wedge and thrust belts above them. The Early Jurassic half-graben has different segments, connected by lateral ramps. These lateral ramps control the strike slip faults developed among the fold and thrust belts, impacting greatly on the migration and accumulation of gas originated from Lower Jurassic source rocks. Finally, we can conclude that the pre-Cenozoic paleo-structures have great influence on the tectonic framework and petroleum accumulation in the intracontinental foreland thrust belts.

Key words: southern Junggar Foreland Thrust Belt, Huoerguosi-Manasi-Tugulu fold and thrust belt, half-graben, Early Jurassic, strike slip faults