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维宝矽卡岩铜铅锌矿床位于新疆与青海两省交界处,大地构造位置属祁漫塔格造山带东段,可以分为维东、主矿段和维西三个矿段。主矿段和维东矿段以铅锌矿化为主,铜矿化很少,而维西矿段铜、铅、锌矿化均较发育。本次我们选取维西矿段的矽卡岩和矿石样品,进行了详细的矿物学研究。根据矿物共生组合、矿石组构以及脉体的穿插关系,可以将维西矿段成矿过程分为4个阶段,即早期矽卡岩阶段、晚期矽卡岩阶段、石英-硫化物阶段和石英-碳酸盐阶段,其中石英-硫化物阶段是主要的成矿阶段。矽卡岩矿物主要为石榴子石、辉石、绿帘石和角闪石等,硫化物主要为黄铜矿、方铅矿、闪锌矿、黄铁矿和磁黄铁矿等。电子探针分析表明,石榴子石成分以钙铁榴石分子(And=59.00%～97.70%)和钙铝榴石分子(Gro=1.92%～40.42%)为主,为钙铁—钙铝系列石榴子石;辉石主要由透辉石分子(Di=45%～91%)和钙铁辉石分子(Hd=8%～53%)组成,表现在矿物上以透辉石为主,而钙铁辉石数量很少;角闪石成分变化范围比较大,但总体上为透闪石—阳起石系列。综合矿物组合和化学成分特征表明维宝矿床维西矿段矽卡岩为钙矽卡岩。此外,具有环带结构的石榴子石从核部到边部,化学成分表现出有规律的变化,Al2O3含量先上升后下降,FeOT含量则先下降后上升。这表明随着交代作用的进行,成矿流体的pH值不断发生变化,由最初的弱酸性—碱性条件转变为近中性条件,最终又恢复到弱酸性—碱性条件。维西矿段硫化物的金属原子与硫原子的比值大部分都大于理论值,表明它们形成于硫逸度较高的环境。此外,闪锌矿中Fe、Zn含量变化范围比较大,Zn=54.50%～64.75%,Fe=1.15%～10.16%,这种大范围变化指示成矿过程中温度和硫逸度可能发生波动。
The Vibo Skarn Copper-Lead-Zinc deposit is located at the junction of Xinjiang and Qinghai provinces. The tectonic location of the deposit is the eastern segment of the Qimantag Orogenic Belt. It can be divided into three main sections: the Weidong, the main ore section and the Weixi ore section. Lead and zinc mineralization is dominant in the main orebody and the Weidong orebody, with little copper mineralization, whereas copper, lead and zinc mineralization in the Weixi orebody are more developed. This time, we selected samples of skarn and ore in the Weixi ore section and conducted detailed mineralogical studies. According to the intergrowth of mineral assemblages, ore structure and veins, the mineralization process of Weixi orebody can be divided into four stages: early skarn stage, late skarn stage, quartz-sulphide stage and quartz Carbonate stage, in which the quartz-sulphide stage is the major metallogenic stage. Skarn minerals are mainly garnet, pyroxene, epidote and amphibole, sulfide mainly chalcopyrite, galena, sphalerite, pyrite and pyrrhotite. Electron probe analysis showed that the garnet composition is dominated by the elements of iron and garnet (And = 59.00% -97.70%) and the molecules of garnet (Gro = 1.92% -40.42%), Garnet; pyroxene is mainly composed of diopside (Di = 45% ~ 91%) and calcium iron pyroxene (Hd = 8% ~ 53% The amount of calcium iron pyroxene is small; amphibole composition changes relatively large, but on the whole for the tremolite - Yang stone series. The comprehensive mineral assemblages and chemical compositions indicate that the skarn in the Weixi ore section is calcium skarn. In addition, the garnet with the zonal structure changes regularly from the core to the periphery, the content of Al2O3 decreases first and then decreases, while the content of FeOT increases first and then decreases. This indicates that the pH value of the ore-forming fluid changes continuously from the initial weak acid-alkaline condition to near-neutral condition and finally returns to the weak acid-alkaline condition with the account of metasomatism. The ratio of metal atoms to sulfur atoms in sulfide in the Weixi ore section is mostly larger than the theoretical value, indicating that they are formed in environments with high sulfur fugacity. In addition, the contents of Fe and Zn in sphalerite range from 54.50% to 64.75% with Fe ranging from 1.15% to 10.16%. This large-scale change indicates that the temperature and the sulfur fugacity in the ore-forming process may fluctuate.