Noritic rocks and associated nickel-copper-sulphide occurrences in Sukkertoppen district, central West Greenland

Abstract

Field work in 1982 included detailed mapping and collection of samples of sulphide occurrences in the so called 'norite belt', Sukkertoppen district. Several nickel-copper-sulphide mineralisations related to norite rocks are known from the work of Kryolitselskabet Øresund A/S who mapped this rock suite and carried out exploratory investigations of the sulphides (Nielsen, 1976). The earlier mapping has revealed a suite of metabasic plutonic rocks of mainly noritic composition which are situated in an arcuate belt, approximately 15 x 75 km, curving around the Finnefjeld gneiss complex east of Sukkertoppen (fig. 8). Metanorites are embedded in quartzo-feldspathic gneisses and rarely in amphibolitic rocks, and they occur as a series of irregular pods up to 6 km Iong within the arcuate belt. The present investigation was carried out as part of GGU's mineral resources mapping and evaluation programme in central West Greenland, which this year focussed on the area covered by the 1:250000 map sheet 65 V.2. The fieId work was carried out in dose cooperation with teams doing systematic reconnaissance geochemical stream-sediment and water sampling (to be discussed elsewhere), detailed soil geochemical investigation (Jensen & Secher, this report) and experimental geophysical investigations (Thorning, this report). The present work aimed at a general description of the structure and the metallogenetic behaviour of the known norite-related sulphide occurrences in order to reach an understanding of the mineral genesis within this section of the Archaean environment.