西藏比如盆地碎屑锆石LA-ICP-MS U-Pb测年及其地质意义  

LA-ICP-MS U-Pb Geochronology of Detrital Zircons from Biru Basin of Tibet and Its Tectonic Significance

作　　者：张士贞[1,2] 向树元[2,3] 万俊[2] 毛鑫[2] 

机构地区：[1]成都地质矿产研究所,成都610081 [2]中国地质大学地球科学学院,武汉430074 [3]西藏自治区地质调查院,拉萨850000

出　　处：《地质科技情报》2010年第5期15-22,共8页Geological Science and Technology Information

基　　金：中国地质调查局项目(1212010610103)

摘　　要：对比如盆地中上侏罗统和下白垩统地层中采集的4个砂岩样品的碎屑锆石进行了LA-ICP-MSU-Pb测年,并将其结果与前人对盆地两侧地质体的测试年龄信息进行对比,据此得出样品405-3物源为盆地北侧喀喇昆仑—南羌塘陆块,其他3个样品物源均来自于盆地南侧的冈底斯—拉萨陆块。通过对比分析认为样品405-3中几组较老的锆石年龄是对羌塘盆地存在结晶基底并遭受后期多期变质变形的肯定。样品417-7,424-1及429-1的年龄既反映了600～500Ma的泛非期活动年龄数据,又显示了拉萨地块存在的中新元古代基底的年龄信息。The U-Pb geochronology of detrital zircons from four sandstone samples in the Middle-to-Upper Jurassic and Lower Cretaceous in the Biru Basin of Tibet were obtained based on the LA-ICP-MS method.The comparison of the present dating results with the previously obtained zircon ages of two sides of the basin illustrates that the detrital zircons of sample 405-3 came from Karakorum-southern Qiangtang block, and the detrital zircons of the other three samples came from Gangdese-Lhasa block.The old ages of some detrital zircons in sample 405-3 confirm the former conclusion that a crystalline basement had existed in Qiangtang Basin and had experienced multiple episodes of metamorphic and deformation since then.The a-ges of the sample 417-7,424-1and 429-1 reflect the activity age data of Pan-African in 600～500Ma,and demonstrate the existence of the Meso-Neoproterozoic basement of the Lhasa block.

关 键 词：比如盆地 碎屑锆石 物源分析 LA-ICP-MSU-Pb测年 中晚侏罗世至早白垩世 

分 类 号：P597[天文地球—地球化学]