Magmatic nickelpotential in Greenland

A workshop on the ‘Assessment ofthe nickel potential in Greenland’ wasarranged by the Geological Survey ofDenmark and Greenland (GEUS) andthe former Bureau of Minerals andPetroleum (BMP) on 27–29 November2012. The purpose of the workshopwas to assess magmatic komatiite-hosted, conduit- and contact-typenickel deposits, and also to assess thepossible presence of undiscoverednickel deposits in Greenland in theuppermost part of the Earth’s crustand to rank the most prospectiveareas. The procedures for the assess-ment and ranking of the individualtracts were designed to comply, asmuch as possible, with the ‘GlobalMineral Resource Assessment Project’(GMRAP) procedures defined by theU.S. Geological Survey (USGS).

This edition of Geology and Ore highlightssome of the results from the workshop,including descriptions of the most impor-tant nickel provinces in Greenland, theirknown mineralisations and the resultingpotential for undiscovered nickel depositswithin these provinces. A more compre-hensive GEUS survey report documentingthe results from the workshop has beenpublished in the GEUS report series (Rosaet al. 2013).

The methodology applied

The evaluation of the potential for undis-covered magmatic nickel deposits inGreenland was carried out according tothe standardised process utilised in theGMRAP. In this process, an assessmentpanel of experts discuss all availableknowledge and data for a specific area(tract) and assess the possibility of findingnew undiscovered deposits within thistract. The assessment panel constitutednineteen geologists from the USGS, GEUS,the former BMP, University of Aarhus andprivate exploration companies; each withspecific knowledge on aspects ofGreenlandic geology and/or expertise in

nickel deposits. Each tract was definedfrom the surface to 1 km depth (1.5 kmfor the conduit-type). The members of theassessment team made their individualestimates (bids) of the number of depositsof a specific size and grade they believedcould be found and mined in a specifictract. A panel discussion of the bids led toa consensus bid, which was used as inputto a statistical simulation. The result was a

grade-tonnage estimate (prediction) ofhow much undiscovered ore and metalcould be found within a tract under thebest circumstances. The consensus bidsand predicted number of undiscoverednickel deposits per tract are shown onpage 5, 8 and 10.

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Magmatic nickel potential in Greenland

Worldwide summary statistics for the mean tonnage and grade for the komatiite-hosted, conduitand contact nickel deposits. Based on data from Barnes (2006), Schulz et al. (2010) and Zientek(2012). Data extracted from Zientek’s (2012) workshop presentation (see Rosa et al. 2013).

Picrite lavas of the Vaigat Formation, Nuussuaq, central West Greenland. The formation consists ofolivine-rich mainly picritic lavas with a thickness of up to more than 5 km and an average thicknessof 1 km. Their extent is 22,000 km2. In parts the formation is crustally contaminated. Photo: L. M.Larsen

Deposit type Tonnage ore Nickel grade Copper grade Number metric tons per cent per cent of deposits

Komatiite-hosted 2.8 3.14 low 51Peridotite-subtype

Komatiite-hosted 148 0.69 low 7Dunite-subtype

Contact-type 62 1.00 0.64 55

Contact-type 206 0.19 0.26 37

Types of nickel mineralisation

It was agreed before the workshop to usethe following three deposit types as theyaccount for most of the world’s knownreserves of nickel:

• Komatiite-hosted deposits• Conduit-type deposits• Contact-type deposits

Descriptive characteristics of the threeknown deposit types (referred to as a min-eral deposit model) were used togetherwith a broader-scaled mineralising systemapproach to set up the targeting-elementsthat should be evaluated.

Each type of nickel mineralisation is asso-ciated with a grade/tonnage model that isobtained through a compilation of globalgrade and tonnage data from knowndeposits that have been formed throughthe same genetic process and can bemined and processed using similar meth-ods. The grade/tonnage models are usedas input for the estimation of undiscov-ered nickel deposits for the different tractand deposit models.

Komatiite-hosted deposits

This type corresponds to the more extru-sive settings of the magmatic continuumand is therefore hosted by extrusive vol-canic rocks. Traditionally, this type hasbeen divided into two subtypes, accordingto their host-rock and correspondingfacies of the volcanic flow system. Sub-type 1 (or peridotite-type) deposits, relat-

ed to komatiite lava flows, in more distalsettings of the volcanic flow-system, andtype 2 (or dunite-type) deposits, related todunite bodies, in more proximal settings.Komatiite-hosted magmatic nickeldeposits tend to be of higher grade, yetlower tonnage, and are typified by theKambalda deposits of Western Australia.

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Tasiilaq

Graah Fjord

Maniitsoq Norite Belt

Hammer Dal

Ilukunnquaq

Ikertoq

Fiskenæsset

Bjørnesund

Kvanefjord

Nuuk

East GreenlandFlood Basalt Province

West GreenlandFlood Basalt Province

Amassalik IgneousComplex

Left: Simplified geological map indicating main lithostratigraphic environments and favorable nickel tract localities in Greenland. Middle and right:Stream sediment and rock sample localities with nickel values higher than 250 ppm. From Steenfelt’s (2012) workshop presentation (see Rosa et al.2013).

Grade and tonnage for the different assessed mineral deposit types. Modified from Zientek’s (2012)workshop presentation (see Rosa et al. 2013).

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0.0110,000 100,000 1,000,000 10,000,000 100,000,000 1,000,000,000 10,000,000,000

1,000,000 tons nickel

100,000 tons nickel

1,000 tons nickel

10,000 tons nickel

Tons, metric

Explanation

Conduit-type

Contact-type

Komatiite-hosted type

Laterite

Deposit type

Conduit-type

Contact-type

Komatiite-hosted type

Conduit-type deposits

This deposit type typically has grades andtonnages that are intermediate betweenthe komatiite-hosted type (high grade,low tonnage) and the contact-type de-posits (low grade, high tonnage). Most ofthe global nickel production can be ac-counted for by this type. It includesdeposits with the largest total nickelresource, among the magmatic nickeldeposits, with giants such as Norilsk andPechenga (Russia), Jinchuan (China) andVoisey's Bay (Canada). The deposits ofSudbury (Canada) can also be consideredto belong to this type; although a uniquemeteorite, impact-related melt sheet hasbeen proposed to be related to theiremplacement (Naldrett 2004). For this rea-son, the Sudbury-type is not part of thegrade/tonnage model for the conduit-type.

This deposit type is associated with hypa-byssal dykes or sills that are associatedwith large volumes of mafic magmatism(such as a continental flood basalt pro-vince). This style of mineralisation is alsocalled conduit-type, a genetic name indi-cating that these deposits form in con-duits in large magmatic systems. Since theamount of metal in the deposits cannotbe derived from the limited volume ofmafic melt in the associated intrusion thisimplies that some type of open system,with a large throughput of energy andmatter, was present. The presence of suchan open system can be recognised by theexistence of bulk compositions which arenot those of liquids and by the evidencefor excess heat (thermal erosion and widecontact metamorphism aureoles). Thismeans that nickel is effectively scavengedfrom streaming magma, through sulphideimmiscibility driven by the assimilationwith crustal sulphur.

Contact-type deposits

In contrast to the komatiite-hosted de-posits, contact-type nickel deposits tendto be of lower grade but higher tonnage.These deposits also have important PGEcontents, and are mined mostly for theseelements. This type corresponds to the

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SourceActive

PathwayS saturation(chemical)

Trap(physical)

Critial• High degree partial melts

• Major metallogenic epoch

Lessrelevant

• Lithospheric architecture

• Paleocraton margins

• Synvolcanic crustal architecture

• Magmatic sulphides

• Chalcophile enrichment

• Olivine-rich cumulate

• Channels and channel size

• Amygdaloidal flows

• Structural complexityProspect

Camp

District

Targeting elements for komatiite-hosted, nickel-copper sulphide mineral systems. The relative impor-tance of targeting elements at various scales is denoted by box colour: red = critical, green = lessrelevant. Especially the elements in the district and camp scale are relevant for the assessed tractsizes. S = sulphur. Modified from McCauig et al. (2010).

C6

C7

C8

C10

C11

C12

C9

C4

C5C2

C3

C1

I3

I1

I2

Conduit-type tracts

300 km

Contact-type tracts

I3

K13

K5

K10

K7

K12b

K8

K12a

K16

K4

K15

K3b

K11

K3a

K14

K2b

K2a

K9

K12a

K2b

Tracts for conduit- and contact-type nickel deposits

Tracts for komatiite-hosted nickel deposits

Komatiite tracts

300 km

The areas (tracts) used for the nickel assessment workshop.More information about the individual tracts can be found in the tables included on page 5, 8, 10.

intrusive settings of the magmatic contin-uum and is therefore hosted by plutonicrocks. The plutonic rocks are mafic toultramafic and typically magmatically lay-ered. Immiscible sulphide, which collectsnickel, as well as other chalcophile ele-ments such as copper and PGE, is formedas the result of fractional crystallisation,magma mixing, assimilation of sulphur orcontamination leading to increase in silicacontent. The nickel-copper-PGE-enrichedsulphides subsequently form disseminated,net-textured and massive sulphide concen-trations, hosted by igneous rocks andcountry rocks, near the lower part or themargin of the layered intrusion. Irregulardistribution of the sulphide concentrationsin this deposit type makes it hard to es-tablish volumes that are large enough tobe mined and for this reason only thePlatinum reef in the Bushveld complex hasbeen mined to date. In order to identifyintrusions with a potential for nickel priorto the workshop, a stepwise filtering of anexisting database of intrusions in Green-land was carried out. Since the workshopwas focused on nickel, intrusions with

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Name Tract no.

Areal extent[km2]

Consensus bid on number of undiscovered nickel deposits at

di!erent con"dence levels

Statistical calculation of:

RankN90 N50 N10 N5 N1 Number of unknown deposits

Deposit density

Mean estimate of undiscovered nickel resources

[metric tons]

Taartoq K2a 380 0 0 0 2 2 0.15 0.00034 9,200 5 K2b 560 0 0 1 2 3 0.41 0.00073 22, 000 3

Paamiut S K3a 932 0 0 0 1 2 0.11 0.00011 6,200 8 Paamiut N K3b 220 0 0 0 0 2 0.06 0.00027 4,300 14 Fiskenæsset K4 463 0 0 0 0 1 0.03 0.000065 2,100 15 Nuuk - Akia K5 2535 0 0 2 3 4 0.71 0.00028 43, 000 2 Maniitsoq E K7 886 0 0 0 1 2 0.11 0.00012 5,900 11 Ikertoq K8 263 0 1 3 3 5 1.40 0.00532 79, 000 1 Nordre Strøm!ord K9 169 0 0 0 1 2 0.11 0.00062 6,000 10 Sisimiut – Illulissat K10 2796 0 0 0 1 2 0.11 0.000038 6,800 7 Inner Nordre Strøm!ord K11 75 0 0 0 0 1 0.03 0.00040 2,100 14 Eqi – Disko - Kullorsuaq K12a 960 0 0 0 1 2 0.11 0.00011 6,800 6 Karrat Group K12b 20 0 0 0 1 2 0.11 0.00580 6,100 9 Melville Bugt K13 734 0 0 0 0 1 0.03 0.000041 1,800 16 Ingle"eld Land K14 137 0 0 0 1 2 0.11 0.00077 5,400 13 Tasiilaq contact halo K15 1040 0 0 1 1 3 0.36 0.00034 21, 000 4 Tasiilaq North K16 1550 0 0 0 1 2 0.11 0.000068 5,700 12

Summary of consensus bids from the nickel assessment workshop on the number of undiscovered komatiite-hosted nickel deposits in Greenland.

N90, N50, N10, N05, N01 = Condence levels; a measure of how reliable a statistical result is, expressed as a percentage that indicates the probability of the result being correct. A condence level of 10% (N10) means that there is a probability of 10% that the result is reliable.

Bjørnesund & Kvane!ord

Detailed saw-channel sampling of the dunite-dominated ultramafic sills at Ikertoq in WestGreenland. Photo: 21st North.

potential for copper over nickel, and like-wise PGE over nickel (stratiform, reef-likemineralisation), were filtered out duringthe evaluation. Step 1 in the filtering ex-tracted all mafic and ultramafic intrusivecomplexes with peridotites, norites, maficgabbros and Mg-rich diorites (because Niand Pt are lost during fractionation) andthe individual intrusions were assigned asize-classification of 0–10 km2, 10–100km2 and >100 km2 based on theirjudged/known extent. All steps involved inthe filtering of the intrusions in Greenlandare described in the GEUS report from theassessment workshop. As very large intru-sive complexes are needed to provide theright settings for the contact-type nickelmineralisation style, the assessment panelfound it most reasonable to only focus onvery large intrusions/complexes in Green-land and a threshold value of >500 km2

on the areal extent was arbitrarily chosenby the panel.

Undiscovered komatiite-hostednickel deposits

Supracrustal (undifferentiated), mafic andultramafic rock units were extracted fromthe 1:500 000 scale geological map of

Greenland. Based on the characteristics ofkomatiite-hosted nickel deposits and theassociated mineralising system, these rockunits were used as a first proxy for permis-sive geology for this type of mineralisa-tion. Units within similar geological set-tings and with similar level of investigationand exploration were then grouped to-gether into tract groups. The groups wereused to define the tracts that were be-lieved to be permissive for komatiite-host-ed nickel mineralisation. A total of 21 ini-tial tract groups were identified in thisway. In total 24,656 km2 were defined asbeing permissive for komatiite-hostednickel. During the course of the workshopthe panel decided to split three of the ini-tial tract groups into two groups. Further-more, seven of the proposed tracts werenot assessed due to time limitations andlimited potential. As a result, a total of 17tract groups were assessed for undiscov-ered komatiite-hosted nickel deposits. Theconsensus bids on the number of undis-covered komatiite-hosted nickel depositsare summarised in the table below.

The Ikertoq K8 tract in central WestGreenland was found to be the area inGreenland that according to the assess-

ment had the highest number of undis-covered komatiite-hosted nickel deposits.This was probably largely attributed to thepresence of known nickel prospects in thearea and the presence of additional geo-physical anomalies. The Ikertoq K8 tractstraddles the foreland of the Palaeopro-terozoic Nagssugtoqidan orogeny in whichArchaean supracrustal, mafic and ultra-mafic rock units were reworked. To thesouth the tract is bounded by the non-reworked North Atlantic craton.

The Nuuk – Akia K5 tract was assessedas to have the second highest number ofundiscovered komatiite-hosted nickeldeposits. It is a large tract that includesseveral continuous belts of supracrustal(undifferentiated), mafic and ultramaficrock units. The tract includes several ter-rane boundaries, which in some cases canbe followed for 150 km, and also containsmany well-known ultramafic rock unitswith komatiites as well as exhalative sul-phides. While some of the ultramaficrocks are Neoarchaean, deemed to be afavourable period for komatiitic nickelmineralisation, pentlandite occurrences inthe area are actually related to Mesoarc-haean, gabbroic, mafic granulites and ser-pentine schist. Gold mineralisations arealso well-known from this tract.

The Bjørnesund & Kvanefjord K2b tractdefines another area that was ranked rela-tive high for its potential to contain undis-covered komatiite-hosted nickel deposits.The tract represents mapped ultramaficrocks and amphibolites but no metasedi-mentary rocks are known in the Bjørne-sund and Kvanefjord areas. Spinifex tex-tures in ultramafic rocks are reported fromKvanefjord. Although there are acid vol-canic rocks, no exhalative massive sul-phides have been documented, so thepotential for the ultramafic magmas tohave reached sulphur saturation from thissource is limited. Several gold showingsand one showing with pentlandite miner-alisation have been reported from theBjørnesund area.

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Typical weathered rusty boulder with disseminated and net-veined Ni-Cu-Co sulphides as theyappear within dunite-dominated ultramafic sills at Ikertoq in West Greenland. Photo: 21st North.

Undiscovered conduit-type nickel deposits

The assessment panel found that the tar-get parameters for the conduit-type nickelmineralisation were present in many partsof Greenland. Several regions hold evi-dence for large magmatic systems that inmany cases are associated with wide-spread swarms of dykes and sills. A totalof 12 tracts were assessed during theworkshop for their potential for undiscov-ered conduit-type nickel deposits.

Three regions in Greenland are well-known for their presence of flood-basaltsand related major magmatic activityincluding numerous dyke and sill systems.The northernmost of these regions, tractC8, is defined by the Zig-Zag Dal basaltsand the presumed contemporaneousMidsommersø dolerites. These wereemplaced during rifting in the Indepen-dence Fjord Basin. The tholeiitic floodbasalt sequence is c. 1,350 m thick andextends over an area of c. 10,000 km2.The overall variation of Ni-MgO in samplesfrom the basalts points towards an olivinecontrol, however, a few more primitivesamples from the lowermost part of the

Zig-Zag Dal basalts are present and mightindicate that nickel was removed via animmiscible sulphide liquid. Tract C8 wasranked number 11 among the tracts forundiscovered conduit-type nickel deposits.The tract has seen very little exploration.

The tracts C6 and C7 cover the EastGreenland Flood Basalt Province(EGFBP) and associated intrusions (includ-ing numerous sill and dyke systems) thatare related to the Palaeogene volcanic-rift-ing and opening of the North Atlantic.The flood basalt sequence is up to c. 7 kmthick and consists of more than 260 flowsthat cover an area of more than 65,000km2 . More than sixty layered gabbrointrusions have been recorded in the pro-vince. The plutonic suite ranges fromultramafic to felsic, from depleted basalticto highly alkaline, and from upper crustalintrusion to sub-volcanic centres and brec-cia pipes with related epithermal vein sys-tems. The magmas were sulphur under-saturated and for most samples it seemsthat nickel is controlled by olivine fraction-

ation. Only the so-called Urbjerget lavasdepart from the olivine line of control ona Ni-MgO diagram which may suggestthat nickel may have been lost to sul-phides in these rocks. The province wassplit into two tracts. The reason for this isthat the lavas and associated dykes/sills tothe south were emplaced into a narrowand rather shallow sedimentary basin(tract C6), while those to the north wereemplaced into a more extensive and deep-er sedimentary basin (tract C7). Also thelevel of investigation and exploration fornickel is different from north to south,with the northern tract C7 having a high-er level. Tracts C6 and C7 were rankednumbers 7 and 8 among the potentialtracts for undiscovered nickel deposits.

The West Greenland Flood BasaltProvince (WGFBP) constituted the lasttracts, tracts C10 and C11, that aredirectly related to known flood basaltregimes in Greenland. WGFBP is consid-ered to be an analogue of the SiberianTraps in Russia to which the giant Norilsk

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Sampling of nickel-copper sulphide mineralisation hosted within a metasedimentary sequence, associ-ated with dioritic and ultramafic rocks at Tasiilaq, South-East Greenland. Photo: NunaMinerals A/S

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A 10 tons boulder of iron found by Falconbridge in 1993 on western Disko Island. Photo: A. K. Pedersen.

Name Tract no.

Areal extent[km2]

Consensus bid on number of undiscovered nickel deposits at

di!erent con"dence levels

Statistical calculation of:

RankN90 N50 N10 N5 N1 Number of unknown deposits

Deposit density

Mean estimate of undiscov-ered resources [metric tons]

N90, N50, N10, N05, N01 = Condence levels; a measure of how reliable a statistical result is, expressed as a percentage that indicates the probability of the result being correct. A condence level of 10% (N10) means that there is a probability of 10% that the result is reliable.

An asterisk (*) marks that the areal extent of the tract corresponds to the mapped rock units. The areal extent for those not marked with an asterisk corresponds to the entire area judged by the assessment panel to comprise the rock units and settings that are permissive for conduit-type

Maniitsoq Norite Belt C1 50* 0 1 2 3 5 1.10 0.25 490,000 270,000 19 1 Fiske!ord C2 420* 0 0 0 1 1 0.07 0.00018 27,000 15,000 1 10 Fiskenæsset C3 350* 0 0 0 1 2 0.11 0.0003 46,000 26,000 1 6 Gardar dykes (oldest) C4 6,570 0 0 0 1 2 0.11 0.000016 43,000 23,000 2 4 Tasiilaq AIC C5 250* 0 0 1 2 3 0.41 0.0017 160, 000 90, 000 7 3 S. of Scoresbysund C6 50,970 0 0 0 1 2 0.11 0.0000021 43, 000 24, 000 2 7 N. of Scoresbysund C7 2,510 0 0 0 1 2 0.11 0.000042 40, 000 22, 000 1 8 Zig Zag Dal C8 4,400 0 0 0 0 1 0.03 0.0000 068 12, 000 7,800 11 Ingle"eld Land C9 460* 0 0 0 1 1 0.07 0.00016 32, 000 18, 000 1 9 N. WG Basalt Prov. C10 10,730 0 0 1 2 3 0.41 0.000038 160, 000 88, 000 7 4 S. WG Basalt Prov. C11 10,880 0 1 2 3 5 1.10 0.0001 460, 000 250, 000 18 2 Skjoldungen C12 270* 0 0 1 1 2 0.33 0.0012 130, 000 73, 000 5 5

Copper PGENickel

Summary of consensus bids from the nickel assessment workshop on the number of undiscovered conduit-type nickel deposits in Greenland.

nickel deposit is related. WGFBP is relatedto the initial phase of continental break-up and initiation of sea-floor spreading ofthe Labrador Sea in the early Palaeogene.The basalts vary in thickness from 4 to 10km and cover at least 68,000 km2. Theywere deposited on a substrate of 6–8 kmthick sediments in a Cretaceous-Paleocenesubsiding basin and a Precambrian base-ment of the continental interior. TheWGFBP is especially noted for its presenceof native iron-bearing basalts and largevolumes of high-temperature picrites andolivine basalts. The picrites probably arethe largest volumes of MgO-rich lavasknown globally. Both basaltic and picriticparts of the lavas have been documentedto be contaminated by sedimentary rocksand to have reached sulphur saturation.The lower part of the lava succession(members of the Vaigat Formation) is ofsignificant volume and has undergonecrustal contamination. These magmasascended along known focused magmaconduits distributed along the N–SKuugannguaq-Qunnilik fault system.

These conduits have native iron and Fe-Ni-Cu-Co-sulphide occurrences.

In the 1930s, 28 tons of massive nickelsulphide was extracted from the Ilukunng-uaq dyke located on the north-east partof the island of Disko. Since then severalcompanies have explored for nickel in thearea, including Cominco, Inco /Falcon-bridge, Vismand Exploration, AvannaaResources and latest Disko Exploration.Deep conductive bodies that are interpret-ed to represent mineralised sills systemswere identified by Vismand Exploration in2003 and 2004, using Titan24 surveys.The conductors were found in theKuugannguaq and Aaffarssuaq Valleys inNorthern Disko and NW Nuussuaq, res-pectively. Deep (>1,000m) drilling to testone of these conductors was attempted in2007 by Vismand, but failed due to tech-nical challenges. Using airborne ZTEM sur-veys supplemented by Vibroseis surveys inKuugannguaq Valley in 2012-2013,Avannaa Resources was able to constrainthree, large conductive bodies at a depth

of ca 800m below the valley floor and afurther two conductive bodies at Aaf-farssuaq Valley. A petrographic study byAvannaa Resources of samples from thecontaminated lava sequences confirmedthe presence of rounded minute sulphideinclusions, interpreted to represent sul-phide melt exsolutions from the basalticmelts. These sulphide inclusions containup to 4wt% Cu and Ni and testify to theprospectivity for large, magmatic sulphidedeposits on Disko-Nuussuaq. Tract C10was ranked number 5, while tract C11was ranked number 2 among all assessedtracts for conduit-type nickel deposits. Theconsensus bid on tract C11 resulted inone conduit-type nickel deposit at a 50%confidence level. Again, although the rocktypes and settings are similar, differentlevels in knowledge, exploration and datamake it appropriate to subdivide thebasalt province into different tracts. TractC10 is the northern part of WGFBP, whichcomprises lesser volumes of picritic lavasand no known occurrences of native ironor nickel. Tract C11 contains large vol-

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An eruption site for Kûgánguaq Member on Disko Island. Contaminated basalt forms basaltic ignimbrite, possibly by interaction with natural gas. Photo:A. K. Pedersen.

umes of picritic lavas, occurrences of nativeiron and nickel, well-established pathways forascending magmas and strong, howeverdeep-seated, EM anomalies.

Tract C1 is defined by the distribution of thenorite and leucogabbroic rock units that aremapped as belonging to the ManiitsoqNorite Belt which lately has been suggestedsurrounding a large Archaean impact struc-ture that triggered fracturing and magmaascension that were active for a long period.There are evidences for crustal accumulation,and iron-sulphide-bearing amphibolite layersare locally associated with the intrusives andmay have provided a source for sulphur satu-ration. Tract C1 is ranked number 1 amongall assessed tracts for conduit-type nickeldeposits. Consensus bid on tract C1 resulted,at a 50% confidence level, in one conduit-type nickel deposit. Exploration in the areason numerous rust zones was initiated in the1950s and 1960s and several nickel-sulphideshowings were identified. The initial workwas only followed up by shallow drilling.Later, in 1995, fixed-wing airborne electro-magnetic surveys were carried out with limit-ed follow-up.

From 2011 through 2013, and again in2015, helicopter-borne TEM and magneticsurveys were carried out by North AmericanNickel (NAN). During these surveys, many

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Location Tract no.

Areal extent[km2]

Consensus bid on number of undiscovered nickel deposits at

di!erent con"dence levels Mean estimate of undiscov-ered resources [metric tons]

RankN90 N50 N10 N5 N1

Number of

deposits

Deposit density

Statistic calculation of:

N90, N50, N10, N05, N01 = Condence levels; a measure of how reliable a statistical result is, expressed as a percentage that indicates the probability of the result being correct. A condence level of 10% (N10) means that there is a probability of 10% that the result is reliable.

Innartivaq (Tasiilaq) I1 >500 0 0 0 1 2 0.11 0.000021 26,000 1 Kap Edvard Holm I2 >500 0 0 0 1 2 0.11 0.000021 1 Qaqujârssuaq I3 >500 0 0 0 0 1 0.03 0.000006 2

CopperNickel

Summary of assessment results including consensus bids on undiscovered contact-hosted nickel deposits in Greenland and statistically derived estimations.

26,0008,100

53,00053,00020,000

Targets drilled by North American Nickel intheir Maniitsoq property. Source: NorthAmerican Nickel Inc.

new conductive bodies were identified whichwere considered to merit drilling. Supportedby three-component drillhole electromagnet-ic surveys (2012-2016), surface electromag-netic surveys (2013-16), surface gravity sur-veys (2014-15), and induced polarisation sur-veys (2016), drilling has tested these conduc-tors. Between 2012 and 2016, NAN hascompleted 133 core drillholes with a com-bined length of 29.841 m, with 42 drillholes(11.577 m) of these focusing on the ImiakHill Complex. Nickel-copper sulphide mineral-isation was intersected in three targets of thiscomplex (Imiak Hill, Mikissoq and Spotty Hill)as well as eleven other locations throughoutthe licence area. NAN has also commis-sioned SGS Canada Inc. to carry out miner-alogical studies by scanning electronmicroscopy (QEMSCAN) and electron micro-probe analysis (EMPA). These studies haveindicated that pentlandite is the main nickel-bearing sulphide mineral containing in excessof 90 percent of the total nickel analysedsamples. In addition, potential recoveries ofpentlandite and chalcopyrite, based solely ongrain liberation, association, and exposureresults, were estimated to be greater than 95and 75 %, respectively.

Undiscovered contact-type nickel deposits

This type of mineralisation is characterised bybeing associated with very large mafic andultramafic complexes. Subsequently, theassessment panel found it appropriate onlyto focus on this type of complexes and athreshold value of 500 km2. Only three com-plexes were found to meet these criteria.

Tract I1 constitutes the Archaean Innartivaqgabbro-diorite-tonalite-granite intrusivecomplex north of Tasiilaq, South-EastGreenland. The complex is presumed to beemplaced early in the Proterozoic evolutionof the Nagssug-toqidian orogeny in South-East Greenland. Minor sulphide occurrences,including pentlandite mineralisation, havebeen found in small gabbroic bodies withinthe complex. The complex is hosted north ofa supposed Palaeoproterozoic crustal bound-ary. The complex has not been investigated.

Tract I2 the Palaeogene Kap Edvard Holmcomplex, South-East Greenland, covers c.800 km2 and constitutes a large layered,tholeiitic gabbro complex that subsequentlywas intruded by syenite, granite and wehrlitethat reflect multiple magma pulses injectedover an extended time period. The complex

is hosted by Precambrian gneisses, near asupposed crustal triple-junction. There is evi-dence for crustal contamination, includingsulphur-rich sediments. Exploration in thecomplex has identified a c. 40 km long goldand platinum anomalous zone.

Tract I3 hosts the Archaean Qaqujârs-suaqcomplex, south of Thule, North-WestGreenland. The complex covers more than1,000 km2 and is mostly made of anorthositebut also contains gabbro and leucogabbro.The complex is intruded into gneisses, ironformations and metas-edimentary rocks. Thecomplex is very poorly known and has notseen any exploration.

Concluding remarks

Greenland comprises geological environ-ments that are highly prosperous for nick-el mineralising processes. Considering thehistorically limited exploration activitiesthat have been carried out in many parts

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Massive sulphide sample from diamond drillhole MQ-13-026 at the Imiak Hill occurrence,part of the Maniitsoq Norite Belt. The sample,which comes from 158.5 metres down thehole assayed 5.26% Ni, 1.78% Cu and 0.18%Co. Photo: North American Nickel Inc.

Coarse-grained pyrrhotite-pyrite-pentlandite-chalcopyrite mineralisation from Imiak Hill. Photo: NorthAmerican Nickel Inc.

of Greenland and the limited amount ofdata and information that are available,the assessment still resulted in an estimate ofundiscovered nickel deposits and an associat-ed nickel endowment that can be consideredsignificant and warrants further opportunitiesand exploration. When the few historicalexploration campaigns that have been direct-ed towards nickel mineralising systems inGreenland, e.g. those on the West Green-land Flood Basalt Province and those withinthe Maniitsoq Norite Belt, are taken into con-sideration, it is worth noticing that each newcampaign has resulted in new targets fornickel. This is mainly due to technical ad-vancements in geological models and theavailable geophysical methods. Recent andon-going exploration campaigns have thusresulted in identification of new nickeldeposits that might represent larger nickeldistricts. The assessment of undiscoverednickel deposits also concluded that num-erous tracts are highly prosperous for nickel,but more investigations and data are neededto increase the certainty with which to evalu-ate the favourability of these tracts. Green-land is especially enriched in geological envi-ronments favourable for hosting conduit-type nickel deposits. However, environmentsfor komatiite-hosted nickel deposits are alsopresent, although to a lesser degree.

Key references

Barnes, S.J. 2006: Komatiites: Petrology, Vol-

canology, Metamorphism, and Geochemistry.

Society of Economic Geologists, Special Pub-lica-

tion 13, p. 13-49.

Barnes, S.J., 2006: Komatiite-Hosted Nickel Sulfide

Deposits: Geology, Geochemistry, and Genesis,

Society of Economic Geologists Special Publication

13, 2006, p. 51-97.

Barnes, S.J. & Fiorentini, M.L. 2012: Komatiite

Magmas and Sulfide Nickel Deposits: A Comparison

of Variably Endowed Archean Terranes. Economic

Geology 107, p. 755-780.

Garde, A.A., Pattison, J., Kokfelt, T.F., McDonald,

I. and Secher, K. 2013: The norite belt in the

Mesoarchaean Maniitsoq structure, southern West

Greenland: conduit-type Ni-Cu mineralisation in

impact-triggered, mantle-derived intrusions?

Geological Survey of Denmark and Greenland Bulletin

28, p. 45 – 48.

Larsen, L.M. & Pedersen, A.K. 2009: Petrology of

the Paleocene Picrites and Flood Basalts on Disko

and Nuussuaq, West Greenland. Journal of Petrology

50, p. 1667-1711.

McCuaig, T.C., Beresford, S., Hronsky, J. 2010:

Translating the mineral systems approach into an

effective exploration targeting system. Ore Geology

Reviews 38, p. 128-138.

Naldrett, A.J. 2004: Magmatic Sulfide Deposits:

Geology, Geochemistry and Exploration, Springer,

Heidelberg, 728 pp.

Rosa, D., Stensgaard, B.M. & Sørensen, L.L. 2013:

Magmatic nickel potential in Greenland. Reporting

the mineral resource assessment workshop 27-29

November 2012. Danmarks og Grønlands Geologiske

Undersøgelse Rapport 2013/57, 134 pp.

Secher, K. & Stendal, H. 2010: Greenland’s nickel

resource potential. Geology and Ore no. 17, 12 pp.

Schulz, K.J., Chandler, V.W., Nicholson, S.W.,

Piatak, Nadine, Seall, II, R.R., Woodruff, L.G.,

and Zientek, M.L., 2010: Magmatic sulfide-rich

nickel-copper deposits related to picrite and (or)

tholeiitic basalt dike-sill complexes - A preliminary

deposit model, U.S. Geological Survey Open-File

Report 2010–1179, 25 pp.

Stensgaard, B.M. & Sørensen, L.L. 2013:Mineral

potential in Greenland. Geology and Ore no. 23,

12 pp.

Thorning, L. 2012: Greenland Mineral Resources

Portal, www.greenmin.gl. Fact Sheet no. 26, 2 pp.

Zientek, M.L., 2012:Magmatic ore deposits in layered

intrusions—Descriptive model for reef-type PGE and

contact-type Cu-Ni-PGE deposits, U.S. Geological

Survey Open-File Report 2012–1010, 48 pp.

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Front cover photographIn the inner parts of the ScoresbySund area(70°N) the lowest units ofthe plateau basalts rest directly ongneisses from the Caledonian foldbelt. The basalt succession shown isabout 800 m thick.

The Ministry of Mineral Resources (MMR)Government of Greenland

Postbox 930Imaneq 1A, 2013900 Nuuk Greenland

Tel: (+299) 34 68 00Fax: (+299) 32 43 02E-mail: mmr@nanoq.glInternet: www.govmin.glwww.naalakkersuisut.gl,

www.greenmin.gl

Geological Survey of Denmark and Greenland (GEUS)Øster Voldgade 10

DK-1350 Copenhagen KDenmark

Tel: (+45) 38 14 20 00E-mail: geus@geus.dkInternet: www.geus.dk

AuthorsBo Møller Stensgaard, Lars LundSørensen, Stefan Bernstein, Diogo

Rosa, GEUS

EditorDiogo Rosa, GEUS

Graphic ProductionHenrik Klinge Pedersen, GEUS

PhotographsGEUS unless otherwise stated

PrintedOctober 2018,

Update of November 2013 © GEUS

PrintersRosendahls A/S

ISSN1602-818x (print)2246-3372 (Online)

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Drill rig and casings used in connection with Vismand Exploration Inc.’s drill programme onNuussuaq in 2007. The aim was to locate nickel-enriched, deeper-lying, lava conduits that con-nect to successions of contaminated flood basalts.

No. 31 - October 2018