Major zinc occurrences
Zinc occurrences, are numerous in Greenland and most are hosted by sedimentary rocks and can be classified as belonging to the Mississippi-Valley Type (MVT) or to the sedimentary-exhalative (SEDEX) deposit types. These occurrences include the Black Angel deposit and related showings, hosted by Palaeoproterozoic marbles of the Karrat Group in West Greenland; the Citronen Fjord deposit and a variety of prospects and showings in the Lower Palaeozoic Franklinian Basin in North Greenland; and possibly the occurrences in the Upper Palaeozoic to Mesozoic Jameson Land Basin in East Greenland.
Palaeoproterozoic Karrat Group
Marbles of the Palaeoproterozoic Karrat Group host the Black Angel Zn-Pb deposit, which was mined between 1973 and 1990 and totalled 13.6 Mt with grades of 12% Zn, 4% Pb and 29 ppm Ag. The stratabound mineralisation is constrained by the distribution of marbles, which have a limited areal extent. Nevertheless, numerous local outcrops of massive to disseminated sulfide occurrences have been identified in the immediate vicinity of the Black Angel deposit towards the south-west and north.
Lower Palaeozoic Franklinian Basin
The Franklinian Basin extends for more than 2.500 km from the Canadian Arctic Islands, hosting the Polaris MVT deposit (mined between 1981 and 2002), and across northern Greenland.
In North Greenland this basin is extensively exposed in an almost 1.000 km long and up to 200 km wide belt along the Arctic Ocean. While no mining has yet taken place in the Greenlandic part of the Franklinian Basin, reconnaissance mineral exploration in the 1990s demonstrated widespread Zn-Pb mineralisation, straddling the stratigraphy. In 2011 all available data from this area was evaluated and calibrated. The same year a mineral potential assessment workshop was held, following the USGS guidelines. The workshop concluded that this basin offers an excellent potential for sediment hosted zinc. Follow up work in 2012 and 2013 led to the identification of new showings.
Zinc mineralisation in the Franklinian Basin can be assigned to two distinct events. Earlier mineralisation, represented by the shale-hosted, exhalative citroen Fjord deposit in eastern North Greenland, believed to be one of the world’s largest undeveloped zinc resources, took place during opening of the basin.
Later mineralisation, exemplified by the Cass Fjord and the Petermann prospects in western North Greenland and several showings along the carbonate platform, is interpreted to be related to brines circulating in the foreland of the developing Ellesmerian Orogen.
Upper Palaeozoic to Mesozoic Jameson Land Basin in East Greenland
Stratabound Zn-Pb-Cu-barite mineralisation is common in the Upper Permian and Triassic of the Jameson Land Basin of East Greenland. It remains ambiguous whether this mineralisation is exhalative, diagenetic or related to later Palaeogene events, as seems to be the case for the sandstone-hosted veins of the nearby Blyklippen deposit , from which 550,000 t at 9% Pb and 10% Zn were mined between 1956 and 1962.
Meso- to Neoproterozoic Hekla Sund Basin in eastern North Greenland
While only very limited exploration has been conducted in the Meso- to Neoproterozoic Hekla Sund Basin in eastern North Greenland, sandstone hosted Pb-Zn mineralisation is known, and its sedimentary succession is considered favourable for SEDEX mineralisation.
Intrusive-related and volcanogenic massive sulphide zinc occurrences
In addition to the sedimentary-rock-hosted zinc potential, intrusive-related zinc occurrences should also be considered. Significant zinc concentrations can be related to alkaline intrusions of the Mesoproterozoic Gardar Province in South Greenland. Examples of this include the Ivittuut cryolite mine, active between 1856 and 1987, where zinc was produced as a by-product, and the Kvanefjeld deposit which, in addition to REE, U and fluorine, hosts a significant Zn resource, expected to be recovered as a by-product.
Finally, Zn-Cu-Pb volcanogenic massive sulphide mineralisation is known, although only small and low grade occurrences have yet been identified within the Archean and Palaeoproterozoic of West Greenland.
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