Denudation Recovery and Prototype Basin Structural Pattern During the Faulting Period in the Southern Part of the Central Depression Area of the Songliao Basin

The Changling Depression, located in the southern part of the central depression zone of the Songliao Basin, is characterized by complex structures and has been shaped by multiple phases of tectonic activity. The strata in this region have undergone significant uplift and denudation, resulting in an incomplete understanding of the prototype basin and hindering progress in oil and gas exploration. To better understand the geological characteristics and exploration potential of the Changling Depression, this study begins with the reconstruction of denudation amounts. Using the stratigraphic trend extrapolation method, the denudation of strata during the faulting period of the Changling Depression is quantified. By combining the denudation thickness with the remaining strata thickness, the original strata thickness is restored. Employing MOVE 2018version and Petrel 2021version software, the paleogeomorphology of different geological periods is reconstructed. Through an analysis of the prototype basin’s structure, its evolution history, sedimentary filling patterns, and paleogeomorphological features, it is determined that the maximum depositional thickness and rate during the Huoshiling period occurred in the Shenzijing, Heidimiao, and Fulongquan areas, with strong central deposition that weakened toward the north and south. During the Shahezi period, depositional thickness and rates exhibited a pattern of weaker deposition in the south and stronger in the north. In the Yingcheng Formation–Denglouku Formation period, the basin entered a subsidence phase, with an expanded range of strata subsidence. During the Denglouku period, the Qianbei area experienced strong deposition, while the Heidimiao area saw even more pronounced deposition; in contrast, the Shenzijing area displayed very weak depositional activity. The study reveals a south-to-north migration of lateral subsidence centers over time, influenced by left-lateral tectonic forces, reflecting a shift in the dominant influence pattern. These findings clarify the morphology of the prototype basin and the distribution and migration of subsidence centers across different periods, providing valuable insights that will facilitate deeper oil and gas exploration efforts in the Changling Depression.