摘要
江西龙头岗铜锌矿床成矿过程可分为:干矽卡岩、湿矽卡岩、硫化物-石英和石英-碳酸盐阶段,铜锌矿化主要发生在硫化物-石英阶段.对不同成矿阶段的钙铁辉石和石英所进行的流体包裹体研究表明,干矽卡岩和石英-碳酸盐阶段主要发育富液相两相包裹体(Ⅰ类),硫化物-石英阶段除Ⅰ类包裹体外,还发育有富气相两相(Ⅱ类)和含子晶三相包裹体(Ⅲ类).干矽卡岩阶段Ⅰ类包裹体均一温度为345℃~418℃,盐度为3.2wt.%~8.7wt.%NaCl equiv.;在硫化物-石英阶段,流体曾发生沸腾,由Ⅱ类包裹体和Ⅲ类包裹体构成的沸腾包裹体组合均一温度分别为295℃~391℃与267℃~360℃,盐度分别为0.7wt.%~3.4wt.%NaCl equiv.和31.6wt.%~38.9wt.%NaCl equiv.;石英-碳酸盐阶段Ⅰ类包裹体均一温度为234℃~274℃,盐度为0.2wt.%~2.2wt.%NaCl equiv..激光拉曼光谱分析表明:三类包裹体的气相组成均以H_2O为主,其次还含有少量的CO_2和CO.认为构造减压可能是导致流体沸腾的重要原因,成矿物质沉淀也与流体沸腾关系密切.
The Longtougang Cu-Zn deposit is located in the Northern Wuyi terrane.Orebodies are primarily hosted in glutenite of the Outangdi formation,the minority hosted in biotite-plagioclase granulite of the Zhoutanyan formation.The mineralization process can be divided into four stages:anhydrous skarn stage,hydrous skarn stage,sulfide-quartz stage and quartz-carbonate stage,Cu-Zn mineralization mainly occurs in the sulfide-quartz stage.Petrographic and microthermometric studies of fluid inclusions in hedenbergite and quartz of different mineralization stages show that there exist three types of fluid inclusions in the Longtougang deposit,namely two-phase liquid-rich(typeⅠ),two-phase gas-rich(typeⅡ)and halite-bearing aqueous inclusions(typeⅢ),all of them can be recognized in the sufide stage while only typeⅠinclusions developed in the anhydrous and quartz-carbonate stage.In order to discuss the evolution of the ore-forming fluids,the homogenization temperature(Th)and salinity of the three types of fluid inclusions have been measured by Linkam THMS600 and calculated formula,respectively.Type I inclusions in the anhydrous stage display Th of 345℃-418℃,and salinities of 3.2 wt.%~8.7 wt.%NaCl equivalent;fluid boiling occurred in the sulfide-quartz stage,which resulted in typeⅡand typeⅢinclusions share similar homogenization temperatures of 295℃~391℃and 267℃~360℃,and contrasted salinities of 0.7 wt.%~3.4 wt.%and 31.6 wt.%~38.9 wt.%NaCl equivalent,respectively;typeⅠinclusions in the quartz-carbonate stage display Th of 234℃~274℃,and salinities of 0.2 wt.%~2.2 wt.%NaCI equivalent.Considering that the filed observation and various types of fluid inclusions,tectonic depression may be a vital factor for fluid boiling,which may also contribute to the late-stage sulfide deposition.
作者
魏滔
倪培
范明森
张鑫
刘政
Wei Tao;Ni Pei;Fan Mingsen;Zhang Xin;Liu Zheng(State Key Laboratory for Mineral Deposit Research,Nanjing University,Nanjing School of Earth Science and Engineering,,210023,China)
出处
《南京大学学报(自然科学版)》
CAS
CSCD
北大核心
2018年第2期308-321,共14页
Journal of Nanjing University(Natural Science)
基金
国家重点研发计划(2016YFC0600205)
