Isotopic and Geochronological Heterogeneity of Granite Porphyry from the Zhireken Porphyry Cu-Mo Deposit (Eastern Transbaikalia)

摘要

Multistage magmatism in ore districts is one of the main factors determining the formation of large-scale porphyry Cu-Mo deposits [1-4].However,there are not enough data characterizing different magmatic stages,which is partially related to the complex structure of porphyric rock associations composing stocks and dikes.The formation of porphyritic textures can be explained by the crystallization of phenocrysts during magma cooling or by the capture of large crystals from older rocks by moving magma [5-7].There are many isotopic geochronological data (results of local dating by ~(87)Sr/~(86)Sr and ~(40)Ar/~(39)Ar methods or dating by non-equilibrium ~(234)U) indicating that phenocrysts from various subvolcanic and,particularly,volcanic rocks can exceed their groundmass in isotopic age [8-10].However,such data are absent for subvolcanic porphyritic rocks of Cu-Mo deposits.