内蒙古达茂旗花岗岩类LA-ICP-MS锆石U-Pb年龄及其地质意义  

LA-ICP-MS zircon U-Pb ages of granitoids in Darhan Muminggan Joint Banner, Inner Mongolia, and their geological significance

作　　者：冯丽霞[1] 张志诚[1] 韩宝福[1] 任荣[1] 李建锋[1] 苏犁[2] 

机构地区：[1]北京大学造山带与地壳演化教育部重点实验室/北京大学地球与空间科学学院,北京100871 [2]中国地质大学北京地学实验中心.北京100083

出　　处：《地质通报》2013年第11期1737-1748,共12页Geological Bulletin of China

基　　金：国家重点基础研究发展计划(973计划)(编号:2013CB429806);中国地质调查局项目(编号:1212011085474、1212011085476)

摘　　要：对内蒙古达茂旗北部构造单元的巴特敖包岛弧带2个花岗闪长岩岩体样品和南部构造单元一个花岗岩岩体的2件样品进行了LA-ICP-MS锆石U-Pb定年。北部构造单元采自2个花岗闪长岩岩体的样品锆石206Pb/238U年龄分别为468Ma±2Ma和452Ma±3Ma,代表了这2个岩体的侵位时间,表明古亚洲洋向华北克拉通之下俯冲不晚于468Ma±2Ma;南部构造单元采自同一花岗岩岩体的2件样品获得的锆石206Pb/238U年龄分别为268Ma±2Ma和264Ma±2Ma,和该单元西部岩体已有的锆石年龄相符。这为华北克拉通北缘岩浆作用研究提供了新的年代学证据。This paper reports four zircon U-Pb ages of granitoids in Darhan Muminggan Joint Banner, Inner Mongolia. Two gran- odiorite samples from Bater magmatic arc in the northern part and two granite samples from a single pluton in the southern part were dated by LA-ICP-MS zircon U-Pb method so as to define their emplacement ages and provide constraints on the subduction and collisional events of the Paleo-Asian Ocean in the central part of Inner Mongolia. The two granodiorite samples yielded zircon U-Pb ages of 468Ma±2Ma and 452Ma±3Ma, respectively, indicating that the southward subduction of the paleo-Asian ocean beneath the North China Craton started at least at 468Ma, which resulted in the formation of Bater Obo magmatic arc, and the two granite samples gave zircon U-Pb ages of 268Ma±2Ma and 264Ma±2Ma, respectively, which are within the range of prexisting age data from the western pluton, although the tectonic setting of the Middle Permian plutonism in the southern part is still uncertain.

关 键 词：达茂旗 奥陶纪 中二叠世 花岗岩类 LA-ICP-MS锆石U-PB年龄 

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