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

To determine the petrogenesis and tectonic setting of the Early Cretaceous granodiorite- porphyry from Huanan area in eastern Heilongjiang，zircon U- -Pb dating and geochemical analyses on the granodiorite- por- phyry samples are carried out． The results of LA- - ICP- - MS zircon U- - Pb dating indicate that the granodiorite- porphy- ry in Huanan area formed during the Early Cretaceous with the age of (123 ±1) Ma． These rocks show character- istics of I- type granites based on their contents of high SiO 2 (66. 06% ～ 68. 75%) and Na 2 O + K 2 O (6. 40% ～ 7. 23%)，with low MgO (1. 19% ～1. 50%)，enrichment in large ion lithophile elements (e. g． ，Rb，Ba，Th， U，K) and light rare earth elements，and depletion in Nb，Ta，Ti and P． The positive ε Hf (t) values ( +6. 30 ～ +11. 51) of the granodiorite- porphyry and their corresponding Hf two- stage model ages (778 ～445 Ma) indicate that the parental magma was derived from partial melting of juvenile crustal material． According to the geochrono- logical data，geochemical features and regional geological surveying，the authors propose that the formation of the Early Cretaceous granodiorite- porphyry in Huanan area was related to the subduction of Paleo- Pacific Plate．