Reconnaissance for noble and base metal mineralisation within the Precambrian supracrustal sequences in the Ivigtut–Kobberminebugt region, South-West Greenland

Abstract

The field programme in the Ivigtut-Kobberminebugt region is a continuation of the investigation of gold occurrences in the Tartoq Group greenstones, just north of the present area (Appel & Secher, 1984; Appel, 1984). The region was mapped by GGU in the late 1950s and early 1960s (Henriksen, 1969; Berthelsen & Henriksen 1975; Harry & Pulvertaft, 1963). The Tartoq and the Ketilidian supracrustal belts were described (Allaart, 1976; Bridgwater et al., 1976); they form regional curved structures around the Arsuk Basin. The major part of the supracrustal sequences south of the Tartoq Group units is expected to be of Ketilidian (Proterozoic) age and deformation. However, some layers in the Nunarssuit peninsula in the southernmost part of the region are undated and might be older (Bridgwater et al., 1973; Appel & Secher, 1984). The investigation was focussed on the supracrustal sequence between Arsuk Fjord and Nunarssuit (fig. 1), with special emphasis on the areas neighbouring the known gold showings at Josva Mine (worked 1910-15) where discrete grains of electrum and gold in the bornite ore were reported by Harry & Den (1964). In the Kînâlik peninsula a skarn boulder with a few grains of gold included in cha1copyrite has been reported by Kryolitselskabet Øresund A/S (Nielsen, 1976). The work was based on reconnaissance rock sampling of lithologies and mineral showings within the supracrustal sequences, with particular attention given to transitions between sedimentary and vo1canic suites and to structural breaks in order to locate potential sources of noble metals.