Mineral resource potential of South Greenland

Assessment of mineral resource potential

		Comprehensive geoscientific data sets for South Greenland have been compiled in ArcView format on CD-ROM. The data include topographical, geological, geochemical and geophysical maps, rock analyses, descriptions of mineral occurrences, and bibliographies. The aim is to provide scientific and commercial interests with all available digital information in one place. This report presents extracts from the total data set to review the geology and mineral potential of South Greenland. Geology and mineralisation Most of South Greenland is underlain by rocks of the Palaeoproterozoic Ketilidian orogen, in the north bounded by Archaean basement. An alkaline igneous province, the Mesoproterozoic Gardar province, covers a large region within the Ketilidian and the basement. The Archaean basement is dominated by orthogneiss but contains a small greenstone assemblage with iron formations and gold mineralisation. The Ketilidian orogen is composed of (1) a Border zone, the southernmost part of the Archaean basement, where Ketilidian supracrustals were deposited and Ketilidian granites have intruded, (2) a Batholith zone with predominance of juvenile calc-alkaline granite-diorite complexes (c. 1850 to 1800 Ma of age), and (3) a zone of metasediments intruded by a post-kinematic, crustally derived, granite-monzonite-norite suite (c. 1755 to 1725 Ma). The Ketilidian orogen hosts mineralisation with gold, arsenic, uranium, copper and graphite. Sulphide mineralised zones with low zinc and copper concentrations are common in the Ketilidian supracrustals. Evolved magmas and hydrothermal alteration zones of the Gardar intrusive complexes constitute large, low-grade deposits of uranium, thorium, speciality metals (zirconium, yttrium, niobium, tantalum, rare earth elements), fluorine, lithium and zinc. A high-grade cryolite deposit has been mined. Potential for ore deposits A potential for economic deposits of gold, uranium and speciality metals are outlined by geochemical data of stream sediments (both fine fraction and heavy mineral concentrates) and rock samples together with known occurrences of mineralisation with these metals. Discovery of mineralisation within bodies of a Ketilidian gabbro suite suggests a potential for deposits of titanium, vanadium, nickel, chromium and platinum group elements. A diamond potential is indicated by the occurrence of kimberlite sheets in the Archaean basement. The compiled data demonstrates significant geochemical and geophysical variations within South Greenland, which must be taken into account in geological modelling. The current geological model for the Ketilidian orogen does not explain these variations and a revision, therefore, seems appropriate. Any alternative plate-tectonic model will obviously have implications for mineral deposit modelling within the region.			Gold potential of South Greenland as indicated by the distribution of high grid values for gold (Au) and pathfinder elements arsenic (As) and antimonu (Sb) in the fine fractions (<0.1 mm) of stream sediments. Click on the map for an enlargement.
			Photos from the Nalunaq gold prospect. Top photo: Pinch-and-swell structures in the gold bearing quartz vein (25 cm across). Middle photo: Extensive underground sampling is executed for grade virification. Drift/raise rounds blasted in the mineralized structure are each treated as bulk samples. Following two-stage crushing a representative field sample is obtained by feeding the bulk sample through consecutive stages of splitters on a sample tower. Lower photo: A Tote-Bag with rejects is kept for referenc while the remaining rejects are stockpiled.