“…The nepheline syenite, essexite, and alkali syenite of the Sakharjok Massif define U-Pb zircon ages of 2613 ± 35 Ma, 2666 ± 10 Ma, and 2682 ± 10 Ma (Bay anova, 2004;Zozulya et al, 2007), which indicates very ancient, Late Archean age of the alkaline magmatism of the Keivy terrane. In addition, ages within 1760-1810 Ma were obtained by U Pb dating on zircon, brit holite, and allanite and by Rb-Sr and K-Ar whole rock dating (Zozulya et al, 2005;Pushkarev et al, 1978), which presumably mark the overprint of the Sve cofennian regional metamorphism.…”