Sedimentary facies and palaeogeography of the Lower Triassic Jialingjiang Formation in Sichuan Basin during the salt-forming period

The Lower Triassic Jialingjiang Formation in Sichuan Basin is the key stratum for potash exploration in China. It is an important basic geological work to study its sadimentary facies and paleogeography. Based on the paleogeographic background and paleoclimatic conditions of Sichuan Basin, the sedimentary facies of the lower Triassic Jialingjiang Formation in the study area are analyzed and studied by means of field section, core observation and thin section identification. Three types of sedimentary facies are identified, including lagoon, lagoon marginal flat and platform beach facies, and a few of microfacies are further divided. Through the study of regional stratigraphic correlation and mapping of sedimentary facies and paleogeography, the evolution of the Lower Triassic Jialingjiang Formation in Sichuan Basin is reconstructed. Combined with previous studies, it is considered that the Jialingjiang Formation in Sichuan Basin belonged to a barrier carbonate platform depositional environment, which evolved from limited marine facies of carbonate to evaporation platform facies from west to east. The barrier of the underwater uplift around the basin and the hot and dry climate conditions affected the evolution process of the platform salinization of the Jialingjiang Formation. The sea level fluctuation was an important factor controlling the development and spatial distribution of the sedimentary facies. Finally, based on the data of this study, the map of sedimentary facies and palegeogrophy of the Jialingjiang Formation in each salt forming period is newly compiled.