内蒙古中部东乌旗地区早古生代花岗岩物源特征及其地壳生长意义

Central Asian Orogenic Belt（CAOB）is the largest region of Phanerozoic continental growth in the world but there still exist a debate whether arc collage or lateral accretion is the main pattern of continental crust growth. This proposed study takes the granitoids rocks of Early Paleozoic from Dongwuqi area, Central Inner Mongolia, as the major object. Based on detail field investigations, reliable zircon U-Pb chronology, major and trace elements analysis, we further test whole rock Sm-Nd and zircon Lu-Hf isotope and compare their characteristics with post-collision to intraplate granitic rocks of Late Paleozoic to Mesozoic in Central Xing’an-Mongolian Orogenic belt. After that, we verify the nature of juvenile or old arc crust of Early Paleozoic in Dongwuqi area, which provides new evidence for identifying whether arc collage or lateral accretion leads to horizontal growth of continental crust in Phanerozoic CAOB.

中亚造山带是地球上最大的显生宙陆壳生长区，但陆壳生长方式是否主要为侧向增生或岛弧拼贴仍存在争议。本申请拟以东乌旗地区早古生代花岗质岩石为研究对象，根据详细的野外调查，在可靠的锆石U-Pb年代学和主微量元素地球化学数据基础上，测试分析全岩Sm-Nd和锆石Lu-Hf同位素，并分析对比兴蒙造山带中段晚古生代-中生代后碰撞-板内花岗岩Nd-Hf同位素特征，确定东乌旗地区早古生代岛弧地壳的新老性质，为鉴别中亚造山带内是否存在因岛弧拼贴或侧向增生而导致的大陆地壳水平生长提供新证据。