1. Heilongjiang Institute of Geological Survey��Harbin 150036��China; 2. College of Earth Sciences��Jilin University��Changchun 130061��China; 3. International Centre for Geoscience Research and Education in Northeast Asia��Jilin University��Changchun 130026��China; 4. State Key Laboratory of Geological Processes and Mineral Resources��China University of Geosciences��Wuhan 430074��China

The Pangkaimen Au --Ag deposit in Great Xing'an Range is concentrated in Upper Jurassic Ganhe Formation basic volcanic rocks and Lower Cretaceous Fulin Formation intermediate and intermediate-acid volcanic rocks�� The single-zircon U--Pb ages for host surrounding altered rhyolite rocks are dated��and the 21 component dot can be subdivided four groups age: one group shows discordant age ( 141 ± 2 Ma��129 ± 2 Ma) ��while three groups show concordant ages ( the weighted averages as 116. 2 ± 3. 4 Ma��112. 5 ± 1. 1 Ma and 108. 2 ± 4. 2 Ma��respectively) �� According to the crystalline shape of zircons and CL image characters��the rhyolite formed in late Early Cretaceous��and it took about 8 Ma from magma chamber cooled down to magmatic hydrothermal�� Mineralization is related to volcanism of Fulin Formation��which happened later than 108 Ma�� The mineralization occurred concurrently with the later Mesozoic large scale epithermal Au deposits of continental margin in northeastern China��