内蒙古阿巴嘎旗比鲁甘干斑岩型钼矿床辉钼矿Re-Os同位素年龄及其地质意义

采用辉钼矿Re-Os同位素定年,获得的内蒙古阿巴嘎旗比鲁甘干钼矿的辉钼矿Re-Os同位素模式年龄变化范围为236.9±3.7~238.7±2.4Ma,年龄加权平均值为237.9±1.7Ma,表明该矿床形成时代应为印支期。辉钼矿的Re含量平均值为74.065×10~(-6),表明其主要为幔壳混合来源特征。该矿床位于贺根山断裂带以南的兴蒙造山系索伦山-霍林郭勒弧盆系内,为斑岩型钼矿床。钼矿体主要赋存在黑云母花岗斑岩和角岩内,受内外接触带控制。接触带控矿容矿断裂主要有北西向、北东向及近东西向,其内多充填有石英脉。细脉状、网脉状石英脉越发育,钼矿化越强。区域研究表明,印支期是兴蒙造山带及其邻区钼(钨)成矿的重要成矿期之一,但在本区尚属首次发现,为开展索伦山-霍林郭勒成矿带区域成矿规律研究提供了重要参考。

Re-Os isotopic dating of molybdenites from the Bilugangan porphyry Mo deposit in Abag Banner, Inner Mongolia, and its geological significa

In this paper, the authors conducted for the first time Re-Os isotope analysis of molybdenite from the Bilugangan porphy-ry Mo deposit in Abag Banner, Inner Mongolia and obtained the molybdenite Re-Os isotope modal ages between 236.9±3.7Ma and 238.7±2.4Ma and weighted average value of 237.9±1.7Ma, which indicate that the mineralization of Bilugangan Mo deposit oc-curred in Indosinian period. The average rhenium content of molybdenite is 74.065×10^-6, suggesting the source of rhenium was char-acterized by mantle-crust mixing. Belonging to a porphyry Mo deposit, the deposit is located within the Slonker-Huolinguole arcbasin system of Da Hinggan Mountains-Inner Mongolia orogenic belt south of Hegenshan fault belt. Controlled by internal or exter-nal contact zones, the Mo orebodies are mainly situated inside the biotite granite porphyry and hornstone. The controlling or hosting faults in the contact zones are principally in NW, NE and approximately EW directions, and are filled with quartz veins. The stronger the development of stringer and stockwork quartz veins, the stronger the molybdenum mineralization. Regional researches reveal that Indosinian is one of the most important Mo(W) mineralization stages in Da Hinggan Mountains-Inner Mongolia orogenic belt and the adjacent areas in spite of the fact that this kind of deposit was discovered for the first time in this region. The results obtained by the authors provide important references for the further study of ore-forming regularity in the Slonker-Huolinguole metallogenic belt.