攀西麻粒岩锆石U-Pb年代学:新元古代扬子陆块西缘地质演化新证据  

Zircon U-Pb Geochronology of Granulites in Panzhihua-Xichang Area:New Evidence for the Neoproterozoic Geological Evolution in the Western Margin of Yangtze Block

作　　者：刘文中[1] 徐士进[1] 王汝成[1] 赵连泽[1] 李惠民[2] 吴俊奇[1] 方中[1] 

机构地区：[1]南京大学地球科学系及内生金属成矿作用国家重点实验室,210093 [2]中国地质调查局天津地质矿产研究所,300170

出　　处：《地质论评》2005年第4期470-476,共7页Geological Review

基　　金：本文为国家自然科学基金项目(编号49972062)教育部科学技术研究重点项目(编号104089)资助的成果。

摘　　要：攀枝花-西昌(攀西)麻粒岩一直被认为是扬子陆块西缘变质程度最高和最古老的结晶基底岩石。最近从麻粒岩中获得的单颗粒锆石U-Pb测年结果表明,攀西麻粒岩的原岩可能形成于古元古代晚期(1870±24 Ma)。17件锆石U-Pb的谐和年龄(858-778 Ma)可能是麻粒岩受新元古代地幔柱活动影响,在快速冷却和抬升过程中发生角闪岩相退变质作用的时代。这一时间正是全球Rodinia超大陆由汇聚转变为裂解地球动力学系统发生改变的重要时期。The Panxi （Panzhihua--Xichang） granulites have long been recognized as the oldest rock of the crystalline basement with the highest metamorphic grade on the western margin of the Yangtze Block. The TIMS zircon U-Pb dating results of the Panxi granulites in this paper indicate that the protoliths of these granulites were formed in the late Paleoproterozoic （1870-4-24 Ma）. Seventeen zircon U-Pb concordant ages （from 858 to 778 Ma） show the time of amphibolite-facies retrogressive metamorphism of the Panxi granulites. Amphibolitefacies retrograde metamorphism took place during rapid cooling and uplift of the Panxi granulite, which was probably correlated with the Neoproterozoic mantle plume activities. This is the key period during which the geodynamic system of the global Rodinia Supercontinent was transited from amalgamation to break-up in the Neoproterozoic.

关 键 词：锆石U—Pb年代学 新元古代 地质条件 结晶基底岩石 地质年代学 同位素年代学 

分 类 号：P597.3[天文地球—地球化学]