内蒙古乌日尼图钼铜矿床辉钼矿铼—锇同位素定年及其地质意义

Re-Os isotopic dating of molybdenite from the Wurinitu molybdenum-copper deposit in Sonid Zuoqi,Inner Mongolia and its geological significance

乌日尼图钼铜矿床位于大兴安岭成矿带,钼矿化主要与中细粒花岗岩有密切关系,辉钼矿主要呈细脉浸染状分布于中细粒花岗岩中.通过对5件辉钼矿样品进行的铼—锇同位素分析,获得同位素等时线年龄为（134±14）Ma,前人研究成果表明花岗岩的成岩年龄为（134±14）Ma,综合矿床地质特征,推测乌日尼图钼铜矿床的形成时间为（133 ～ 134） Ma前后,属燕山早期构造—岩浆活动的产物.

The Wurinitu molybdenum-copper porphyry deposit is located in the Daxinganling metallogenic belt.The molybdenum mineralization is closely associated with the medium-fine grained granite.The molybdenite mianly occurs in the granite as disseminated and vienlets forms.Five molybdenite samples were collected from different ores for the analysis on Re-Os isotopic dating.The obtained isochron age is about （134 ± 14） Ma.By comparing with the previous isotope age of the granite intrusion as （133.6 ± 3.3） Ma,it can be concluded that the Wurinitu molybdenum-copper deposit was formed in the early Cretaceous period and it is derived from the Early Yanshanian tectono-magmatic activities.