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| 甘肃阳山金矿田载金矿物特征及金赋存状态研究 | |
| 引用本文： | 毛世东,杨荣生,秦艳,郭俊华.甘肃阳山金矿田载金矿物特征及金赋存状态研究[J].岩石学报,2009,25(11):2776-2790. |
| 作者姓名： | 毛世东 杨荣生 秦艳 郭俊华 |
| 作者单位： | 1. 中国科学院广州地球化学研究所,成矿动力学重点实验室,广州,510640;中国人民武装警察部队黄金第十二支队,成都,610036;中国科学院研究生院,北京,100049 2. 北京大学造山带与地壳演化重点实验室,北京,100871 3. 中国科学院广州地球化学研究所,成矿动力学重点实验室,广州,510640 4. 中国人民武装警察部队黄金第十二支队,成都,610036 |
| 基金项目： | 国家973项目，国家自然科学基金项目，国家危机矿山项目，科学院百人计划项目和武警黄金部队科研项目资助 |
| 摘 要： | 采用电子探针分析,详细研究了甘肃阳山类卡林型金矿田原生矿石中不同成矿阶段载金矿物的Au、As、S、Fe等元素含量及其分布规律,确定含砷黄铁矿和毒砂是最重要的载金矿物,发现不同成矿阶段的黄铁矿具有不同的成分特点;沉积成岩期黄铁矿为草莓状、胶状,砷和金含量最低,分别为0.10%和0.08%;热液成矿期早阶段黄铁矿粒度较粗(0.40～1.00mm),是较高温度(270～300℃)下缓慢结晶的产物,其砷和金含量较低,分别为0.27%和0.09%;热液成矿期主阶段(包括M1,M2和M3亚阶段)黄铁矿粒度微细(0.05～0.20mm),是210～270℃条件下快速结晶的产物,砷和金含量最高,M1亚阶段分别为3.45%As和0.11%Au,M2亚阶段分别为3.88%As和0.14%Au.在含砷黄铁矿中,金可能有自然金和离子金两种存在方式.沉积成岩期和热液成矿期早阶段低砷黄铁矿中金主要以纳米级自然金(Au~0)颗粒形式分布,而在热液成矿期主阶段含砷黄铁矿中金主要以Au+的形式存在.当热液中As活度高时,含砷黄铁矿在快速生长条件下,其生长面的空穴和缺陷较多,有利于热液中Au(HS)~0络合物通过吸附反应直接进入含砷黄铁矿生长表面.此外,主阶段流体的硫化和沸腾作用均可导致H_2S的减少,有利于形成砷黄铁矿和Au沉淀富集. |
| 关 键 词： | 载金矿物 金赋存状态 电子探针分析 含砷黄铁矿 毒砂 阳山金矿田 |
Characteristics of gold-bearing mineral and occurrence of gold in the Yangshan gold field, Gansu Province |
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| MAO ShiDong,YANG RongSheng,QIN Yan,GUO JunHua.Characteristics of gold-bearing mineral and occurrence of gold in the Yangshan gold field, Gansu Province[J].Acta Petrologica Sinica,2009,25(11):2776-2790. | |
| Authors: | MAO ShiDong YANG RongSheng QIN Yan GUO JunHua |
| Abstract: | In this paper we use electron microprobe analyzer(EMPA)to insight the distribution and concentration of gold,arsenium,sulfur,iron in the gold-bearing minerals of different ore-forming stages of the Yangshan Carlin-like gold field,Gansu province,China.Arsenian pyrite and arsenopyrite are recognized as the most important gold-bearing minerals in this deposit.Pyrites of different ore-forming stages have distinct features and element contents.The framboidal and colloidal pyrite formed in sedimentary diagenesis have the lowest contents of As(0.10%)and Au(0.08%);and the coarse-grain pyrite(0.40～1.00mm)formed in early-stage hydrothermal metallogenesis,which were crystallized slowly at relatively high temperature(270～300℃),is the next,with As and Au contents of 0.27% and 0.09%,respectively.The fine-grain arsenian pyrite(0.05～0.20mm)rapidly precipitated in middle(main)hydrothermal stage at temperature of 210～270℃,contains maximum As and Au(3.45% As and 0.11% Au for M1 substage;and 3.88% As and 0.14% Au for M2 substage).In As-poor pyrites formed in sedimentary diagenesis and early hydrothermal stage gold mainly occurs as nanometer-sized particles of native Au(Au~0),whereas gold in middle-stage arsenian pyrite mainly presents as Au+.Because of the absorption of S-bearing Au complex(Au(HS)~0)on pyrite,the content of Au+in arsenian pyrite has a strong dependence on the availability of vacant sites and/or defects on the surface,which results from the increase of As activity.The loss of H_2S during sulifidation and fluid-boiling causes gold deposition and formation of arsenian pyrite in the main hydrothermal stage. |
| Keywords: | Gold-bearing mineral Gold occurrence EMPA Arsenian pyrite Arsenopyrite Yangshan gold field |
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