新疆维宝矽卡岩铜铅锌矿床维西矿段矿物学特征

发布时间：2018-02-15 22:58

本文关键词： 钙矽卡岩电子探针维宝矿床新疆祁漫塔格　出处：《地质学报》2017年05期 　论文类型：期刊论文

【摘要】：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。
[Abstract]:The Weibao skarn copper-lead-zinc deposit is located at the junction of Xinjiang and Qinghai provinces. The geotectonic position belongs to the eastern section of the Qimantage orogenic belt, which can be divided into three ore segments: Weidong, main ore and Weixi. The main ore segment and Weidong ore section are mainly lead-zinc mineralization. Copper mineralization is rare, but copper, lead and zinc mineralization are relatively developed. In this paper, we selected skarn and ore samples from Weixi ore section to carry out detailed mineralogical study. According to the mineral symbiotic assemblage, The ore-forming process of Weixi formation can be divided into four stages: early skarn stage, late skarn stage, quartz-sulfide stage and quartz-carbonate stage. The quartz-sulfide stage is the main metallogenic stage. Skarn minerals are mainly pomegranate, pyroxene, verdanite and hornblende, while sulfides are chalcopyrite, galena, sphalerite, etc. Electron probe analysis of pyrite and pyrrhotite shows that the main components of pomegranate are calc-iron eclogite molecule And59.00 (97.70) and calcium aluminoeclogite molecule Gros1.92 and 40.42%, which are mainly calcium ferrium-calcium aluminum-series garnet. The pyroxene is mainly composed of diopside molecule Dixene 45 and Calciferopyroxene molecule Hdf8. The pyroxene is mainly diopside in minerals, but the quantity of calcium ferroxene is very small, and the amphibole composition has a relatively large range of changes. But in general, it is tremolite-actinolite series. The comprehensive mineral assemblage and chemical composition characteristics indicate that skarn is calcium skarn in Weixi formation of Weibao deposit. In addition, the garnet with annular structure is from the core to the edge. The chemical composition showed a regular change. The content of Al _ 2O _ 3 increased first, then decreased and then increased. This indicated that the pH value of the ore-forming fluid changed continuously with the metasomatism. From the initial weak acidic to basic condition to the near neutral condition, and finally to the weak acidic basic condition, the ratio of metal atom to sulfur atom in the Vesi ore section is mostly larger than the theoretical value. The results show that they are formed in the environment with high sulfur fugacity. In addition, the variation range of Fe ~ (2 +) Zn content in sphalerite is larger than that of Zn ~ (2 +) 54.50 ~ 64.750.10 ~ (16), which indicates that the temperature and sulfur fugacity may fluctuate during the metallogenic process.
【作者单位】：中国地质科学院矿产资源研究所国土资源部成矿作用与资源评价重点实验室;
【基金】：国土资源部公益性行业科研专项经费项目(编号201411025) 中国地质调查局地质调查项目(编号1212011085528;12120113093600);中国地质调查局高层次地质人才培养计划(编号201309)和青年地质英才计划(编号201112)资助的成果
【分类号】：P618.4

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