安徽省东源斑岩型钨矿床白钨矿原位微量元素特征及其指示意义

新兴的白钨矿面扫描技术对于解释矿物微量元素特征具有重要的指示意义。文章选择皖南地区东源斑岩型钨矿床中白钨矿为研究对象,利用面扫描和阴极发光图像技术对矿物微区结构和原位微量元素特征进行系统研究。分析结果显示,白钨矿具有核边结构且微量元素特征具有明显的分带性,同一白钨矿颗粒核部亏损Mo、Nb、Ta元素,富集REEs,而边部相反。在此基础上,文章通过系统的白钨矿单点微量元素分析,反演了成矿流体性质和演化过程,提出东源钨矿床成矿流体氧逸度逐渐增高,成矿流体富集F挥发分且F含量逐渐增加,成矿物质很可能有幔源组分加入。通过白钨矿面扫描和阴极发光图像查明矿物微区结构,进而开展了白钨矿微区微量元素单点分析,有可能对成矿流体和矿质来源作出合理的解释。

Scheelite trace element compositions from Anhui Dongyuan porphyry deposit: Implications for tungsten mineralization

The burgeoning technology of scheelite mapping image is of great significance to explain the characteristics of mineral trace elements. The Dongyuan tungsten deposit, located in southern Anhui Province, is currently the largest W deposit in this region. Based on geological characteristics of the deposit, we carried out the systematical study of cathodeluminescence and LA-ICP-MS analyses in scheelite. We combine the mapping image and cathodeluminescence to divide the scheelite into two zones and illuminate the characteristics of ore-forming fluid and source. The results show two zones of scheelite in the deposit have been distinguished. The distribution of Mo, Nb and Ta strongly follows zonation, with high contents in the rim and low contents in core. By using the different trace elements of core and rim from Dongyuan scheelite, we concluded that the oxygen fugacity of ore-forming fluid increasing, the partition coefficient of REE deduced and the fluid is full of fluorine volatile. Both core and rim trace elements shown that the mantle material is probably contribution to Dongyuan deposit. We hold that mapping and cathodeluminescence images of scheelite are necessary before we elucidate the characteristic of oreforming fluid and the source of metal. Overall, we proposed that the image of scheelite is quite important and should mapping before analyzing the trace element of scheelite.