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Quo Vadis Exploration? © Condor Consulting 2011 The evolution of the use of geophysics in the search for blind VHMS deposits in the Abitibi greenstone belt, Ontario-Québec Canada Ken Witherly Condor Consulting, Inc. Michel Allard Xstrata Zinc Canada The Target © Condor Consulting 2011 Abitibi Subprovince of the Superior Province (Archean) CHIBOUGAMAU SELBAIE MATAGAMI JOUTEL NORMETAL GREVET KIDD CREEK LARONDE KAMISKOTIA NORANDA LOUVICOURT 50 km © Condor Consulting 2011 MINING CAMP Mt KIDD CREEK 161.4 NORANDA 132.2 CHIBOUGAMAU 52.3 SELBAIE 47.3 MATAGAMI 47.7 VAL D’OR 48.9 LA RONDE 59.3 GREVET 10.7 NORMETAL 10.2 KAMISKOTIA 7.9 JOUTEL 9.6 %Cu 2.41 1.86 1.80 1.00 0.84 1.65 0.44 0.46 2.17 1.23 1.60 %Zn g/tAu 6.17 0.05 2.36 4.16 1.68 1.92 0.61 8.80 0.46 1.58 0.51 2.31 4.10 8.41 0.10 5.40 0.85 1.47 0.05 2.95 0.33 62 VHMS Deposits (>0,2Mt) Discovery vs time Stone age Experimental 15 Joutel Golden age Analog, qualitative copper New age Digital, quantitative Geophysical contribution in 43 cases Norita Bell Allard S Poirier New Hosco 10 Lac Garon Orchan Selbaie B Louvicourt Matag. Lake Lac Scott B- Hébert Louvem Selbaie A1-A2 Aldernac 7-8 Kidd Creek Magusi Norita Est Explo-Zinc P- Dodge 1 Estrades Caber Perseverance New Comex Ribago Caber nord Equinoxe Norbec Lemoine G- Langlois Bell Allard Bracemac/ New Insco Ansil Orchan ouest McLeod Laronde Penna West-Ansil Jay Copper 5 Aldermac East-sullivan Normetal Gallen Waite Amulet Gallen s-t Newbec 0 Coniagas Mobrun Barvallee Vendome Abcourt Laronde Manitou Kam Kotia Quemont Vauze Millenbach Horne Horne z5 Joliet Potter Delbridge 30-40 40-50 1920-30 © Condor Consulting 2011 50-60 60-70 Corbet 70-80 Isle-Dieu 80-90 90-2000 2000- Depth to the top 62 VHMS Deposits (>0,2Mt) 30 From surface Kidd Creek Selbaie Matagami Lake Perseverance Orchan Bell Allard sud Phelps Dodge 1 Lac Garon Norita New Hosco Mobrun Gallen Magusi Baie fabie Poirier Estrades Explo-Zinc Joutel Copper Vendome Barvallée ( vendome) New Comex Lac Scott Lemoine Jay Copper Louvem 25 20 15 10 5 0 GonzagueLanglois Laronde East-Sullivan Abcourt Horne Newbec Waite Amulet Normétal Manitou Coniagas Kam Kotia Potter 0 Aldermac Vauze Joliet 1 © Condor Consulting 2011 50m From drill holes 50 blind deposits West-Ansil Equinoxe Caber Bracemac Quémont Delbridge McLeod Louvicourt Caber nord Bouchard-Hbert Norbec Isle Dieu Gallen (underg.) 200m Norita Est Bell Allard Ribago Millenbach La Ronde (Penna) Corbet 500m Orchan west Ansil Horne (zone 5) 1000m 1500m Depth of drilling vs time Abitibi Subprovince Shallow drilling <100 m © Condor Consulting 2011 Deeper drilling >100 m Fewer new VHMS discoveries? Hypotheses explaining the relative decrease in new discoveries. All the big deposits have been found. The undiscovered ones are typically too small, too deep and therefore uneconomic. Since the Abitibi has been intensively explored in the past, the chance of finding is decreasing; this results in less exploration effort which in turn leads to fewer discoveries and so on. Intrinsic limits of detection technologies and geological knowledge © Condor Consulting 2011 1999 : Difficult time for Noranda and the industry October 1999: Closing of Mine Gaspé, Murdochville. 300 lay off November 2001: Noranda annonces temporary closure of its smelting infrastructures April 2002: Definitive closure of the smelter. 300 more lay off. $2010 $5.00 $0.00 “ask not what your country can do for you - ask what you can do for your country.” Quebec government asked the industry: “what your country can do for you?” to prevent more infrastructure closings. The industry (Noranda) suggested tax credits on exploration work! Solution : an incentive plan 40% refundable tax credit for non-producing companies 20% for producers + 40% non-refundable tax credit applicable on capital tax for all exploration work . 2001 Exploration Objectives: • Generate high quality VMS exploration targets in order to discover 5-50 Mt deposit with NSR > 80$/t • Find new ore to replace 3 years reserves of Louvicourt • Provide Noranda Horne smelter with polymetallic concentrate having gold credits • Prevent more closure following the one of Gaspe Smelter in Murdochville in August 2002. $/ton vs VHMS tonnage Economic model $700 Smaller higher grade deposits (brownfield target) US$/ton $600 IDEAL ABITIBI TARGET $500 Larger lower grade deposits (greenfield target) $400 $300 $200 $100 0,1Mt © Condor Consulting 2011 1Mt 10Mt 100Mt MegaTEM Rational : New Search space Relatively few deposits found at a depth below 50 m Limited drilling below 100 m In-house tests had demonstrated that the MEGATEM system could detect typical VHMS at least to a depth of 250 m. Typical VHMS deposit has a high in-situ value (Figure 5). A stand alone 20 Mt deposit shows an insitu value of 350$US/t (at current prices) is deemed as an attractive target Exploration risk could be shared with the government and junior companies. © Condor Consulting 2011 MegaTEM Rational : New Search space Relatively few deposits found at a depth below 50 m Limited drilling below 100 m In-house tests had demonstrated that the MEGATEM system could detect typical VHMS at least to a depth of 250 m. Typical VHMS deposit has a high in-situ value (Figure 5). A stand alone 20 Mt deposit shows an insitu value of 350$US/t (at current prices) is deemed as an attractive target Exploration risk could be shared with the government and junior companies. © Condor Consulting 2011 The Dream AEM Performance Best Case 1975 = 10% (Input) 1990 = 46% (GEOTEM) 2001 = 100% (MEGATEM) 200m 1975 1975 1990 1990 2001 2001 50 m 100 m 150 m 200 m Repeat the sequence of discoveries generated by the first airborne surveys during the late ‘50s: Brunswick 12, Mattagami Lake, Kidd Creek… The Dream Nb 35 deposits 30 25 20 15 10 5 0 Prospecting and shallow geophysics 40 Kidd Creek Horne MEGATEM 200m Perseverance TARGETS Lack of deposit due to the limitation of the Normétal previous technology. Potential range 50-200 m Selbaie 1975 1975technology for VMS discoveries using the present Grevet 50 La m Ronde Matagami Lake 100Mobrun m 0 © Condor Consulting 2011 1990 1990 Equinoxe 150 mCaber 200 Quémont mDelbridge Norbec Louvicourt 2001 Isle Dieu Bouchard-Hébert Corbet La Ronde (z20) Bell Allard Millenbach 2001 Norita Est Ribago Orchan west MEGATEM TARGETS Ansil Horne zone 5 Stratigraphic drilling 50 200 500 Deposits to Top (metres) 1000 1200 MegaTEM Surveys Coverage from 2001-2006: (180 207 lkm) Including 140 000 by Xstrata and partners © Condor Consulting 2011 Typical VMS Terrain TMI 50 km EM Ch 3 Typical VMS Terrain Zoom in… TMI 10 km EM Ch 3 Area and Target Selection 1) “Subjective” priorities based on the following criteria: Favorable geology (Scale 2-3) Coincident MAG-EM anomalies Isolated anomalies (avoid formational) On Xstrata properties or open ground Untested by previous drilling 2) “Objective” priorities based on a large geologicalgeochemical database was used in parallel to query AEM results using intelligent GIS algorithms. © Condor Consulting 2011 Area and Target Selection © Condor Consulting 2011 End Results On the Québec side 40,000 EM picks 349 AEM anomalies were followed up 203 were drilled tested for a total 267 DDHs. While discoveries can occur well after the initial generative work, at this stage no new deposits have been attributed to the MEGATEM initiative. WHY ? © Condor Consulting 2011 WHY ? • Geological concepts/models • Geophysical technology • Managing “luck” © Condor Consulting 2011 Scales 1 and 2 © Condor Consulting 2011 Scale 1 : Deposit Scale Typical VHMS Massive sulphides Exhalite Sp Sp Hydrothermal alteration zone and pipe chlorite, sericite, quartz Adapted from J Lydon © Condor Consulting 2011 Stockwork Cp+Py+Po stringers Magnetite zones Scale 2 : Property scale ex: Noranda camp Local Felsic dome VHMS Synvolcanic faults © Condor Consulting 2011 mafics After Gibson, 1999 Scale 3: Area selection cartoon © Condor Consulting 2011 Scale 3: Magnetic and density modeling © Condor Consulting 2011 Smaller probability of finding a large barren deposit EROSION 100m 100 x 1Mt 500m 26 x 10Mt Assuming a uniform vertical distribution (down to 500m) and a statistically true size distribution 5 x 100Mt l L th 400 1250 50 100 000 000.00 200 500 25 10 000 000.00 © Condor Consulting 2008 100 175 15 1 050 000.00 © Condor Consulting 2011 nb eroded 5 (4%) 26 (20%) 100 (76%) 0 4 25 remaining outcropping 0-100m 5 25 75 2 5 8 0 3 9 outcropping blind 0-100m 40% 19% 11% 60% 81% 89% 0% 7% 12% False Positives 1. Few good targets in the right geological setting. ♦ 2. Barren sulfides (mainly Py-Po stringers) Numerous targets that appear like VHMS targets but are not in the right geological setting ♦ Barren sulfides and graphite One easy solution : no selection of “ formational” conductors Consequence : Lost opportunity or reduced search space VHMS have been found in the so-called “formational” settings THUS : Need for better predictive models “Only good fishermen are successful, first by selecting the good lakes and then the good spots” © Condor Consulting 2011 The evolution : Reid Mahaffy example Gravity data at this scale can help to constrain and refine EM conductors in gravity lows © Condor Consulting 2011 Quo Vadis Toronto, 2 June 2011 Xstrata Zinc has entered into a binding agreement with Sabina Gold and Silver Corporation to purchase the Hackett River and Wishbone exploration properties in the Western Kitikmeot region of Nunavut, North Canada. Under the terms of the agreement, Xstrata will pay a cash consideration of C$50 million and will grant a silver royalty to acquire the properties. Additionally, Xstrata will commit a further C$50 million in exploration and to complete a bankable feasibility study within four years of the transaction’s closing. © Condor Consulting 2011 Now and into the future Near mine exploration will remain quite effective. Incremental advances in technology can be expected and in the right geological circumstances, ex: Lalor Deposit The efficacy of geophysical techniques to search at depth (2-3 km) will remain challenging. More integrated modeling of multiple data sets is expected to help define areas of interest. Specific targeting (i.e. where to drill) will likely require some new definitions of geoscience infrastructure such as systematic seismic-MT transects and deep drilling for geological control and to feed-back into modeling. Economically the shortest returns could be realized if the means could be developed to target effectively in the areas classified now as “formational conductors” © Condor Consulting 2011 PDAC 2011 © Condor Consulting 2011 ASEG 2009 © Condor Consulting 2011 SEcG-I © Condor Consulting 2011 SEcG-II © Condor Consulting 2011 Way Ahead… © Condor Consulting 2011 Way Ahead… © Condor Consulting 2011