Sedimentary facies and palaeogeography of the middle-upper Yangtze area during the Leikoupoan (Middle Triassic)

The quantitative sedimentary facies and palaeogeographic map of the middle-upper Yangtze area during the Leikoupoan (Middle Triassic) is constructed on the basis of single factor and multiple factors mapping methods. Two ancient landmasses dominated by the marine deposits were once developed during the Leikoupoan. The regressions resulted in the gradation of the study area into the shallow-water depositional area, and no basin and slope were developed. The stable Xikang-Yunnan old land in western China and the uplifted Cathaysian old land in southeastern China display the tectonic framework of being higher in the east and lower in the west. The eastern part exhibits the clastic platform and the western part exhibits the carbonate platform. The Leikoupoan (Middle Triassic) palaeogeographic evolution and sedimentary model are presented in this study for the study area.