吉林小西南岔金-铜矿床辉钼矿Re-Os同位素定年研究及其地质意义

小西南岔金-铜矿床为一主体产于海西期花岗闪长岩-石英闪长岩体内的大型石英脉-蚀变岩型矿床,目前对其金、铜成矿时代认识主要有海西期、燕山期(148～123.35±0.8)Ma及108～98Ma等3种不同观点。本文利用矿区新发现的穿切金-铜矿体的辉钼矿-石英脉辉钼矿Re-Os同位素定年方法,对该矿床成矿时代进行了重新限定,确定了矿区金-铜成矿作用时代上限为109 Ma,提出了矿床形成时代介于(123.35±0.8)～109 Ma,金-铜矿化与燕山晚期细粒(花岗)闪长岩活动有关的认识。

The Re-Os isotope dating of molybdenite and its geological significance of Xiaoxinancha gold-copper deposit

Xiaoxinancha gold-copper deposit is a large quartz vein-altered rock type that occurred in granodiorite-quartz diorite intrusion of Hercynian epoch.Three main viewpoints concerning with the mineralization age of the deposit existed at present,which are Hercynian epoch,148～123.35±0.8Ma as well as 108～98Ma of Yanshan epoch respectively.In the present study,we reconstricted the metallogenetic epoch of the deposit by using the Re-Os isotope dating method of molybdenite collected from the newly discovered quartz-molybdenite veins that cutting through the gold-copper ore bodies and concluded the upper limit of gold-copper mineralization age is 109Ma.Combined with other evidence,we proposed the mineralization of gold-copper in Xiaoxinancha occurred between 123.35±0.8Ma～109 Ma and related with the intrusion of late Yanshanian granodiorite in origion.