Re-Os isotopic dating and geological significance of molybdenite from Xintian Cu-Mo polymetallic deposit in Yanbian,Jilin

Xintian polymetallic deposit is a hydrothermal vein type Cu-Mo deposit. Analysis on Re-Os isotopic dating for the molybdenite from this deposit is undertaken to determine metallogenic epoch and dynamics setting of the deposit. Re-Os isotopic dating for the molybdenite yields model ages ranging from 123. 9 ± 1. 9 Ma to 124. 7 ± 1. 8 Ma,with a weighted mean age of 123. 4 ± 0. 81 Ma,and an isochron age of 127 ± 16 Ma,MSWD= 0. 25,indicating that the metallization was at late Yanshanian. The content of Re in molybdenite is( 330. 1± 4. 0--367. 9 ± 3. 1) × 10,which demonstrates mantle derived metallogenic sources. Integrating the regional tectonic evolution and the metallogenic characteristics of other contemporaneous Cu-Mo deposits in the region,it is suggested that the Cu-Mo mineralization of this deposit occurred in an active epicontinental environment under lithospheric extension resulted from the subduction of the Izanagi plate to the Paleo-Asia continental margin at late Yanshanian. The Mantle wedge was partially melted with large amount of metallogenic elements dissolved in it. Under the favorable conditions of crust-mantle interaction,large-scale magmatic activity turns out to be the important mechanism of the mineralization of many Cu-Mo deposits in the Xiaoxingan Range--Zhangguangcai Mountain metallogenic belt,including the Xintian Cu-Mo polymetallic deposit.