Characteristics of gold-bearing mineral and occurrence of gold in the Yangshan gold field, Gansu Province.

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...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 An (0.08%); and the coarse-grain pyrite (0.40 similar to 1.00mm) formed in early-stage hydrothermal metallogenesis, which were crystallized slowly at relatively high temperature (270 similar to 300 degrees C), is the next, with As and Au contents of 0.27% and 0.09%, respectively. The Fine-grain arsenian pyrite (0.05 similar to 0.20mm) rapidly precipitated in middle (main) hydrothermal stage at temperature of 210 similar to 270 degrees C, contains maximum As and An (3.45% As and 0.11% An 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 (An(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(2)S during sulifidation and fluid-boiling causes gold deposition and formation of arsenian pyrite in the main hydrothermal stage.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000273455000008&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701SCI(E)中文核心期刊要目总览(PKU)中国科技核心期刊(ISTIC)中国科学引文数据库(CSCD)12112776-27902