Geochronology framework of late Paleozoic dioritic-granitic plutons in the Bayan Obo area,Inner Mongolia, and tectonic significance
内蒙古白云鄂博地区晚古生代闪长质-花岗质岩石年代学框架及其地质意义

Dioritic-granitic plutons,composed of gabbro,gabbroic diorite,granitic diorite,adamellite,biotite granite and moyite,are distributed at Bayan Obo,Inner Mongolia in the north margin of North China Craton.These plutons were once regarded as intruding from Devonian to Jurassic.New geochronology data reveal that these plutons were formed in late Paleozoic.15 zircon LA-ICP-MS U-Pb ages from different dioritic-granitic plutons show that these plutons intruded at a narrow time of 263～281 Ma with peak age of 269 Ma.These new ages indicate no relationship between REE-Nb-Fe mineralization and dioritic-granitic plutons,and also provide evidence to re-recognize tectonic environment and evolution of the North China Craton in the late Paleozoic.