Structural analysis of multi-stage superimposed deformation in the southwestern Sichuan Basin: An example from the Ziliujing anticline

Due to the tectonic uplift and deformation propagation of adjacent orogens, complex structural styles have developed in the southwestern Sichuan Basin. However, there is still a lack of precise age constraints on their evolution history. Based on high−quality seismic reflection data, we conduct a structural analysis on the structural geometry and kinematic features of the low−amplitude Ziliujing anticline as an example using fault−related folding theory for exploring the history of structural evolution in the study area. The results demonstrate distinct stratified tectonic deformation. In the deep, fault− propagation folds and detachment folds develop above the Cambrian salt. Folds and thrusts in the intermediate are primarily confined between the top of the Silurian shales and soils and the lower Triassic salt layer. In the shallow, it is primarily characterized by gentle folds and minor faults. Significantly, the regional structural styles in this area are controlled by the deep Cambrian detachment. The identified growth strata, in conjunction with the results of balanced structural restorations, indicate that the study area has undergone three main stages of tectonic compression; late Caledonian, Indosinian, and Yanshanian and Himalayan epochs. Furthermore, the development of NW−directed faults in the upper Triassic strata implies a structural imposition likely resulting from the propagation of deformation due to eastward movement of the eastern margin of the Tibetan Plateau.