云南丘北大铁铝土矿地球化学特征及成矿物质来源

Geochemical Characteristics and Sources of Ore-forming Metals of Datie Bauxite Deposit,Qiubei County,Yunnan Province,China

通过对丘北大铁矿区主量元素地球化学特征、微量元素地球化学特征、稀土元素地球化学特征的研究,结果表明,铝土岩的钛率与玄武岩的较接近,而与灰岩的相差较远。主量、微量元素特征研究表明,相对于灰岩,各铝土矿层与玄武岩具有较强的相关性。大铁铝土矿矿石中Al2O3/Sc,Al2O3/V,Sc/V,Sc/Nb,Sc/Ta,Nb/Ta和Zr/Hf比值与玄武岩相近,而Al2O3/Ta,Al2O3/Nb,V/Nb和V/Ta比值与灰岩较为相近,说明本区成矿物质可能具多来源特征。其中玄武岩可能为主要的成矿物质来源,灰岩提供了部分的物质来源。铝土岩的稀土配分模式及特征参数与玄武岩基本一致,仅表现为ΣREE值明显偏高,而与灰岩相差较大,且铝土岩中稀土总量ΣREE相对灰岩浓集系数K=64.86,相对玄武岩K=2.46。由此可以推断,玄武岩与铝土矿的成因关系密切,成矿物质主要来源于玄武岩。认为滇东南地区铝土矿的成矿物质具多来源特征,由于古地理位置、基底、风化剥蚀及沉积环境等的差异,导致了不同地区铝土矿亦有不同的物源供给区。

This research on geochemical characteristics of main element from Datie bauxite deposit shows that Ti content in bauxite is similar to that in basalt but very different from limestone. The geochemical characters of main elements and trace elements show that bauxite deposit has closer relation with basalt than with limestone. Values of A1203/Sc, A1203/V, Sc/V, Sc/Nb, Sc/Ta, Nb/Ta and Zr/Hf of ore from Datie bauxite deposit were close to basalt and values of A1203/Ta, AIaO3/Nb, V/Nb and V/Ta of ore were close to limestone, indicating that mineralizing materials have the characters of multifarious source, and basalt would be the main mineralizing material source and limestone provides part mineralizing materials also The rare-earth element partitioning model and its , characteristics parameter showing high value of ZREE are similar to basalt but very different from limestone. Concentrative coefficient K is 64.86 for ZREE of bauxite to ZREE of limestone but 2.46 for ZREE of bauxite to ZREE of basalt. Therefore, basalt has very close genetic relationship with bauxite and is the main source of mineralizing material of bauxite deposit. It is conSidered that mineralizing materials of bauxite in southeast Yunnan have characters of multifarious source and different bauxite deposits have different areas providing mineralizing material source because the diversity of ancient geography site, basement, weathering, denudation and sedimentary environment.