Detailed mapping in the southern part of the Ilímaussaq alkaline intrusion, South Greenland

Abstract

The detailed mapping programme in the southern part of the Ilimaussaq intrusion begun in 1972 by the present author (see Andersen et al., 1973) was continued during the summer. The area investigated is situated around hill 435 m, one kilometre south-east of the bay Tuperssuatsiait, to the south of Tunugdliarfik fjord. Up to the present time, about 2 km² has been mapped at the scale of 1:5000. The study area contains four main rock types: sodalite-foyaite, naujaite, black arfvedsonite-Iujavrite and green aegirine-Iujavrite, all of which form distinct units. The greater part of the area consists of naujaite. To the east the naujaite is interwoven with an increasing number of lujavrite sheets and the primary aim of the work was to establish the nature of the so-formed lujavrite-breccia. The sodalitefoyaite overlies the naujaite to the west.