Greenland Day: Nickel potential in Greenland

Transcription

1 Greenland Day: Nickel potential in Greenland Bo Møller Stensgaard, Marco Fiorentini *, Jochen Kolb, Leon Bagas * Geological Survey of Denmark and Greenland (GEUS) * Centre of Exploration Targeting, UWA Perth, Australia, December 4, 2012 With acknowledgements to members and observers in the BMP-GEUS Mineral Assessment Workshop 2012 on potential for undiscovered nickel deposits in Greenland and and special thanks to: M. Zientek, USGS; A. Steenfelt, GEUS; 21stNorth; Avannaa Resources

2 Nickel Assessment Workshop Potential nickel mineralising environments What do stream sediment data tell us Examples on areas with potential for undiscovered nickel deposits Summary Proterozoic Elenore Bay Supergroup, NE Greenland host of several Cu occurrences

3 BMP-GEUS workshop Assessment of undiscovered nickel deposits in Greenland within the first one kilometre of the crust November 27 29, 2012 Expert panel 19 members Nickel deposit experts from CET and USGS Economic and regional geologist Company, Survey and Academic; international 15 observers All data, maps, information, etc. is assessed and discussed Bids on number of undiscovered nickel deposits in certain areas in Greenland that are found to be geological permissive for nickel mineralisation at different confidence levels Standard 3-Part Assessment procedure Former workshops have been carried out for sedimentary-hosted Copper and Zinc-Lead deposits Mineral Assessment Workshops (MAW) will continued in the years to come would you like to participate?

4 Globally distribution vs. Greenland Maier & Groves 2010 Distribution of magmatic PGE ( ) and Ni-Cu ( ) deposits worldwide. Shaded areas is Archaean crust. Outlines of cratons amalgamated during the Proterozoic are from Bleeker (2003).

5 Three deposit types assessed Komatiite-hosted nickel Kambalda, Mt. Keith, Perseverance deposits Sill- or dyke-hosted nickel conduit style Noril sk, Taknakh, Voisey s Bay deposits Intrusion-hosted nickel contact style Duluth complex deposits (not presented here) Means of the deposit types that were assessed for based on global deposit inventory Deposit type Ore tonnage [mt] Nickel grade [%] Copper grade [%] Global number deposits Kambalda Komatiiteperidotite type low 51 Noril sk Conduit-type Duluth Contact-type M. Zientek, 2012 Noril sk massive nickel ore, M. Zientek, 2012

6 Nickel Assessment Workshop Potential nickel mineralising environments What do stream sediment data tell us Examples on areas with potential for undiscovered nickel deposits Summary Proterozoic Elenore Bay Supergroup, NE Greenland host of several Cu occurrences

7 Kambalda Komatiite-style ~ km 2 permissive geology Archaean and (minor) Palaeoproterozoic supracrustal and mafic-ultramafic units Archaean craton areas Palaeoproterozoic reworked areas Putting it all together km

8 Putting it all together Mineral System Approach Scale dependency of targeting elements for mafic intrusion-hosted Ni mineral system McCuaig et al., 2010

9 Zig-Zag Dal Flood basalts Noril sk Conduit-style ~ km 2 flood basalt Three flood basalt regions Even larger regions with potential West Greenland Flood basalt province Manitsoq norite belt Fiskenæsset Gardar dykes Tasiilaq norites 400 km East Greenland Flood basalt province Numerous larger magmatic systems and voluminous sill-dyke swarms throughout Greenland with no direct link to flood basalts Workshop concluded: more time is needed to assess the swarms and larger magmatic systems not directly associated with flood basalt regions much more to do! Putting it all together...

10 Noril sk Conduit-style what needs to be present There are sills, and, there are sills. Zientek, 2012 Magmatic Hosted by mafic to ultramafic rocks Occur in small intrusions (areas are 10s km 2 ) Intrusions have irregular shape Usually part of a large magmatic system 100s of intrusions, sill and dike complexes, plutonic complexes, large volcanic fields can be nearby Magmatic complex not clearly associated with a particular plate margin interaction Open systems, multiple magma influx Large throughput of heat and matter Excellent place to accumulate minor phases (sulphides) Undifferentiated sheets Differentiated chonolith (tubes) Zientek, 2012

11 So what about scale M. Zientek, 2012

12 So what about scale West Greenland Flood basalt province Potential for Noril sk type deposit Plenty of room 400 km Voisey s Bay Noril sk M. Zientek, km

13 Nickel Assessment Workshop Potential nickel mineralising environments What do stream sediment data tell us Examples on areas with potential for undiscovered nickel deposits Summary Proterozoic Elenore Bay Supergroup, NE Greenland host of several Cu occurrences

14 GEUS stream sediment geochemistry data - Agnete Steenfelt, GEUS Samples from second to third order streams. The <0.1 mm grain size fraction analysed for major and trace elements. BMP contributed to data acquisition. Nickel determined by X-ray fluorescence spectrometry (l.l.d. ~50 ppm) or inductively coupled plasma emission spectrometry (l.l.d. ~10 ppm) or instrumental neutron activation (l.l.d. ~200 ppm) Location of ~10000 stream sediment samples One regional dataset that can be used to support decisions on potential for undiscovered nickel deposits A. Steenfelt, 2012

15 % Ni ppm Ni 0 0 MgO % 70% 50% 30% 10% 2% Samples: Minimum: Maximum: Mean: Geo.Mean: Median: Mode: Std.Dev.: Std.Err.: Skew: Kurtosis: Anomalies generally correspond to areas with high background A. Steenfelt, 2012

16 A. Steenfelt, 2012

17 hi Archaean/Palaeoproterozoic Outlines belts of mafic metavolcanics Craton margins outlined Flood basalt regions r Ba Archaean craton 4-grid composite map Sr ppm Rb ppm Ba ppm Ni ppm Cr ppm Cu ppm TiO2 % A. Steenfelt, 2012

18 Komatiite deposit type Conduit deposit type Areas identified as having anomalous nickel in rock samples and stream sediment geochemistry Rock sample Ni ppm Rock sample Ni ppm Stream sediment Stream sediment Ni ppm Ni ppm

19 Nickel Assessment Workshop Potential nickel mineralising environments What do stream sediment data tell us Examples on areas with potential for undiscovered nickel deposits Summary Proterozoic Elenore Bay Supergroup, NE Greenland host of several Cu occurrences

20 Undiscovered Komatiite nickel deposits area 8 Individual bids on undiscovered Individual expert deposit estimates XXth percentile confident intervals 90% 50% 10% 5% 1% Consensus km Kangerlussuaq region 8

21 Undiscovered Komatiite nickel deposits Nuuk region km Kangerlussuaq region 8 2b Bjørnesund Paamiut region 15 Tasiilaq region Tract Name Size [km 2 ] Consensus undiscovered deposit estimates XXth percentile confident intervals 90% 50% 10% 5% 1% 2a b a b a a na b na na na

22 21stNorth, Undiscovered Komatiite Ni deposits area 8 Ikertoq Ni-Cu-(Co) prospect licenseholder 21stNorth

23 Undiscovered Komatiite Ni deposits area 8 Detailed map of the Ikertoq Ni-Cu-(Co) prospect 21stNorth, 2012 Østergaard & Lie, stNorth, 2012 Regional aeromagnetics total magnetic intensity field NIAQORNARSSUIT 21stNorth, 2012 Komatiite Area 8

24 Ikertoq Ni-Cu-(Co) prospect (year one) License taken on the basis of a few historical samples from the area Rusty beds within dunite and peridotite within an area of 1000x150 meters Mostly disseminated to network mineralisation) 14 samples with more than 1% Ni (aqua regia) with max. grades 5.18% Ni, 2.1% Cu and 0.31% Co The average grade of all mineralised samples is 2.0% Ni, 0.33% Cu and 0.1% Co (aqua regia) The average nickel tenor of mineralised samples is 18.65% (Ni content in 100% sulphide) Ore consists of 50% pentlandite 21stNorth, 2012 VTEM survey results in several conductors Drill targets identified

25 Undiscovered Conduit nickel deposits West Greenland Flood basalts North 10 Maniitsoq Norite belt 1 11 West Greenland Flood basalts South 12 Tasiilaq region 5 Skjoldungen region 400 km Consensus undiscovered Tract Name deposit estimates XXth percentile confident intervals 90% 50% 10% 5% 1%

26 www. avannaa.com Undiscovered nickel deposits conduit area 11 Disko-Nuussuaq Ni-Cu-PGE prospect licenseholder Avannaa Resources Maligât Formation in western Disko L.M. Larsen, 2012

27 www. avannaa.com Undiscovered nickel deposits conduit area 11 Disko-Nuussuaq Ni-Cu-PGE West Greenland Tertiary Igneous Province is a recognized analogue to Siberian Traps Lava composition, fault control, sedimentary basin, level of erosion, sites of sulphide segregation Five criteria: 1.High-Mg, olivine-rich magmas 2.Proximity to crustal-scale faults/ magma conduit systems 3.Sulphide/sulphur-bearing country rocks 4.Prolonged episodes of assimilation of siliceous crustal rocks 5.Chalcophile element depletion in crustally contaminated rocks Avannaa Resources, 2012

28 www. avannaa.com 1. High-Mg, olivine-rich magmas Vaigat Fm contains 2-5 km of lavas, mainly picrites Typical Naujánguit Mb picrite has 7-29 wt% MgO - picrites inherently have high Ni(+Cu) and they are hot and low viscosity, thus assimilate more crust 2. Proximity to crustal-scale faults/ magma conduit systems Avannaa Resources, 2012 Dam et al, 2009 Arndt et al, 2003

29 www. avannaa.com 3. Sulphide/sulphur-bearing country rocks Sulphur-bearing shales and coal in Atane Fm sandstone 4. Prolonged episodes of assimilation of siliceous crustal rocks Several intervals with strongly contaminated lavas Avannaa Resources, 2012 Dam et al, 2009 Volcanic rocks deposited on a substrate of 6-8 km thick sediments in a subsiding basin Larsen & Pedersen, 2009

30 www. avannaa.com 5. Chalcophile element depletion in crustally contaminated rocks Sulphur-bearing shales and coal in Atane Fm sandstone Olivine phenocryst compositions: Known eruption site for contaminated units Inferred eruption site Fe Native iron Whole-rock compositions: F e Fe Avannaa Resources, 2012 Data from Pedersen, 1985; Keys & Lightfoot, 2007; Lightfoot et al, 1999 Fe Fe Larsen, 2012

31 www. avannaa.com Avannaa Resources, 2012 ZTEM shows low-resistivity, sub-horizontal body consistent with a sulphide-bearing gabbro sill at 1000m depth below surface Drill-target identified

32 Undiscovered Komatiite Nickel Deposits Undiscovered Conduit Nickel Deposits Tract Name Size [km 2 ] Consensus undiscovered deposit estimates XXth percentile confident intervals 90% 50% 10% 5% 1% 2a b a b a a na b na na na Consensus undiscovered Tract Name deposit estimates XXth percentile confident intervals 90% 50% 10% 5% 1%

33 Nickel Assessment Workshop Potential nickel mineralising environments What do stream sediment data tell us Examples on areas with potential for undiscovered nickel deposits Summary Proterozoic Elenore Bay Supergroup, NE Greenland host of several Cu occurrences

34 Plenty of room for other nickel projects Nuuk region km Kangerlussuaq region 8 2b Bjørnesund Paamiut region 15 Tasiilaq region West Greenland Flood basalts North 10 Maniitsoq Norite belt 5 Example Gardar rift dyke 11 West Greenland Flood basalts South Tasiilaq region 5 12 Skjoldungen region

35 Stream sed Ni ppm Stream sed Ni ppm Archaean craton Mafic dyke swarm of Early Gardar age (~1350 Ma): Voisey s Bay analogy? Voisey s Bay A. Steenfelt, 2012

36 Several ongoing nickel projects Environments for komatiite-hosted nickel is present (Kambalda, Mt. Keith types) Environment for conduit-hosted nickel is present (Noril sk and Voisey s Bay types) Three established flood basalt provinces, Numerous large magmatic provinces with 100s of intrusions, sill and dike complexes, plutonic complexes many have not been investigated for conduit mineralisation Potential regions can be assessed both conceptual and by regional data Results of nickel workshop will be released within the next year until that visit GEUS and CET for further discussion

37 Thank you... Marco Fiorentini, Bo Møller Stensgaard, Jochen Kolb, Leon Bagas,

38 the end...