大兴安岭甲乌拉铅锌银矿床石英二长斑岩锆石U-Pb年代学及地质意义

甲乌拉铅锌银矿床是大兴安岭西坡得尔布干铜（钼）-银铅锌成矿带内大型铅锌银矿床之一，长期以来被认为是一个与火山-次火山热液作用有关的浅成低温热液矿床.在野外调研的基础上，对含矿岩体石英二长斑岩开展年代学研究，结果表明：与成矿关系密切的石英二长斑岩的LA-ICP-MS锆石U-Pb年龄为152.2±1.5 Ma （MSWD=4.7，n=31）.结合前人成岩、成矿年代学研究，认为甲乌拉矿床为晚侏罗世-早白垩世早期成矿，与区域上同类矿床产于同一时代，形成于蒙古-鄂霍次克洋闭合碰撞造山后的伸展构造背景.

ZIRCON U-Pb CHRONOLOGY OF QUARTZ MONZOPORPHYRY IN JIAWULA Pb-Zn-Ag DEPOSIT,DAXINGANLING MOUNTAINS: Geological Implications

The Jiawula Pb-Zn-Ag Deposit, one of the large-scale deposits in the Derbugan Cu(Mo)-Ag-Pb-Zn metallogenic belt in the western slope of Daxinganling Mountains, genetically has long been considered as epithermal type related to volcanic-subvolcanic hydrothermal process. The chronology of ore-bearing quartz monzoporphyry is studied on the basis of field investigation. The results show that the LA-ICP-MS zircon U-Pb is dated 152.2±1.5 Ma. Combined with previous diagenetic and metallogenic chronology researches, it is thought that the Jiawula Deposit was formed in Late Jurassic to the early stage of Early Cretaceous, contemporaneous with similar deposits in the region, which is a product of post-collisional orogeny extensional tectonic setting after the closure of Mongolia-Okhotsk Ocean.