投稿时间：2013-06-18
修订日期：2014-03-31
网络发布日期：2014-09-15
中文摘要:八大关斑岩铜钼矿床是中国内蒙大兴安岭地区典型的斑岩型铜钼矿床之一。对矿区Ⅱ号岩体不同位置的2件岩石样品采用高精度的LA-ICP-MS锆石U-Pb测年，获得的锆石U-Pb年龄分别为（230.6±2.8）Ma和（230.5±4.4）Ma，两者在误差范围内非常一致，由此确认花岗闪长斑岩体的形成年龄约为230 Ma；对矿区7件辉钼矿样品采用Re-Os同位素测年，获得的Re-Os等时线年龄为（228.7±3.1）Ma，指示了八大关铜钼矿床辉钼矿的沉淀时间约为228.7 Ma。结合矿区岩相学、矿物学特征，辉钼矿呈浸染状分布于花岗闪长斑岩体内，且辉钼矿与黄铜矿密切共生，以及上述2种精确方法获得的年龄在误差范围内的一致性，说明花岗闪长斑岩即为成矿岩体，成岩与成矿大致同时或成矿略晚于成岩，表明八大关铜钼矿床形成于中三叠世，属于印支期成矿。
Abstract:The Badaguan porphyry Cu-Mo deposit is one of the typical porphyry Cu-Mo deposits in the Da Hinggan Mountains. Systematic isotope dating was conducted to constrain the age of the deposit. LA-ICP-MS zircon U-Pb dating of two different rock samples yielded the ages of (230.6±2.8) Ma and (230.5±4.4) Ma respectively. The two ages are in agreement within the deviation, suggesting that the rock-forming age is about 230 Ma. Meanwhile, Re-Os isotopic age analysis of seven molybdenite yielded a weighted average model age of (228.7±3.1) Ma, which implies that the precipitation age of the molybdenite is about 228.7 Ma. Mineralogical and petrological characteristics show that molybdenite occurs within the quartz diorite porphyrite in dissemination form and is closely associated with chalcopyrite. The dating results of the two precise methods are concordant within the error range, which suggests that the quartz diorite porphyrite might have been the metallogenic intrusive mass and the mineralization approximately occurred simultaneously with or slightly later than the rock-forming process. These data suggest that the Badaguan Cu-Mo deposit was formed in the Middle Triassic and belonged to indo-Chinese mineralization.
keywords:geochemistry LA-ICP-MS zircon U-Pb dating mineralization age porphyry Cu-Mo deposit Middle Triassic Badaguan Inner Mongolia
文章编号：
中图分类号：P618.41;P618.65
文献标志码：
基金项目:本文得到地质调查项目（编号：1212011120992）和国家重点基础研究计划项目（编号：2013CB429803）联合资助
引用文本：
康永建,王亚君,黄光杰,佘宏全,向安平,田京,郭志军,董旭舟.2014.内蒙古八大关斑岩型铜钼矿床成岩成矿年代学研究[J].矿床地质,33(4):795~806KANG YongJian,WANG YaJun,HUANG GuangJie,SHE HongQuan,XIANG AnPing,TIAN Jing,GUO ZhiJun,DONG XuZhou.2014.Study of rock-forming and ore-forming ages of Badaguan prophypy Cu-Mo deposit in Inner Mongolia[J].Mineral Deposits33(4):795~806
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