中天山巴仑台地区变形花岗岩类LA-ICP-MSU-Pb年代学及其构造意义  

Zircons LA-ICP-MS U-Pb Dating on the Baluntai Deformed Granitoids, Central Tianshan Block, Northwest China, and Its Tectonic Implications

作　　者：陈义兵[1,2] 张国伟[2] 柳小明[2] 熊小林[1] 袁超[1] 陈林丽[1] 

机构地区：[1]中国科学院广州地球化学研究所同位素地球化学国家重点实验室,广州510640 [2]西北大学大陆动力学国家重点实验室,西安710069

出　　处：《地质论评》2012年第1期117-125,共9页Geological Review

基　　金：国家自然科学基金资助项目(编号40002016);中国科学院创新项目(编号GIGCX-03-01);中国博士后科学基金资助项目(编号20070411138);中石化海相前瞻性项目(编号YPH08012);西北大学大陆动力学国家重点实验室开放课题基金项目(编号06LCD17)和自主研究课题(BJ081331)的成果

摘　　要：本文对巴仑台地区中天山南北边缘的变形花岗岩体进行了详细的锆石LA-ICP-MSU-Pb年代学研究。中天山北缘花岗质片麻岩中岩浆锆石结晶年龄为630.0±5.0Ma,代表了中天山微陆基底的新元古代岩浆事件年龄;其变质增生锆石边的年龄为440.9±3.3Ma,精确限定了中天山北缘洋盆闭合与碰撞造山作用的时代为早志留世。中天山南缘糜棱岩化花岗闪长岩中岩浆锆石结晶年龄为389.5±3.2Ma,指示出中天山南缘洋壳在中泥盆世向北俯冲形成陆缘岩浆弧;其变质增生锆石边的年龄为362.1±4.3Ma,精确限定了中天山南缘洋盆闭合与碰撞造山作用的时代为晚泥盆世末期。研究结果还表明中天山微陆块具有年龄为2.5Ga和1.8Ga的古老结晶基底。Zircons LA-ICP-MS U-Pb dating was performed systematically on deformed granitoids in the Baluntai area of Central Tianshan Mountains. The gneissic granite occurring along the northern margin of the Central Tianshan block was formed during the Neoproterozoic, based on the magmatic zircons age of 630.0±5.0 Ma. The metamorphic zircon rims was dated at 440.9±3.3 Ma, which probably was related to the deformation process in the studied Neoproterozoic granite during the collision between the Central Tianshan block and the North Tianshan block in Early Silurian. The mylonitized granodiorite occurring along the southern margin the Central Tianshan block was formed during the Middle Devonian, based on the magmatic zircons age of 389.5±3.2 Ma, which indicate that the oceanic crust subducted northward under the Central Tianshan block at that time. The metamorphic zircon rims was dated at 362.1±4.3 Ma, which probably was related to the deformation process in the studied granodiorite during the collision between the Central Tianshan block and the South Tianshan block at the end of Late Devonian. Our dataset also shows that the zircon cores have apparent U-Pb ages of 2.5 Ga and 1.8 Ga, which was believed to be components of the Precambrian basement of the Central Tianshan Block.

关 键 词：锆石LA-ICP-MSU-PB定年 变形花岗岩类 巴仑台 中天山 新疆 

分 类 号：P597.3[天文地球—地球化学]