Zircon U-Pb age,geochemical feature and tectonic significance of the granite pluton in northern Hegen Mountain of Inner Mongolia

Wulandele plulon is a large-scale complex massif generated by twice magmatism.The complex massif is made up of biotite-granite and biotite-monzogranite,aged in 140±2 Ma and 161±1 Ma,respectively.The biotite-granite reflects highly fractionated characteristics geochemically.While the biotite-monzogranite implies low Sr and high Yb in geochemical characteristics.Geochemical data suggest that the biotite-monzogranite are A-type granites,which tectonic setting was are mainly dominated by the extensional system.