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现代地质 ›› 2024, Vol. 38 ›› Issue (04): 1177-1191.DOI: 10.19657/j.geoscience.1000-8527.2024.018

• 构造物理化学控矿机理与找矿应用 • 上一篇    下一篇

东秦岭夜长坪钼矿床流体包裹体特征及对成矿作用的指示

丁高明1(), 晏国龙2(), 王坤明3, 许永中4, 唐一昂2, 刘骥阳1   

  1. 1.中国煤炭地质总局,北京 100038
    2.中国黄金集团地质有限公司,北京 100011
    3.中国地质科学院矿产资源研究所自然资源部成矿作用与资源评价重点实验室,北京 100037
    4.中国黄金集团中原矿业有限公司,河南 三门峡 472000
  • 出版日期:2024-08-10 发布日期:2024-10-16
  • 通信作者: 晏国龙,男,1976年出生,正高级工程师,主要从事矿产勘查与资源评价和开发。Email: 65284076@qq.com
  • 作者简介:丁高明,男,1987年出生,高级工程师,主要从事矿产勘查与资源评价和开发。Email: dinggaoming@126.com
  • 基金资助:
    中国地质调查局地质调查项目(DD20230291);中国黄金集团有限公司地质探矿增储项目(DT2023001)

Characteristics of Fluid Inclusions and Mineralization Indications of the Yechangping Mo Deposit,East Qinling

DING Gaoming1(), YAN Guolong2(), WANG Kunming3, XU Yongzhong4, TANG Yi’ang2, LIU Jiyang1   

  1. 1. China Coal Geology Group Co.,Ltd.,Beijing 100038,China
    2. China Gold Group Geological Co.,Ltd.,Beijing 100011,China
    3. MLR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,CAGS,Beijing 100037,China
    4. China Gold Group Zhongyuan Mining Co.,Ltd.,Sanmenxia,Henan 472000,China
  • Published:2024-08-10 Online:2024-10-16

摘要:

夜长坪钼矿床位于东秦岭钼成矿带中段,其矿石类型以矽卡岩型为主,其次为斑岩型。在东秦岭钼成矿带,针对矽卡岩型-斑岩型复合钼矿床流体包裹体研究相对较少,其流体演化特征及成矿作用机制是需要关注的重要科学问题。夜长坪钼矿床成矿阶段从早到晚划分为早期矽卡岩阶段、晚期矽卡岩石英-钾化阶段(Ⅰ阶段石英)、石英-辉钼矿阶段(Ⅱ阶段石英,主成矿阶段)、石英-多金属硫化物阶段(Ⅲ阶段石英)和石英-碳酸盐阶段(Ⅳ阶段石英)。对上述Ⅰ—Ⅳ阶段石英采集包裹体样品进行岩相学特征、显微镜下观察及显微测温和激光拉曼光谱特征分析。结果表明,矿床石英中流体包裹体类型包括WG型(NaCl-H2O富气型)、WL型(NaCl-H2O富液型)、C型(CO2型)和S型(含子晶型)。从成矿早阶段到晚阶段,流体包裹体的均一温度依次集中在380~437℃、331~370 ℃、312~320 ℃和257~350 ℃,对应的平均盐度(NaCleqv.)分别为10.83%、9.29%、7.16%和4.51%,成矿流体从早阶段高中温、中高盐度与富(含)CO2的NaCl-H2O-CO2体系逐渐演化为晚阶段中低温、低盐度与贫CO2的NaCl-H2O体系。流体混合作用导致流体的温度下降、盐度降低,流体由氧化状态转化为还原状态,由此造成流体中的Mo元素溶解度大幅降低并迅速卸载与沉淀富集成矿。进一步根据“岩浆流体-建造”成矿体系,构建了矿区(床)尺度成矿模式。

关键词: 东秦岭钼矿带, 夜长坪钼矿床, 矽卡岩-斑岩型钼矿床, 流体包裹体

Abstract:

The Yechangping molybdenum (Mo) deposit is located in the middle East Qinling molybdenum orogenic belt.Its metallogenic type mainly belongs to the skarn type in the early stage,followed by the porphyry type.In the East Qinling molybdenum mineralization belt,there are relatively fewer studies focusing on the fluid inclusions of the skarn-porphyry composite molybdenum deposits,particularly their fluid evolution characteristics and the metallogenetic mechanisms,which are essential to understanding ore genesis.This study classifies the hydrothermal mineralization stages of the Yechangping Mo deposit from early to late as follows: early silica and late silica quartz-potassic stage (stage I: quartz),quartz-pyroxene stage (stage II: quartz,main mineralization stage),quartz-polymetallic sulfide stage (stage III: quartz),and quartz-carbonate stage (stage IV: quartz).Based on this preliminary study,inclusion samples were collected from stages Ⅰ to Ⅳ quartz and analyzed using microscopy,micro-thermometry,and laser Raman microprobe.The results show that the types of fluid inclusions within the quartz are NaCl-H2O gas-rich type (WG type),NaCl-H2O liquid-rich type (WL type),CO2 type (C type),and daughter mineral-bearing type (S type).From the early to the late stage of mineralization,the homogeneous temperatures of fluid inclusions are concentrated at 380-437 ℃,331-370 ℃,312-320 ℃ and 257-350 ℃,corresponding to average salinity (NaCleqv.) of 10.83%,9.29%,7.16%,and 4.51%,respectively.The mineralizing fluids gradually evolved from a high-temperature,medium-high salinity,and CO2-rich NaCl-H2O-CO2 system at the early stage to a low-temperature,low-salinity,and CO2-poor NaCl-H2O system at the late stage.The fluid mixing effect leads to a decrease in fluid temperature and salinity,and the fluid transforms from an oxidized state to a reduced state.This results in a drastic decrease in the solubility of the Mo element in the fluid,and the rapid unloading and precipitation of Mo.Consequently,we constructed a mineralization model on the scale of mining area based on the “magma-fluid-construction” mineralization system.

Key words: East Qinling molybdenum ore belt, Yechangping molybdenum deposit, silica-porphyry molybdenum deposit, fluid inclusion

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