The metamorphic evolution of granulites at Fyfe Hills; implications for Archaean crustal thickness in Enderby Land, Antarctica

Abstract

Abstract Granulites at Fyfe Hills in Enderby Land, Antarctica, crystallized at temperatures in excess of 850°C, and possibly as high as 1000°C, and at pressures of 8‐10kbar during the mid to late Archaean. A number of features, including repeated retrograde metamorphism at 5.5‐8kbar, retrograde reaction textures, and rimward zoning in pressure sensitive systems, suggest that following peak metamorphism the granulites stabilized at a depth of 18‐26 km. After stabilization, the granulites cooled near‐isobarically to temperatures of 600‐700°C. Assuming a total crustal thickness of 35‐40 km during this late Archaean interval of isobaric cooling, the peak metamorphic crustal thickness is estimate..