【作者】 李帅；

【导师】 王建国；

【作者基本信息】 中国地质大学(北京) ， 矿物学、岩石学、矿床学， 2012， 硕士

【摘要】 峨眉山玄武岩广泛分布于川、滇、黔三省境内，而在滇黔交界地区，二叠世玄武岩组中广泛发育自然铜矿化现象。本次研究对象位于滇黔交界地区，通过野外观察，室内的岩石学、岩相学、岩石地球化学，同位素地球化学以及流体包裹体的研究探讨本矿区自然铜矿床的矿床特征、矿床成因问题。通过本次研究主要获得了一下几点认识：（1）本区玄武岩主要出露第二段到第四段，玄武岩中Cu含量较高，平均为287ug/g；铜矿化主要为自然铜与孔雀石矿化，热液蚀变发育，矿化主要产出在二叠世玄武岩组第三段上部与第四段中上部及与宣威组交界处，呈鸡窝状、团块状产出。（2）主量元素研究表明本区玄武岩为亚碱性-碱性的石英拉斑玄武岩，岩石中活动元素Rb强烈负异常，表明玄武岩形成后遭到了热液蚀变作用影响。（3）玄武岩铜矿石中铅同位素为：²⁰⁶Pb/²⁰⁴Pb为17.9652¹8.885，²⁰⁷Pb/²⁰⁴Pb为15.497¹5.658208，²⁰⁸Pb/²⁰⁴Pb为38.321³9.18；玄武岩中铅同位素为：²⁰⁶Pb/²⁰⁴Pb为18.228¹9.0915，²⁰⁷Pb/²⁰⁴Pb为15.528¹5.672，²⁰⁸Pb/²⁰⁴Pb为38.457³9.4112，两者铅同位素组成相似，成矿物质可能来自热液对玄武岩的淋滤。（4）研究玄武岩铜矿中的有机质以及矿石矿物和脉石矿物中的碳氧同位素13表明，矿石中的δ¹³C_PDB与自然界δ¹³C储库中生物成因的碳同位素组成相符，表明其为有机成因。进一步研究表明其可能是生物沉积后脱羟基形成，且不同矿床的碳同位素组成一致，暗示该区碳为同一来源。（5）研究矿石中石英和方解石中的流体包裹体特征及其氢氧同位素特征表明：该区成矿流体可能分为两个期次，第一期次主要为岩浆水混合少量大气降水，温度较高，平均为325.1℃，该期热液可能为有机质的形成提供了热源；第二期次主要为大气降水或盆地热卤水混合少量建造水，温度较低，平均为126.6℃。热液流体通过淬取玄武岩中的Cu并在构造有利部位沉淀成矿，有机质的还原作用及吸附作用对成矿流体的卸载成矿与成矿物质的运移均起到了积极的作用。更多还原

【Abstract】 Emeishan basalt is widely distributed in Sichuan, Yunnan and Guizhou provinces,and the one located in the Yunnan-Guizhou border area of the Permian basalt group iswidely developed in the native copper. The research object is located in theYunnan-Guizhou border region, through the outside observations, the indoor petrology,petrography, geochemistry, isotope geochemistry and fluid inclusion studies we canexplore the characteristics of natural deposits of copper deposits in this mining area.Through this study we can get a few achievements like these:（1） Explore the relationship between the Emeishan basalt and coppermineralization in this area. The Emeishan basalt in this area just outcrop the second tothe fourth paragraph, and with a higher Cu content, the average of the Cu contentcomes to287ug/g; the ore mineralization is mainly native copper and malachitemineralization, and widely development hydrothermal alteration, the mineralizationmajorly outputs in the upper part of the fourth paragraph and the third paragraph ofthe Permian basalt group, the ore shape likes a chicken coop or a massive.（2） Through the major elements study we can find that the basalt in this area aremainly the sub-alkaline—alkaline quartz tholeiite, the active elements Rb in the rockshow strongly negative anomalies, this indicates that the basalts was intense affectedby the hydrothermal alteration.（3） The lead isotope of the ore shows like this:²⁰⁶Pb/²⁰⁴Pb swings in the range of17.9652¹8.885,²⁰⁷Pb/²⁰⁴Pb swings in the range of15.497¹5.658,²⁰⁸Pb/²⁰⁴Pbswings in the range of38.321³9.18；and the lead isotope of the basalt shows like this:²⁰⁶Pb/²⁰⁴Pb swings in the range of18.228¹9.0915,²⁰⁷Pb/²⁰⁴Pb swings in the range of15.528¹5.672,²⁰⁸Pb/²⁰⁴Pb swings in the range of38.457³9.4112. Both lead isotopiccomposition is very similar to each other, this phenomenon shows that themetallogenic material probably come from leaching that hydrothermal leaching doingto the basalt.（4） By studying the organic matter’s carbon and oxygen isotopes that in thebasalt copper ore minerals and the ore minerals and gangue minerals’ carbon andoxygen isotopes of the ore, we found that the constitute of13δCPDBin ore are similarwith the constitute of biogenic13C in the nature, this conclusion shows that the carbonin the ore is organic causes. By further studies, it shows that it maybe come from thedehydroxylation of biological deposition, and different deposits’ carbon isotopic havethe similar composition, which suggest that the carbon of this area have the same source.（5） By the studying of the hydrogen and oxygen isotopes in the quartz andcalcite’s fluid inclusions in the ore, we can see that there is two stages to theore-forming fluids. To the first phase, the ore-forming fluids maybe consist ofmagmatic water and few amount of atmospheric precipitation water, which with ahigher temperature and to the second phase, the ore-forming fluids maybe consist ofhot brine mixing a small amount of the construction of water, which with a lowertemperature, and this phase there should have the organic fluid join in the ore-formingfluids, too. The hydrothermal fluids dissolved Cu from the basalt and deposited the Cuelement in the right position. In this progress, the organic matter can give a restoreenvironment to the ore-forming fluids and its adsorption can give a important hand tothe deposited of the Cu element.更多还原