Geochemical Characteristics and Ore-forming Environment of the Songgui Bauxite Deposit in Heqing County, Northwest Yunnan Province

In this paper, it took the sedimentary bauxite of the Songgui bauxite deposit as the research object,its geochemical characteristics have been studied, and then its ore-forming materials sources as well as metallogenetic environment have been discussed. The Songgui bauxite deposit is characterized by high Al₂O₃ content and highA/Sratio.In aluminum-containing rock series, the overall total REE contents are higher, with large differences among the samples, moderate Eu anomaly and more positive Ce anomaly. REE distribution patterns are tilted to the right of the weak V-shaped curve or the weak M-shaped curve, reflecting the varying degree of REE fractionation. LILE (U), HFSE (Nb, Ta) and siderophile element (Cr) are significantly enriched in aluminum-containing rock series, the remaining elements are significantly loss. Cluster analysis shows that Al₂O₃ is positively correlated with Nb, TiO_2, REE, and Li, and their correlation is obvious. Aluminum-containing rock series are associated with black metal (Ti and V), rare earth elements, and rare metals (Nb and Li), and all of these elements can be comprehensively utilizated with Al₂O₃. REE distribution pattern fornormalized aluminum-containing rock series are nearly horizontal "U"-shaped curve, the TiO₂/Al₂O₃ratio of Aluminum-containing rock series (17.91) is close with the TiO₂/Al₂O₃ ratio of underlying limestone and sandstone of Beiya Formation (26.21), illustrating that the aluminiferous rock series are closely related with the underlying limestone in Beiya Formation.Among the aluminum-containing rock series, the Becontent is low (2.23×10^-6), Th/U ratio is medium (3.68), and Ce anomalies are more negative Ce anomalies. These characteristics indicate that the ore-forming materialsof the Songgui bauxite deposit were sourced from weathering crust, and they experienced the sedimentation transformation. Ga, Sr, Ba contents and Eu/Sm ratio are low (12.71×10^-6, 43.0×10^-6, 27.9×10^-6 and 0.17, respectively),which show the continental sedimentary characteristics; Sr/Ba ratio is high (1.73), which indicates the sea facies characteristics. These geochemical characteristics indicate that the ore-forming material of the Songgui bauxite deposit was came from the weathering crust, without obvious sedimentation transformation.