湘东北万古矿区金矿迁移沉淀机制与找矿突破

Migration and Precipitation Mechanisms of Gold and Breakthrough in Prospecting in the Wangu Gold Deposit, Northeastern Hunan

摘要: 湘东北万古矿区作为“江南造山带”上的关键成矿节点，其金矿成因并非单一的纯沉积变质型，而是“陆内造山热液叠加型”，成矿混合流体具有“深源流体”与“壳源流体”双重属性。金的高效迁移依赖于流体中悬浮的纳米金颗粒(Au-NP)与硫氢络合物($Au{\left(HS\right)}_2^{-}$ )的协同作用，而沉淀机制则主要受控于断层阀控引起的流体沸腾(Flash Vaporization)、围岩褪色化蚀变(菱铁矿诱发硫化)及有机质吸附–解吸附过程。在万古矿区东部实施的2000米级深部钻探验证了“深部找矿”模型的有效性，证实了深部隐伏岩体与盲矿体的存在。

Abstract: The northeastern Hunan Wangu mining district, a critical metallogenic node within the Jiangnan Orogenic Belt, hosts gold deposits whose genesis is not solely of pure sedimentary-metamorphic type but rather belongs to an “intracontinental orogenic hydrothermal overprinting type”. The ore-forming fluids exhibit dual characteristics, comprising both deep-sourced and crustal-derived components. Efficient gold migration relies on the synergistic interaction between suspended nanoparticulate gold (Au-NP) and hydrosulfide complexes ($Au{\left(HS\right)}_2^{-}$ ) within the fluid. Precipitation is primarily controlled by fluid boiling (flash vaporization) induced by fault-valve mechanisms, wall-rock bleaching alteration (triggered sulfide formation associated with siderite), and organic matter adsorption-desorption processes. Deep drilling to depths exceeding 2000 meters in the eastern part of the Wangu district has validated the “deep prospecting” model, confirming the presence of concealed intrusions and blind ore bodies at depth.