The Sichuan Basin located in the western region of the Yangtze block was a stable craton basin in the Permian. The structural differentiation caused by the Dongwu movement and the Emei rifting activity controlled the sedimentary system and the Permian carbonate gas reservoirs in the Sichuan Basin. In this study, we have investigated the stratigraphic characteristics of each Permian formation, studied the depositional systems of each period of the Permian stage, and discussed the overall tectono-sedimentary evolution of the sedimentary basin. During the Permian, the Sichuan Basin experienced an intense tectonic activity, controlling the variations of the sedimentary environments occurring in the basin. The depositional systems of the basin were controlled by the tectonic setting of the intra-cratonic depression and marginal rifts during the period. Therefore, this is an important period in the tectono-sedimentary evolution of the study area, which can be divided into the following stages: (1) From the Late Carboniferous to the Early Permian, the Sichuan Basin was dominated by tectonic uplift and denudation. In the Middle Permian, a regional transgression occurred in the whole upper Yangtze region, and the sedimentary environments of the Sichuan Basin and its adjacent areas gradually changed to the carbonate platform. (2) In the early phase of the Late Permian (the Wujiaping period), being influenced by the Emei rift, the Sichuan Basin and its adjacent areas formed a complex pattern of structural highs and adjacent depressions, controlled by a differential subsidence. (3) In the late phase of the Late Permian (the Changxing period), with the cessation of the volcanic activity and the enhancement of the regional extension, the pattern of structural highs and depressions is more obvious, and the relatively calm structural environment makes the carbonate sedimentary environment tending to dominate.
Part of the book: Geochemistry