湘西沃溪金锑钨矿床中白钨矿的稀土元素地球化学  

Rare earth element (REE) geochemistry for scheelite from the Woxi Au-Sb-W deposit, western Hunan

作　　者：彭建堂[1] 胡瑞忠[1] 赵军红[1] 符亚洲[1] 袁顺达[1] 

机构地区：[1]中国科学院地球化学研究所,贵州贵阳550002

出　　处：《地球化学》2005年第2期115-122,共8页Geochimica

基　　金：国家自然科学基金(40472053);中国科学院"西部之光"人才培养计划项目;中国科学院知识创新工程重要方向项目(KZCX3-SW-125)~~

摘　　要：对湘西沃溪金锑钨矿床进行了研究,结果表明,该矿床中白钨矿的稀土元素(REE)含量相对较高,为40.5～123.6μg/g;且有明显的空间变化趋势,随矿区标高的增加而减少,这可能与流体运移过程中流体的REE浓度不断降低有关。不同产状的白钨矿均以轻稀土元素(LREE)亏损、中稀土元素(MREE)和重稀土元素(HREE)富集为特征;白钨矿样品的REE分布模式均存在着明显的M型四分组效应,暗示白钨矿的形成与流体作用或水/岩反应有关。进一步的研究表明,在沃溪白钨矿的沉淀过程中,成矿流体中的REE发生了明显分异,白钨矿对HREE,特别是MREE,具有明显的优先选择性;REE这种分配行为主要是受晶体化学因素的控制,与白钨矿晶体中Ca位置的大小密切相关,而与成矿流体中REE相对浓度、REE络合物的稳定性关系不大。Hunan is an important Au-, Sb-and W-producer in China. The gold, antimony, tungsten deposits are widespread in western Hunan, and the Woxi Au-Sb-W deposit is the largest in this region. The Woxi deposit was found in 1875 and began to mine in 1895. Due to the characteristic element association and a lasting mining history, the Woxi deposit is famous and attracts a lot of geologists. In spite of previous detailed researches on geological feature, ore genesis, fluid inclusion, stable isotope, ore fabric, ore-controlling tectonic and mineralogy, few attempts have made to study the widespread mineral scheelite in this deposit. The objectives of this contribution are to investigate the rare earth elements of scheelites in the Woxi Au-Sb-W deposit, and attempt to provide some constraints on the REE distribution behavior between scheelite and ore-forming fluid in this deposit. All samples were decomposed through the acid dissolution+alkaline fusion digestion, and analyzed by the ICP-AES method at the Wuhan Analysis Center of Rocks and Minerals, Hubei Province. It is revealed that scheelite samples from this deposit contain considerable concentrations of rare earth elements, with the total REE contents in the range of 40.5 to 123.6 μg/g, and there exists an obvious spatial tendency for REE concentrations in scheelite, i.e. the total REE contents decrease with an increasing elevation in the Woxi mining district, which may be ascribed to a decrease in the total REE concentrations of the ore-forming fluid during transport. All scheelite samples are characterized by MREE-and HREE-enriched, LREE-depleted pattern; the M-type tetrad effect, upward convex curve in REE pattern is observed in all samples, which reveals that fluid effect or water-rock interactions is responsible for scheelite precipitation in the mining district. There exists an obvious fractionation for rare earth elements during scheelite precipitation in the Woxi Au-Sb-W deposit, HREE, especially MREE preferentially incorporate into scheelite lattices by substit

关 键 词：白钨矿 稀土元素 四分组效应 沃溪金锑钨矿床 湖南省 

分 类 号：P595[天文地球—地球化学]