The Grusgraven locality: border relationships between Precambrian supracrustal rocks and orthogneisses, Kangikajik, South-East Greenland

Abstract

Kangikajik peninsula in the northern part of the Ammassalik region is composed of a high grade complex of Precambrian gneisses and supracrustal rocks. Amphibolites occur both in the gneisses and supracrustal rocks which are folded together and generally interleaved. At Grusgraven, a corrie on the south coast, a particularly well-exposed outcrop reveals border relationships between gneiss and supracrustal rocks. These relationships, as well as the internal characters of the rocks, favour a model where the regional gneisses present a basement to a cover sequence composed of metasediments and amphibolites. Whether this involves an Archaean – early Proterozoic association, as isotopically dated elsewhere in the region, is unknown.