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南岭成矿带大义山地区锡多金属矿成矿规律及找矿预测

Metallogenic regularity and prospecting prediction of tin-polymetallic deposits in Dayishan Area, Nanling Metallogenic Belt

  • 摘要: 为厘清大义山地区锡多金属矿成矿规律并指导找矿预测,通过野外地质调查、地层岩性分析、构造与岩浆岩特征研究及矿床时空分布规律、矿化富集规律梳理,系统探讨了该地区锡多金属矿的成矿条件及成矿规律,并构建成矿模型、圈定找矿靶区。结果表明:大义山地区处于湘中凹陷与南岭隆起多组构造岩浆岩带复合交会部位,成矿受北西向大义山式断裂控制显著;成矿作用与中、晚侏罗世岩浆侵位密切相关,空间上发育东、中、西3条北西向矿化带,不同矿化带因地层、构造与岩浆岩组合特征差异,发育岩体型、云英岩脉型、矽卡岩型、热液充填交代型等矿化类型;泥盆纪—三叠纪碳酸盐岩为核心赋矿地层,大义山式断裂、岩浆侵位接触构造体系及岩体上凸构造构成联合控矿体系,燕山期汤市铺超单元介头单元为核心成矿单元。基于成矿规律构建了“岩体内部云英岩型—接触带矽卡岩型—外带热液充填型”的成矿模型,圈定桂阳县小塘铅锌矿区为找矿靶区,该找矿靶区具有良好的找矿潜力。该研究揭示了大义山地区锡多金属矿成矿规律,为南岭成矿带北缘同类锡多金属矿的勘查与研究提供了理论依据和实践参考。

     

    Abstract: This paper aims to clarify the metallogenic regularity of tin-polymetallic deposits in the Dayishan Area and guide prospecting prediction. To this end, the metallogenic conditions and metallogenic regularity in this area were systematically investigated through field geological surveys, lithostratigraphic analysis, structural and magmatic rock characteristic research, as well as the review of the spatiotemporal distribution and mineralization enrichment regularity of the deposits. Meanwhile, a metallogenic model was built, and prospecting targets were delineated. The results indicate that the Dayishan Area is located at the composite intersection of multiple tectono-magmatic belts between the Central Hunan Depression and the Nanling Uplift. Mineralization is significantly controlled by the NW-trending Dayishan-type faults. The metallogenic processes are closely associated with Middle–Late Jurassic magmatic emplacement. Spatially, three NW-trending mineralization belts (eastern, central, and western) are developed. Due to variations in stratigraphic, structural, and magmatic rock assemblages, different mineralization types are recognized in these belts, including the granite type, greisen vein type, skarn type, and hydrothermal filling-replacement type. The Devonian to Triassic carbonate rocks constitute the primary ore-hosting strata. The Dayishan-type fault system, the magmatic emplacement-related contact structural framework, and the apical protrusions of the granite collectively form a composite ore-controlling system. The Jietou unit of the Tangshipu Superunit (Yanshanian) is identified as the key metallogenic unit. Based on the metallogenic regularity, a metallogenic model was built, characterized by "greisen-type mineralization within the pluton, skarn-type mineralization along the contact zone, and hydrothermal filling-type mineralization in the outer zone". The Xiaotang Pb−Zn ore area in Guiyang County is delineated as a prospecting target with considerable prospecting potential. This study reveals the metallogenic regularity of tin-polymetallic deposits in the Dayishan Area and provides a theoretical basis and practical reference for the exploration and research on similar tin-polymetallic deposits on the northern margin of the Nanling Metallogenic Belt.

     

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