新疆东戈壁斑岩型钼矿床斑岩体与脉体关系研究

Study on relationship between porphyry bodies and veins of porphyry-type molybdenum deposit in east Gobi of Xinjiang

新疆东戈壁斑岩型钼矿床是新疆境内发现的第一个特大型钼矿床,与典型的斑岩型钼矿床不同的是矿体不是产于斑岩体的内外接触带,而是产于斑岩体外侧围岩脉体中。与矿化有关的脉体主要为具一定规模的石英脉,其次为钾长石脉,此外尚有复成分脉体如方解石—石英脉、萤石—石英脉、萤石—钾长石脉等。脉体之外围岩中基本无矿化。文章从东戈壁成矿斑状花岗岩体与矿化脉体的岩石学、岩石地球化学特征对比入手研究了斑状花岗岩体与矿化脉体的同源性,即二者为同源岩浆演化序列,各种脉体是斑状花岗岩浆演化至期后分异的产物,说明成矿热液主要来源于斑状花岗岩浆,此研究对进一步深入探讨岩浆热液成矿作用方式及成矿作用过程具有借鉴及指导意义。

The porphyry-type molybdenum deposit in east Gobi is the first oversize molybdenum deposit in Xinjiang.Being different than a typical porphyry-type molybdenum deposit,the orebody is not located in the internal or external contact zone of porphyry bodies,but is situated in the veins of surrounding rock outside the porphyry body.The veins related with mineralization primarily consist of quartz veins（largest in scale）,potassium feldspar veins（second largest in scale）,and some other polygenic veins（such as calcite-quartz vein,fluorite-quartz vein,fluorite-potassic feldspar vein etc.）.Mineralization is almost not found in surrounding rocks outside the veins.After comparing porphyritic granite mass and mineralized veins in east Gobi in terms of the petrology and petrogeochemistry characteristics,the paper studies the homology between porphyritic granite mass and mineralized veins,and it shows that both of the two belong to comagmatic evolutionary series.The various kinds of veins are products of differentiation of porphyritic granite magma in the later period of evolution.The author also believes that the hydrothermal ore-forming solution mainly originated from porphyritic granite magma.The results of study are intrusive and can be used for reference to the further discussion of methods and process of magmatic hydrothermal mineralization.