12 tunjic minsys gold exploration

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Mineral Systems & Gold Exploration Outline of talk   Exploration Success- examples   Phoenix Gold probability analysis test case Relevance to exploration targeting at different scales Current state of play for exploration industry? Janet Tunjic Exploration Success using Mineral Systems Concepts Deposit scale target identified in a mature well explored camp by incorporating mineral system concepts Critical Concepts • Structural architecture (particularly influence of early growth faults) (J Miller & R Blewett) • Role of an intrusion to the south of the deposit as a possible source/heat/fluids? (S Halley) • • Chemistry of different basalts and preference for hosting gold deposits Fluid migration and redox depositional environments (J Walshe & S Halley) HAMLET DEPOSIT from Neumayr et al., 2008 >1Moz deposit discovered Success in Applying Mineral Systems Concepts -Prediction through to Discovery Camp scale target identified in a poorly explored region of the West African craton with extremely sparse data (identified for possible acquisition) Critical Concepts • What are the “fundamental building blocks” of the craton (J Hronsky & G Begg)? • • • • • Where are the mantle tapping structures? How does this all fit together (Jon Claoue-Long)? Needed to construct a layer of greenstone belts? Investigated alteration patterns through ASTER? Integrated into a prospectivity analysis Identified Mineralised Position Before Discovery Success in Applying Mineral Systems Concepts From -Prediction Through to Discovery Fekola Deposit Fekola Deposit Regional Geology, Gold Deposits Rand Gold Boron soil anomalies Source latest Papillion Resources website Source Rand Gold annual report >3Moz deposit discovered (and growing) Success in Applying Mineral Systems Concepts -Prediction Through to Discovery Camp scale target identified in the Yilgarn (potential acquisitions) Critical Concepts • • • • • • Architecture and where were the mantle tapping structures? Folds and granite cored domes Defined anomalism in magnetic and gravity data? Fluids/alteration through ASTER? Influence of intrusions? Integrated into a prospectivity analysis Mineralised System Predicted and Subsequently Discovered Mineral System Models Source Jon Hronsky http://www.wesminllc.com/cms assets/documents/34704-560500.gsa-talksep2010-compatibilitymode.pdf http://www.ga.gov.au/webtemp/image_cache/GA16579.pdf Fluid centric gold mineralisation models of Jon Hronsky & Steven Cox Geodynamics: Application to Exploration From an explorers perspective • Thinking about an area as a collection of individual components and how they interact • • Youngest domains host most of the gold Understanding of stratigraphy/structure, granites also important Literature Compilation of Age Dating for Ghana - 2009 D2 D3 NW-SE Comp NNW-SSE Comp Eburnean Orog Sinistral Slip (2090 – 2075 Ma) Au (~2060Ma) 14 Au (~2100Ma) 12 10 Gold Mineralisation Orogenic Tarkwa reef mineralisation Hydrothermal Gold Hydrothermal Gold (2122- 2099Ma) (2070- 2034Ma) Paleoplacer Gold Ashanti Belt Tarkwain Seds Birimian Sed/volcanics Kumasi granitoids Sefwi Belt Rhyolite Granite suite Bui Belt Granitoid Cape Coast Granites (2120- 2050Ma) 2300 2250 2200 2150 2100 2050 2000 1950 1900 Cape Coast Granite 2090 – 2075 Ma NW-SE Compression Kib i Be lt Be lt an ti As h Ku m as iB as in Se fw i Be lt Eburnean Orogeny Kumasi Intrusive Activity Dating of samples 2090-2075Ma New Discoveries in the Kumasi Basin 2070 – 2034 Ma NNW-SSE Compression Sinistral Strike Slip D3 Au Mineralization Dating of samples 2070-2034Ma Ashanti belt - explored - 116Moz discovered Kibi-Winneba belt - Underexplored 0.5Moz discovered recently Metamorphic Facies with Au Showings- Abitibi Source Flood Consulting Gold preferentially found at greenschist-sub-greenschist boundary and greenschist-low amphibolite boundary Detail from “Metamorphic Map of the Canadian Shield” GSC Map 1475A Phoenix Gold - Test Case Mineral systems and prospectivity mapping for Broads Dam Tenements Process: • Define data sets that are best proxies for mineral system components • • Broads Dam Tenements Location Map Evaluate correlations statistically Integrate layers with best correlations Metamorphism, source of reduced fluids, structural weakness… Broads Dam Tenements • • • • • • Outline of interpreted extent of M3a thermal anomaly (pre main gold event) Strong correlation to gold deposits Edge of Kurrawang basin- source of reduced fluids Increased permeability and fluid flow Weakened crustal region Abundance of N/S trending structures which are incredibly important for localising gold are located preferentially within this domain Source Ben Goscombe Depositional Environment: Redox Gradients Oxidised fluids • • Mo & Bi geochemistry Mag anomalies Reduced Fluids • • As and Sb Edge of Kurrawang basin Fluids/Alteration/Intrusions Broads Dam Tenements • • • • • • Gradients are important Strong correlation to gold deposits Mapping potassic alteration Lithology Fluid movement Intrusions Final Probability Map for Broads Dam Area Final map, 15 layers incorporated …not just structure! • Data layers were proxies for mineral system components Probability Map • Predicted the spatial position of known deposits • Identify targets , currently being drilled Mineral Exploration Expenditure Australia 2013 Better indication is the amount of exploration geologists recently retrenched Explorers have been remarkably unsuccessful at discovering new deposits in Australia Why would investors want to give their money to explorers? http://www.abs.gov.au/ausstats/abs@.nsf/mf/8412.0 Are we Doing Anything Different to Paddy’s Exploration Methods? Tried and tested methods of testing gold soil anomalies, stream sediment sampling and stumbling across outcrop deposits are great exploration tools but not the only tools available There is a overwhelming need to change and be smarter, more cost efficient, more reliable…mineral systems! Drowning in Data? Modern day explorers are required to effectively analyse multiple datasets and identify map patterns critical for predicting mineralisation: • e.g gravity, magnetics, IP, AEM, worms, geology, structure, folding, domes, spectra, metamorphic maps, redox gradients, DEM, alteration haloes, regolith maps, porphyry composition, mineralogy, ASTER, HYMAP, geomorphology, basaltic compositions, tomographic data, seismic, MT, alteration geochemistry, whole rock geochemistry, till geochemistry • And derivatives of these datasets Applying Conceptual Mineral System Thinking to Exploration Finds Deposits Knowledge and Systems Thinking • Provides the explorer with a means of understanding the enormous data as proxies for processes that formed deposits Creativity • Explorer have a framework to work within but still be creative Open Mind • Opens the search space to new possibilities beyond existing dogma Take Home Messages • • • • • Applying mineral systems concepts to exploration finds deposits Challenging existing biases by engaging with academics and consultants is a good thing Use data/concepts creatively We don’t have a very good discovery success rate, support research and be more innovative! Important for researchers to disseminate new findings to the wider community Thank you Janet Tunjic Principal Geologist Optiro JTunjic@Optiro.com [...]... Better indication is the amount of exploration geologists recently retrenched Explorers have been remarkably unsuccessful at discovering new deposits in Australia Why would investors want to give their money to explorers? http://www.abs.gov.au/ausstats/abs@.nsf/mf/8 412. 0 Are we Doing Anything Different to Paddy’s Exploration Methods? Tried and tested methods of testing gold soil anomalies, stream sediment... Tenements • • • • • • Outline of interpreted extent of M3a thermal anomaly (pre main gold event) Strong correlation to gold deposits Edge of Kurrawang basin- source of reduced fluids Increased permeability and fluid flow Weakened crustal region Abundance of N/S trending structures which are incredibly important for localising gold are located preferentially within this domain Source Ben Goscombe Depositional... important Strong correlation to gold deposits Mapping potassic alteration Lithology Fluid movement Intrusions Final Probability Map for Broads Dam Area Final map, 15 layers incorporated …not just structure! • Data layers were proxies for mineral system components Probability Map • Predicted the spatial position of known deposits • Identify 3 targets , currently being drilled Mineral Exploration Expenditure...Metamorphic Facies with Au Showings- Abitibi Source Flood Consulting Gold preferentially found at greenschist-sub-greenschist boundary and greenschist-low amphibolite boundary Detail from “Metamorphic Map of the Canadian Shield” GSC Map 1475A Phoenix Gold - Test Case Mineral systems and prospectivity mapping for Broads Dam Tenements Process: • Define data sets... to Exploration Finds Deposits Knowledge and Systems Thinking • Provides the explorer with a means of understanding the enormous data as proxies for processes that formed deposits Creativity • Explorer have a framework to work within but still be creative Open Mind • Opens the search space to new possibilities beyond existing dogma Take Home Messages • • • • • Applying mineral systems concepts to exploration. .. We don’t have a very good discovery success rate, support research and be more innovative! Important for researchers to disseminate new findings to the wider community Thank you Janet Tunjic Principal Geologist Optiro JTunjic@Optiro.com ... http://www.abs.gov.au/ausstats/abs@.nsf/mf/8 412. 0 Are we Doing Anything Different to Paddy’s Exploration Methods? Tried and tested methods of testing gold soil anomalies, stream sediment sampling and stumbling across outcrop deposits are great exploration tools but not the only tools available There is a overwhelming need to change and be smarter, more cost efficient, more reliable…mineral systems! Drowning in Data? Modern day explorers are
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