藏南查拉普金矿床载金矿物特征与金的赋存状态  

Characteristics of gold-bearing minerals and modes of occurrence of gold in Chalapu gold deposit, southern Tibet

作　　者：周天成[1] 孙祥[1,2] 郑有业[1,2,3] 吴松[1] 耿学斌[1] 于淼[1] 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]中国地质大学地质过程与矿产资源国家重点实验室,北京100083 [3]中国地质大学资源学院,湖北武汉430074

出　　处：《矿床地质》2015年第3期521-532,共12页Mineral Deposits

基　　金：中国地质调查局工作项目(编号:1212011220664);"973"国家重点基础研究发展计划(编号:2011CB403100);教育部长江学者和创新团队发展计划(编号:IRT1083)项目共同资助

摘　　要：黄铁矿和毒砂是卡林型和造山型金矿床重要的载金矿物。文章通过电子探针(EPMA)分析研究了藏南查拉普金矿床不同类型黄铁矿和毒砂中Au、As、S、Fe等元素的含量变化和分布规律,发现不同阶段的黄铁矿具有不同的结构特征和元素组成特点。沉积成岩期黄铁矿(Py1)主要呈草莓状、胶状,常构成环带状黄铁矿的核心,其中金的含量最高,显示了金在沉积成岩期的大量富集。热液期早阶段黄铁矿(Py2)主要呈自形-半自形的立方体,与Py1元素(S、Fe、As)组成相近,显示了一定的继承演化关系。热液期主阶段黄铁矿(Py3)与毒砂共生,多呈自形-半自形的五角十二面体、立方体,常包裹早期的黄铁矿形成环带结构。Py3中As的含量明显升高,其增加量近似等于S的减少量,说明As主要进入黄铁矿晶格替代了S的位置。各个阶段的黄铁矿和毒砂中Au的分布在EPMA微束的分辨率下均显示是不均匀的,Au在Py1和大部分Py2中主要以纳米级自然金(Au0)的形式存在;而在Py3中主要以(Au+)的形式存在,少部分以纳米级自然金(Au0)形式存在。Py1的结构及元素组成与典型卡林型金矿和造山型金矿沉积成岩期黄铁矿的特点相似,而Py3的大量发育则符合卡林型金矿的特征。Pyrite and arsenopyrite are important gold-bearing minerals in Carlin-type and orogenic gold deposits. In this paper the authors used electron microprobe analyzer （EMPA） to investigate the variation and distribution of Au, As, S, Fe in different types of pyrite and arsenopyrite in the Chalapu gold deposit, southern Tibet. Pyrites of different ore-forming stages have different features and element values. Py1 formed in sedimentary environment exhibit framboidal and colloidal forms and lie in the core of zoned pyrite. They have the highest content of Au, suggesting Au enrichment at the sedimentary diagenetic stage. Py2 formed at the early hydrothermal stage occur as euhedral-subhedral cube. They show similar elementary composition to Py1, suggesting an inheritance relationship. The main hydrothermal stage Py3 accompanied by arsenopyrite exhibit euhedral-subhedral tetrahedral pentagonal form and occur as outer rims of zoned pyrite. The content of As in Py3 increases rapidly and is equal to the decrement of S, indicating that As entered the crystal lattice of pyrite instead of S. The distribution of Au in all kinds of pyrites and arsenopyrites is heterogeneous under the resolution of EMPA microbeam. In pyrites formed in Py1 and Py2 Au mainly occurs as nanometer-sized particles of native Au（Au0）, in Py3 Au mostly exists as Au＋, and the rest Au is existent as Au0. The structure and composition of Py1 are similar to features of typical Carlin-type and orogenic gold deposits, and the abundance of Py3 is similar to that of the typical Carlin-type gold deposit.

关 键 词：地球化学 载金矿物 金的赋存状态 卡林型金矿 黄铁矿 毒砂 电子探针分析 查拉普金矿 

分 类 号：P618.51[天文地球—矿床学]