���ӱߵ�������ʯӢ�����ҽ����ʯ U- -Pb ���ѧ����ʯ����ѧ���������ʯӢ������ LA- - ICP- - MS �ʯ U- - Pb ��Ȩƽ������Ϊ 139 ±2 Ma���������������ʯ����ѧ��������Ϊ�����ʸ߼ظƼ���; ϡ��Ԫ�������ϵͣ���ϡ��Ԫ����Ը���������ϡ����������ԣ������ĸ� Eu �쳣����������ʯԪ�� (��b��Ba��Sr) ����õIJ�����Ԫ�� (U��Th) �������߳�ǿԪ�� (Nb��Ta��P��Zr��Hf�� Ti) ����΢��Ԫ�ر�ֵ����ӽ��ؿ�ƽ��ֵ����ӳ�ҽ�Դ��Ϊ�µؿǡ���ϵ���ѧ�������������ݻ���������Ϊ�������ʯӢ�����������γ�����̫ƽ���鸩����صĻ��½��Ե�����������������������һ������Ҫ�ĸ���׶Σ��������ҽ���λ���Ϊ������

The study of the zircon U- Pb age and petrogeochemistry of Xintian quartz diorite in Yanbian area is reported in this paper�� The weighted average age of zircon LA -ICP - MS U - Pb dating for the quartz diorite is 139 ±2 Ma��indicating that it was generated in the Early Cretaceous�� Geochemical characteristics of the diorte indicate of peraluminous high - - K calc- alkaline�� The rocks have low ��EE contents��and are relatively enriched in light rare earth (L��EE)��with obvious fractionation of L��EE and H��EE��and weak negative Eu anomalies�� They are en- riched in large ion lithophile elements (��b��Ba��Sr) and incompatible elements (U��Th)��relatively depleted in high field strength elements (Nb��Ta��P��Zr��Hf��Ti)��and the trace element ratios are similar to the average value of the crust��suggesting a parent magma sourced within the lower crust�� Based on the geochemical data and the regional geological background��we propose that the Xintian quartz diorite formed in active continental margin environment related to the subduction of the Paleo- Pacific Plates�� The Early Cretaceous was an important subduc- tion stage with strong intermediate- acid magmatic emplacement activities��