| 湘东锡田燕山期A型花岗岩黑云母矿物化学特征及其成岩成矿意义 |
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| 引用本文： | 周云,梁新权,蔡永丰,付伟.湘东锡田燕山期A型花岗岩黑云母矿物化学特征及其成岩成矿意义[J].地球科学,2017,42(10):1647-1657. |
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| 作者姓名： | 周云 梁新权 蔡永丰 付伟 |
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| 作者单位： | 1.桂林理工大学广西隐伏金属矿产勘查重点实验室，广西桂林541004 |
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| 基金项目： | 国家自然科学基金项目41503021国家自然科学基金项目41502180国土资源部公益科研专项201211024-03广西高等学校科学研究项目重点项目KY2015ZD052广西自然科学基金项目2014GXNSFAA118304桂林理工大学科研启动费资助项目002401003472广西自然科学基金项目2015GXNSFBA139204 |
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| 摘 要： | 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.
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| 关 键 词： | 黑云母 矿物成分 成岩成矿 花岗岩 锡田钨锡多金属矿床 地球化学 |
| 收稿时间： | 2017-01-16 |
Petrogenesis and Mineralization of Xitian Tin-Tungsten Polymetallic Deposit: Constraints from Mineral Chemistry of Biotite from Xitian A-Type Granite,Eastern Hunan Province |
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| Abstract: | Chemical composition of biotite is always used to reveal source characteristics, tectonic environment, late hydrothermal process and enrichment of ore-forming elements. The Xitian tin-tungsten polymetallic deposit is one of the most important polygenetic compound deposits in South China. This study presents detailed mineral composition of biotites and feldspars from Xitian granite, which is closely related to the formation of the deposit. Electron microprobe analyzer (EMPA) analysis indicates that the biotites have low MgO (0.12%-1.35%) and high FeOT (15.47%-23.24%) contents with Fe/(Fe+Mg) ratios of 0.87 to 0.99, resembling to those of siderophyllite. These features indicate that their host rocks were mainly derived from partial melting of crustal materials. Estimation results of crystallization temperatures and oxygen fugacity suggest that the Xitian granite has high crystallization temperatures and low oxygen fugacities. Therefore, it is proposed that hydrothermal fluids during the late stage of magmatic evolution are favour of Sn enrichment. These hydrothermal fluids could be an important source of ore-forming fluids. High iron indexes and crystallization temperatures and low oxygen fugacities in the ore-forming system are favorable for mineralization of Xitian tin-tungsten deposit. |
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