西藏新嘎果铅锌矿床矽卡岩矿物及金属矿物特征

新嘎果矿床是西藏冈底斯成矿带北缘矽卡岩多金属成矿带的一个典型矽卡岩型铅锌矿床。矽卡岩矿体主要呈层状、似层状产于下白垩统塔克那组地层中。电子探针测试结果表明，矽卡岩矿物主要为钙铝榴石、钙铁辉石和绿帘石，少量的硅灰石、密绿泥石等，构成典型的钙质矽卡岩。金属矿物主要为闪锌矿、方铅矿、磁黄铁矿、黄铜矿、黄铁矿，少量的白铁矿、毒砂、自然铋、斜方辉铅铋矿、辉砷镍矿等。该矿床中石榴子石成分特征指示成矿环境是变化的，在早期进变质阶段由氧化环境向还原环境转变，而晚期退变质阶段由氧化环境向还原环境转变。金属矿物中闪锌矿主要为铁闪锌矿，表明其形成于中高温环境。而含铋的矿物主要为自然铋、斜方辉铅铋矿和方铅矿，并且在这些矿物中Ag和Bi的含量呈正相关性，指示铋对银的富集可能起着重要的作用；此外，铋也是新嘎果矿床重要的伴生有用元素，具有较高的综合利用价值。

Skarn mineral and metallic mineral characteristics of Xin' gaguo lead-zinc deposit, Tibet

The Xin''gaguo deposit is a typical skarn-type lead-zinc deposit along the skarn polymetallic metallogenic belt in the north of the Gangdise metallogenic belt in Tibet. The skarn orebody has a bedded or bedded-like structure and was formed in the Takna Formation of Lower Cretaceous. The results of the electron microprobe analysis show that the skarn is a typical calcareous skarn mainly consisting of grossularite, hedenbergite and epidote as well as a small amount of wollastonite and pycnochlorite. The metal minerals mainly consist of sphalerite, galena, pyrrhotite, chalcopyrite and pyrite as well as a small amount of marcasite, arsenopyrite, native bismuth, cosalite, and gersdorffite. The metallogenic environment changed according to the composition characteristics of the garnet in this deposit, with an early prograde metamorphic stage characterized by transforming from oxidation environment to reducing environment and a later retrograde metamorphic stage characterized by transforming from oxidation environment to reducing environment. The sphalerite in the metal minerals mainly consists of christophite, which indicates that it was formed in the environment with medium and high temperature. However, the bismuth-bearing minerals mainly consist of native bismuth, bjelkite and galena, and the values of Ag and Bi contained in these minerals are positively correlated, indicating that bismuth may have played an important role in the enrichment of silver;in addition, bismuth has a high comprehensive utilization value and is also an important associated useful element.