Monazite of alkaline ore metasomatites of the Lower Mezen ore field (Middle Timan): Th-U-Pb-data

Abstract

Monazite from rare-metal-rare-earth alkaline metasomatites of the Lower Mezen occurrence of the Middle Timan has a predominantly cerium composition (Ce2O3 > La2O3). The weighted average value of the point (Th-U-Pb, CHIME) age of monazites was (564 ± 27) Ma, the age of monazites, obtained from the ThO2*–PbO isochrone, is (566 ± 127) Ma. The age of the monazite is close in time to the monazites of the Novobobrovsky ore field and the Vendian igneous formations (ultramafic rocks and carbonatites of the Chetlas Complex) formed as a result of a plume pulse.