摘要
架底金矿是近年来在黔西南新发现的主要赋存于玄武岩中的大型微细粒浸染型金矿床。为查明其成矿流体特征,探讨流体成矿机制,针对矿床不同成矿阶段采取流体包裹体样品开展工作。根据野外观察和室内分析,架底金矿热液成矿期可分为3个阶段:黄铁矿阶段、烟灰色石英阶段和硫化物阶段,其中烟灰色石英阶段为主要成矿阶段。流体包裹体以NaCl-H_(2)O和CO_(2)-NaCl-H_(2)O型为主,黄铁矿阶段富CO_(2)包裹体,均一温度(T_(h))为211~231℃,盐度(wt)为2.10~7.60(%NaCl equiv);烟灰色石英阶段见大量NaCl-H_(2)O和CO_(2)-NaCl-H_(2)O型包裹体,均一温度(T_(h))为182~218℃,盐度(wt)为1.40~5.90(%NaCl equiv);硫化物阶段包裹体均一温度(T_(h))普遍小于183℃,盐度(wt)为0.90~5.30(%NaCl equiv)。激光拉曼光谱分析显示包裹体中含CO_(2)、CH_(4)、N_(2)、SO_(2)等气相组分,随着成矿流体均一温度、盐度和密度的不断下降,包裹体中气相组分种类也趋于简单。通过计算成矿流体的ρ、P、pH、Eh和ƒO_(2)等物理化学参数,表明成矿环境具有中低温、低盐度、低密度、近中性、相对还原及低氧逸度的特征。流体包裹体组合变化表明成矿作用发生在流体CO_(2)含量不断降低的过程,主成矿阶段流体混合和区域伸展构造引起流体沸腾作用强烈,大量金属成分(黄铁矿、自然金等)快速沉淀形成金矿体。
The Jiadi gold deposit,located in southwestern Guizhou Province,is a newly discovered large-scale basalt-hosted and fine-grained disseminated gold deposit.This article focuses on the characteristics of ore-forming fluid in order to discuss the ore-forming mechanism by the fluid inclusion analyses from different mineralization stages of the deposit.Based on the field observations and laboratory analyses,the hydrothermal ore-forming processes of the deposit can be divided into three stages:the pyritization forming-stage(1st stage),the smokygray quartz forming-stage(2nd stage)and the sulfide forming-stage(3rd stage),among which the smoky-gray quartz forming-stage is the primary stage.The fluid inclusions are mainly composed of NaCl-H_(2)O and CO_(2)-NaCl-H_(2)O type,and CO_(2)-rich inclusions are frequently observed in the first stage minerals,with homogenization temperature(T_(h))ranging from 211 to 231℃,and salinity(wt)from 2.10 to 7.60(%NaCl equiv).There are a lot of NaCl-H_(2)O and CO_(2)-NaCl-H_(2)O type of inclusions in the second stage,with the homogenization temperature(T_(h))changing from 182 to 218℃,and the salinity(wt)from 1.40 to 5.90(%NaCl equiv).The homogenization temperature(T_(h))of the third stage is generally lower than 183℃,with the salinity(wt)varying from 0.90 to 5.30(%NaCl equiv).The results of laser Raman spectroscopy analysis show that the inclusions generally contain CO_(2),CH_(4),N_(2),SO_(2)and other gas components,and the types of gaseous components in the inclusions also are tending to be simple as the continuously decreasing of the homogenization temperature,the salinity and density of the ore-forming fluid.The value of the physical and chemical parameters of ore-forming fluids such asρ,P,pH,Eh,and ƒO_(2)are subsequently calculated from the above temperature and salinity values,and the results suggest that the ore-forming environment has the characteristics of medium to low temperature,low salinity,low density,weak acidity,with relative oxidation and low oxygen fugacity.The chan
作者
闵壮
陈正乐
潘家永
周振菊
张文高
吴玉
张涛
MIN Zhuang;CHEN Zhengle;PAN Jiayong;ZHOU Zhenju;ZHANG Wengao;WU Yu;ZHANG Tao(School of Earth Sciences,East China University of Technology,Nanchang 330013,Jiangxi,China;Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China;Beijing Research Institute of Uranium Geology,CNNC,Beijing 100029,China;Research Institute No.270,CNNC,Nanchang 330299,Jiangxi,China)
出处
《地质力学学报》
CSCD
北大核心
2022年第3期448-463,共16页
Journal of Geomechanics
基金
贵州省科技计划项目(2021-408)
中国地质调查局地质调查项目(DD20190161,DD20221660-3)
贵州省卡林型金矿成矿与找矿科技创新人才团队建设项目(CXTD2021-007)
中国铀业有限公司-东华理工大学核资源与环境国家重点实验室联合创新基金项目(NRE2021-01)
东华理工大学核资源与环境国家重点实验室开放基金项目(2020NRE04)。
关键词
黔西南
架底金矿
流体包裹体
激光拉曼
成矿流体
southwestern Guizhou
Jiadi deposit
fluid inclusions
laser Raman spectroscopy
ore-forming fluid
