Reaction Textures in Gneisses from Dallmannfjellet - Conrad Area, Orvin Range, Central Dronning Maud Land, East Antarctica : Implication for Metamorphic Evolution

Preliminary study of metamorphic reaction textures coupled with thermobarometry suggests that the metapelites. garnet-clinopyroxene gneisses. calc-silicate gneisses and orthopyroxene bearing quartzo-feldspathic gneisses exposed in Dallmannfjellet-Conrad area, central Dronning Maud Land, East Antarctica were metamorphosed to granulite grade. Peak metamorphic conditions evaluated from core thermobarometry are ~900 - 1050°C and pressure ~9 kbar. Sillimanite and garnet growth over spinel in metapelites suggests cooling of the rocks to 800°C, followed by a mild decompression inferred on the basis of orthopyroxene+plagioclase moats around garnet in metanorite pods within metapelite. The metanorite pods record P-T conditions of 7-10 kbar and 750-850°C. Late component of the P-T segments is represented by cooling stage and eventual exhumation of the terrain.