| 湘赣边界鹿井铀矿床流体包裹体及成矿机制 |
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| 引用本文： | 张笑天,潘家永,夏菲,刘颖,黄迪,赵奇峰,张勇,刘国奇,钟福军.湘赣边界鹿井铀矿床流体包裹体及成矿机制[J].地球科学,2022,47(1):192-205. |
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| 作者姓名： | 张笑天 潘家永 夏菲 刘颖 黄迪 赵奇峰 张勇 刘国奇 钟福军 |
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| 作者单位： | 1.东华理工大学核资源与环境国家重点实验室, 江西南昌 330013 |
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| 基金项目： | 国家自然科学基金项目41772066国家自然科学基金项目41862010国家自然科学基金项目42002095核资源与环境国家重点实验室开放基金2020NRE12核资源与环境国家重点实验室联合创新基金项目NER202109 |
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| 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CO2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% NaCleqv. 成矿流体自早阶段至晚阶段逐渐由中低温、中低盐度的NaCl-H2O-CO2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.
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| 关 键 词： | 流体包裹体 成矿流体 铀矿 鹿井 诸广山 矿床学 |
| 收稿时间： | 2021-02-24 |
Fluid Inclusion Constraints on Ore-Forming Mechanism of Lujing Uranium Deposit in Jiangxi-Hunan Border Region |
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| Zhang Xiaotian,Pan Jiayong,Xia Fei,Liu Ying,Huang Di,Zhao Qifeng,Zhang Yong,Liu Guoqi,Zhong Fujun.Fluid Inclusion Constraints on Ore-Forming Mechanism of Lujing Uranium Deposit in Jiangxi-Hunan Border Region[J].Earth Science-Journal of China University of Geosciences,2022,47(1):192-205. |
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| Authors: | Zhang Xiaotian Pan Jiayong Xia Fei Liu Ying Huang Di Zhao Qifeng Zhang Yong Liu Guoqi Zhong Fujun |
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| Abstract: | The Lujing uranium deposit located in the southwestern part of the Nanling metallogenic belt is a representative granite-related 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 CO2-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% NaCleqv. 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 CO2-H2O-NaCl system in the early stage to a NaCl-H2O 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. |
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