The First U–Pb Isotopic Systematics of Natural Aeschynite and Coexisting Monazite

Abstract

We have been the first to study in situ the U–Pb isotopic system of aeschynite identified in the gold-bearing magnetite–chlorite–dolomite rocks of the Karabash serpentine massif in the Southern Urals. In the concordia diagram, the U–Pb LA–ICP–MS data on aeschynite are characterized by a considerable discordance, which is consistent with the regression line, the lower crossing of which with the concordia corresponds to an age of 298 ± 18 Ma, whereas the figurative ellipses of coexisting monazite reveal an almost concordant cluster corresponding to the U–Pb age of 317.3 ± 3.3 Ma. It has been established that the closure temperature of the aeschynite system is lower than that of the coexisting monazite.