Abstract:

The Tianshengqiao bauxite deposit in Wenshan County, Yunnan is a typical sedimentary bauxite deposit. The ore bodies occur in the Upper Permian Longtan Formation, which is underlain by the Upper Carboni-ferous limestones and the basalt related to the Emeishan LIP. The ore is dominated by pelitomorphic textures, with a few detrital textures and ooidic textures. These textural features suggest that the bauxitic soils were transported over a short distance. Constant elements analysis reveals that Al₂O₃ of bauxite has a negative relationship with Fe₂O₃ and TiO₂. Trace elements such as Zr, Hf, Nb, Ta and Bi were enriched during the bauxitization process more than Li, Rb, Sr, Ba．Elements of Zr, Hf, Nb and Ta demonstrate significant correlation with TiO₂ respectively. Studies of stable elements correlation such as Zr-Hf, Nb-Ta, bivariate plots of lgNi and lgCr, and REE pattern suggest that the basalt is the major source of materials for the bauxite formation. Meanwhile, the carbonate rocks may provide a small amount of source of materials for the formation of bauxite ores.

Key words: bauxite, geochemistry, ore-forming material source, Wenshan County, Yunnan