Geochemical Characteristics of the Shazitang Bauxite Deposit in Guangnan County, Southeast Yunnan

Shazitang bauxite deposit is a rare high-quality bauxite deposit in Southeast Yunnan, which is characterized by high Al₂O₃ content and A/S ratio. In this paper, the sedimentary bauxite has been taken as the research object to study its geochemical characteristics, and then its ore-forming materials sources and metallogenetic environment have been discussed. Aluminum-containing rock series has higher REE contents, showing moderate negative Eu anomaly, positive Ce anomalies and negative Ce anomalies; REE distribution patterns are tilted to the right curve with weak "V"-shaped and various slope, reflecting the varying degree of REE fractionation. LILE (U), HFSE (Nb, Ta, Zr, Hf, Th) and siderophile element (Cr) are significantly enriched in aluminum-containing rock series, the other elements are significantly loss. Cluster analysis shows that Al₂O₃ is positively correlated with Nb, TiO₂ and REE, but it has significantly negative correlation with Ga, Fe₂O₃ and Li. Aluminum-containing rock series is associated with black metal (Ti), rare earth elements, dispersed elements (Ga), rare metals (Nb and Li), and it can be comprehensively utilizated with Al₂O₃. REE distribution pattern for normalized aluminum-containing rock series are nearly horizontal "U"-shaped curve, the TiO₂/Al₂O₃ ratio of aluminum-containing rock series (16.89) is close with the TiO₂/Al₂O₃ ratio of limestone in Weining Formation (13.09), illustrating the close relationship between aluminiferous rock series and underlying limestone in Weining Formation. Among aluminum-containing rock series, Be content is low (3.60×10^-6), Th/U ratio is high (6.07), and more samples have negative Ce anomalies. These geochemical characteristics indicate that the Shazitang bauxite deposit was sourced from weathering crust and experienced the sedimentation transformation. Ga content is high (25.25×10^-6), Sr content is low (77.7×10^-6), Ba content is low (34.4×10^-6), and V/Zr ratio (0.22) is lower, Eu/Sm ratio is lower (0.21), which shows the continental sedimentary characteristics; Sr/Ba ratio is high (3.28), which indicates the sea facies characteristics; these characteristics indicate that the Shazitang bauxite deposit was derived from the weathering crust, without obvious sedimentation transformation.