投稿时间：2020-07-09
修订日期：2021-04-22
网络发布日期：2021-07-12
中文摘要:文章在野外地质勘查、研究的基础上，系统介绍了三官庙金矿床基本地质特征。通过系统的光学显微镜、扫描电镜观察，将三官庙金矿床热液期成矿阶段划分为成矿早阶段（S1）、主阶段（S2）和晚阶段（S3），主阶段形成大量硫化物及方解石石英脉（团块），并形成金矿化；载金硫化物主要为毒砂、黄铁矿，均为同一世代，形成环境条件稳定，总体与金同时生成。利用电子探针（EPMA）对载金硫化物进行分析，结合元素面扫描成像，认为三官庙金矿石中“不可见金”普遍分布于黄铁矿、毒砂等硫化物中，在黄铁矿中主要以超显微包裹的纳米金形式存在，在毒砂中以固溶体金形式存在。三官庙金矿床热液黄铁矿电子探针（EPMA）分析具有较高的Co/Ni比值，在As-Co-Ni微量元素图解中位于岩浆热液区，这些特征指示黄铁矿为岩浆热液成因；依据金矿石、围岩、钠长角砾岩全岩稀土元素数据，认为三官庙金矿床矿石显示了对钠长角砾岩稀土元素特征的继承演化，说明二者之间具有成因联系；Au/Ag比值、热液硫化物共生组合、毒砂标型特征等表明三官庙金矿床成矿主阶段流体性质为碱性，氧逸度logfO2<-28.5、硫逸度logf（S2）平均-8.4，毒砂温度计计算成矿温度约350℃。综合地质、地球化学特征认为，三官庙金矿床成因类型为与钠长岩相关的受断裂构造控制的岩浆热液型金矿床。
Abstract:Based on field geological exploration and research, this paper systematically describes the basic geological characteristics of the San’guanmiao gold deposit. According to the systematic observation with optical microscope and scanning electron microscope (SEM), the hydrothermal metallogenic stage of the San’guanmiao gold deposit is divided into pre-ore stage (S1), main-ore stage (S2) and post-ore stage (S3). Massive sulfide and calcalite quartz veins were formed in the main stage with gold mineralization. The gold-bearing sulfides are mainly arsenopyrite and pyrite, which are of the same paragenesis and were formed under stable environmental conditions and at the same time as gold. Based on the electron probe micro analysis (EPMA) results of gold-bearing sulfides and the scanning images, the authors hold that "invisible gold" in the San’guanmiao gold deposit is widely distributed in pyrite, arsenopyrite and other sulfides, "invisible gold" mainly exists as nanoparticles in pyrite, and there exists solid solution in arsenopyrite. The hydrothermal pyrite in the San’guanmiao gold deposit has a high Co/Ni value and is located in the magmatic hydrothermal region on the ternary diagram of As-Co-Ni. It is indicated that pyrite is of magmatic hydrothermal origin. Based on REE concentrations of ores, albitite-breccias and wall rocks of the San’guanmiao gold deposit, it is considered that the ore shows the inheritance and evolution from albitite-breccia and, meanwhile, indicates the genetic relationship between the deposit and albitite-breccia. According to the Au/Ag value, hydrothermal sulfide association combination, and typomorphic characteristics of arsenopyrite, the authors consider that the fluid properties of the main metallogenic stage are alkaline, oxygen fugacity logf(O2)<-28.5, and average of sulfur fugacity logf（S2）=-8.4. The mineralization temperature calculated with the arsenopyrite thermometry is about 350℃. Based on the comprehensive geological and geochemical characteristics, the authors have reached the conclusion that the San’guanmiao gold deposit is a magmatic hydrothermal deposit, which is controlled by fault structures and genetically related to albitite(-breccia).
keywords:geochemistry electron probe micro analysis (EPMA) modes of occurrence of gold genesis San’guanmiao gold deposit
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基金项目:本文得到中国地质调查局“矿集区矿产调查和深部找矿预测”项目（编号：DD2019057018）、陕西省地勘基金项目（编号：61201707317）和国家自然科学基金面上项目（编号：41872219）联合资助
引用文本：
汪超,王瑞廷,刘云华,薛玉山,胡西顺,牛亮.2021.陕西商南三官庙金矿床地质特征、金的赋存状态及矿床成因探讨[J].矿床地质,40(3):491~508WANG Chao,WANG RuiTing,LIU YunHua,XUE YuShan,HU XiShun,and NIU Liang.2021.Geological characteristics, modes of occurrence of gold and genesis of San’guanmiao gold deposit, Shangnan, Shaanxi Province[J].Mineral Deposits40(3):491~508
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