Neoproterozoic and Devonian Granites of the Koolen Granite–Gneiss Dome, Arctic Chukotka

New U–Pb zircon dating of rock samples from the core of the Koolen granite–gneiss dome in Chukotka yielded a Neoproterozoic age (650–530 Ma) for orthogneisses and a Devonian age (390–360 Ma) for granitoids. Devonian granites and quartz monzonites are attributed to the peraluminum magnesian calc-alkaline varieties of volcanic arc granitoids formed during the Ellesmerian orogeny of the Arctic. All rocks of the complex show evidence of having been subjected to the last peak of metamorphism and extensional deformation in the Early Cretaceous, as follows from the age of syndeformational pegmatites.