Tectonic evolution and prototype basins Reconstruction in the Jimsar and Jinan depressions, Eastern Junggar Basin

Since 2020, with the in-depth research of the Shuangji structure belt in the Jimsar depression of the Junggar Basin, and the high-yield oil flow obtained from the Triassic Jingjingzigou Formation in the Sa Tan 1 well, it has been demonstrated that the Jimsar depression and Jinan depression have good potential for conventional oil and gas exploration. In order to further study the geological characteristics and exploration potential of the Jimsar and Jinan depressions, this paper comprehensively analyzes data from core samples, logging, well logging, and seismic surveys, identifies regional unconformities, divides different tectonic stages, and establishes the relationship between tectonic and stratigraphic evolution. Based on this, the development process of each stratum is restored, the coupling relationship between tectonic and the evolution of the uplift and depression within the research area is established, and the prototype basin is restored. The study shows that there are five large unconformities in the Jimsar and Jinan depressions, which have undergone four tectonic activities. The stratigraphic evolution characteristics of the study area have developed from "north high and south low" in the early Permian to "south high and north low" in the Paleogene and Neogene. The original basin also changed from the "multi-convex and multi-concave" pattern in the early Permian to the "few convex and large concave" structural pattern in the Paleogene and Neogene. The establishment of the coupling relationship between tectonic and the evolution of the uplift and depression at different times and the restoration of the prototype basin at each period lays an important foundation for clarifying the basin characteristics of the Jimsar and Jinan depressions at different periods and helps to deepen oil and gas exploration in these areas.