Abstract
The mineral potential of the Karrat Group in West Greenland became important after exhaustion in 1990 of the Black Angel lead-zinc mine situated within this supracrustal unit. It consists of shelf and turbidite type metasediments and subordinate metavolcanics deposited in an epicontinental marginal basin. Known mineralization comprises the Black Angel deposit and a number of other marble-hosted lead-zinc occurrences, as well as extensive sulphide facies iron formations and vein type base and precious metals mineralisation in quartzites and metagreywackes. Further areas with anomalously high contents of both base metals and gold-arsenic-tungsten are indicated by drainage geochemistry. The mineral potential of the Karrat Group is for massive base metal sulphide deposits hosted in marbles or clastic metasediments, and turbidite hosted gold-bearing veins and shear zones.
Highlights
The mineral potential of the Karrat Group in West Greenland became important after exhaustion in 1990 of the Black Angel lead-zinc mine situated within this supracrustal unit
Geological reconnaissance of the supracrustal rocks in the area commenced in the nineteenth century, and systematic mapping at scale 1:100000 was carried out between 1962-1983 by the Geological Survey of Greenland (GGU) (Escher & Stecher, 1980; Grocott & Vissers, 1984; Henderson & Pulvertaft, 1987)
The approaching closure of the Black Angel mine induced GGU to initiate an assessment of the mineral potential of this part of Greenland
Summary
The mineral potential of the Karrat Group in West Greenland became important after exhaustion in 1990 of the Black Angel lead-zinc mine situated within this supracrustal unit. The Lower Proterozoic Karrat Group (Fig. 1) is the most extensive supracrustal unit in the Precambrian shield of West Greenland It hosted the largest commercial ore deposit of Greenland, the Black Angel (Sorte Engel) lead-zinc deposit at Mårmorilik, which was mined during the period 1973-90. In this context selected mineralised 10caIities in the Umanak district were reconnoitred in 1989 (Thomassen, 1989), and an orientation survey was carried out 1989-90 in the Ingia area in the northem part of the district (Thomassen, 1990; 1991a) (Fig. 1). This paper summarises the geology, mineralisation and drainage geochemistry of the Karrat Group and presents an assessment of mineral potential
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