Geochronology and metallogenesis of porphyry Mo deposits in east-central Jilin province, China: Constraints from molybdenite Re-Os isotope systematics

摘要

The east-central part of Jilin Province, located on the eastern continental margin of northeast China along the eastern Xing-Meng orogenic belt, hosts more than 10 large-and medium-scale Mo deposits. The major types of mineralization include porphyry, skarn, and quartz vein. To better understand the formation and distribution of porphyry Mo deposits in this area, we investigated the geological characteristics of the deposits and applied molybdenite Re-Os isotope dating to constrain the age and source of mineralization. The results, combined with existing data, show that; (a) the Daheishan Mo deposit yields an isochron age of 168.7 +/- 3.1 Ma; (b) the Shuangshan Mo deposit yields an isochron age of 171.6 +/- 1.6 Ma; (c) the Liushengdian Mo deposit yields a weighted mean model age of 168.7 +/- 1.4 Ma; (d) the Jiapigou Mo deposit yields a weighted mean model age of 196 +/- 4 Ma; and (e) the Sancha Mo deposit yields a weighted mean model age of 183.1 +/- 1.8 Ma. Therefore, the Mo mineralization occurred in the Early-Middle Jurassic (196-167 Ma), during the late stages of magmatism or during the late evolution of magma chambers. The geodynamic setting at this time was dominated by subduction of the paleo-Pacific Plate beneath the Eurasian continent. The rhenium content of molybdenite varies from 0.2 to 99.7 ppm, suggesting that the ore-forming materials may come from a crustal source or a mixed crustal and mantle source. (C) 2015 Elsevier B.V. All rights reserved.