First Petrographical Description of Rock Occurrences in the Steingarden Area, Dronning Maud Land, East Antarctica
Rock samples from previously undescribed nunataks and moraines of the Steingarden area, southeasternmost central Dronning Maud Land, Antarctica, were petrographically studied. The nunatak rocks comprise banded felsic and mafic gneisses and amphibolites with some minor marbles. They underwent granulite-facies peak metamorphism. Moraine rocks, which were sourced from ice-covered occurrences in the south, comprise garnet-biotite gneisses, kyanite-staurolite-sillimanite gneisses, amphibolites, late-tectonic and post-tectonic igneous rocks as well as an assemblage of conspicuous dark graphite-bearing and pyrite-bearing schists with related vanadium-green muscovite bearing lithologies. The dark schists represent greenschist-facies to amphibolite-facies grade metamorphosed black-shale-type sediments. The nunatak rocks and parts of the moraine rocks are comparable to lithologies in central Dronning Maud Land. The dark graphite-bearing and pyritebearing schists and related vanadium-green muscovite bearing lithologies have higher-grade metamorphosed equivalents in central Sør Rondane. These rocks indicate the existence of a tectonic boundary south of Steingarden, which may represent the Pan-African suture between West and East Gondwana.