��ʯ������ǽ�������С�˰���—�Ź������ɿ����Ե�·��ֵ�һ��������󴲡����������ư�״�����������嶥������ϸ����Ⱦ��; ���ر������Ҫ�ʺ������ʯӢ����������dz�������С����������������Ͳ��������϶���ƣ�����ʴ��������Եķִ��ԣ�����������󴲡��Բ��Կ���dz�������е�5 ���������Ʒ������Re-Os ͬλ�ز��꣬���ģʽ����( 182. 1 ± 2. 7) �� ( 191. 9 ± 2. 6) Ma����Ȩƽ������( 186. 7 ± 5. 0) Ma��MSWD ֵΪ11. 8��������ʯ������γ�����ɽ���ڡ���Ͻ�����С�˰���—�Ź������ɿ��������õij��ҳɿ��������ݣ���Ϊ160 �� 190 Ma �Ǹ���ɿ�������ɿ����õļ����ڡ��������Ʒ��Re ����Ϊ3. 549 �� 4. 362 μg·g �� 1��ָʾ�ɿ�����Ϊ��Դ���ۺϷ�����Ϊ����ʯ�����Ϊ������ɽ���ڴ��ģ�ɿ��¼��IJ���γ��ڹ����޹�����ͻ�̫ƽ��������Ӻ�ת���ڵĹ��컷����

Dashihe deposit is one of the large-size molybdenum deposits recently discovered in the southern margin of Xiaoxinganling--Zhangguangcailing molybdenum metallogenic belt�� Deep ore bodies in this deposit are located in the top of porphyaceous granodiorite��veinlet-disseminated in shape�� The near-surface ore bodies mainly occurred in the low-grade metamorphic rocks as molybdenite-bearing quartz veins�� Molybdenum mineralization was controlled by the explosive breccia pipe and the fissures��and the mineralization and alteration are obvious in zonaition�� belonging to porphyry molybdenum deposit�� Re-Os dating of five molybdenite samples collected from the shallow ore bodies showed that the model ages as 182. 1 ± 2. 7 Ma �� 191. 9 ± 2. 6 Ma��with the weighted mean age of 186. 7 ± 5. 0 Ma��and MSWD = 11. 8��which indicates the deposit formed in Early Yanshanian�� Combined with other obtained lithogenic and metallogenic ages from the Xiaoxinganling--Zhangguangcailing molybdenum metallogenic belt��it can be inferred that 160 �� 190 Ma is a concentrated period for large-scale molybdenum mineralization of this belt�� The content of Re in the molybdenite is 3. 549 �� 4. 362 μg·g �� 1��indicating ore-forming materials derived from crustal sources�� Comprehensive analysis showed that the Dashihe deposit might be resulted by the largescale mineralization events of the Early Yanshanian in the area��and formed in the tectonic environment during the superposition and transformation of Paleo-Asian and Circum-Pacific tectonic domains��