藏东类乌齐地区花岗质片麻岩锆石Cameca U-Pb定年及其地质意义  

Zircon Cameca U-Pb dating of granitoid gneisses in the Leiwuqi area of the eastern Tibet,China and its geological implication

作　　者：曾庆高[1,2] 王保弟[2,3] 强巴扎西 尼玛次仁[2,4] 李虎 

机构地区：[1]中国科学院广州地球化学研究所,广东广州510640 [2]西藏地勘局区域地质调查大队,西藏拉萨851400 [3]中国地质调查局成都地质矿产研究所,四川成都610081 [4]中国地质大学,湖北武汉430000

出　　处：《地质通报》2010年第8期1123-1128,共6页Geological Bulletin of China

基　　金：国家"973"项目(编号:2009CB421003);中国地质调查局项目(编号:1212010510214)资助

摘　　要：西藏东部类乌齐一带吉塘岩群中新识别出一套花岗质片麻岩。花岗质片麻岩中锆石Th/U比值较高(Th/U>0.49),阴极发光图像显示锆石内部韵律环带明显,具典型岩浆锆石成因的特征。Cameca锆石U-Pb同位素加权平均年龄为282.1Ma±0.9Ma,表明花岗岩岩体形成于早二叠世,暗示澜沧江结合带在早二叠世存在岩浆增生事件。The granitic gneiss was identified from the Jitang Group in the Leiwuqi area,eastern Tibet.All zircons from the granitic gneiss have shown regular oscillatory magmatic zoning and high Th/U ratios（0.49）,being consistent with those of magmatic zircons.So we quoted 206Pb/238U ages to indicate crystallization age of the granitic magma.Analysis of Cameca zircon U-Pb isotope yielded a weighted mean 206Pb/238U age of 282.1±0.9Ma.The age of granitic gneiss implies that this magmatism event was triggered by the southwest subduction of the Lancangjiang suture in early Permian.In another word,magmatic growth in Lancangjiang suture had been taken place during early Permian.

关 键 词：锆石CamecaU-Pb年龄 花岗质片麻岩 澜沧江结合带 类乌齐地区 

分 类 号：P588.121[天文地球—岩石学] P597.3[天文地球—地质学]