东南极拉斯曼丘陵暗色麻粒岩锆石的U-Pb年龄及其地质意义

东南极拉斯曼丘陵地区代表性的原岩为镁铁质堆晶岩的暗色麻粒岩，其中锆石的Ｕ－Ｐｂ同位素年代测定表明，本区在泛非事件（５００Ｍａ）之前的晚元古中期可能经历过一次麻粒岩相变质作用，主要由斜方辉石－单斜辉石－斜长石－石英组成的暗色麻粒岩的Ｕ－Ｐｂ不一致线年龄结果为７７２．４＋７１．１／－４８．０（２σ）Ｍａ。结合野外地质证据，此年龄可能代表了该区已识别出的早期中压麻粒岩相变质作用事件并对应于罗迪尼亚事件

THE U Pb DATING OF ZIRCON IN THE MAFIC GRANULITE FROM THE LARSEMANN HILLS, EAST ANTARCTICA AND ITS GEOLOGICAL IMPLICATIONS

The U Pb isotopic dating of zircon in the mafic granulite which derived from mafic cumulate from the Larsemann Hills, East Antarctica, suggested that a granulite facies metamorphic event earlier than the Pan African event (500Ma) possibly occurred in the middle of Neoproterozoic in this region. The U Pb discordia of zircon in the mafic granulite mainly composed of Opx Cpx Pl Qtz is 772.4+71.1/-48.0(2σ)Ma.Combining with the field evidence, this result possibly represents the earlier mid pressure granulite facies metamorphic event recognized in this region and maybe corresponds to the Rodinia event.