贵州戈塘金矿萤石微量元素特征及钐—钕测年

对与戈塘金矿共生的萤石微量元素特征研究表明:萤石中Mo,W,As,Cd,Bi等高温元素含量均高于地壳值,V,Cr,Cu,Cs,Th,Mo,Ga和Ge等元素变异系数大,活化能力强。萤石的稀土总量很低,仅为10.299×10-6～17.455×10-6,明显富集重稀土(LREE/HREE为0.48～0.69),并具有Eu和Ce的负异常(δEu为0.71～0.91,δCe为0.62～0.78),Tb/Ca-Tb/La图解显示萤石为热液成因且为热液的晚期阶段。萤石的Rb/Sr比值和初始87Sr/86Sr比值均与地幔值较为接近,反映出其成矿流体主要来源于上地幔或(岩浆)深部。萤石的形成经历了长期演化的热液活动,成矿温度较低(<200°～250°),成矿年龄为(35.83±0.37)Ma(Sm-Nd等时线年龄)。

Trace Element Characteristics of Fluorite and Its Sm-Nd Isotopic Dating in Getang Gold Deposit,Guizhou Province

Trace element characteristics of symbiotic fluorite with Getang gold deposit have shown that: Its high-temperature element (including Mo, W, As, Cd, Bi, etc.) have higher contents than the crustal values. Those elements (including V, Cr, Cu, Cs, Th, Mo, Ga, Ge, etc.) have bigger coefficient of variation and strong activation energy. Fluorite’s total REE is low, only 10.299×10^-6~17.455×10^-6, and enrichment of heavy rare earth is obvious (LREE/HREE is 0.48-0.69), and have negative anomalies of Eu and Ce (δEu=0.71-0.91，δCe=0.62-0.78). The Tb/Ca vs. Tb/La diagram shows that fluorite is hydrothermal and is in its late stage. Rb/Sr ratios of fluorite and its initial ⁸⁷Sr/⁸⁶Sr ratios are closer to the mantle value, which reflect that its ore-forming fluids are from the upper mantle or (magma) deep. The formation of fluorite experienced a long-term evolution of the hydrothermal activity, lower ore-forming temperature (<200°~250°), and mineralization age is 35.83±0.37 Ma (Sm-Nd isochron age)