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    南岭东段含稀土矿花岗岩体中暗色包体地质特征—以陂头岩体为例

    Geological features of dark enclaves in REE-bearing granites in eastern Nanling: an example from the Pitou rock mass

    • 摘要: 在野外地质调查和室内综合研究的基础上,通过研究南岭东段风化壳淋积型矿中含稀土矿花岗岩层中暗色包体的地质特征,发现分布在岩体中的大量暗色包体具流面和流线构造,主要组成矿物为石英、辉石和斜长石,具典型的辉长结构。暗色包体低硅、钾和钠,高钙、铝、镁、铁、钛和锰,属亚碱性—铝不饱和型;富集U、La、Pr、Nd、Sm、Dy,亏损Nb、Sr、Zr、Hf、Ti等微量元素;REE总量低于寄主含矿花岗岩层稀土总量,Ce和Eu具有明显的负异常。这些特征说明暗色包体的原岩可能来自早期基性岩,其形成与燕山早期陂头岩体的分异演化关系密切。与南岭地区花岗岩中此类暗色包体进行对比,有助于在该区寻找稀土矿床和稀有金属矿床。

       

      Abstract: On the basis of field geological survey and indoor integrated study, this study analyzed the geological features of dark enclaves from the REE-bearing granites in weathering crust infiltration deposits in eastern Nanling. A large amount of dark enclaves in the rock mass is found to occur in platy and linear structures, and consists of quartz, pyroxene and plagioclase with typical gabbro texture. The dark enclaves are low in Si, K and Na, and high in Ca, Al, Mg, Fe, Ti and Mn, belonging to sub-alkaline-aluminum unsaturated type; enriched in U, U, La, Pr, Nd, Sm, Dy and depleted in Nb, Sr, Zr, Hf, Ti. The total REE content of dark enclaves is lower than that of host bearing granite, with obvious negative Ce and Eu anomalies. All these characteristics suggest that the protolith may originate from the early mafic rocks related to differentiation and evolution of Pitou rock mass in early Yanshanian. Comparison with dark enclaves of granites in the Nanling area will help search for rare earth deposits and rare metal deposits.

       

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