Application of hyperspectral data for assessing 3D lithological and alteration architecture of porphyry Cu-Au systems
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This document discusses the application of hyperspectral data in assessing the 3D lithological and alteration architecture of porphyry Cu-Au systems. It emphasizes the importance of collecting and processing data to identify anomalies and validate findings through mineralogical variability and spatial plotting. Challenges with current methods, including limitations of the hylogger and the need for broader-scale datasets, are acknowledged as critical areas for further exploration and validation.
Application of hyperspectral data for assessing 3D lithological and alteration architecture of porphyry Cu-Au systems
- 1. Application of hyperspectral data for assessing 3D lithological and alteration architecture of porphyry Cu-Au systems Jamie Robinson David Tilley, Charlotte Barry, Peter Downes, John Greenfield, Joel Fitzherbert and Phil Blevin
- 2. This work is part of the surveys efforts to develop training or system type characterisation datasets We want to get to a point where we can develop spatial vectors into systems • To do this, how we collect and process our data is very important • Need to break-up/domain data to isolate variables Need to be able to identify ‘anomaly’ from ‘background’ • Nymagee type system the transition from background into the alteration system is over scales of tens of metres • For Cargo, we are not seeing the edge of the system. The transition is likely to be over kilometres or tens of kilometres Need broader-regional scale datasets. How? • As well as drill core/chips, hyloggerTM can scan slabs/rock samples
- 3. We need to move from looking at hyperspectral logged drill holes in isolation, and start to look at mineralogical variability over mineral system scale, rather than the drill hole scale Even in simple systems you cannot directly plot meaningful system scale spatial mineralogy
- 4. Projects aim to fill the gap between hyperspectral data collection and exploration outcomes ? How do we take the raw data, process, validate and provide an outcome which has significant system vectoring application?
- 5. Limitations of Hylogger that need to be recognised to examine the data: • The hylogger outputs mineral point count data • Recognition of minerals within the core can be affected by: • Grain size • Grain orientation • Mineral colour/reflectivity • The output point count data is based on matching spectral signatures of scanned points against signatures in the TSG library • Current work only based on shortwave infrared (clays, phyllosilicates, amphiboles, sulphates, carbonates).
- 6. Downes et al in review Strongly shoot controlled Cu within a NNW trending fault zone Metamorphosed clay-rich • Quartz–muscovite/illite • Minor scattered plagioclase & chlorite • Trace K-feldspar Quartzo-feldspathic • quartz–muscovite- plagioclase • minor chlorite • trace K-feldspar white mica feldspar Fe-chlorite Mg-chlorite sulfides (aspectral) & Fe-oxide quartz The margins of the alteration system are clearly observed across strike MelroseMelroseMelroseMelroseMelroseMelroseMelroseMelroseMelrose TroughTroughTroughTroughTroughTroughTroughTroughTrough RastRastRastRastRastRastRastRastRast TroughTroughTroughTroughTroughTroughTroughTroughTrough Canbelego - MineralCanbelego - MineralCanbelego - MineralCanbelego - MineralCanbelego - MineralCanbelego - MineralCanbelego - MineralCanbelego - MineralCanbelego - Mineral Hill Rift ZoneHill Rift ZoneHill Rift ZoneHill Rift ZoneHill Rift ZoneHill Rift ZoneHill Rift ZoneHill Rift ZoneHill Rift Zone Mount HopeMount HopeMount HopeMount HopeMount HopeMount HopeMount HopeMount HopeMount Hope TroughTroughTroughTroughTroughTroughTroughTroughTrough Winduck ShelfWinduck ShelfWinduck ShelfWinduck ShelfWinduck ShelfWinduck ShelfWinduck ShelfWinduck ShelfWinduck Shelf WaltersWaltersWaltersWaltersWaltersWaltersWaltersWaltersWalters RangeRangeRangeRangeRangeRangeRangeRangeRange ShelfShelfShelfShelfShelfShelfShelfShelfShelf Wiiltagoona ShelfWiiltagoona ShelfWiiltagoona ShelfWiiltagoona ShelfWiiltagoona ShelfWiiltagoona ShelfWiiltagoona ShelfWiiltagoona ShelfWiiltagoona Shelf Kopyje ShelfKopyje ShelfKopyje ShelfKopyje ShelfKopyje ShelfKopyje ShelfKopyje ShelfKopyje ShelfKopyje Shelf Winduck ShelfWinduck ShelfWinduck ShelfWinduck ShelfWinduck ShelfWinduck ShelfWinduck ShelfWinduck ShelfWinduck Shelf Cobar TroughCobar TroughCobar TroughCobar TroughCobar TroughCobar TroughCobar TroughCobar TroughCobar Trough Winduck ShelfWinduck ShelfWinduck ShelfWinduck ShelfWinduck ShelfWinduck ShelfWinduck ShelfWinduck ShelfWinduck Shelf Beloura Tank Boomerang Tank Kilparney Mountain dam White Tank Rookery Booth Blue Mountain Stoney Tank Elura Lerrida McKinnons Tank Kirry Wiralong Lillvale Mineral HillMineral HillMineral HillMineral HillMineral HillMineral HillMineral HillMineral HillMineral Hill Tallebung MineTallebung MineTallebung MineTallebung MineTallebung MineTallebung MineTallebung MineTallebung MineTallebung Mine Girilambone MineGirilambone MineGirilambone MineGirilambone MineGirilambone MineGirilambone MineGirilambone MineGirilambone MineGirilambone Mine TrittonTrittonTrittonTrittonTrittonTrittonTrittonTrittonTritton Pipeline RidgePipeline RidgePipeline RidgePipeline RidgePipeline RidgePipeline RidgePipeline RidgePipeline RidgePipeline Ridge Nymagee Copper MineNymagee Copper MineNymagee Copper MineNymagee Copper MineNymagee Copper MineNymagee Copper MineNymagee Copper MineNymagee Copper MineNymagee Copper Mine Mt BoppyMineMt BoppyMineMt BoppyMineMt BoppyMineMt BoppyMineMt BoppyMineMt BoppyMineMt BoppyMineMt BoppyMine Nymagee - HeraNymagee - HeraNymagee - HeraNymagee - HeraNymagee - HeraNymagee - HeraNymagee - HeraNymagee - HeraNymagee - Hera New OccidentalNew OccidentalNew OccidentalNew OccidentalNew OccidentalNew OccidentalNew OccidentalNew OccidentalNew Occidental PeakMinePeakMinePeakMinePeakMinePeakMinePeakMinePeakMinePeakMinePeakMine PerseverancePerseverancePerseverancePerseverancePerseverancePerseverancePerseverancePerseverancePerseverance WonawintaWonawintaWonawintaWonawintaWonawintaWonawintaWonawintaWonawintaWonawinta GilgunniaGilgunniaGilgunniaGilgunniaGilgunniaGilgunniaGilgunniaGilgunniaGilgunnia GoldfieldsGoldfieldsGoldfieldsGoldfieldsGoldfieldsGoldfieldsGoldfieldsGoldfieldsGoldfields ShutteltonShutteltonShutteltonShutteltonShutteltonShutteltonShutteltonShutteltonShuttelton MayDayMayDayMayDayMayDayMayDayMayDayMayDayMayDayMayDay Great CobarGreat CobarGreat CobarGreat CobarGreat CobarGreat CobarGreat CobarGreat CobarGreat Cobar CSA MineCSA MineCSA MineCSA MineCSA MineCSA MineCSA MineCSA MineCSA Mine CnesneyCnesneyCnesneyCnesneyCnesneyCnesneyCnesneyCnesneyCnesney New CobarNew CobarNew CobarNew CobarNew CobarNew CobarNew CobarNew CobarNew Cobar Mt HopeMt HopeMt HopeMt HopeMt HopeMt HopeMt HopeMt HopeMt Hope Mt Allen MineMt Allen MineMt Allen MineMt Allen MineMt Allen MineMt Allen MineMt Allen MineMt Allen MineMt Allen MineWagga TankWagga TankWagga TankWagga TankWagga TankWagga TankWagga TankWagga TankWagga Tank EluraEluraEluraEluraEluraEluraEluraEluraElura Mc KinnonsMc KinnonsMc KinnonsMc KinnonsMc KinnonsMc KinnonsMc KinnonsMc KinnonsMc Kinnons TankTankTankTankTankTankTankTankTank COBARCOBARCOBARCOBARCOBARCOBARCOBARCOBARCOBAR 0km 50km RookeryFault Nymage Fault Sandy Creek Fault Gilmorelinament W agga -Nym agee Structu re WoonarraFault RookeryFault Plug Tank F AmphitheatreFault JackermarooFault BuckwaroonFault CoonaraFault COBAR SUPERBASIN Simplified Geology and Mineral Deposits David 2007 Cobar Sydney
- 7. = mineralised zone Fe-chlorite Mg-chlorite NMD053W1 NMD047 Transition from Fe to Mg chlorite proximal to mineralised zone Consistent finding of broader Cobar-Nymagee Alteration study Spatial plotting Fe and Mg chlorite should recognise a gradient within the plane of the host structural zone. Potential vector towards mineralisation within the plane of the host structural zone Downes et al. in review Downes et al in review
- 8. Much greater alteration complexity associated with Porphyry Cu-Au systems: • Alteration over broader scales • Superposition of assemblages • Prograde and retrograde assemblages • Broader range of pre-, syn and post mineralisation lithologies Holliday & Cooke 2007 Cadia Orange Bathurst Cargo Cadia Bathurst 250k MetalogenicSimplifiedgeology – Downes et al 2013 Orange Bathurst Orange Sydney
- 9. Stage 1: Translating and simplifying logging code system Stage 2: Data domained by lithology and spatial variability of mineralogy examined between holes evaluated Stage 3: 1st pass point data interpolation 16 holes scanned with Hylogger
- 10. Translating and simplifying logging code system Combination of translating codes to GSNSW system where textural qualifiers separated from basic lithology code & checking the logged lithology against spectral signature e.g. 4 textural variations of andesite merged to one (with textural qualifier)
- 11. Numeric data domained by lithology and drillhole Data does not extend to or beyond the edge of the system to estimate background but clear trends exist in the data Part of argillic or phyllic assemblage as per Leach 2008Part of Potassic assemblage as per Leach 2008Part of propylitic assemblage as per Leach 2008
- 12. Why the difference? • Hylogger data needs validation using petrography and xrd • Possible some biotite variants not recognised in hylogger data & spectral library needs update • Biotite may be fine grained or misoriented relative to the scanner • Biotite may be overestimated in logs • Biotite may be retrogressing (to Mg Chlorite?) Note: All current interpolation given identical elipsoid constrains for first pass comparison First pass anisotropic interpolations Visually Logged biotite within holes scanned Hylogged data Interpolated biotite-phlogopite
- 13. Example: Spatial variation in Fe and Mg Chlorite • As observed in 2D plots of domained data, Fe and Mg chlorite • Mg chlorite appears spatially related to copper, Fe chlorite occurs on margins • Margins of system are not constrained by current scanned drillholes
- 14. The Nymagee study demonstrated in a relatively simple system that the background metamorphic mineralogy can be separated from alteration mineralogy Increased Mg chlorite relative to Fe chlorite could be used as an indicator of proximity to mineralisation In the more complex porphyry systems we need to domain data to better isolate mineral gradients However, there are trends in the hylogger data that can be recognised at this early stage
- 15. Validation of observations in first pass analysis (petrography & XRD) Use thermal Infrared data Characterisation of plagioclase Determination of alteration vs magmatic K feldspar How does the observed alteration relationship compare to magnetic susceptibility? Re-evaluate methods and relationships in other systems