| 西藏帮布勒矿床磁铁矿化学成分特征及其地质意义 |
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| 引用本文：荀帅杰,张弘彬,章奇志,王勇,吴江华,洪晨瑜,曹锐.2026.西藏帮布勒矿床磁铁矿化学成分特征及其地质意义[J].地球学报,47(3):541-554. |
| DOI：10.3975/cagsb.2025081311 |
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| 基金项目:本文由国家自然科学基金项目(编号: 42302098)、国家重点研发计划项目(编号: 2022YFC2905002)和自然资源部深地科学与探测技术实验室开放基金项目(编号: SL202415)联合资助。 |
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| 中文摘要:西藏帮布勒矿床位于冈底斯成矿带西段, 是近年来新发现的大型矽卡岩型铅锌矿床。磁铁矿在矿床中广泛发育, 其结构及化学成分特征对揭示成矿物理化学条件和成矿流体演化过程具有重要意义。本次研究以帮布勒矿床不同世代磁铁矿为研究对象, 开展矿相学观察与电子探针分析, 揭示其结构与成分特征。结果表明, 帮布勒矿床磁铁矿可划分为2个世代: MagⅠ多充填于钙铁辉石颗粒间隙, 化学成分上呈现高Mn的特征; MagⅡ与石英共生, 整体Mn含量低。磁铁矿化学成分上呈现高Mg、Al、Ca、Mn, 低Ti的特征, 表明其形于中高温环境, 具有典型矽卡岩型矿床热液成因磁铁矿化学成分特征。此外, 从MagⅠ→MagⅡ, 成矿流体经历了高氧逸度、低水岩比条件到低氧逸度、高水岩比的转变, 形成环境相对稳定于中高温。这一研究构建了帮布勒矿床磁铁矿形成过程的流体演化模式, 为精细刻画帮布勒矿床成矿流体演化过程具有一定指示意义, 系统分析磁铁矿化学元素与矿床成因的关系也为智能找矿和机器学习提供数据来源及约束性条件。 |
| 中文关键词:磁铁矿 结构与成分 成矿过程 西藏帮布勒 |
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| Chemical Composition Characteristics and Geological Significance of Magnetite from the Bangbule Deposit, Xizang |
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| Abstract:The Bangbule deposit, located in the western section of the Gangdise metallogenic belt in Xizang, is a recently discovered large skarn-type lead-zinc deposit. Magnetite is widely developed in the deposit, and its texture and chemical composition characteristics are of great significance for revealing the physical-chemical conditions of ore formation and the evolution of ore-forming fluids. This study investigated different generations of magnetite in the Bangbule deposit using mineralogical observations and electron microprobe analyses to reveal their textural and compositional characteristics. The results showed that magnetite in the Bangbule deposit could be categorized into two generations: MagⅠ, which predominantly filled gaps within hedenbergite grains and was chemically characterized by high Mn content; and MagII, which was associated with quartz and exhibited a low Mn content. The chemical composition of magnetite was characterized by high levels of Mg, Al, Ca, and Mn, as well as low Ti levels, which was typical of skarn deposits with hydrothermal origins. Furthermore, from MagⅠ to MagII, the ore-forming fluid underwent a transition from conditions of high oxygen fugacity and low water–rock ratio to low oxygen fugacity and high water–rock ratio. The formation environments remained relatively stable at medium to high temperatures. This study developed a fluid evolution model for magnetite formation in the Bangbule deposit, which indicated the fine delineation of the metallogenic fluid evolution. Systematic analyses of the relationship between magnetite chemical elements and deposit genesis provided data sources and constraints for intelligent mineral exploration and machine learning applications. |
| keywords:magnetite texture and chemical composition mineralization processes Bangbule, Xizang |
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