Permian sequence stratigraphy of slope facies in southern Guizhou and chronostratigraphic correlation

The Permian in slope facies area of southern Guizhou consists of 16 third order sequences, which can be grouped as four sequence sets and further into two mesosequences. Most of them are delineated by conformable or submarine erosion surfaces, and well controlled by conodont and fusulinid zones. Four important sea-level falls are recognized in the area, which occur respectively at the basalSweetognathodus whitei zone, lowerS.aff.hanzhongensis zone, middleJinogondolella xuanhanensis zone and the basalClarkina yini zone. Among the recognized transgression events, three are regarded as the most significant. They occur respectively at the basalNeogondolella exculptus zone, basalJinogondolella nankingensis zone and the lowerClarkina postbitteri zone, and are all accompanied by faunal turnovers. The key surfaces in sequences can be used to fine-tune the boundaries of bio-chronozones, stages and series.