Crystal size distribution of garnet in quartzo-feldspathic gneisses from the Lützow-Holm Complex at Skallen, East Antarctica

Crystal size distributions (CSDs) of garnet in quartzo-feldspathic gneisses from the Lützow-Holm Complex at Skallen, East Antarctica, indicate that significant annealing with Ostwald ripening did not take place even though the rocks underwent regional granulite-facies metamorphism with a peak phase of ultrahigh-temperature conditions. Absence of fluid as a result of the complete consumption of hydrous minerals during garnet-forming reactions could restrain intergranular diffusion and inhibit Ostwald ripening. Garnet-poor gneisses have experienced a single nucleation and growth event associated with a continuous garnet-forming reaction. In contrast, garnet-rich gneisses from the same outcrop have undergone additional garnet-forming reactions responsible for multiple stages of nucleation and growth.