陕西凤太矿集区典型金矿地质特征及其成矿规律

    Geological characteristics and metallogenic regularity of typical gold deposits in Fengtai ore concentration area, Shaanxi Province

    • 摘要: 凤太矿集区金矿资源丰富,近年来金矿勘查取得了较大成果和找矿突破。通过分析对比矿集区内典型金矿的地质特征与成矿流体特征,总结了凤太矿集区的成矿规律。凤太矿集区金矿的矿化类型多样,但其成矿流体的性质和来源、成矿物质的来源具有统一性,成矿深度较浅的金矿流体中大气降水的参与程度较高,而成矿深度较深的金矿流体来源则具有更多的变质流体和岩浆热液属性。庞家河金矿为中低温-低盐度-低密度-中浅成的成矿环境; 八卦庙金矿为中高温-富CO2-中高盐度-中深成的成矿环境; 双王金矿为中高温-富CO2-中低盐度-中高压-中深成的成矿环境,3个金矿的变质流体特征显著,均有造山型金矿的特征。区内金矿的成矿过程具多期次、多阶段的特征,由地层中的Au元素预先富集,由印支期(主成矿期)构造事件作用以及其产生的岩浆热液、变质热液、地下水共同作用成矿,在燕山期热液叠加改造作用使Au元素再富集。

       

      Abstract: Fengtai ore concentration area is rich in gold resources, with great achievements and breakthrough from gold deposit detection in recent years. The authors in this paper summarized the metallogenic regularity in Fengtai ore concentration area through analysing and comparing the geological and ore-forming fluids characteristics of typical gold deposits. There are various types of gold mineralization in Fengtai ore concentration area, but properties and sources of ore-forming fluids and materials are unified. The ore-forming fluids with shallow metallogenic depth were mainly from atmospheric precipitation, while those with deep metallogenic depth were mainly from metamorphic fluid and magmatic hydrothermal fluid. The metallogenic environment of Pangjiahe gold deposit is medium and low temperature- low salinity- low density- medium hypabyssal, while the metallogenic environment of Baguamiao gold deposit is medium and high temperature-CO2 rich-medium and high salinity- medium plutonic. Besides, the metallogenic environment of Shuangwang gold deposit is medium and high temperature-CO2 rich-medium and low salinity-medium and high pressure-medium plutonic. The metamorphic fluid characteristics in these three gold deposits are obvious, with similar characteristics of orogenic gold deposits. The gold mineralization process in the study area was characterized by multi-period and multi-stage. And the gold mineralization was first pre-enriched by Au element in the strata, then mineralized with magmatic hydrothermal fluid, metamorphic hydrothermal fluid, and groundwater caused by the Indosinian (main metallogenic period) tectonic events. At last, the gold mineralization was superimposition reformed and enriched by the hydrothermal fluid during the Yanshanian.

       

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