Evolution and Subsidence History of the Sichuan Basin, Southwest China

摘要

The Sichuan Basin of southwest China is a large, petroleum-bearing, complex, intracratonic sedimentary basin. In the Neoproterozoic, South China was part of a major supercontinent which commenced to extend and fragment at about 800 Ma. The effects of this fragmentation are preserved in the depositional records of the Sichuan Basin. Subsidence commenced with an initial extensional event in the Neoproterozoic. Subsidence during the Neoproterozoic and Early Palaeozoic was controlled by thermal relaxation of the crust that was punctuated by shortlived extensional events. The later history was dominated by compressional events that produced several foreland loading phases, that resulted from collisional events due to the accretion of terranes to the Asian plate. We recognise separate foreland loading phases in the Late Permian to earliest Triassic, in the Late Triassic to Early Jurassic, and in the Middle Jurassic to the end of the Jurassic. The Longmenshan, forming the northwestern boundary of the Sichuan Basin, is the northeastern part of the Cenozoic Himalayan system, and is still seismically active, with thrust fault motions on northeast striking faults indicating that foreland loading is still occurring today at the northwest margin of the Sichuan Basin.