THE SEQUENCE-STRATIGRAPHIC FRAMEWORK AND THE EVOLUTION OF PALEOGEOGRAPHY FOR CARBONIFEROUS OF THE GUIZHOU AND GUANGXI AREAS

Carboniferous system in the Guizhou and Guangxi areas can be divided into two series (the lower series and the upper series): the lower series includes the Yanguanian, the Datangian and the Dewuan stages; and the upper series includes the Luosuan, the Huashibanian, the Dalan and the Xiaoyaoan stages. Therefore, the Maping Formation that has been used as the top strata of Carboniferous system for many years becomes an intersystem lithostratigraphic unit. The strata from Carboniferous to the Lower Permian epoch form a secondorder sequences, the top and the bottom boundaries of which are longterm punctuated surfaces genetically related to the unconformities of tectonic movement, the bottom one is the unconformity of the second episode of the Ziyun Movement, and the top one is that of the second episode of the Qiangui Epeirogeny. Six thirdorder sequences that are briefly named as SQ14 to SQ19 can be discerned in the strata from Carboniferous to the Early Permian epoch. In the research areas, there are three different paleogeographic settings such as the attached platform, the isolated platform and the interplatform ditch. Coalmeasures strata and relative more dolomitic strata make up the strata of the atta ched platform, carbonates constitute the strata of the isolated platform, and in interplatform ditch more dark and fine sediments mainly form the strata from Carboniferous to the Early Permian epoch. The lithofaciessuccession fabric of thirdorder sequences is changed with the changes of the paleogeographic settings, but there is a synchronism for the process of sealevel changes indicated by the lithofaciessucession of the thirdorder sequences. On the basis of the research on paleobiology, a series of the penal diagrams of sequencestratigraphic framework and the corresponding maps of sedimentary facies and paleogeography, can be used to reflect the complex and the regular facieschanges in time and in space from Carboniferous to Early Permian in the Guizhou and Guangxi areas.