Abstract
Gneisses of Grenvillian age from Storsata and Svarthornkammen, Petermann Range, central Dronning Maud Land, East Antarctica, show a fluid imprint, characteristic of arrested charnockitization. Charnockite formation took place at Svarthornkammen, where fluid composition is dominantly pure CO2. At Storsata, P–T conditions of the amphibolite–granulite transition facies during Pan-African metamorphism were insufficient to produce orthopyroxene-bearing charnockite s. str. Typical high-density CO2–N2 fluid inclusions (0.62–0.86g/cm3) were found in garnet and quartz. At retrograde upper greenschist facies conditions a later generation of aqueous, low-salinity fluids (3.0±1.9mol% NaCleq) were entrapped. Finally, high-salinity fluids originated in connection with the late-tectonic emplacement of granitic to granodioritic dykes. These fluids leached the formerly charnockitizized gneisses which resulted in irregularly bleached rock areas.
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