Tectonic evolution and prototype basin reconstruction in the Jimsar and Jinan depressions, eastern Junggar Basin

Abstract

Since 2020, with in-depth research on the Shuangji structural belt in the Jimsar Depression, Junggar Basin and high-yield oil flow data obtained from the Triassic Jingjingzigou Formation in the Well Satan 1, it has been demonstrated that the Jimsar and Jinan depressions have promising potential for conventional oil and gas exploration. Objective To further study the geological characteristics and exploration potential of the Jimsar and Jinan depressions, Methods this paper comprehensively analyses data from core samples, logging, well logging, and seismic surveys; identifies regional unconformities; categorizes different tectonic stages; and establishes the correlation between tectonic and stratigraphic evolution. Based on this, the development process of each stratum is restored, and the coupling relationship between tectonics and the evolution of uplift and depression within the research area is established, and the prototype basin is restored. Results This study revealed five large unconformities in the Jimsar and Jinan depressions, which have undergone four episodes of tectonic activity. The stratigraphic evolution characteristics of the study area ranged from "north high and south low" in the Early Permian to "south high and north low" in the Palaeogene and Neogene. The original basin also changed from a "multiconvex and multiconcave" pattern in the Early Permian to a "few convex and large concave" structural pattern in the Palaeogene and Neogene. Conclusion The establishment of the coupling relationship between tectonics and the evolution of uplift and depression at different times and the restoration of the prototype basin during each period lays an important foundation for clarifying the basin characteristics of the Jimsar and Jinan depressions during different periods and helps to enhances oil and gas exploration in these areas.

Keywords

• tectonic curtain
• prototype basin
• jinan depression
• jimsar depression
• junggar basin