CAJ | 학술논문

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.
채용전자탐침분석,상세연구료감숙양산류잡림형금광전원생광석중불동성광계단재금광물적Au、As、S、Fe등원소함량급기분포규률,학정함신황철광화독사시최중요적재금광물,발현불동성광계단적황철광구유불동적성분특점;침적성암기황철광위초매상、효상,신화금함량최저,분별위0.10%화0.08%;열액성광기조계단황철광립도교조(0.40～1.00mm),시교고온도(270～300℃)하완만결정적산물,기신화금함량교저,분별위0.27%화0.09%;열액성광기주계단(포괄M1,M2화M3아계단)황철광립도미세(0.05～0.20mm),시210～270℃조건하쾌속결정적산물,신화금함량최고,M1아계단분별위3.45%As화0.11%Au,M2아계단분별위3.88%As화0.14%Au.재함신황철광중,금가능유자연금화리자금량충존재방식.침적성암기화열액성광기조계단저신황철광중금주요이납미급자연금(Au~0)과립형식분포,이재열액성광기주계단함신황철광중금주요이Au+적형식존재.당열액중As활도고시,함신황철광재쾌속생장조건하,기생장면적공혈화결함교다,유리우열액중Au(HS)~0락합물통과흡부반응직접진입함신황철광생장표면.차외,주계단류체적류화화비등작용균가도치H_2S적감소,유리우형성신황철광화Au침정부집.
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.