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右江盆地低温热液矿集区金锑成矿过程研究进展

Research progress on Au−Sb mineralization processes in low-temperature hydrothermal metallogenic province of Youjiang Basin

  • 摘要: 右江盆地低温热液矿集区以发育卡林型金矿和脉状锑矿为特色,但有关金、锑之间的成矿联系和成矿过程异同仍需要开展系统的分析研究工作。针对这一问题,以前期大量研究成果为基础,分析并总结了金、锑成矿过程流体来源和演化,以及富集沉淀机制,在此基础上揭示了金、锑成矿过程异同。分析结果显示,金、锑成矿初始流体主要来源于深部(岩浆/变质),在成矿过程中可能有盆地流体和大气降水的参与,导致不同程度的流体稀释。另一方面,金、锑在成矿作用方式上存在差异,金成矿流体为弱酸性—中性,成矿方式以水−岩反应为主;而锑成矿流体以酸性为主,流体混合导致的氧逸度、温度和pH的改变是辉锑矿沉淀的主要机制。据此认为,成矿流体演化过程中不同来源流体的混合,以及金、锑不同的成矿作用方式,可能是金、锑存在差异成矿的主控因素。根据金、锑成矿模型,认为燕山期形成的张性构造体系是锑成矿的有利场所。研究成果可为区域“十五五”资源潜力评价提供理论支撑。

     

    Abstract: The low-temperature hydrothermal metallogenic province in the Youjiang Basin is characterized by Carlin-type gold deposit and vein-type antimony deposit. However, the mineralization links and the similarities and differences between the Au and Sb mineralization processes require further systematic analysis. To address this issue, this paper built upon extensive previous research to analyze and summarize the fluid sources and evolution, as well as the enrichment and precipitation mechanisms of the Au−Sb mineralization process. On this basis, the paper revealed the similarities and differences in their mineralization processes. The analysis indicates that the initial ore-forming fluids for both gold and antimony originated primarily from deep sources (magmatic/metamorphic). During the mineralization process, these fluids likely underwent varying degrees of dilution due to the involvement of basin fluids and meteoric water. Moreover, significant differences exist in the mineralization mechanisms of Au and Sb. Gold mineralizing fluids are predominantly weakly acidic to neutral, with fluid-rock interaction serving as the primary mineralization mechanism. In contrast, Antimony mineralizing fluids are dominantly acidic, where changes in oxygen fugacity, temperature, and pH induced by fluid mixing are the main mechanisms for stibnite precipitation. Consequently, it is proposed that the mixing of fluids from different sources during the evolution of ore-forming fluids, along with the distinct mineralization styles of gold and antimony, may be the main controlling factors for the differential mineralization of Au and Sb. Based on the Au−Sb metallogenic model, it is proposed that the extensional structural system formed during the Yanshanian period serves as a favorable locus for antimony mineralization. The results provide theoretical support for the regional resource potential assessment during the "15th Five-Year Plan" period.

     

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