1. College of Earth Sciences, Jilin University, Changchun 130061, China;
2. International Center for Geoscience Research and Education in Northeast Asia, Jilin University, Changchun 130026, China;
3. Shenyang Center of Geological Survey, CGS, Shenyang 110034, China

Zircon U-Pb geochronology, whole-rock geochemistry, and Lu-Hf isotope compositions were analyzed for the Ailinyuan granites in Chuoer area of Da Hinggan mountains. Ailinyuan pluton is composed mainly of monzogranite. Zircon U-Pb ages from two samples of 132 Ma and 137 Ma indicate that the Ailinyuan pluton formed in the Early Cretaceous. The geochemical data indicate that monzogranites are characterized by high SiO₂ and K₂O, but low total Fe₂O₃ and MgO, and moderate-weak negative europium anomalies with(Eu/Eu^*)=0.46~1.07, ��REE=54.11×10^-6~191.42×10^-6,LREE/HREE=11.38~18.03, with significant fractionation of HREE and LREE[(La/Yb)_N=12.12~23.52]. The monzogranites show enrichment in large ion lithophile elements (e.g., Rb, Ba, K) and depletion in high field-strength elements (e.g., Nb, Ta, Ti) and P. Zircon Lu-Hf isotope characteristics show that the two zircon samples from these granites have positive ��_Hf(t) values of 3.9~7.9 and 2.9~8.0, respectively, and young Hf two-stage model ages of 709~942 Ma and 677~1 001 Ma, respectively. Combined with regional geology investigation, the authors suggested that the granitic magma was derived from partial melting of juvenile crustal material, possibly related to the subduction of the Paleo-Asian oceanic plate to the Xing'an Block.