���˰����Կ��Ž����󴲸�������٪��ͳ�ʺ�������Һ��°���ͳ�����������Ի�ɽ���У��丳��Χ��ʴ���������е������ʯU-Pb ����ⶨ������21 ���ɷֵ�����1 �鲻г������( 141 ± 2 Ma��129 ± 2 Ma) ��3 ��г�����䣬���ߵļ�Ȩƽ��ֵ�ֱ�Ϊ116. 2 ± 3. 4 Ma��112. 5 ± 1. 1 Ma �� 108. 2 ± 4. 2 Ma������ʯ���κ�CL ͼ����������һ��ȷ�������ҵij���ʱ��Ϊ����������ڣ��ҽ�����ȴ���ҽ���Һ�ھ���Լ8 Ma���ɿ������븻�����ɽ�����йأ�������108 Ma ֮����ɿ����й�������½Ե��������dz����Һ�����ģ�ɿ�ʱ����һ�¡�

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��