【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。更多还原

【Abstract】 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.更多还原