1�� College of Earth Sciences��Jilin University��Changchun 130061��China; 2�� Manage Center of Central Geological Exploration Fund��Ministry of Land and ��esources��Beijing 100045��China

The authors studied the geochemistry��zircon U-Pb ages��Hf isotope of the granite porphyry and its petrogenesis and tectonic setting in the studied area�� The zircon U-Pb dating indicates the formation of the gran- ite porphyry is in Early Cretaceous (125�� 1 ±1�� 5 Ma)�� The granite porphyry has high-SiO2and alkali-rich fea- tures��which belongs to high-K calc-alkaline series rocks (A/CNK = 0�� 95%--1�� 25%)�� The analyses of trace elements show the characteristics of a swallow-shaped ��EE distribution pattern with enrichment in L��EEs and most of LILEs and HFSEs��depletion in Ba��Sr��Nb��P and Ti��and especially strong depletion in Eu��which indicates the granite porphyry belongs to the aluminous A-type granite�� Their εHf(t)range from 5�� 94 to 8�� 80 with Hf two-stage model ages (TDM2) of 620 Ma to 803 Ma�� Combining with the regional tectonic background�� we conclude that the source of the rocks is the new crust materials accreted from depleted mantle in Neoprotero- zoic and is the product of partial melting of middle and lower crustal rocks��which may be suffered from the dual impact of the subduction of the Palaeo-Pacific Ocean and the closure of the Mongol-Okhotsk Ocean��