U-Pb AGE OF ZIRCON FROM THE SYENOGRANITE IN ADELAGAWULA, INNER MONGOLIA

The Adelagawula syenogranite occurs in Abaga Qi, Inner Mongolia, near the Sino-Mongolian border. The intrusive rock was assigned to Early-Yanshanian (Kγ₅²) by 1:200 000 regional geological surveyor or Lower Permian as alkali feldspar granite(P₁χγ) in 1:250 000 regional geological survey. The U-Pb isotopic dating of the syenogranite shows the age of 273.1±0.4 Ma. Combined with regional geological data and previous research, it is possibly a product of Early Permian magmatism. The syenogranite, with high silica, high potassium, per-aluminum and poor calcium-magnesium-iron, belongs to post-orogenic I-type granite. The REE distribution is in V-shaped pattern, with low total rare earth content, unobvious fractionation of LREE and HREE, δEu values ranging from 0.07 to 0.60 and strongly depleted Eu.