���Ź�����ϲ��������������������ʯ U-Pb ���ꡢ�ʯԭλ Lu-Hf ͬλ�ء�����Ԫ�ء�ϡ��Ԫ�غ�΢��Ԫ�ز��Է���������������������������������Ϊ����ĸ���������ң���ʯӢ (40% ��45%)�����Ƴ�ʯ (35% �� 40%)��б��ʯ (12% �� 15%)������ĸ (3% �� 5%) �ͽ���ʯ (1% ��3%) ��ɡ������������Ϊ 198. 5 ±1. 6 Ma������٪������A/CNK ֵ�仯�� 1. 01 �� 1. 03������ָ�� DI =93. 69 ��95. 95��������������ʯԪ�� K����b �� L��EE����b/Sr �ϸ� (2. 06 ��2. 76)��ƶ Ba�� Sr �͸߳�ǿԪ�� Nb��Ta��P��Ti�����쳣�е� (δEu =0. 26 ��0. 57)���������������������������� I �ͻ����ҵ��������ʯ ε Hf (t) =5. 7 ��9. 7��T DM2 =618 ��874 Ma����ʾ�ҽ���Դ����Ԫ�Ŵ����������ĵؿ����ʣ��γ��ڹ�̫ƽ���鸩��Ļ��½��Ե������

Zircon U- - Pb ages and geochemical characteristics of Hengdaohezi pluton as well as Lu- - Hf isotope�� major��trace and ��EE elements were determined�� The Hengdaohezi pluton mainly consists of biotite syenogranites�� The biotite syenogranite contains quartz (40% ��45%)��perthite (35% ��40%)��plagioclase (12% ��15%)��bi- otite (3% ��5%) and amphibole (1% ��3%)�� Zircon U-Pb isotopic dating is 198. 5 ±1. 6 Ma��belonging to Ear- ly Jurassic�� The A/CNK values ranging from 1. 01 to 1. 03 with high fractionated index (DI) are 93. 69 ��94. 95�� Trace elements of the granites are characterized by enrichment in K����b and L��EE��depletion in Ba��Sr��Nb��Ta�� P��Ti��and high ��b/Sr ratio (2. 06 ��2. 76)�� Chondrite ��normalized ��EE patterns are right- inclined and display moderate negative europium anomalies (δEu =0. 26 ��0. 57)�� The geological and geochemical data suggest that the Hengdaohezi pluton can genetically be ascribed to slightly peraluminous I- type granites�� Its variable zircon Hf iso- tope composition ( ε Hf (t) = 5. 7 ��9. 7��T DM2 =618 ��874 Ma) shows that the primary magma originated from the partial melting of the juvenile crusts during the Neoproterozoic��and formed in an active continental margin set- ting related to the subduction of the Paleo-Pacific plate��