College of Earth Sciences, Jilin University, Changchun 130061, China

Zircon U-Pb geochronology and geochemical data for the granite porphyry in Yinaowan region of northern Great Xing'an Range has been studied, the results show that the weighted mean age of the rock was 140.5±2.4 Ma,belonging to Early Cretaceous, with captured zircons of Middle-Late Triassic(223~232 Ma) in the samples. Petrogeochemically, SiO₂ contents is 63.73%~64.35%,(K₂O+N₂O)is 6.77%~7.31%,Al₂O₃ contents is 15.20%~15.40%,MgO and Mg^# are of 1.85%~2.01% and 32~34, Fe₂O₃/FeO is 1.37~1.53, and aluminum saturation index(A/CNK)is 0.94~0.96,respectively, belonging to high-K calc-alkaline volcanic rock series, quasi-aluminous rock and I-type granite. The total amount of rare earths is relatively low (��REE=110.37×10^-6~117.55×10^-6), fraction of light and heavy rare earth elements is high ((La/Yb)_N=22.39~31.72), Eu anomaly is not obvious (Eu/Eu*=0.91~1.07). The samples are also enriched in light rare earth elements and large ion elements (Rb, K), depleted in heavy earth elements and high field strength elements (Nb, Ta, Ti, P). High Sr content (515×10^-6~665×10^-6) and low Y content (6.73×10^-6~7.39×10^-6) indicate the character of adakite. Combined with regional tectonic, it is suggested that the granite porphyry was originated from the partial melting of the thickened lower crust, and was related to continental collision orogeny after the closing of Mongolia-Okhotsk Ocean.