吉林省海沟石英脉型金矿床流体包裹体特征及地质意义  

The characteristics and its geological significance of fluid inclusions in Haigou lode gold deposit,Jilin Province

作　　者：张松[1,2] 曾庆栋[1] 刘建明[1] 汪在聪[1,2] 王永彬[1,2] 任德奎[3] 高吉河 

机构地区：[1]中国科学院地质与地球物理研究所矿产资源研究重点实验室,北京100029 [2]中国科学院研究生院,北京100049 [3]吉林海沟黄金矿业有限责任公司,吉林133600

出　　处：《岩石学报》2011年第5期1287-1298,共12页Acta Petrologica Sinica

基　　金：全国危机矿山接替资源综合研究项目(20089931)资助

摘　　要：海沟金矿床地处夹皮沟-海沟成矿带东南端,为典型的石英脉型金矿。该矿床产于海西期花岗杂岩体中,由多条含金石英脉组成。成矿过程可分为4个阶段:Ⅰ.钾长石-石英脉阶段;II.乳白色石英-(少)黄铁矿-(少)金阶段;III.多金属硫化物-石英-金阶段;IV.碳酸盐-石英-黄铁矿阶段。流体包裹体研究表明,海沟金矿各阶段流体包裹体存在一定差异,早期成矿阶段(第Ⅱ阶段)以H2O-NaCl包裹体(Ⅰ类)为主,偶见含子晶包裹体(Ⅳ类);主成矿阶段(第Ⅲ阶段)以CO2-H2O-NaCl包裹体(II类)为主,并含有少量纯CO2包裹体(III类);成矿后阶段(第Ⅳ阶段)以H2O-NaCl包裹体(Ⅰ类)为主。早期成矿阶段、主成矿阶段、成矿后阶段均一温度范围分别为227～497℃、189～427℃、130～267℃,对应盐度分别为0.53%～10.23%NaCleqv、0.35%～9.23%NaCleqv、0.18%～3.27%NaCleqv。早期成矿阶段和主成矿阶段包裹体均一温度、盐度相对较高,成矿后阶段包裹体均一温度、盐度明显降低;在空间上,主成矿阶段矿床深部包裹体的盐度较矿床浅部偏高。拉曼和气相色谱结果显示,包裹体气相成分以H2O、CO2、N2、CH4、C2H6为主,并含有少量H2S,成矿流体为低盐度的H2O-CO2-NaCl±CH4流体;包裹体液相离子成分主要为Na+、K+、Ca2+、Cl-,个别包裹体中含有少量Mg2+、F-离子。主成矿阶段不同类型、不同相比包裹体均一温度相近,显示不混溶特征。流体减压引起的不混溶作用可能是海沟金矿金沉淀的主要原因。Haigou gold deposit,located in the southeast of the Jiapigou-Haigou gold belt in Jilin Province,is a typical lode gold deposit.It is hosted by Hecynian granitoid complex,and consists of gold-bearing quartz veins.It can be devided into four ore-forming stages：I,quartz-K-feldspar;II,quartz-pyrites,occasionally with gold;III,polymetallic sulfides-quartz-gold;and IV,carbonate-quartz-pyrite stage.Four types of fluid inclusions are identified in auriferous quartz veins：（1）H2O-CO2-NaCl inclusions;（2）CO2 inclusions;（3）H2O-NaCl inclusions;（4）a few high-salinity inclusions with daughter mineral.Homogenization temperature of the inclusions in the three stages are range from 227-497℃（II stage）,189~427℃（III stage）,130-267℃（IV stage）,and salinity are 0.53%-10.23% NaCleqv,0.35%-9.23% NaCleqv,0.18%-3.27% NaCleqv respectively.Inclusions with variable CO2 phase ratio within same clusters having similar homogenization temperature shows that immiscibility is common.The homogenization temperature of inclusions in the II and III stages are higher than the IV stage;and the salinity of inclusions are higher in the bottom of the orebody.The ore-bearing fluids were low salinity H2O-CO2-NaCl±CH4.The composition of gas phase in fluid inclusions are dominanted by H2O,CO2,N2,CH4,C2H6 with minor H2S;and liquid phase composition are Na^＋,K＋,Ca26＋ and Cl-with minor Mg^2＋ and F-.It is proposed that the onset of gold deposition in Haigou gold deposit is related to the onset of fluid unmixing with the decreasing of fluid pressure.

关 键 词：石英脉型金矿 流体包裹体 成矿流体演化 海沟 

分 类 号：P618.51[天文地球—矿床学]