Sedimentary Facies And Palaeogeographic Setting Study Of Early Wujiaping Stage In Wenshan Area Of Yunnan

With the acceleration of China’s industrialization, urbanization and agricultural modernization progress, the demand for mineral resources is increasing day by day. The mining industry is one of the pillar industries in Yunnan province. But raw materials of aluminum plant are purchased from outside the province and domestic. While the800000tons of aluminum oxide factory building in Yunnan, Wenshan is badly in need of bauxite resources.Therefore, the strengthening of bauxite scientific research and exploration work has a positive practical significance and practical value in Yunnan Province. In this thesis, we have studied the early formation of the Upper Permian Wujiaping Stage in Wenshan and its framework, sedimentary characteristics, sedimentary facies, structural setting and furthermore, discussed its sedimental paleogeographic environment.This study area is a relatively stable area through regional geological evolution analysis, same with adjacent areas in Late Palezoic era. Using major element, trace element and rare earth element method, we have analyzed material sources of clastic rocks and origin of the siliceous rocks here, and found that same with adjacent areas, the Late Paleozoic era formation which developed form the Caledonian fold basement has long been part of Southern China or Dianqinggui basin and nurtured Devonian, Carboniferous and Permian stable sedimentation dominant in carbonate rocks, reflecting a relatively stable tectonic environment. In early Wujiaping Formation of the Upper Permian, the area of Wenshan was located in a transitional sedimentary environment from continental margin to bathyal region of Southern China oceanic basin or Dianqiangui oceanic basin, the terrigenous detritus mainly originated from bordered old land and the water body of studying area became deeper from southwest to northeast.The Permian Wujiaping Formation in Wenshan is an important set of bauxite containing clastic rocks. According to the measured section sedimentary characteristics and regional geological data, it is believed that the Wujiaping order was located in a silty coastal depositional environment with low energy, and we have constructed the sedimentary facies pattern and summarized the characteristics of all kinds of facies, subfacies and microfacies. Based on the qualitative and quantitative analysis of the lithological and sedimentary characteristics of56outcrop section, using methods of single factor analysis and multifactor comprehensive mapping, we have worked out all kinds of single-factor and lithofacies paleogeographic maps of the early Wujiaping Formation in Wenshan. This study shows that in general, the early Wujiaping Formation in Wenshan lied in a offshore-epicontinental sea environment. According to lithology and sedimentary types, the Wenshan area can be divided into four phase regions, that is, from southwest to northeast, marsh-supratidal zone, intertidal zone, subtidal zone, limited shallow sea.