Geochemistry and Genesis of the Bauxite Ore (Rock) in the Feichijiao Ore District, Qiubei City, Yunnan Province

The Feichijiao bauxite deposit in Qiubei City of Yunnan Province is a newly discovered large-size bauxite deposit. A study of major and trace elements and REE of the sedimentary bauxite ore (rock), underlying limestone and Emeishan basalts was carried out in this paper. The result shows that the major components are Al2O3, SiO2, TFeO and TiO2. The sedimentary bauxite ore (rock) is characterized by high iron, intermediate content of silicon and low aluminum. Al/Si ratios (Al/Si=0.69~5.19) and Al/Ti ratios (Al/Ti=5.01~29.47) of sedimentary bauxite ore (rock) are close to Al/Si ratios (Al/Si=0.65~1.33) and Al/Ti ratios (Al/Ti=3.53~14.32) of the underlying limestone respectively, and the linear relationship between basalts and bauxite ore (rock) is more significant on the Harker diagram of oxide, which indicates that the source of bauxite had multi-source characteristics, with the underlying limestone and basalt making some contribution. Trace element spider diagram shows that bauxite ore (rock) enrichment of HFSE (Th, Nb, Zr, Hf and Ti) is similar to that of the underlying Emeishan basalts. The bauxite ore (rock) spots are relatively concentrated in the basalt distribution area and its vicinities. REE patterns as well asΣREE and Ce anomalies of bauxite ores are similar to those of basalts, and they display positive Ce anomalies, moderate Th/U ratios and high Sr/Ba ratios. The petrological, petrogeochemical and metallogenic backgrounds suggest that the sedimentary bauxite ore (rock) was formed by sedimentation in an oxygen-rich marine environment, and the underlying Emeishan basalt provided the major materials for the formation of bauxite ore (rock), with the underlying limestone contribution making insignificant contribution.