锡矿山锑矿床萤石稀土元素地球化学研究  

Geochemical study of REE in fluorite from Xikuangshan antimony deposit, central Hunan Province, China

作　　者：林芳梅[1] 彭建堂[1,2] 胡阿香[1] 邓穆昆 

机构地区：[1]中南大学地球科学与信息物理学院有色金属成矿预测教育部重点实验室,湖南长沙410083 [2]中国科学院地球化学研究所矿床地球化学国家重点实验室,贵州贵阳550002

出　　处：《矿物学报》2015年第2期214-220,共7页Acta Mineralogica Sinica

基　　金：国家自然科学基金项目(批准号:41272096);国土资源部公益性行业科研专项课题(200911007);中国地调局危机矿山项目(20109901)

摘　　要：湘中锡矿山锑矿是世界上最大的锑矿床,尽管前人对其进行了大量深入研究,但其矿床成因及成矿机制目前仍存有争议,本文对该矿研究程度很低的萤石的地质特征进行了总结,并对其进行了稀土元素地球化学研究。研究表明,锡矿山矿区的萤石具有较高的稀土元素含量(100.09×10-6~139.38×10-6),其标准化配分模式呈现出明显富MREE、相对富HREE、明显亏损LREE、弱负Eu异常的特征。进一步的研究表明,该区萤石中的MREE和HREE的分配行为主要是受其离子半径控制,其REE配分模式与溶液中REE络合物的稳定性关系不大;该区萤石可能形成于还原条件,为后期热液充填的产物;温度和压力的变化是导致该区萤石发生沉淀的主要原因。萤石中的Ca和F可能分别来自于围岩碳酸盐岩和深部岩浆岩。Xikuangshan antimony deposit, located in central Hunan Province, China, is the largest antimony deposit in the world. Many studies have been done on this deposit but there still exist many different opinions on its ore genesis and the metallogenic mechanisms involved. Fluorite from the Xikuangshan deposit has received little attention during the past several decades. Geological characteristics of fluorite from this deposit are described in this paper. As well, a REE geochemistry study was carried out on fluorite samples collected from the deposit. It is revealed in this study that fluorite usually contains higher REE concentrations(100.09×10-6~ 139.38×10-6). Furthermore, its normalized REE pattern is characterized by obvious LREE-depletion, MREE and HREE enrichment, and a weak negative Eu anomaly. MREE3+ and HREE3+ substituting Ca2+ into fluorite are mainly controlled by their ionic radius. Behaviour of REE distribution between fluorite and hydrothermal fluids has little relationship with the stabilities of REE complexes in the ore-forming fluid. In addition, it is concluded that the fluorite formed under a reduction condition where fluorite precipitation is predominately caused by drastic variations of temperature and pressure. Ca and F in the fluorite are likely derived from limestone and deep magmatic rocks from the mining area respectively.

关 键 词：萤石 稀土元素 成矿流体 沉淀机制 锡矿山锑矿床 

分 类 号：P618.66[天文地球—矿床学]