Sedimentary facies and palaeogeography of the tectonics and sequences in the Yunnan-Guizhou-Guangxi region, southwestern China during the Doushantuoan(Late Sinian)

Sequence stratigraphy is the study of rock relationships within a chronostratigraphic framework of repetitive, genetically related strata bounded by surfaces of erosion or nondeposition, or their correlative conformities. The fundamental unit of sequence stratigraphy provides a chronostratigraphic framework for correlating and mapping sedimentary rocks, and is defined and identified by the physical relationships of strata, including the lateral continuity and geometry of the surfaces bounding the units, vertical and lateral stacking patterns, and the lateral geometry of the strata within these units. The emphasis of the present study on sequence stratigraphy of the Yunnan Guizhou Guangxi region during the Doushantuoan will be on:(1) the measured Upper Sinian Wangjiawan section in Jinning, Yunnan, that made it possible to reconstruct the parent sequence section in the shallow marine areas of the Upper Yangtze area, and (2) the measured Xiling section in Lingchuan, Guangxi, that permitted the parent sequence section in the deep sea areas of the Upper Yangtze area to be reconstructed. The field observations of the auxiliary sections have also been made for the working area in order to compile the sedimentary facies and palaeogeographic maps of the tectonics and sequences in the second-order sequences of the transgressive and highstand systems tracts. This approach allows us to reveal the relationship among tectonism, sediment complexes and sea-level changes, and to develop the framework of the spatio temporal evolution of this region during the Doushantuoan.