青藏高原东南缘哀牢山大坪金矿成矿流体演化  

Evolution of ore forming fluid of Daping gold deposit in Ailaoshan tectonic zone,Southeast Tibet

作　　者：朱路华[1,2] 戚学祥[1] 彭松柏[3] 李志群 

机构地区：[1]大陆构造与动力学国家重点实验室,中国地质科学院地质研究所,北京100037 [2]广东省有色金属地质勘查局地质勘查研究院,广州l510080 [3]中国地质大学地球科学学院,武汉430074 [4]云南省有色地质局,昆明650051

出　　处：《岩石学报》2011年第11期3395-3408,共14页Acta Petrologica Sinica

基　　金：中国地质调查局项目(1212010918009、1212011121266);科技部深部探测技术与实验研究专项(SinoProbe-05-03)联合资助

摘　　要：大坪金矿是青藏高原东南缘哀牢山构造带中的大型石英脉型金矿床,由北矿区和南矿区组成。北矿区和南矿区的成矿流体包裹体均一温度及其氢、氧、硫同位素、气液相成份的测试结果表明其成矿温度为:187～329℃(平均为281℃)和168～338℃(平均为264℃)、氢同位素组成(δDV-SMOW)为:-70‰～-81‰和-71‰～-86‰、氧同位素组成(δ18OH2O)为:2.9‰～9.8‰和3.5‰～5.1‰、硫同位素值(δ34S)为:0.7‰～15.5‰和10.6‰～15.8‰。在氢-氧同位素图解上,所有样品均落在岩浆水和地下水趋势线之间。其中,北矿区样品更靠近岩浆水区域,部分样品落在岩浆水区域内,南矿区相对靠近地下水区域。流体包裹体成份分析表明,气相成份主要为H2O和CO2,其次为N2,并含有少量CH4、C2H2、C2H4、C2H6和CO;离子成份主要为K+、Na+、Ca2+、Cl-和SO42-,及少量NO3-、Mg2+、F-和Br-。含金石英脉ESR定年数据揭示了北矿区成矿时代为27.2～29.1Ma,南矿区为17.3～22.1Ma。总体来看,北矿区成矿时代要早于南矿区;北矿区成矿流体是以岩浆流体为主,并有少量地下水混入,而南矿区成矿流体中地下水的参与程度要大于北矿区;成矿流体具有从北矿区向南矿区、从早到晚以及从深部向浅部,岩浆流体组分相对减少,地下水组分逐渐增加的演化趋势。Daping gold deposit is a large quartz-vein gold deposit in Ailaoshan tectonic zone,made of north and south fields.Fluid inclusion homogenization temperatures range from 187℃ to 329℃（average is 281℃） in north field,and from 168℃ to 338℃（average is 264℃） in south field,respectively.Corresponding,the δDV-SMOW values range from-70‰ to-81‰ and from-71‰ to-86‰,and the δ18OH2O values rang from 2.9‰ to 9.8‰ and from 3.5‰ to 5.1‰,respectively.All samples plotted at the field between magmatic water and underground water in the plots of δD vs.δ18OH2O,and that for north field are near magmatic water area,and for south field are near underground water area.The sulfur isotopic compositions（δ34S） for north and south fields are 0.7‰～15.5‰ and 10.6‰～15.8‰,respectively.The vapour compositions in fluid inclusions are H2O,CO2 and N2,with a little of CH4,C2H2,C2H4,C2H6 and CO.The ion compositions in fluid inclusions are K＋,Na＋,Ca2＋,Cl-and SO42-,with a little of NO3-,F-,Br-and Mg2＋.ESR dating data for quartz in gold-bearing quartz veins from north and south fields are 27.2～29.1Ma and 17.3～22.1Ma,respectively.All above show,that the ore forming fluids are mixing of postmagmatic solution and underground water,from north to south,deep to shallow fields and from earlier to later stage,the contents of the postmagmatic solution and sulfur are decreasing,and that of the underground water is increasing,and the age of minerallization is youngling,gradually.

关 键 词：流体包裹体 氢、氧同位素组成 硫同位素组成 大坪金矿 哀牢山构造带 

分 类 号：P618.51[天文地球—矿床学]