ͨ�� LA-ICP-MS �ʯ U-Pb ���꼰��ʯ��ѧ�������о��˺�������������Ծ�����������ͷ������������ѧ������ѧ���γɻ��������������Ծ�����������ͷ�������������ֱ�Ϊ 213 ± 3 Ma �� 209 ±3 Ma���������������������塣Ծ��������������ʯӢ������Ϊ��������׼���ʡ��Ƽ���ϵ�У���ϡ��Ԫ�ظ�������ϡ��Ԫ���Կ������� I �ͻ����ҡ���ͷ�������������Լ������Ϊ��������׼���ʡ�����ϵ�У���ϡ��Ԫ�ظ�������ϡ��Ԫ���Կ������� A �ͻ����ҡ�������������γ��ں���—ӡ֧����ɽ������ɽ¡��������ɽ��չ������ת���ڡ�

Using zircon LA-ICP-MS dating and petrological geochemical methods��the authors study the geo-chronology��geochemical characteristics and tectonic setting of Yuejincun and Yuntoulazi plutons in Chenming area�� Heilongjiang�� The zircon LA-ICP-MS dating for Yuejincun and Yuntoulazi plutons are 213 ± 3 Ma and 209 ± 3 Ma��respectively��belonging to the middle of Late Triassic�� The Yuejincun pluton is composed mainly of quartz monzonite��which belongs to aluminous��calc- alkaline series and I- type granites�� Their ��EE models are character- ized by enrichment in L��EE and depletion in H��EE�� The Yuntoulazi pluton is composed mainly of alkali feldspar granite��which belongs to aluminous��alkaline series and A- type granites�� Their ��EE models are characterized by enrichment in L��EE��LILE and depletion in H��EE��HFSE�� The characteristics indicate that these two plutons could have formed during the Hercynian to Indosinian period of transition from an orogenic setting to a post- colli- sional extension��