Basic rocks of the inner Fiskefjord area, southern West Greenland

Abstract

During mapping for the Fiskefjord map sheet (64 V.1 N - 1:100000) observations were made on the basic rocks. Earlier reports on the mapping of the Fiskefjord area have been given by Garde (1984, 1986) and Garde et al. (1987), and the reader is referred to these for more detailed descriptions af the general geology. Most of the inner Fiskefjord area is made up of a variety af gneisses, correlated with the late Archaean Nûk gneisses. The most common type is a weakly banded, tonalitic gneiss, usually grey, sometimes with a Iilac tint. Metagranites and more mafic gneisses of dioritic to quartz dioritic composition form mappable units as well as bands of inclusions in the tonalitic gneisses. The gneisses show intrusive relationships to a group of basic and ultrabasic rocks, mainly two-pyroxene basic granulites (named 'pyribolites' by Berthelsen, 1960) with minor dunite and norite. Small amounts of metasedimentary gneiss are associated with the norite.