豫西萑香洼金矿地质与成矿流体地球化学

发布时间：2019-01-26 14:07

【摘要】：豫西萑香洼金矿是小秦岭-熊耳山金矿集中区最具代表性的蚀变岩-石英脉复合型金矿床之一。该矿成矿条件优越,找矿潜力较大。本文通过野外调查与室内分析研究,查明了萑香洼金矿矿床地质和成矿流体地球化学特征,探讨了萑香洼金矿成矿过程。根据矿石中金属硫化物类型、矿物共生组合和结构构造特征,可将豫西萑香洼金矿矿石分为蚀变岩型和石英脉型两种。蚀变岩型矿石具有交代结构,组成矿物主要是钾长石、黄铁矿、石英和绢云母。石英脉型矿石具有热液充填结构,组成矿物主要是石英和黄铁矿。野外调查与镜下观察发现,萑香洼金矿床的围岩蚀变和矿化存在明显的空间分带,从矿体向两侧依次出现黄铁绢英岩化带、黄铁钾硅化带、青磐岩化带和新鲜围岩。根据矿脉穿插关系和蚀变矿物组合,将豫西萑香洼金矿床蚀变矿化过程分为热液期和表生期,其中热液期又可进一步分为钾长石化、石英-黄铁矿、石英-多金属硫化物、萤石-多金属硫化物和碳酸盐化五个阶段。石英-黄铁矿阶段是次要成矿阶段,在这一阶段形成了石英脉型矿石,而石英-多金属硫化物阶段是最主要的成矿阶段,在这一阶段形成了最重要的蚀变岩型金矿石。流体包裹体镜下观察与分析测定结果表明,萑香洼金矿床矿物流体包裹体主要有Na Cl-H2O、含二氧化碳和含子晶多相包裹体,不同阶段成矿流体分别属于挥发分-盐水和氯化钠-水体系。从早期的钾长石化阶段到晚期的碳酸盐阶段,成矿流体的温度和盐度总体上逐渐降低,δ18O和δD逐渐减小,表明成矿流体中的天水热液逐渐增多。根据已经获得的矿床地质和流体地球化学资料,认为在萑香洼金矿床蚀变矿化过程中,钾长石化阶段的降温冷却使金在成矿流体中初步富集,而石英-黄铁矿阶段的脱气作用、石英-多金属硫化物阶段的水岩反应和萤石-多金属硫化物阶段的流体不混溶作用使金从成矿流体中沉淀出来而形成不同类型金矿石。
[Abstract]:Huanxiangwa gold deposit is one of the most representative altered rock-quartz vein complex gold deposits in the Xiaoqinling-Xiong 'ershan gold deposit concentration area. The ore-forming conditions are superior and the prospecting potential is great. Based on field investigation and laboratory analysis, the geological and ore-forming fluid geochemical characteristics of Huanxiangwa gold deposit are investigated, and the metallogenic process of Huanxiangwa gold deposit is discussed. According to the types of metallic sulphide mineral symbiotic assemblages and structural characteristics Huanghuangwa gold ore can be divided into altered rock type and quartz vein type. Altered rock type ores have metasomatic structure, mainly composed of potassium feldspar, pyrite, quartz and sericite. Quartz vein type ores have hydrothermal filling structure, and the main minerals are quartz and pyrite. Field investigation and microscopic observation show that the wall rock alteration and mineralization of Huanxiangwa gold deposit have obvious spatial zonation, and from the ore body to the two sides, there are yellow iron sericite zone, Huang Tie potassium silicification zone, Qingwangyan zone and fresh surrounding rock in turn. According to the interpenetrating relation of vein and altered mineral assemblage, the alteration and mineralization process of Huexiangwa gold deposit in western Henan is divided into hydrothermal period and epigenetic stage, in which the hydrothermal period can be further divided into potassium feldspar, quartz pyrite, quartz polymetallic sulfide, etc. Fluorite-polymetallic sulphide and carbonation are five stages. The quartz-pyrite stage is a secondary metallogenic stage, in which quartz vein type ore is formed, while quartz polymetallic sulfide stage is the most important metallogenic stage, in which the most important altered rock type gold ore is formed. The results of observation and analysis of fluid inclusions under microscope indicate that the main mineral fluid inclusions in Huanghuangwa gold deposit are Na Cl-H2O, containing carbon dioxide and sub-crystalline polyphase inclusions. The ore-forming fluids in different stages belong to volatile saltwater and sodium chloride-water systems respectively. The temperature and salinity of the ore-forming fluid gradually decreased, and 未 18O and 未 D gradually decreased from the early stage of potash petrifaction to the late stage of carbonate, indicating that the hydrothermal fluid in the ore-forming fluid increased gradually. Based on the obtained geological and fluid geochemical data of the deposit, it is considered that in the process of alteration and mineralization of Huanxiangwa gold deposit, the cooling and cooling of the stage of potassium feldspathitization lead to the preliminary enrichment of gold in the ore-forming fluid, and the degassing of quartz to pyrite stage. The water-rock reaction in quartz-polymetallic sulphide stage and fluid immiscible in fluorite-polymetallic sulfide stage resulted in the precipitation of gold from the ore-forming fluid and the formation of different types of gold ores.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.51

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