(Th+U)-Pb monazite ages from Al-Mg-rich metapelites, Rauer Group, east Antarctica

Abstract

The age of high-temperature granulite-facies metamorphism (>� 800-850 � C) in the Rauer Group, Prydz Bay, east Antarctica, is relevant for establishing the metamorphic and temporal architecture of the Prydz Bay mobile belt. Monazites within Al-Mg-rich granulite- facies metapelites give an overall tanh-estimated Pan- African age of � 511±4 Ma (2r) using in-situ electron microprobe-based (Th+U)-Pb chronology, consistent with existing U-Pb zircon geochronology from the Rauer Group and Prydz Bay. Monazite occurs primarily within cordierite-bearing coronae and symplectic min- eral reaction textures, and also within biotite. Pan- African granulite-facies metamorphism is preferred as responsible for the development of the cordierite-bearing microstructures, and probably (peak) coarse-grained assemblages, constrained using an integrated geologic, geochronologic and metamorphic framework. Thus, Pan-African granulite-facies metamorphism affected the Rauer Group, within the Prydz Bay mobile belt. Moreover, integrated monazite geochronology may be used to decipher the temporal metamorphic histories of potentially complex high-temperature terrains.