GEOCHEMCIAL CHARACTERISTICS OF THE SONGGUI BAUXITE DEPOSIT IN HEQING, NORTHWESTERN YUNNAN PROVINCE

The orebodies of researched area are hosted in the unconformity between the Triassic oil shale at the bottom of the Zhongwo Formation and the underlying limestone and dolomitic limestone of Beiya Formation, showing as lenticular and funnel-shaped. Impacted by magma intrusion and karst development, the thickness of ore bed is unstable. The ore minerals are mainly diaspore. According to the structure, the ore types can be divided into oolitic bauxite, dense bean-like bauxite and loose (soil-like) bauxite. The lithochemical data of the deposit such as Al/Si ratio generally reflect the positive correlation between Al₂O₃, SiO₂ and TiO₂. The ore samples show enrichment of ΣREE, positive anomalies of δCe and negative anomalies of δEu. The study of trace elements indicates the characteristics of sedimentary origin, showing the multi-source of oreforming materials. It could be inferred that the bauxite was deposited in a marine environment.