The pre-Ketilidian history of the gneisses north-west of Frederikshåbs Isblink, Fiskenæsset region

Abstract

The geometry and field relationships of the gneisses and their associated rocks in the area immediately north-west of the Frederikshåbs Isblink reflect a complex intrusive, metamorphic and deformational history. All the rocks have been affected to a greater or lesser extent by amphibolite facies metamorphism and they comprise predominantly dark grey biotite and hornblende gneiss, together with thin anorthosites (mostly brecciated to white agmatites), intercalated striped green and dark grey amphibolite (sometimes garnetiferous), black hornblendites, gamet-kyanitesillimanite gneisses, sillimanite quartzites and pegmatitic pale creamy brown marbles and calc-silicate gneiss and fine-grained leucocratic gneisses. Early discordant layers include hornblendites, amphibolites, peridotites, silico-carbonatites and aplitic rocks.