黔西南水银洞爆破角砾岩筒与金元素超常富集

Fluid Explosion Breccia Pipe and Gold Supernormal Enrichment in Shuiyindong Gold Ore Deposit, Southwest Guizhou Province

水银洞金矿床曾被认为是滇黔桂地区最有代表性的微细浸染型金矿(卡林型金矿),然而矿床的金品位明显高于一般意义上的卡林型金矿床,且金矿体与气液爆破角砾岩关系密切。气液爆破角砾岩呈垂直筒状产状,两侧断裂矿化带呈向上扩张的"喇叭口"状成矿空间,富金矿体紧密围绕角砾岩筒分布。根据野外和显微镜观察,角砾岩块成分复杂与显著磨圆。气液角砾岩筒的角砾岩显著富集金、稀土、亲地幔过渡元素Ti、Cr、Ni、Co、V等,以及Zr、Hf等,明显地区别于围岩,反映出深源流体快速上升的气液爆破角砾岩的特征,角砾岩筒实际上具备含金成矿流体的上涌通道的功能。岩筒中早期角砾岩的角砾含Au达18×10^(-6),属于深部金矿体的爆破碎块,显示出水银洞金矿床可观的深部找矿勘探前景。

Shuiyindong gold ore deposit is known as a typical fine-grain disseminated gold deposit(Carlin-type gold deposit) in Dian–Qian–Gui area;however, its gold grade is evidently higher than that of the common Carlin-type gold deposit, and its orebody is closely related to fluid explosion breccia. The chief breccia pipe is of a vertical columnar occurrence, the fractural mineralized broken zones on both sides of the pipe form a trumpet shape upwards in the expanded metallogenetic space, and high-grade orebodies are distributed around the pipes.Field investigation and microscopic observation indicated that the composition of breccia was quite complex;its rubbles had good abrasion and showed a space-dependent relationship with high-grade gold deposits. The pipe breccias were rich in Au, REE, and siderophile transition elements including Ti, Cr, Ni, Co, V, Zr, and Hf, and were evidently different from the surrounding rocks, reflecting the features of fluid explosion breccia resulting from the rapid uplifting of deep resource fluid, that is, the breccia pipes are the upwelling path of gold metallogenetic fluid. The rubble comprising early breccia in the pipe was of 18×10^(-6)gold grade, likely from the explosion fragment of the deep gold orebody, revealing considerable gold prospects in the depths of the Shuiyindong gold ore deposit.