Palaeoclimate of the Early Permian: Evidence from characteristicsof bauxite beds in Wuchuan-Zheng′an-Daozhen area, northern Guizhou Province
Yu Wenchao1, Du Yuansheng1, Zhou Qi2, Jin Zhongguo3, Wang Xiaomei4, Cui Tao4
1 State Key Laboratory of Biogeology and Environmental Geology,China University of Geosciences(Wuhan),Wuhan 430074,Hubei 2 Bureau of Geology and Mineral Exploration and Development of Guizhou Province,Guiyang 550004,Guizhou 3 Non-ferrous Metals and Nuclear Industry Geological Exploration Bureau of Guizhou Province,Guiyang 550005,Guizhou 4 Faculty of Earth Resource,China University of Geosciences(Wuhan),Wuhan 430074,Hubei
Abstract：Bauxite,as a kind of climatically sensitive deposit,mainly formed during the pedogenesis under the tropical or subtropical climatic condition.The integrated information of major elements and clay minerals from drilling core samples of bauxite beds in Wuchuan-Zheng′an-Daozhen area,northern Guizhou Province,was measured to investigate the palaeoclimate environment during the formation process of bauxite. Chemical index of alteration(CIA)and index of compositional variability(ICV)of samples from bottom to top of the drilling core revealed that CIA increased from 80 to >90,while ICV decreased from 0.8 to 0.1.Both of them indicated the strong chemical weathering which changed composition of bauxite beds greatly. The clay mineral compositions of bauxite beds were dominated by kaolinite,illite and chlorite.Kaolinites,which appeard in debris or matrix,widely distributed in every drilling core and had a high content in most layers;illites mainly appeard in debris,occurring in clay layers of the deposit,with illite crystalline index varying in wide range;while chlorite matrix derived from kaolinite during later diagenesis.High CIA value and clay mineral composition in bauxite beds indicated moist and warm palaeoclimate environment in northern Guizhou Province during the Early Permian which related to palaeogeography position of this area.Change of ICV value in the bauxite beds was related to element migration during leaching process.
Yu Wenchao,Du Yuansheng,Zhou Qi et al. Palaeoclimate of the Early Permian: Evidence from characteristicsof bauxite beds in Wuchuan-Zheng′an-Daozhen area, northern Guizhou Province[J]. JOPC, 2014, 16(1): 30-40.
