Multi-Stage Tectonic Superposition and the Evolution of Strike–Slip Faults in the Central Sichuan Basin of China

In recent years, laterally extensive strike–slip faults with relatively small displacement have been recognized in the central Sichuan Basin during deep hydrocarbon exploration. These faults segment the structural framework and provide key conduits for fluid migration and pathways for reservoir reworking, thereby exerting first-order control on hydrocarbon migration and accumulation. To characterize their geometry, kinematics, multi-stage evolution, and genetic mechanisms—and to address structural uncertainties limiting deep exploration—we integrate newly processed high-resolution 3D seismic data covering ~22,000 km2 with drilling data from 28 drillings that penetrate the Sinian Dengying Formation in the central and western Sichuan Basin. Using coherence–attribute imaging and detailed fault interpretation, we examine the coupling between tectonic superposition and strike–slip fault development. Three fault systems are identified: E–W trending, N–E trending, and N–W trending, of which the E–W and N–E systems dominate the regional tectonic framework and hydrocarbon distribution. Faults preferentially occur along boundaries of secondary structural units and exhibit pronounced multi-stage activity. Integrated fault–stratigraphic relationships, deformation of seismic reflectors, and restoration results indicate five principal activity episodes: Tongwan, Caledonian–Middle Hercynian, Late Hercynian, Indosinian, and Yanshanian, each characterized by distinct intensity, scale, and spatial extent. We propose that establishment of the central Sichuan paleo–uplift prior to the Permian initiated the E–W trending strike–slip system, whereas a Late Hercynian tectonic regime shift—followed by Indosinian foreland overprinting associated with the Longmen Shan—promoted widespread development and reactivation of N–E trending faults, which became dominant. These findings provide a structural basis for deep gas exploration in the Sinian–Cambrian Anyue giant gas field and the Permian Qixia–Maokou reservoirs, and offer insights into strike–slip faulting and hydrocarbon controls within stable cratonic basins.