LA-ICP-MS zircon U-Pb ages and geological implications for the Bagadeerji granitic plutons in the central Qilian Mountains, Gansu

The Bagadeerji granitic plutons mainly made up of moyite and adamellite occur in the Yemananshan area, central Qilian Mountains, Gansu. The LA-ICP-MS zircon U-Pb age dating gives an emplacement age of 462.5±1.4 Ma for the Bagadeerji granitic plutons. Geochemically, the Bagadeerji plutons are characterized by strong peraluminous granites, high K and K/Na ratios, low Mg, Fe and Ca contents, enriched K, Rb, Ba and Th elements, depleted Zr, Hf, Y and Yb elements, and slight Eu negative anomaly. The trace element discrimination plots indicate that these intrusions have a "syn-collision" affinity as defined by Pearce et al. (1984), and thus may be interpreted to be the continent-continent collisional products formed during the late Caledonian orogeny.