Palaeoclimate of the Early Permian: Evidence from characteristics of bauxite beds in Wuchuan-Zheng'an-Daozhen area, northern Guizhou Province

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 deposi