�ں������������������Ա����������ҵ� LA- ICP- MS �ʯ U- Pb ͬλ�ز��Խ�����������γ�ʱ��Ϊ��٪���� ((163. 8 ±1) Ma)����Щ��٪�������������������������ʸ߼ظƼ���ϵ�е� I �ͻ����ң����Ը�����������ʯԪ�� (��b��Ba��Th) �Ϳ���߳�ǿԪ�� (Zr��Hf��Nb��Ta)��Ԫ�� Sr �������Եĸ��쳣��������ԭʼ�ҽ���Դ�ڵؿǻ���ҵIJ������ڡ������������ͬʱ������ҵ���������͹�̫ƽ����Ĺ����ݻ�����Ϊ�ö����������γ��ڻ��½��Ե�������γɵĵ�����ѧ��������Ϊ��̫ƽ������ŷ�ǰ�鸩����ɽ�����չ������

Zircon U- - Pb dating by LA- ICP- MS technique indicates that the monzonitic granitic from the north- ern Xigulan river in Xingsheng area of Heihe were formed in Middle Jurassic (163. 8 ±1) Ma�� These granites be- long to peraluminous high- K calc- alkaline I- type granite series��The rocks were obviously rich in LILE (��b��Ba and Th) and depleted in HFSE (Zr��Hf��Nb and Ta) with pronounced negative Sr anomalies��Their primary mag- mas were derived from partial melting of lower crust�� Combined with the feature of igneous rock associations and tectonic evolution history of paleo- - Pacific Plate��the authors proposed that monzonitic granite anitic from the north- ern Xigulan river in Xingsheng area of Heihe were formed in the active continental margin tectonic setting related to the subduction of paleo- Pacific tectonic plate from the east to the west��