Licence covers historic high-grade gold targets within the Nanortalik Gold Belt and unexplored areas on major structural trends.
Nuna Nutaaq, licence 2019/113, comprises 5 sub areas within the Nanortalik Gold Belt and covers all major gold showings and prospective areas identified by AEX’s regional machine learning study. Targets were previously investigated by Crew Gold, NunaMinerals and Goldcorp.
The property lies on the southern side of Kangerluluk Fjord where rocky terrain slopes steeply down to the fjord from an icecap along the southern edge of the licence block at 500-600 m above sea level.
Geology and Mineralisation
The Kangerluluk gold prospect lies at the northern edge of the Psammite Zone of the Ketilidian Mobile Belt and has been mapped and described by Mueller and Stendal (Stendal et al. 1997; Mueller et al. 2000). Supracrustal rocks occur cover an area of about 4 km2 and consist of a 200-300 m thick volcano-sedimentary sequence that rests unconformably on the Julianehåb Batholith.
Gold has been reported in samples from the Kangerluluk property that are closely related to NNE-striking, steeply dipping quartz-bearing shear zones in the supracrustal sequence (Stendal et al., 1997). An alteration halo characterised by silicification and epidotisation is found along these zones. The most prominent shear zone is over 1 km long and up to 20 m wide, cutting across the western side of the mapped area. Gold is associated with copper and only occurs in quartz and zones of hydrothermal alteration that are 2-5 m wide.
Stendal et al. (1997) described three groups of alteration types, each with associated mineralisation:
Group I: syn-volcanic alteration
Alteration is dominated by epidote and relates to extensive, pervasive hydrothermal interaction of seawater with basalts during or shortly after solidification. It is not structurally controlled. Pyrite-pyrrhotite associations formed at this stage, with sulphides disseminated throughout the rock mass. Gold and copper concentrations are low at 20-31 ppb and 35-463 ppm respectively.
Group II: early-stage, post-volcanic alteration
Gold mineralisation in this type of alternation is spatially associated with larger faults and shear zones that cut the supracrustal rocks (Figures 2 and 3) and varies according to the host rock type: quartz veins occur in sedimentary rocks (“quartz-association”) whilst epidote alteration occurs in mafic volcanic rocks (“epidote-association”).
Quartz-association gold mineralisation contains pyrrhotite and pyrite, locally with massive pyrrhotite layers up to 5 cm thick at the contacts of quartz veins. Silicified alteration halos up to 40 cm wide are found along the veins and can contain very high gold grades (e.g. 118 g/t gold in a grab sample). This type of mineralisation is also found in NE-striking shear zones as en echelon sets of quartz veins, 1-2 m wide, 3-10 m long and containing iron sulphides and grades up to 1.15 g/t gold. Stendal et al. (1997) report grades of 7.5 g/t gold over 5 m from chip sampling across one such quartz-rich shear zone.
Epidote-association gold mineralisation is found with pyrite and chalcopyrite mineralisation along ESE- and NNE-trending faults. Grades of 1.1 g/t gold and 1.6% copper over 0.5 m, and 3.3 g/t gold and 1.6% copper have been reported from chip sampling (Stendal et al. 1997).
Group III: late-stage, post-volcanic alteration
The final phase of alteration can be observed as several different types:
- “Bleaching” due to sericitisation of host rocks along ESE- and NNE-trending faults with hairline veinlets of quartz and opaque minerals;
- Calc-silicate alteration comprising garnet, epidote and amphibole recrystallised in former epidote veins of group II alteration. Ore minerals and quartz occur interstitially;
- Copper-gold mineralisation in veinlets, breccias and faults/shears. In pillowed sequences, crosscutting veinlets contain chalcopyrite, bornite and minor chalcocite, and most copper-bearing samples grade 0.1-1.0 g/t gold (and one sample of 6.2 g/t). Some aplites in the batholith have also been altered and contain up to 5 vol% pyrrhotite with associated gold (up to 1.39 g/t);
- Late carbonatization in brittle faults in both supracrustal rocks and the batholith. Haematite, iron and copper sulphides, galena and sphalerite may be found, but this alteration type does not contain gold.
Stendal et al. (1997) propose that gold mineralisation occurred at about 1,800 Ma, around the same times as late phases of emplacement of the Julianehåb Batholith and just after the deposition of the supracrustal volcano-sedimentary sequence. Gold was then concentrated into brittle structures during subsequent deformation, becoming associated with copper sulphides in mafic rocks, and found as native gold with iron sulphides in quartz veins. This remobilisation of gold in the supracrustal rocks may have been aided by heat from emplacement of Rapakivi granites at about 1,740 Ma.
Prospective supracrustal rocks were identified at Kangerluluk in 1992 during the SUPRASYD project (SUPRASYD took place between 1992 and 1996; it was Government-funded and aimed to assess the economic potential of the Ketilidian Mobile Belt via a series of geological, geophysical and geochemical work programmes). Mapping and sampling by GEUS in 1995 and 1996 identified gold mineralisation, reporting grades in grab samples of up to 118 g/t gold, and 12 of 74 grab samples graded over 1 g/t gold (Stendal et al. 1997). These results were announced by GEUS in April 1997 and an exploration licence was granted to Goldcorp Inc. in July of the same year after several competing applications were considered (Sannes, 1998).
Goldcorp Inc. immediately undertook a short programme of reconnaissance, mapping and sampling in August 1997, collecting 112 rock samples of which 105 were from the main mineralised NE-trending shear structure identified by GEUS, including 82 channel samples taken with a diamond rock saw.
It was reported that in the north-eastern third of the shear structure quartz veins were discontinuous and averaged less than 1 m thick (locally up to 2 m). In some places then veins are folded and have extensive dip slope exposures that make them appear much larger than they really are. Widespread rust straining from the weathering of sulphides in the veins and the wallrock also gives a misleading impression of the extent of mineralisation.
The remainder of the shear structure to the southwest reportedly contains much less quartz, occurring as thin sheeted veins or rarely as larger veins and pods of up to 1 m thick. Locally, however, more favourable veining can be found but with very erratic gold grades. Thicker veining, up to 1.5 m, was found in the final 100 m of the shear before it disappeared beneath moraine at the edge of the icecap although grab samples contained no gold.
As may be expected of this style of gold mineralisation, Goldcorp’s sample results include very erratic gold grades (high nugget effect). About a third of their samples were below the detection limit for gold, whilst the average grade for 100 channel and chip samples was about 2 g/t (max. 110 g/t over 80 cm true thickness in one channel sample). If the five highest grade samples were eliminated, the average would be 0.23 g/t gold.
Goldcorp considered the prospect to be intriguing on account of its strong structural setting and acknowledged that the extent of mineralisation at depth and below the icecap was unknown, and that there was potential to improve continuity along strike. However, given the highly erratic nature of mineralisation, the remote location and high cost of further exploration, they decided not to proceed and concentrated on other gold prospects in South Greenland.
In 2010, the Kangerluluk prospect was included in a new exploration licence (number 2010/39) owned by NunaMinerals A/S. They undertook a very short (four day) field programme in August of that year, aiming to follow up and expand on Goldcorp’s work via rock sampling of the shear and fault zones as well as material beyond these in order to improve the geochemical understanding of the area. NunaMinerals took 63 rock samples, 10 of which graded more than 1 g/t gold from a rusty shear zone with massive quartz veins and reported that the mineralised zone was some 20 m wide and more than 700 m long. NunaMinerals also noted that low gold grades (less than 0.2 g/t) were found in pillow lavas along the shear zone, possibly indicating potential to expand the width of prospective material (Pedersen, 2010). They recommended further sampling and structural assessment to increase the understanding of grade continuity and controls on mineralisation.
The Kangerluluk prospect has a relatively well-defined mineralised shear zone with some promising gold grades. It remains open along strike and at depth and has only been lightly explored. Work must now focus on establishing the continuity of mineralisation along and across the structure. AEX plans to carry out structural work and further sampling in the 2020 field season.
The Ippatit project area is covered by the largest sub-area of AEX’s exploration licence number 2019/113. The licence boundary covers mountainous terrain on the southern side of the Ippatit Kua valley that runs in a south-easterly direction between the large fjords of Søndre Sermilik and Tasermiut. A major feature of the area and a focus of much historical exploration is the 1,775 m high Ippatit mountain.
Geology and Mineralisation
The area’s geology has been described by Petersen and Olsen (1995) and, broadly speaking, represents an enclave of Paleoproterozoic amphibolites overlying the meta-arkose sediments that are extensive on the central Nanortalik peninsula. Along the Ippatit Kua valley, granodiorite of the Julianehåb Batholith is found between the amphibolites and the underlying meta-arkose rocks, increasing in thickness towards the east.
The amphibolites are considered to be the main gold-prospective target in the area, and Petersen and Olsen (1995) state that there are three varieties of them:
- Thick piles of pyroclastic amphibolites form most of the metabasic rocks in the area. These are very variable in terms of clast size, deformation and texture, but typically contain cm- to dm- size andesitic clasts with light green colour and flattened forms. These deposits dominate the southern outcrops of the amphibolites;
- Fine-grained amphibolites are found as more massive basic rocks, especially along the northern side of the amphibolite outcrop. These rocks are quite homogenous and black in colour with pronounced, sometimes schistose, foliation due to deformation, leaving little evidence of primary structures. They have been interpreted as metabasalts grading into andesites.
Calc-silicate alteration may be found although is patchy and confined to specific 2-5 m wide horizons that can be traced for several hundred metres, usually parallel to the foliation. Silicification is limited, but ankerite alteration and veinlets are locally abundant;
- Metadolerites occur near the summit of the Ippatit mountain and along the northwest border of the amphibolite occurrence. The authors confidently interpreted these as being intrusive metagabbroic rocks; their appearance parallel to foliation and their conformable borders suggest an origin as dolerite sills. Similar amphibolitic sills occur in the surrounding meta-arkose rocks and may be of the same generation.
Underlying metasediments consist of two types:
- Thinly laminated meta-pelitic and meta-psammitic biotite schists often with rusty, stratiform sulphide- (pyrrhotite) and graphite-bearing horizons. These rocks are particularly abundant in the northwest part of Ippatit Kua.
The contact between the amphibolites and the meta-psammites is marked by a thick, continuous, very rusty horizon. This contains strongly folded graphite-pyrrhotite schists and several 0.5-1 m thick chert beds separated by micaceous and graphitic schists. The contact dips gently to the south and is proposed by Petersen and Olsen (1995) to be tectonically modified or even purely tectonic;
- A thick pile of homogenous, coarsely-bedded meta-arkose rocks (sandstones) with abundant primary sedimentary features, including regular sub-horizontal layering, despite having been deformed and metamorphosed to a grey biotite gneiss. These rocks are found along the southern border of the amphibolites.
The contact between the meta-arkose and the amphibolites is steeply dipping (Figure 5) and very sheared, and a higher degree of migmatisation and recrystallisation has occurred along it. It is a high-angle fault contact. In places, amphibolite has been detached to form enclaves within the meta-arkose. The steep dip to foliation gradually flattens away from the contact, becoming sub-horizontal in the south. In the central Ippatit area, an unusual conglomerate (or possibly a felsic agglomerate) occupies the contact between the meta-arkose and the amphibolite.
Subconcordant aplite veins, 0.3-2 m thick, are found in the meta-pelites. They are parallel to low-angle thrust contacts and have clearly exploited these zones of weakness. Aplites may also be found in the amphibolites where they are again sub-concordant or form en echelon veins in sheared parts of the pyroclastic amphibolites. Dolerite dykes are also found; these strike northwest and represent late magmatic events. Structurally, the principal features of the area are (in order of formation) sedimentary lamination/foliation, folding, low-angle thrusting and high-angle faulting.
Petersen and Olsen (1995) describe three types of mineralisation in the Ippatit area to which gold mineralisation could potentially be associated:
- Stratiform iron sulphides occur at a few stratigraphic horizons, particularly the contact of the meta-pelites and the amphibolites where they are found within a very rusty and strongly folded sequence together with chert and graphitic schists. This is 0.5-3 m thick but locally can reach more than 50 m due to deformation. It is a similar feature, if not the same, as that which contains abundant iron sulphides between amphibolites and underlying meta-arkoses in the Nalunaq area.
Thinner sulphide horizons can be found in the amphibolite sequence. Sulphides occur as layers or lenses of massive pyrrhotite with disseminated pyrite, often accompanied by abundant graphite. These layers show consistently low gold grades of 5-10 ppb and are not thought to be important targets.
Near the summit of Ippatit mountain, there is a similar rusty section of chert and graphitic schists. This is 40 m wide and overlain to the south by thick sericite schists. In places, strong silicification has occurred to form zones 20 m thick and 200-300 m long. It contains sparse disseminations of arsenopyrite and may be of more interest; grades of 20-120 ppb gold and 500-2,000 ppm arsenic have been reported.
- Several quartz veins are found in the area, many of which are single fracture fillings in the amphibolites or along sheared margins of the meta-arkose rocks. Some veins occur in en echelon fracture features and a 2 m wide example with a well-developed sheeted structure has been reported on the northern side of Ippatit mountain summit. Gold grades in this, however, were very low (9-12 ppb) and the same is true for other amphibolite-hosted quartz veins in the area.
One location with more a promising gold grade of 832 ppb was reported from a vein in meta-pelites in Ippatit Kua. This was found as part of a series of minor discontinuous veins, 0.3 x 3 m in size, immediately above a rusty chert horizon. Samples from other veins did not contain gold. The possibility of more widely occurring minor gold-bearing veins in the meta-pelites may provide some explanation for gold anomalies in heavy mineral concentrates in this area.
Blomsterberg (2005) reported several occurrences of quartz veining in amphibolites in areas east of Ippatit mountain, describing one area as a swarm of veins. The veins were reported to have limited strike length and usually less than 0.5 m thick. Notably, it was proposed that they are found along a structure that shows continuity for several kilometres. The highest grade reported from this type of mineralisation was one grab sample from a quartz vein with epidote, garnet and sulphides graded 1.14 g/t gold.
- Localised sulphide mineralisation with some silicification and ankerite was found along the steeply dipping southern contact between the amphibolites/pyroclastics and the meta-arkose rocks. Gold grades in these features are slightly elevated at 26-37 ppb.
The Ippatit area has been subject to several short exploration programmes by NunaOil and Crew Gold and has been included in regional geochemical sampling by GEUS. Figure 6 shows a compilation of historical sampling results overlain onto the 1:100,000 geological map and includes anomalies for alteration minerals (jarosite and haematite) derived from Sentinel satellite data (SRK ES, 2019).
The Ippatit prospect has been subject to fairly little exploration to date and covers quite a large area. There is a relatively high volume of prospective lithologies, several similarities to Nalunaq’s geological setting and some gold anomalies in historical geochemical data. Several small gold-in-quartz showings have been discovered by previous workers which may be associated with larger structures suggesting that greater continuity is possible. Exploration should aim to identify this via more geochemical sampling and systematic prospecting traverses of the ground on foot. The prospect has year-round coastal access and is close enough to Nalunaq and the Niaqornaarsuk Peninsula for logistics to be shared between projects.
Geology and Mineralisation
At Jokum’s Shear, gold mineralisation is found in a northeast-trending shear zone system that is up to 1,000 m wide and has a strike length of about 2 km between approximately 250 m and 1,150 m elevation. It is possible that the strike length could be considerably longer; extensions of it to the northeast have been exposed by retreating ice and it has even been proposed that the structure continues for about 25 km and hosts gold mineralisation at the Kangerluluk prospect (Schlatter and Hughes, 2012).
The mineralised material is found in strongly altered, sheared and sulphidised rocks of gabbroic composition, mainly within a several tens of metres wide ‘gold zone’. These gabbros are not shown on the regional GEUS geological map for the area. Rust staining is common (Figure 7) and the gabbro shows variable degrees of hydrothermal alteration in the form of silicification, biotite-chlorite alteration, traces of chalcopyrite and pyrrhotite (Schlatter and Hughes, 2012).
Hughes et al. (2014) suggest that secondary structures to the main shear zone may be the main host of gold mineralisation, and that the primary shear itself is barren.
Slightly anomalous gold grades, with one sample up to 239 ppb gold, were recorded from rock samples collected during the SUPRASYD programme from the northeast part of the shear zone where there is extensive low temperature alteration at about 1,000 m a.s.l. (Swager et al., 1995).
These observations were followed up in 1997 by Softrock Petroleums Ltd. who completed less than one day’s work in the western part of the shear zone, taking 16 grab samples. Six of these samples were described as being anomalous for gold, with grades of between 0.24 g/t and 3.22 g/t (Swiatecki, 1997). Some correlation between Au, Cu, Mo, and Bi was noted, thus sharing some similarity with Au-Bi-W-Cu-(Mo-Sn) associations seen in other gold-bearing regional shears along the southeast margin of the Julianhab Batholith (Swager et al., 1995, Garde and Schønwandt, 1994 and 1995), although the presence of significant quartz veining is notably absent from reports.
There are no records of further exploration work having taken place on the prospect until 2010 when it was included in NunaMinerals’ exploration licence number 2010/39. NunaMinerals spent one day on Jokum’s Shear that year and collected 61 rock grab samples along traverses that were orientated across a rust-stained alteration zone that included anomalous gold grades reported by previous exploration. Of these samples, 8 graded more than 0.5 g/t gold, with a maximum grade of 2.45 g/t. NunaMinerals also reported that the gold was found in sulphide-mineralised granodiorite, the main sulphides being pyrrhotite and pyrite, and appeared not to be related to quartz veining (Pedersen, 2010).
NunaMinerals completed a further four days of sampling at Jokum’s Shear in 2012, taking 36 rock chip samples on the shear zone in an area between 650 m and 1,150 m a.s.l. These provided further evidence of gold mineralisation, and identified new occurrences to the northeast, on the same structure but in an area that was newly-exposed by a retreating glacier. Highlights from the 2012 sampling were as follows (Schlatter and Hughes, 2012):
- 3.1 m at 9.3 g/t Au;
- 2.0 m at 3.7 g/t Au;
- 2.7 m at 3.4 g/t Au;
- 3.0 m at 2.1 g/t Au.
Schlatter and Hughes (2012) recommended that further work at Jokum’s Shear should be carried out, including channel sampling to better understand the extent and grade continuity of gold mineralisation. They suggested that large portions of the rock along the shear could be mineralised, and that gold mineralisation remains open in all directions. Jokum’s Shear and additional nearby targets identified by AEX will be followed up in coming field seasons.
The locality was first noted during the SUPRASYD programme that took place between 1992 and 1996 (Garde and Schønwandt, 1994; Garde and Schønwandt, 1995; Nielsen et al., 1993; Stendal and Schønwandt, 1997). Boulder sampling has produced anomalous grades of up to 9 g/t gold and 4% copper hosted by narrow quartz and/or carbonate veins in weakly deformed metabasalts (Swager et al., 1995). The geological setting is somewhat similar to Nalunaq.
NunaMinerals visited the location very briefly (for two hours) in 2013 and managed to obtain a sample of in-situ mineralised rock containing gold in quartz veins with carbonate alteration. The sample was taken near the unconformable contact between Julianehåb granites and the overlying metavolcanics and assayed at 5 g/t gold. It was suggested that gold mineralisation was associated with the unconformity.
The part of the Niaqornaarsuk peninsula that is covered by the sub-area of licence 2019/113 along the inner shores of Søndre Sermilik is unexplored. Reconnaissance exploration is required to generate targets; scree sediment and grab sampling will be conducted as a first phase of work, with priority targets being contacts between the small amphibolite outcrops and the granodiorites, and the regional shear that parallels the fjord. The geology of this area is the same as the southern part of the Niaqornaarsuk peninsula which is covered by AEX’s Vagar licence 2006/10 and hosts high-grade gold mineralisation at Amphibolite Ridge.
Blomsterberg, J., 2005: Gold exploration in Niaqornaarsuk Valley, Lake 410 and Ippatit, field season 2004. Nanortalik I/S exploration licence 2004/05.
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Garde, A.A., & Schønwandt, H.K. 1995: Project SUPRASYD 1994: Ketilidian supracrustal rocks in South-East Greenland and gold-bearing shear zones in the Julianehåb batholith. Rapport Grønlands Geologiske Undersøgelse 165, 59-63.
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Pedersen 2010: Exploration in the Taateraat Licence 2010/39, 2010. NunaMinerals A/S 2010
Petersen, J. S. & Olsen, H. K., 1995: Gold exploration in Ippatit area – Søndre Sermilik – Amitsoq island, South Greenland. Exploration licence 12/93. Internal report, Nunaoil A/S, 25 pp., 5 app., 6 plates.
Sannes, D.L., 1998: Geological report on the Kangerluluk gold prospect, Southeast Greenland. GoldCorp Inc. pp. 1-57.
Schlatter and Hughes, 2012: Gold exploration in License 2010/39. Fieldwork conducted at Jokum’s Shear within the Hugin Licence during 2012
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