U–Pb Isotope and REE Composition of Zircon from the Pyroxene Crystalline Schists of the Irkut Terrane, Sharyzhalgai Uplift: Evidence for the Neoarchean Magmatic and Metamorphic Events

Abstract

The Early Precambrian granulite-gneissic complexes are typically characterized by a long evolutionary history, which involves formation of their protoliths and repeated metamorphism related mainly with collisional events. Zircons from high-grade metamorphic rocks usually consist of cores inherited from the protolith, and one or several mantles and rims that were formed during later metamorphism or partial melting. High-resolution methods of U–Pb dating make it possible to determine the age of cores and rims.