AEX’s 100% owned Tartoq project covers the entire Tartoq Gold Belt and all known gold occurrences, for a total of 248 km2. Locally high-grade orogenic gold mineralisation is hosted in a classic Archean greenstone belt setting
Exploration for gold and base metals in the Tartoq area was carried out by several companies between the 1970s and 1990s. Work was focussed on targets in the Nuuluk and Iterlak areas, and included geological mapping, surface rock sampling and two small drilling programmes totalling 1,824 m. The best drill intersections were 6.60 g/t gold over 2.00 m at Nuuluk, and 8.28 g/t gold over 1.97 m at Iterlak1. AEX considers exploration to be at an early stage overall – several targets warrant further investigation and drilling.
The licence is situated on the headlands either side of the Sermiligaarsuk Fjord some 80 km southeast of the town of Paamuit and 170 km WNW of Narsarsuaq international airport. The topography varies between sea level and 500 m elevation. As is typical of South Greenland, rock outcrop is abundant within the licence.
Geology and Mineralisation
The Tartoq Project lies on the northern edge of the North Atlantic Craton on the contact with the Ketilidan Mobile Belt that formed between 1,850 Ma to 1,725 Ma during the subduction of an oceanic plate under the southern margin of the North Atlantic Craton. The Archaean greenstone belts that represent the gold-bearing Tartoq Group are supracrustal rocks composed of metasedimentary units, submarine mafic metavolcanics and mafic to ultramafic intrusives. The units have all been metamorphosed varying from greenschist to amphibolite facies increasing from west to east with sharp tectonic or intrusive contacts with the surrounding Archaean tonalite–trondhjemite–granodiorite (“TTG”) basement rocks.
The Tartoq Group has undergone two main phases of ductile deformation and one phase of brittle faulting. The ductile deformation has resulted in north- to northeast-trending kilometre scale, multi-phase complex folding with brittle cataclasites. Unlike other greenstone belts in Greenland, much of the Tartoq Group has retained its primary fabric and has a more variable, generally lower metamorphic grade. Deformation and associated fluid flow has resulted in pervasive alteration including carbonatisation from late-stage structurally controlled hydrothermal infiltration, which has been linked to the orogenic gold mineralisation within the belt.
The diversity in lithologies at Tartoq provides a range of physical and chemical traps for the deposition of gold. The greenstone belt is typified by widespread chlorite-ankerite-pyrite alteration, a feature observed in significant orogenic gold camps globally. The belt is structurally complex, including the presence of major regional structures. At Nuuluk, one of the principle targets, thrust imbrication and shearing provide both large pressure-temperature gradients and fluid pathways, which are both critical parameters in the deposition of gold.
At Nuuluk gold is hosted in quartz-ankerite veins hosted within mainly magnetite- and graphite schists. Four parallel tabular zones have been identified forming the “Nuuluk Linear Belt”, a 350 to 400 metre wide and 4 to 5 kilometre long NNE-trending, moderately (40 – 60 degrees) WNW-dipping hydrothermally altered zone (divided into the “Western and Eastern Carbonate Zones”) associated with thrusting. Channel sampling of the ECZ by AEX in 2017 and historically has demonstrated high grades in quartz veins and lenses at surface (e.g. 0.68 m @ 16.85 g/t Au1, 0.5 m @ 106 g/t Au3). The erratic grades suggest a high nugget effect. In most instances, continuity remains to be tested at depth.
Gold is mainly hosted in two NNE–SSW trending, approximately 100 m wide and 200–400 m long zones, namely the Western valley zone and the Eastern valley zone, both located in the footwall of larger thrust zones. The Western valley zone comprises hydrothermally altered greenschist and banded iron formation. VLF-data suggests a 400 m by 50 m lens-shaped body of hydrothermally altered banded iron formation tapering in both lateral directions (Petersen and Madsen, 1995)5. Gold mineralisation occurs in the proximal alteration zones and altered banded iron formation, mainly in quartz-rich samples, i.e. quartz–ankerite veins. Gold precipitation is thought to have been triggered by Fe-rich lithologies like the banded iron formation. The recorded gold concentrations are up to 12 g/t in rock chip samples at the Iterlak occurrence.2
Amitsuarsua consists of a relatively large (approximately 12 x 4 kilometre) greenstone belt which is poorly investigated compared to Nuuluk and Iterlak. Gold mineralisation is already known to occur (>1 g/t gold) in zones of carbonate alteration, silicification and sulphidation2. Further surface exploration is warranted.
Besides Nuuluk, Iterlak and Amitsuarsua, other smaller areas of greenstone occur within the Licence area (e.g. Naalagaaffik, Akuliaruseq and Bikuben) and are known to display widespread hydrothermal alteration up to several hundred metres along strike, surrounding quartz veining4. These areas are very poorly explored but have the potential to host further gold mineralisation and warrant exploration.
The Nuuluk area is well sampled at surface and future exploration should involve drilling of the best targets to test their continuity at depth. Banded iron formations at Iterlak are of particular interest as these are favourable host rocks for orogenic gold mineralisation in many deposits globally. The eastern prospects of Amitsuarsua, Naalagaaffik, Akuliaruseq and Bikuben are at a much earlier stage of exploration, but have favourable geology and warrant further exploration.
1 An Independent Technical Report on the Tartoq Project, South Greenland (SRK Exploration Services Ltd, 2017)
2 Steenfelt A., Kolb J., Trane, K. (2016). Metallogeny of South Greenland: A review of geological evolution, mineral occurrences and geochemical exploration data. Ore Geology Reviews 77:197-245
3 Refer to Announcement by AEX Gold on 30th November 2017 titled “AEX Successful 2017 Summer Work Programme Results”
4 Kolb, J., Dziggel, A. & Schlatter, D.M., 2013: Gold occurrences of the Archean North Atlantic craton, southwestern Greenland: A comprehensive genetic model. Ore Geology Reviews 54:29-58
5 Petersen, J.S., & Madsen, A.L., 1995: Shear-zone hosted gold in the Archaean Taartoq greenstone belt, South West Greenland. In: Ihlen, P.M., Pedersen, M., Stendal, H. (Eds.), Gold Mineralization in the Nordic Countries and Greenland Extended Abstracts and Field Trip Guide: Open File Series Grøndlands Geologiske Undersøgelse, pp. 65-68.