湖南万古金矿地质地球化学特征及其成因探讨

Geochemistry and Its Genesis of Wangu Gold Deposit,Hunan

万古金矿位于江南古陆金成矿带中段的湘东北金成矿区。地质地球化学研究表明,万古金矿的成矿作用受区域构造控制,NE向断裂断为主要控矿构造,含矿构造是低序次的NWW向扩容断裂构造;成矿物质具有多源性,成矿流体具有岩浆水与变质水的混合水特征。结合区域大地构造背景的分析,认为在中生代中国东部受太平洋板块向西俯冲的影响,形成一系列NE向大断裂,万古金矿的形成与NE向长平大断裂密切相关,携带成矿物质的深部流体沿该断裂上升与浅部残余变质热液混合,并通过淋滤抽提地层中的成矿物质,使流体系统中的成矿物质不断富集,最终在适宜的温压条件下于剪切扩容空间中沉淀成矿。

The Wangu gold deposit situated at gold mineralization area of the Northeast Hunan belong to the milddle section of the gold mineralization belt of Jiangnan oldland. Gold mineralization was controlled by regional metallotectonics. The large NE - trending faults are major ore - controlling structure, and some low end dilatational faults are ore - hosting structures. Mineral materials are of multi - sources, and ore - forming fluid has characteristic of mixed water of magma and metamorphic water. Combined to regional tectonic background, the author thought that a series of NE - trending faults formed in eastern China due to subduction of the Pacific plate to Eurasia continent during the Mesozoic. The mineralization of the Wangu gold deposit was related to large Changping fault which led the deep source fluid bring mineral materials moved upwards a- long it and mixed with remainder metamorphic fluid in shallow crust. And through the leaching and extracting from the stratum, ore -forming material in the fluid system was unceasingly enriched, fmally mineralization formed in shearing dilatational space under the suitable thermobaric conditions.