Outcrop sequence stratigraphy of the Middle-Lower Triassic strata in the Huaxi region,Guiyang,Guizhou

The Middle-Lower Triassic strata in the Huaxi region,Guiyang,Guizhou are assigned to three sedimentary facies: carbonate platform,platform-margin and basin facies,including five type I and one type Ⅱ depositional sequences.The study area once experienced a complete second-order cycle of sea-level fluctuation during the Early-Middle Triassic: a rising trend during the Early Triassic and a falling trend due to the effects of regional tectonic movement during the Middle Triassic.