The Potential for Iron Oxide Copper-Gold Occurrence in Greenland
by
Bo Møller Stensgaard, Jochen Kolb, Department of Petrology and Economic Geology, Geological Survey of Denmark and Greenland, Copenhagen, Denmark, Henrik Stenda, Bureau of Minerals and Petroleum, Nuuk, Greenland and T. Mike Porter, Porter GeoConsultancy Pty Ltd, Adelaide, South Australia.
in Porter, T.M. (Ed), 2010 - Hydrothermal Iron Oxide Copper-Gold and Related Deposits: A Global Perspective, Advances in the Understanding of IOCG Deposits; PGC Publishing, Adelaide. v. 4, pp. 357-378.
ABSTRACT
Focused exploration for iron oxide copper-gold ±Ag±Nb±P±REE±U (IOCG) style deposits in Greenland has, to date, been limited. However, tantalising indications, including regional-scale sodic and iron-oxide alteration, crustal- to local-scale structural preparation and magmatic complexes thought to be fertile for the formation of IOCG mineralising systems are found in many tectonic provinces in Greenland. Furthermore, several Cu-Au-(±Co±Nb±P±REE) occurrences possibly represent IOCG-type mineralisation, although more detailed investigations are neceseary to confirm such a classification.
The two tectonic provinces that are regarded as being the most prospective are the Palaeoproterozoic Ketilidian mobile belt and the Inglefield Land mobile belt in southern and northwestern Greenland respectively. The Ketilidian mobile belt, which is situated south of the Archaean North Atlantic craton, represents an arc environment with wide-spread calc-alkaline magmatism and later syn- to post-tectonic A-type granitic intrusion. Within this environment, widespread, structurally controlled sodic alteration has been recorded within a known metallogenic province of copper, gold and uranium mineralisation, locally with associated iron oxides. In particular, the Au-Bi-Ag-As-W-Cu-Mo mineralisation at Niaqornaarsuk and at Qoorormiut is interpreted to be genetically related to the ca 1780 Ma calc-alkaline intrusions of the Julianehåb batholith and hydrothermal iron oxide-albite alteration.
The Inglefield Land mobile belt hosts a 1950 to 1915 Ma meta-igneous complex, which comprises intrusions, mainly of dioritic, quartz dioritic, granodioritic and tonalitic composition, with subordinate metagabbro and magnetite-rich phases. Late post-tectonic granites, including monzogranite and syenite complexes (1785 to 1740 Ma), were emplaced during later deformation. The northeastern part of the mobile belt embraces the 70x4 km 'North Inglefield Land gold belt', which coincides with a crustal-scale lineament and hosts an extensive string of fault controlled hematite matrix breccias, locally enriched in Cu and Au, as well as associated hydrothermal pyrite-barite-hematite alteration.
Other provinces, that may potentially host IOCG mineralising systems, include areas within the North Atlantic craton in southern Greenland, the Palaeoproterozoic Nagssugtoqidian orogen and the Ammassalik mobile belt in West and East Greenland respectively, and the East Greenland Caledonides, which include large blocks of Palaeoproterozoic basement.
Although there are no known IOCG deposits and major prospects in Greenland, the geology is favourable for this type of hydrothermal mineralisation and some occurrences have the potential for detailed exploration within the outlined areas.
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