内蒙古乌兰德勒钼铜多金属矿区细粒二长花岗岩SHRIMP锆石U-Pb年龄及意义

中蒙边境内蒙古苏尼特左旗乌兰德勒钼铜多金属矿床是内蒙古二连-东乌旗成矿带上新发现的一个规模较大的矿床。矿床地质特征研究表明,区内发育的隐伏细粒二长花岗岩与钼铜多金属矿床的形成有密切的时空、成因联系。为了揭示本区成矿规律,对细粒二长花岗岩进行了单颗粒SHRIMP锆石U-Pb测年,获得~(206)Pb/~(238)U年龄加权平均值为131.3±1.6Ma(MSWD=1.7),该年龄与矿石中的辉钼矿Re-Os同位素年龄134.1±3.3Ma基本一致,表明其形成时代为早白垩世。地质勘查成果表明,矿床的形成主要与隐伏的燕山期细粒二长花岗岩有着密切关系。上述同位素年龄的获得,为本区成矿规律的研究提供了重要依据。

SHRIMP zircon U-Pb age of the fine-grained monzonitic granite in the Wulandele molybdenum-copper polymetallic ore deposit of Inner Mongolia and its significance

The Wulandele molybdenum-copper polymetallic deposit in Sonid Left Banner of Inner Mongolia is a large deposit dis-covered recently during the geological survey in the Erlian-Dong Ujimqin Banner metallogenic belt of Inner Mongolia. Ore geology characteristics show that the formation of the molybdenum-copper polymetallic deposit had spatial-temporal and genetic relation-ships with the concealed fine-grained monzonitic granite in this area. In order to reveal the metallogenic regularity in this area, the authors determined the SHRIMP single particle zircon U-Pb age of the fine-grained monzonitic granite. The results show that the weighted average ²⁰⁶Pb/²³⁸U age of 131.3±1.6Ma(MSWD=1.7)is consistent with the molybdenite Re-Os age of 134.1±3.3Ma, sug-gesting that the formation age was Early Cretaceous. The result of geological exploration shows that the formation of the deposit was closely related to the concealed Yanshanian fine-grained monzonitic granite. The result of isotopic dating is important for the study of the regularity of ore formation.