铟矿床时空分布、成矿背景及其成矿过程

铟是一种稀散金属元素,特殊的地球化学性质导致其难以形成独立的矿床,均以伴生矿产的形式产出于富锡岩浆热液与陆相火山-次火山热液系统,以及相对贫锡的海底(火山)热液系统。研究表明,铟矿床广泛分布于活动的大洋或大陆板块边缘,成因上主要与板块俯冲以及碰撞作用密切相关,少量与火山岩以及喷流沉积岩相关的块状硫化物矿床形成的有利构造背景则是弧后环境和裂谷环境。在不同地质历史时期,铟的巨量堆积作用主要有新第三纪、白垩纪、泥盆纪三个时期,对应的矿化类型分别以浅成低温热液-锡多金属脉型、矽卡岩型以及块状硫化物(VMS)型矿床为主,其中与铟成矿作用相关的岩浆岩多为A型或S型花岗岩。铟独立矿物目前报道约15种,主要包括自然铟、硫铟铜矿、铟石、樱井矿、羟铟石等,其中以硫铟铜矿最为广泛。绝大多数铟主要以类质同象的形式赋存于闪锌矿中,其次为黝锡矿、锌黄锡矿、黄铜矿、锡石、黝铜矿、砷黝铜矿等。富铟闪锌矿通常形成于高温热液体系,常显示阶段性富集特征,最普遍的置换机制为(Ag,Cu)~++In~(3+)2Zn~(2+)。文章指出为完善铟金属成矿理论,需进一步加强铟的成矿物质来源、铟沉淀的物理化学条件及其与主矿种成生关系的研究。

Spatial and temporal distributions, metallogenic backgrounds and processes of indium deposits

Indium is a rare and dispersed metallic element. Hitherto, no independent indium deposit has been reported worldwide due to specific geochemical properties of indium. The indium mineralization as the by-product mainly associates with tin-rich hydrothermal systems, including magmatic-hydrothermal and continental volcanic-subvolcanic systems, and relatively tin-depleted submarine volcanic hydrothermal system. The indium mineralization usually formed in the plate boundary, which is closely related to slab subduction and collision, whereas a few sulfide deposits associated with volcanic rocks and sedimentary rocks produced in the post-arc environment and rift environment. The significant development of indium in geologic historical period mainly focuses in the Neogene, Cretaceous, and Devonian, corresponding to main mineralization types of epithermal, skarn, and VMS, respectively. Most magmatic rocks associated with indium mineralization are A-type or S-type granites. There are approximately 15 kinds of independent minerals of indium, including natural indium, roquesite, indite, sakuraiite, and dzhalindite. In addition to forming individual indium minerals, the majority of indium is principally hosted in sphalerite, followed by stannite, stannoidite, chalcopyrite, cassiterite, tetrahedrite, and tennatite. Indium is mainly formed in the high temperature condition, and generally displays multi-stage enrichment. Sphalerite is the most important indium bearing mineral, in which the incorporation mechanism is (Ag, Cu)⁺+In³⁺↔2Zn²⁺. This paper suggests that it is necessary to further strengthen the research on the origin of indium, the physical and chemical conditions of indium precipitation, and the genetical links between indium and the main ore species.