�������ϲ�������������Ҫ�ɼ�����ҡ����������ҡ����������Ҽ����ڰ�����ɡ����� LA--ICP--MS ���������������ϲ������ҽ��е��ʯ U--Pb ����ⶨ���������������������ҽ����Ϊ 3 ��: ��—�������� ( 208 ��239 Ma) ����٪���� ( 179 �� 185 Ma) ����٪����—������� ( 137 �� 151 Ma) �����������˰��������������ҵ����ѧ��ܻ���һ�£��붫�����Ź����—С�˰�������������ҽ��ʱ��Ҳ���ԶԱȡ��ʯ LA--MC--ICP--MS Hf ͬλ���о���ʾ�����������������ҵ��ʯ εHf( t) ����Ϊ +0. 7 �� +9. 5�����׶�ģʽ����Ϊ 0. 6 �� 1. 2 Ga�����������ҽ���ҪԴ����—��Ԫ�Ŵ������ĵؿ����ʡ���϶�����ɵؿ����������ҵ��ʯ Hf ͬλ�����ϣ���Ϊ������ɵؿ����� —��Ԫ�Ŵ�ʱ��������һ����Ҫ�ĵؿ������¼������˰��ؿ�ĵؿ�����ʱ��Ϊ��Ԫ�Ŵ�—��������ص㲻ͬ��

The granites in southern Manzhouli region of Inner Mongolia are composed mainly of alkaline-feld- spar��orthoclase and adamellite granite�� We present new zircon U--Pb dating of granites using ablation LA--ICP--MS technique�� The result shows that three stages of granites in the southern Manzhouli region: Middle to Late Triassic (208 ��239 Ma)��Early Jurassic (179 ��185 Ma)��Late Jurassic to Early Cretaceous (137 ��151 Ma)��which are consistent with all of the Da Hinggan Mountain��and this geochronological framework is also comparable to that in the Zhangguangcai-Lessor Hinggan Mountain in the East�� Zircon Hf analyses conducted by LA--MC--ICP--MS show that these granites have εHf(t) values of +0. 7 �� +9. 5 with Hf modal ages of 0. 6 ��1. 2 Ga��indicating that thecrust in the Ergun block was extracted from mantle during Meso-Neoproterozoic��which is different from the Xing'an block to the south��where the crustal accretion was aged in the Neoproterozoic-Phanerozoic��