Sequence stratigraphic division of the Upper Sinian-Lower Cambrian strata in the Cili-Dayong region, northwestern Hunan

The Cili-Dayong region in northwestern Hunan lay on the passive continental margin of the southeastern Yangtze landmass during the Late Sinian to Cambrian. The bulk of the Upper Sinian strata are represented by the carbonate rocks, while the Lower Cambrian strata consist dominantly of a variety of shales and limestones. The above-mentioned strata within the platform-margin to slope facies zones are divided in this study, on the basis of sequence boundary, depositional characteristics, parasequences, systems tracts and transitional surfaces and outcrop sequence stratigraphy, into eleven third-order type 2 sequences, including seven for the Upper Sinian strata and four for the Lower Cambrian strata. Other aspects of outcrop sequence stratigraphic analysis are dealt with as well.