【摘要】 上寨矿床为华南地区新发现的一个同时富含轻重稀土的离子吸附型稀土矿床,矿体位于粗粒黑云母花岗岩风化壳中。褐帘石是粗粒黑云母花岗岩中一种重要的副矿物（占比约为0.11%）。化学成分分析结果显示原生褐帘石具有富轻稀土元素的特征,其轻稀土（LREE）和重稀土元素（HREE）含量以及（La/Yb）_N值分别为177940～188928μg/g、3732～5499μg/g和92.6～153。这些原生褐帘石轻稀土元素含量约占全岩轻稀土元素总量的86%,为上寨矿床轻稀土元素的主要来源。通过显微观察结合背散射图像可以发现,上寨矿床成矿母岩中的原生褐帘石被热液流体交代后蚀变形成了氟碳钙铈矿,在这个过程中褐帘石中的轻稀土和Ca元素被淋滤出来后主要进入了氟碳钙铈矿中,指示褐帘石被交代形成氟碳钙铈矿的过程中轻稀土元素发生了活化、迁移和富集。另外,被交代的褐帘石其Fe₂O₃^T、MnO和MgO含量降低,而Sr、Y、Nb、W、Th、U、Zr以及HREE含量增加,这些增加的HREE可能来源于热液流体或其他富HREE的原生矿物。本研究表明,原生褐帘石被热液流体交代有利于轻稀土元素的富集成矿,但对重稀土矿化的贡献较小。更多还原

【Abstract】 The Shangzhai deposit in South China is a newly discovered ion-adsorption rare earth element（REE） deposit with both LREE and HREE mineralization. The ore body occurs in the weathered coarse-grained biotite granite（CGBG）.Allanite is an important accessory mineral in the CGBG with a volume proportion of about 0.11%. Geochemical results show that magmatic allanite is characterized by enrichment of LREE with LREE, HREE, and（La/Yb）_N ranging from 177940 μg/g to 188928 μg/g, 3732 μg/g to 5499 μg/g, and 92.6 to 153, respectively. The LREE of magmatic allanite accounts for about 86% of the total LREE of the CGBG and is the most important source of LREE at Shangzhai. Photomicrographs and BSE images show that the magmatic allanite grains in the CGBG have been replaced by hydrothermal synchysite-（Ce）.During the magmatic hydrothermal alteration, LREE and Ca released from the allanite were mostly scavenged by synchysite-（Ce）, indicating remobilization and enrichment of LREE. Meanwhile, the Fe₂O₃^T, MnO, and MgO contents of the magmatic allanite also decreased during the replacement process, whilst the Sr, Y, Nb, W, Th, U, Zr, and HREE contents increased,of which the increased HREE contents were sourced from the magmatic-hydrothermal fluid or other HREE-rich minerals.Above all, the interaction between magmatic allanite and hydrothermal fluid and the formation of synchysite-（Ce） contributed significantly to the LREE mineralization and much less significantly to the HREE mineralization in the Shangzhai deposit.更多还原