Huayingshan fault: multi-stage segmented activity and controls on the structural evolution of the Sichuan Basin’s sedimentary cover, southwest China

In the Sichuan Basin, the activity of the Huayingshan fault significantly affects the structural evolution of the sedimentary cover and promotes the formation of oil and gas fields, but further research is needed on its multi-stage segmented activity process. Based on aeromagnetic data, seismic profiles, well data, and previous research results, this study investigated the distribution characteristics, multi-stage activity process and segmentation characteristics of the Huayingshan fault as well as its influences on the structural evolution of sedimentary cover, and further explored the tectonic evolution of the Basin. This study found the following: (1) The Huayingshan fault is SW-NE-trending and extends into the sedimentary cover, causing fault-propagation folds in some seismic profiles. (2) The activity characteristics of different segments and different periods of the Huayingshan fault vary, and we divided it into three segments. (3) The Huayingshan fault controlled the local boundary of the uplift during the Cambrian–Middle Triassic, leading to different structural frameworks in central and eastern Sichuan during the Jurassic–present. (4) During the Cambrian, NW-SE extensional stress intensified, particularly in the basin’s northeastern region; during the Late Silurian, the NW-SE extensional stress peaked in the Early Paleozoic; and during the Middle Triassic, the Sichuan Basin was located in the superposition area of the SE-NW-directed and NE-SW-directed compressive stresses.