滇东南晚二叠世铝土矿地球化学特征及物源分析

摘要

The bauxite deposits in southeastern Yunnan Province are typical karst bauxite deposits.The orebo-dies occur in the Upper Permian Wujiaping Formation (Longtan Formation).It is significant to analyze geo-chemical characteristics of this deposit for the material source of bauxite ores.Whole rock analysis reveals Al2 O3 ,Fe2 O3 ,SiO2 and TiO2 are the main components of the bauxite ores.And Al2 O3 has a negative relation-ship with Fe2 O3 and SiO2 .Trace elements such as Cr,Zr,Hf,Ta,Th,U and REE were enriched during the bauxitization process.Elements of Zr and Hf,Nb and Ta display significant correlation with each other.Studies of bivariate plots of lgCr-lgNi,immobile elements ratios such as Zr/Hf,and REE pattern suggest that the Emeishan basalts are the major source of materials for the bauxite formation.And the underlying limestones may provide some source of materials for the formation of bauxite ores.%滇东南地区晚二叠世铝土矿属典型的喀斯特型铝土矿，矿体赋存于上二叠统吴家坪组（龙潭组），分析其地球化学特征对研究其物质来源具有重要意义。全岩分析显示铝土矿石成分以Al2 O3、Fe2 O3、SiO2和TiO2为主，其中Al2 O3与Fe2 O3、SiO2具有较好的负相关关系。微量元素Cr、Zr、Hf、Ta、Th、U 和稀土元素在铝土矿矿化过程中不断富集，元素Zr－Hf、Nb－Ta之间具有明显的正相关关系。lg Cr－lg Ni图解、稳定元素比值（Zr／Hf）及稀土元素配分模式等地球化学特征说明峨眉山玄武岩为铝土矿的形成提供了主要的物质来源，同时下伏碳酸盐岩也提供了部分成矿物质。