南秦岭金龙山金矿床中砷的赋存特征及其对金沉淀的影响  

Mode of occurrence of arsenic and its influence on the precipitation of gold in the Jinlongshan gold deposit,southern Qinling

作　　者：杨永春[1,2] 刘家军[1,3] 刘新会[4] 吴胜华[1] 

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]甘肃地矿局第四地质矿产勘查院,甘肃酒泉735000 [3]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 [4]中国人民武装警察部队黄金第五支队,陕西西安710100

出　　处：《中国地质》2011年第3期701-715,共15页Geology in China

基　　金：国家自然科学重点基金(41030423);国家自然科学基金(40973035;40773036);教育部长江学者和创新团队发展计划(IRT0755);高等学校学科创新引智计划(B07011);中国地质大学(北京)地球科学与资源学院本科生优秀论文资助计划资助

摘　　要：金龙山金矿床位于南秦岭印支褶皱带镇安—旬阳盆地内,是20世纪80年代末发现的一个超大型微细浸染型金矿床。矿床赋存于上泥盆统南阳山组和下石炭统袁家沟组,为一套由钙质粉砂岩、粉砂质页岩、粉砂质灰岩、泥质灰岩互层组成的浊积岩建造。矿体受断裂控制明显。笔者采用显微镜观察、电子探针、扫描电镜等分析技术,对原生矿石中黄铁矿、毒砂等热液矿物中的Fe、As、S等元素含量及其分布进行了系统研究。结果显示,低含量的砷在黄铁矿中易富集,且砷在黄铁矿中可以稳定存在。但当砷含量大于6%时,以黄铁矿和毒砂两相混合为稳定相。赋矿围岩中含Fe碳酸盐矿物溶解释放Fe以及溶解Fe的大量硫化物化,部分亚稳定相含金的含砷黄铁矿的出溶,可能是金龙山金矿中次显微金以小圆球状和链状存在的一个重要因素。Located in Zhen＇an-Xunyang basin of southern Qinling Mountains,the Jinlongshan gold deposit is a superlarge Carlin-type disseminated gold deposit discovered in the 1980＇s.The ore deposit occurs in Upper Devonian and Lower Carboniferous clastic and carbonate strata composed of calcareous siltstone,silty shale,silty limestone and argillaceous limestone intercalated with flyschoid formation.Ore bodies are strictly controlled by fault zones.Ores were examined by such means as optical microscope,electron microprobe analyzer（EMPA） and X-ray surface scanning for the purpose of probing into the content and distribution of Fe,As and S in arsenian pyrite and arsenopyrite in primary ore samples from the Jinlongshan ore deposit.The results show that As of low content is likely to be concentrated in pyrite,and As in pyrite is stable.When the As content is higher than ~6 wt%,two-phase mixtures of pyrite and arsenopyrite are stable.The dissolution of ferruginous limestone in the host rocks,the sulfidation of the dissolved iron by H2S,and the exsolution of partial metastable auriferous arsenian pyrite may provide favorable conditions for gold precipitation in the Jinlongshan gold deposit.

关 键 词：金矿床 地质特征 砷的赋存形式 金沉淀 金龙山 

分 类 号：P618.51[天文地球—矿床学]