Abstract

Small inclusions of hypersthene, augite, hornblende, and Fe-Ti oxides occur in plagioclase cores of granitoids from the Permian Barrington Tops Granodiorite, New South Wales. Mineralogically and chemically the ferromagnesian inclusions match larger discrete grains in the granitoids. Pyroxenes of both parageneses yield temperatures ranging from ∼1000 to < 500°C, indicating partial equilibration of these magmatic phases during slow cooling. A magmatic origin for the ferromagnesian inclusions demands a similar origin for their plagioclase host material. Plagioclase cores, therefore, cannot be used as unequivocal evidence of restite (residual high-grade metamorphic source material) in discussions of granitoid genesis. The Barrington Tops Granodiorite crystallized from silicate liquid with little or no restite entrained from the source.

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