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黑云母的化学组成特征对揭示花岗岩的源区特征、形成环境、后期热液作用以及成矿元素富集特征具有重要的指示意义.对与锡田钨锡多金属矿床成矿作用密切相关的锡田燕山早期花岗岩黑云母和长石成分进行了系统的电子探针分析.分析结果表明,黑云母具有富铁贫镁、高铝低钠的特征,其MgO和FeOT含量分别为0.12%~1.35%和15.47%~23.24%,类似于高铁黑云母;其含铁指数Fe/(Fe+Mg)较高,集中在0.87~0.99,属于铁叶云母;其长石主要以正长石和钠长石为主.这些特征暗示了寄主岩石源区以壳源为主.结合相关区域地质资料,表明锡田燕山早期花岗质岩浆具有较高的温度和较低的氧逸度.黑云母具有高的含铁指数、较高的结晶温度和低的氧逸度等特征均有利于锡成矿,可以作为勘探锡矿的标志之一.综合分析认为,在锡田花岗质岩浆演化过程中,岩浆结晶期后分异出的流体趋向于向富锡的方向演化,是锡田多金属矿床成矿流体的重要来源.
The chemical composition of biotite is of great significance in revealing the characteristics of source area, forming environment, late hydrothermal fluids and enrichment characteristics of mineralization elements.It is concluded that the biotite Tian Yanshan Early granite biotite mica and feldspar components of the electronic probe analysis.The results show that the biotite has the characteristics of iron-poor magnesium, high aluminum and low sodium, the MgO and FeOT content of 0.12% to 1.35% And 15.47% ~ 23.24%, respectively, similar to that of high-speed iron biotite. The Fe / (Fe + Mg) is higher in iron concentrates ranging from 0.87 to 0.99 and belongs to iron micas. These characteristics imply that the host rock source area is dominated by the crust.Combining with the geological data of the relevant areas, it indicates that the early granitic magmatic rocks in the Yantian Early Stage have higher temperature and lower oxygen fugacity.The biotite has high content of The characteristics of iron index, high crystallization temperature and low oxygen fugacity are all favorable to tin mineralization and can be used as one of the symbols of tin exploration.A comprehensive analysis shows that during the evolution of the Xitian granitic magma, the magma crystallization After the period of separation of the fluid tend to rich tin The direction of the evolution of tin-tin polymetallic deposits is an important source of fluid.