赣南峰山离子型稀土矿床成矿机理探讨

以赣南大埠岩体西部峰山钻孔风化壳剖面为研究对象，在风化壳剖面各层地质特征研究的基础上，对风化壳剖面各层中含稀土矿物开展了扫描电镜和电子探针分析，探讨了风化壳剖面各层主、微量（包括稀土）元素和离子相稀土元素特征。研究表明，风化壳中稀土元素呈“弓背式”分布，矿体位于风化壳剖面2~9 m，w(REE)平均为516.8×10^-6，离子相稀土元素浸出率为51%~84%，离子相与全项稀土元素总量分布特征一致。风化壳中稀土元素主要以离子吸附态形式和独立矿物（次生方铈矿和风化残余的磷钇矿、褐钇铌矿）形式存在，以离子吸附态形式为主。峰山风化壳离子吸附型稀土矿为轻、重稀土元素共生型稀土矿，以重稀土元素占主导，矿体上部相对富集轻稀土元素，下部相对富集重稀土元素。风化壳剖面中稀土元素的富集分异主要受轻重稀土元素地球化学行为的差异性、风化程度和黏土矿物含量联合控制。

Metallogenic mechanism of Fengshan ion adsorption REE deposit, southern Jiangxi Province

The representative borehole drilling through the weathering crust at Fengshan in southern Jiangxi Province is selected as the research object in this paper. Based on the geological characteristics of each layer in the weathering crust, the characteristics of major and trace elements (including rare earth) and ionic-phase rare earth elements in each layer of the weathering crust are comprehensively discussed. The rare earth-bearing minerals in each layer of the weathering crust are analyzed by scanning electron microscopy and electron probe microanalysis. The distribution of rare earth elements in the weathering crust shows an "arching" pattern. The ore body is located 2 to 9 m below the surface in the weathering crust. The average total rare earth elements (including Y) is 516.8×10^-6, the leaching rate of ionic phase rare earth elements is 51%~84%, and the distribution patterns of the ionic phase rare earth elements are consistent with those of the total phase rare earth elements. The rare earth elements in the weathering crust are in the form of ion adsorbed state and independent minerals such as secondary cerianite, residual xenotime and fergusonite, the ion adsorbed state is dominant. The Fengshan REE deposit is characterized by coexisting LREE and HREE, with a dominance of heavy rare earth elements. The upper part of the ore body is relatively enriched with LREE, and the lower part is enriched with HREE. The enrichment and differentiation of REE in weathering crust is mainly controlled by the difference of geochemical behavior of LREE and HREE, weathering degree and clay mineral content.