Times zircon U-Pb age of Bayinnuoergong granite pluton of Alxa Block, Inner Mongolia

The Bayinnuoergong granite pluton in the southeast of Alxa Block is located to the northwest of North China Craton and distrbuted in Yabula-Bayinnuoergong tectonic belt in the south of Huoershen-Chaganchulu tectonic belt, controlled generally by NEE-trending structure. It consists of medium to fine grained biotite granite and medium to coarse porphyritic biotite granite. Re-searchers have done some research on the ages of the Bayinnuoergong granite, which provides a favorable condition for analyzing and discussing whether the Bayinnuoergong intrusion formed in multiperiodic magmatic activities. TIMS U-Pb dating of zircons from the Bayinnuoergong medium to fine grained biotite granite and medium to coarse porphyritic biotite granite yielded two ages of 304.7± 2.8Ma and 289.0± 3.8Ma, respectively, indicating that the pluton should be the Late Carboniferous-Early Permain intrusion. Combined with the previous research in the study area, it is held that there are at least two magmatic activities in this area, which oc-curred in Late Carboniferous (304Ma) and Early Permian (289~272Ma).