Characteristics and Evolution of Reverse Structures in the Tiangongtang Area, Southern Sichuan

The Tiangongtang area，located on the southwestern margin of the Sichuan Basin，is a key target zone for marine shale gas exploration. The multiphase tectonic superimposition in this region has resulted in a complex tectonic evolution history. Through comprehensive interpretation and analysis of 3D seismic data，this study reveals for the first time that the area exhibited extensional fault-depression characteristics during the Late Caledonian. By integrating geometric analysis of tectonic deformation，it is determined that the Tiangongtang area underwent three major deformation periods: Late Caledonian extensional fault-depression，terminal Caledonian compressional inversion， and intense Mesozoic-Cenozoic compression. Additionally，the regional kinematic evolution process was established through kinematic reconstruction using balanced restoration techniques. This paper systematically identifies the seismic response characteristics of early fault depressions，elaborates on the geometric patterns and kinematic mechanisms of inverted structures，and discusses the influence of multi-stage structural superposition on the preservation and enrichment of shale gas，thereby providing an important geological basis for shale gas exploration in the complex structural area of southern Sichuan Basin.