西藏隆子县扎西康锌多金属矿床矿石组构研究及成因探讨

通过详细的钻孔地质编录和显微镜下鉴定,对扎西康锌多金属矿床的矿石组构特征进行系统研究。矿区矿石构造主要为典型的由充填交代作用形成的块状构造、(网)脉状构造、浸染状构造、角砾状构造、晶洞及晶簇状构造。矿石结构主要为结晶作用和交代作用形成的结构,其次为压力作用和固溶体分离作用形成的结构。由于矿区构造作用和矿化作用具多期次性和复杂性,因而由交代作用形成的结构最为普遍且类型繁多。基于本次矿石组构研究成果,结合前人的研究资料,将矿区成矿期大致分为沉积成岩期、中低温热液成矿期和表生氧化期,其中,中低温热液成矿期是矿床最主要的成矿期。根据矿物组合特征,划分出6个成矿阶段:黄铁矿-石英-方解石阶段、闪锌矿-黄铁矿-方铅矿-毒砂-铁菱锰矿阶段、方铅矿-闪锌矿-硫盐矿物阶段、石英-方解石-辉锑矿阶段、石英-方解石阶段和氧化物阶段。最终,确定扎西康锌多金属矿为受构造-岩浆活动控制的中低温热液充填交代型矿床。

A Tentative Discussion on Ore Fabric and Genesis of the Zhaxikang Zn-polymetallic Deposit, Lhunze County, Tibet

Based on detailed drilling geological record and microscopic identification, the authors conducted a systematic study of the ore fabric characteristics of the Zhaxikang zinc-polymetallic deposit. In the mining area, the main ore structures are blocky, stockwork, disseminated, brecciated, geode and druse ones, formed by typical filling and metasomatism. The ore textures were formed mainly by crystallization and metasomatism, and subordinately by the influence of the pressure and the solid solution. Tectonism and mineralization of this mining area are of multi-stage and complex characteristics, and thus the textures formed by metasomatism are most common and of various types. Based on the research result of the ore fabric, combined with previous studies, the authors roughly divided the metallogenic periods into diagenesis, middle to low-temperature hydrothermal mineralization and supergene oxidation, with the low-temperature hydrothermal mineralization period being the most important metallogenetic period in this deposit. According to the features of mineral assemblages, six stages of mineralization were recognized, i.e., pyrite-quartz-calcite stage, sphalerite-pyrite-galena-arsenopyrite-iron rhodochrosite stage, galena-sphalerite- sulfosalt minerals stage, quartz-calcite-stibnite stage, quartz-calcite stage and oxidized minerals stage. It is held that the Zhaxikang zinc polymetallic deposit is a middle to low-temperature hydrothermal deposit, formed by filling and metasomatism and controlled by tectonic-magmatic activity.