Sedimentary Features and Paleogeographic Evolution of the Middle Permian Trough Basin in Zunyi, Guizhou, South China

Based on detailed field surveys, numerous sections and drillcores as well as analyses of lithofacies and sedimentary facies, sedimentary differentiation in the Middle Permian Zunyi (northern Guizhou, South China) trough basin was studied in detail. Caused by activities of the Emeishan mantle plume, the regional extensional setting and the extinguishing of carbonate production factories were shown from Guizhou to Yunnan. Three types of sedimentary enironments were developed in the study area: platform, slope, and basin. In this work, we established a sedimentary model for the study area, identified 14 syndepositional faults, and created the detailed reconstruction of the trough basin via a sedimentological investigation. It is found that the paleogeographic evolution of the study area can be divided into six stages: (1) a pre-rifting stage, (2) rapid rifting and subsidence, (3) stable rifting and subsidence, (4) the second stage of rifting and subsidence, (5) silicification, and (6) regional uplift and denudation. The sedimentary features and paleogeographic evolution of the Maokou Formation in Zunyi show that the platform, slope, and basin sedimentary features coexisted. In addition, the extensional setting and extinguishing of carbonate production factories were important preconditions for the evolution of the platform region in the study area, and the activity of syndepositional faults also played an important role in the paleogeographic evolution of this area.