赣南江贝变质岩风化壳离子吸附型稀土矿床特征及成因
Characteristics and genesis of the ion adsorption REE deposit in Jiangbei metamorphic weathering crust, Southern Jiangxi Province
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摘要: 通过对赣南江贝稀土矿床进行岩相学、矿床学和地球化学研究,表明该矿床成矿母岩主要为寻乌岩组变质岩,岩性有变粒岩、片岩和片麻岩,其中云母片岩稀土元素含量最高,是最有利的成矿母岩,属轻稀土富集型母岩,是近些年新发现的1处中深变质岩风化壳离子吸附型稀土矿。矿区呈低缓丘陵地貌,风化壳平均厚度12.33 m,矿体主要赋存于全风化层中,矿体平均厚度4.68 m,SRE2O3品位0.035%~0.122%,属离子吸附型稀土矿。稀土主要来源于易风化的水磷酸盐类矿物和稀土氟碳酸盐类矿物,风化壳化学蚀变指数CIA>90%,表明了强烈的风化作用为矿床的形成创造了有利条件。会昌—安远—寻乌地区中深变质岩广泛分布,具有大型稀土矿成矿潜力。Abstract: Through the petrographic, geochemical and mineral deposit studies of Jiangbei rare earth deposit in Southern Jiangxi, the results show the metallogenic mother rocks are mainly the metamorphic rocks of Xunwu Formation complex, with the lithology of granulite, schist and gneiss, among which the mica schist with the highest content of REEs serves as the most favorable parent rock, belonging to the LREE-enriched parent rock. The orefield is a low hilly terrain with average weathering crust thickness of 12.33 m. The orebody is mainly occurred in the completely weathered layer with the average thickness of 4.68 m and SRE2O3 grade of 0.035%~0.122%, belonging the ion adsorption rare earth deposit. The rare earth mainly comes from easily weathered water phosphate minerals and rare earth fluorocarbon minerals, with the chemical alteration index of weathering crust CIA>90%, indicating that the strong weathering contributes to the formation of deposit. The Huichang-Anyuan-Xunwu area where the mesometamorphic rocks are widely distributed has metallogenic potential of large rare earth deposits.