摘要
位于南岭成矿带南西部的鹿井矿床是华南热液型铀矿的典型代表.为查明其成矿流体来源、性质与演化以及成矿机制,开展了不同成矿阶段石英、萤石及方解石中流体包裹体的显微测温和不同阶段石英的氢-氧同位素分析.矿床地质特征表明成矿过程可划分为(Ⅰ)粗晶石英+黄铁矿±绿泥石±绢云母、(Ⅱ)沥青铀矿+硫化物+绿泥石+绢云母+暗灰色微晶石英、(Ⅲ)紫黑色萤石+肉红色方解石+灰色微晶石英+赤铁矿+铀石±黄铁矿和(Ⅳ)梳状石英+浅色萤石+白色方解石四个阶段;其中阶段Ⅱ和Ⅲ代表成矿主阶段.成矿早阶段和主阶段捕获水溶液包裹体和少量含CO;包裹体,而晚阶段仅见水溶液包裹体.早、主、晚阶段包裹体的均一温度依次为186~317、169~236、149~189℃,盐度依次为9.9~12.9、6.3~9.9、4.5~7.0 wt%NaCl_(eqv).成矿流体自早阶段至晚阶段逐渐由中低温、中低盐度的NaCl-H_(2)O-CO_(2)体系演化为低温、低盐度的NaCl-H2O体系,期间由压力降低引发的流体沸腾作用是重要的成矿机制.H-O同位素数据表明,初始成矿流体来自岩浆水与大气降水的混合,成矿过程伴随着大气降水的持续加入.
The Lujing uranium deposit located in the southwestern part of the Nanling metallogenic belt is a representative graniterelated hydrothermal uranium deposit in South China.In this paperit presents new detailed fluid inclusion and H-O isotope data to constrain the source,nature,and evolution of the ore-forming fluids and reveal the ore-forming mechanism.Four stages of mineralization have been identified in the Lujing deposit:(Ⅰ) macrocrystalline quartz+pyrite+chlorite+sericite,(Ⅱ) pitchblende+sulfide+chlorite+sericite+microcrystalline quartz,(Ⅲ) purple-black fluorite+reddish calcite+microcrystalline quartz+hematite+coffinite+pyrite,and(Ⅳ) comb quartz+light-green fluorite+white calcite.The stages Ⅱ and Ⅲ represent the main uranium mineralization.The early and main stages of mineralization contain aqueous inclusions and a small amount of CO;-bearing inclusions,whereas the late stage of mineralization contains only aqueous inclusions.The fluid inclusions in early-stage quartz have homogenization temperature of 186-317 ℃ and salinities of 9.9-12.9 wt% NaCleqv.The fluid inclusions in the quartz,fluorite,and calcite forming the main stage have homogenization temperatures of 169-236 ℃ and salinities of 6.3-9.9 wt% NaCl_(eqv).The fluid inclusions in late-stage quartz,fluorite,and calcite have homogenization temperatures of 149-189 ℃ and salinities of 4.5-7.0 wt% NaCleqv.The ore-forming fluid system evolved from a CO_(2)-H_(2)O-NaCl system in the early stage to a NaCl-H_(2)O system in the late stage.Fluid boiling was the dominant mechanism for uranium precipitation.The H-O isotope results indicate that the initial ore-forming fluid is the mixture of magmatic water and meteoric water,and the meteoric water was continuously added to the ore-forming fluids during mineralization.
作者
张笑天
潘家永
夏菲
刘颖
黄迪
赵奇峰
张勇
刘国奇
钟福军
Zhang Xiaotian;Pan Jiayong;Xia Fei;Liu Ying;Huang Di;Zhao Qifeng;Zhang Yong;Liu Guoqi;Zhong Fujun(State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China;No.270 Research Institute,China National Nuclear Corporation,Nanchang 330200,China)
出处
《地球科学》
EI
CAS
CSCD
北大核心
2022年第1期192-205,共14页
Earth Science
基金
国家自然科学基金项目(Nos.41772066,41862010,42002095)
核资源与环境国家重点实验室开放基金(No.2020NRE12)
核资源与环境国家重点实验室联合创新基金项目(No.NER202109)。
关键词
流体包裹体
成矿流体
铀矿
鹿井
诸广山
矿床学
fluid inclusion
ore-forming fluid
uranium deposit
Lujing
Zhuguangshan
mineral deposit
