The Characteristics Of Lithofacies Paleogeography Of Early Wujiaping Age In Qiubei Area，Southeast Of Yunnan

Based on the theories and methods of sedimentology, stratigraphy andpalaeogeography, combining with the data of outcrop observing, explotary tranch anddrilling, using the method of point-line-surface and combining the qualitative andquantitative analysis, the lithofacies paleogeographic character of early Wujiapingianin Permian in Qiubei Area was studied.In Qiubei Area, southeast of Yunnan,the Wujiapingian in Permian is composedof clastic rocks with bauxite. According to the sedimentary characteristics of localgeological data and the data of field geological investigation, the sedimentaryenvironment of the study area in early Wujiapingian was mud coast to restrictedshallow marine. We established this sedimentary facies model, furthermore,analysised the characteristics of each sedimentary facies, subfacies and microfacies.Based on the analysis of qualitative and quantitative data of the characteristics of54outcrop sections, single factor maps, lithofacies paleogeographic map andpaleogeographic maps of system tracts were drawn, adopting the Single FactorAnalysis and Comprehensive Mapping Method. The study can draw followingconclusions: Firstly, the dominant sedimentary environment of the study area in theearly Wujiapingian is tidal flat to shallow marine; Secondly, bauxite beds developedin the third-order sequence of Lower Wujiaping Stage. The transgressive systemtracts(TST) is mainly in intertidal zone to subtidal zone facies, formed aretrogradation sequence; early highstand system tract (EHST) developed in subtidalzone to shallow marine environment with aggradation effect; the late highstandsystem tract (LHST) show a process of rapid regression from SW to NE of the studyarea, sedimentary facies range from swamp to intertidal zone. Finally, according tothe relation between paleogeography and the distribution of known mineralizationpoint, it can be speculated that subtidal zone to upper shallow marine environment ismore conducive to the formation of bauxite.