ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    阿尔金盖吉克萤石矿床成矿过程:来自萤石微量元素地球化学的证据

    Mineralization Processes in the Giant Gaijike Fluorite Deposit, Altyn Tagh, NW China: Evidence from Fluorite Trace-element Chemistry

    • 摘要: 萤石是新能源、新材料等新兴产业中不可或缺的原材料。近年来,阿尔金造山带萤石勘查取得重大突破,相继发现了卡尔恰尔、皮亚孜达坂、盖吉克等世界级矿床。然而,这些矿床的成矿流体性质和成因类型仍不明确。笔者以阿尔金阿中地块中南部的盖吉克萤石矿床为研究对象,在详细查明地质特征基础上,开展了不同阶段萤石的微量元素地球化学研究。结果表明,不同阶段的萤石均富集轻稀土元素,稀土配分曲线呈“右倾型”,矿化发生在早阶段热液活动中。Tb/La-Tb/Ca关系图指示萤石为热液成因,热液流体与围岩发生了水岩反应。La/Ho-Y/Ho关系图显示,Y、Ho强烈分馏,萤石具同源多阶段特征,早阶段萤石角砾经历重结晶过程,而中阶段萤石胶结物在流体迁移过程中沉淀。δCe-δEu关系图显示,萤石具有强烈的Eu负异常和Ce正异常,反映成矿流体处于中低温还原环境,氧逸度较低,受到水岩反应作用影响。岩体中F含量较高,地层富含Ca元素,推测萤石中的F来自正长花岗岩,Ca来自变质地层和大理岩。研究认为,盖吉克萤石矿床形成于中低温还原环境,矿床成因类型为与碱性侵入岩相关的中低温热液矿床。

       

      Abstract: Fluorite is an indispensable raw material in strategic emerging industries such as new energy and new materials. In recent years, significant breakthroughs have been achieved in fluorite exploration in the Altyn Tagh orogenic belt, with the discovery of world-class deposits such as Kaerqiaer, Piyazidaban, and Gajike. However, the nature of the ore-forming fluids and the genetic types of these deposits remain unclear. This study focuses on the Gajike fluorite deposit in the central and southern parts of the Altyn Tagh, conducting detailed geochemical research on trace elements in fluorite from different stages based on thorough geological characterization. The results indicate that fluorite from all stages is enriched in light rare earth elements, with rare earth element patterns showing a "right-leaning" type, and mineralization occurring during early hydrothermal activity. The Tb/La-Tb/Ca diagram suggests that fluorite is of hydrothermal origin, with hydrothermal fluids undergoing water-rock reaction with the surrounding rocks. The La/Ho-Y/Ho diagram reveals strong fractionation of Y and Ho, indicating that the fluorite exhibits homologous multi-stage characteristics, where early fluorite breccia underwent recrystallization while middle-stage fluorite cement precipitated during fluid migration. The δCe-δEu diagram shows strong negative Eu anomalies and positive Ce anomalies in fluorite, reflecting a medium-low temperature reduction environment with low oxygen fugacity and water-rock reaction effects. The high F content in the rock mass and the Ca-rich strata suggest that the F in fluorite originates from K-feldspar granite, while Ca comes from metamorphic strata and marble. Comprehensive analysis concludes that the Gajike fluorite deposit formed in a medium-low temperature reduction environment, and its genetic type is classified as a medium-low temperature hydrothermal deposit.

       

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