U-Pb age of igneous and metamorphic events on the Fisher Massif (East Antarctica) and its significance for geodynamic reconstruction

Abstract

This report presents the main results of LA-ICPMS studies of zircon from metamorphosed magmatic rocks of the Fisher Massif in East Antarctica. The minimum age of crystallization for still unexplored granitoid intrusion in the southeastern part of the massif amounts to 1399 ± 11 Ma. The presence of inherited zircon of 1786 ± 23 Ma age in the rocks points to their fusion from a crustal source of Paleoproterozoic age. The time of the eruption of vulcanites of basite composition amounts to 1244 ± 11 Ma. The vulcanites contain xenogenic zircon of Late Archean and Middle Proterozoic age; hence, their initial melt interacted with the heterogeneous continental crust. The earliest metamorphism of the amphibolite facies proceeded 1213 ± 16 Ma ago, and was accompanied with intense shift deformations. The time of volcanism complies with the age of a large basite dike swarm in Vestfold Hills, intruded about 1250 Ma ago, which is associated with the destruction of the hypothetical Paleoproterozoic Nuna (Columbia) continent.