湖南通道地区金矿床成矿流体特征及成矿物质来源:来自流体包裹体、H-O-S同位素的证据  

Ore-forming Fluid Characteristics and Material Source of Gold Deposits in Tongdao County,Hunan Province:Evidence from Fluid Inclusions and H-O-S Isotopes

作　　者：谢玉华 高华 张哲 杨亮 柯新星 刘晓敏 罗建镖 刘琦[2,3] 许坤林 刘继顺 王智琳[2,3] 孔华[2,3] 刘飚[2,3] XIE Yuhua;GAO Hua;ZHANG Zhe;YANG Liang;KE Xinxing;LIU Xiaomin;LUO Jianbiao;LIU Qi;XU Kunlin;LIU Jishun;WANG Zhilin;KONG Hua;LIU Biao(301 Brigade,Hunan Nuclear Industry Geological Bureau,Changsha 410114,Hunan,China;Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring,Ministry of Education,Central South University,Changsha 410083,Hunan,China;School of Geoscience and Info-physics,Central South University,Changsha 410083,Hunan,China)

机构地区：[1]湖南省核工业地质局三〇一大队,湖南长沙410114 [2]中南大学有色金属成矿预测与地质环境监测教育部重点实验室,湖南长沙410083 [3]中南大学地球科学与信息物理学院,湖南长沙410083

出　　处：《黄金科学技术》2021年第1期74-89,共16页Gold Science and Technology

基　　金：湖南省核工业地质局科研项目“雪峰弧形带西南段金、锑矿成矿条件分析及找矿前景研究”(编号:KY2018-301-01)资助。

摘　　要：通道地区金矿床位于雪峰弧形金锑矿带西南段,主要包括茶溪、金坑和黄垢3个中小型金矿床,矿脉发育在前寒武系浅变质地层中,受断裂控制明显,矿石类型为石英脉型与蚀变岩型。通过野外地质调查、显微鉴定、流体包裹体测试及H、O、S同位素分析,对成矿流体特征与成矿物质来源进行约束。分析结果表明:成矿过程主要划分为2个阶段,一是石英+黄铁矿+毒砂+绢云母+金阶段;二是石英+绢云母+少量金阶段;其中茶溪矿区第一阶段石英包裹体均一温度为155~297℃,峰值为210~220℃,盐度[w(NaCl)]为4.9%~11.7%,第二阶段石英包裹体均一温度为135~233℃,峰值为160~170℃,盐度为3.3%~9.7%;金坑矿区第一阶段石英包裹体均一温度为202~261℃,峰值为210~220℃,盐度为5.6%~10.1%,第二阶段石英包裹体均一温度为134~203℃,峰值为150~160℃,盐度为3.8%~8.8%;黄垢矿区第一阶段石英包裹体均一温度为176~319℃,峰值为220~240℃,盐度为5.1%~11.7%;3个矿床中成矿流体的H-O同位素组成具有相似的变化趋势,第一阶段δ^(18)O_(fluid)变化较小,分布在+4.95‰~+6.95‰之间,第二阶段δ^(18)O_(fluid)分布在+1.08‰~+1.38‰之间,而δD值变化较大,分布在-83‰~-33‰之间,因此第一阶段成矿流体为中温中低盐度的流体,来源以变质流体为主,可能有岩浆热液的叠加,第二阶段成矿流体为低温低盐度的流体,指示有大气水的混入。另外,黄垢矿区黄铁矿中的δ^(34)S值分布范围较广,为-15.79‰~+3.88‰;金坑矿区硫化物δ^(34)S值较为集中,为-5.02‰~+0.74‰。结合区域地层中S同位素组成与黄铁矿电子探针分析,认为载金硫化物硫源(δ^(34)S值接近零值)主要为深部岩浆,而不含金或含微量金的硫化物(δ^(34)S值为负值)来源于围岩地层。A large number of medium-large gold deposits developed in the Xuefeng arc-shaped structural belt,which mainly composed of precambrian strata and undergo low-grade metamorphism with multi-stage tectonic movement.In addition,long-term large-scale magma activity(e.g.Silurian,Triassic)occurred in the TaojiangChengbu fault zone on the eastern margin of Xuefeng Mountain.Due to the overprint of regional metamorphic hydrothermal and deep magma hydrothermal fluid,both metamorphic hydrothermal and magmatic hydrothermal Au-Sb deposits are occurred in Xuefeng Mountain region.Previous research and exploration mainly focused on gold deposits in the northern and middle district of the metallogenic belt,that is lacking in the southern district(e.g.Huitong,Jingzhou,Tongdao).The gold deposits in the Tongdao County are composed of the Chaxi,Jinkeng,and Huanggou small-medium quartz vein and altered rock type gold deposits,which developed in low-grade precambrian metamorphic strata and controlled by faults.To constrain the ore forming fluids characteristics and source,field investigations,microscopic rock-mineral determination,fluid inclusion and H-O-S isotope analysis were completed in this research.The representative ore-bearing quartz vein samples were selected to identify the petrographic characteristics of inclusions for micro-thermal analysis.In addition,the H,O isotope composition were analyzed with a single mineral of quartz and the in-situ S isotope analysis of gold-bearing sulfides(e.g.pyrite and arsenopyrite)are obtained by LA-ICP-MS.Analysis results show that it can be divided into two metallogenic stages,stageⅠis quartz+pyrite+arsenopyrite+sericite+gold,stageⅡis quartz+sericite+minor gold.The homogenization temperature of stageⅠquartz fluid inclusions in the Chaxi deposit is 155~297℃with a peak value of 210~220℃and the salinity[w(NaCl)]is 4.9%~11.7%.The homogenization temperature of stageⅡquartz fluid inclusions in the Chaxi deposit is 135~233℃with a peak value of 160~170℃and the salinity is 3.3%~9.7%.The

关 键 词：雪峰弧形构造带 金矿床 石英流体包裹体 H-O-S同位素 流体特征 通道地区 湖南省 

分 类 号：P618.51[天文地球—矿床学]