Geological models Mineral Systems after Kelley et al 2006 Supergene regolith processes Hypogene source pathway depositional site outflow Contrasting physicochemical conditions ID: 1021506
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1. Alteration Spectral Mineral Models
2. Geological models – “Mineral Systems”after Kelley et al., 2006 Supergene : regolith processes Hypogene : source, pathway, depositional site, outflow Contrasting physicochemical conditions Large mineral alteration footprints Mineral-chemical gradients litho-geochemical modelling Asking the right questions2 |Alteration Spectral Mineral Models
3. TechnologiesGeoscience-tuned VIRS systemsProximal (hyperspectral)VNIR &/or SWIR: PIMA, FieldSpec/TerraSpec (ASD)handheld FTIRsDrill core: HyLogging (CSIRO, FLSmidth), HCI-3 (Corescan), HCIS (Terracore)3 |Alteration Spectral Mineral ModelsAirborne (hyperspectral)HyMap , HyVista corporation SEBASS , Aerospace CorporationCASI-SASI-MASI-TASI-TADI , ITRESaisaFENIX, aisaOWL, SpecimHySpex, Norsk Elektro OptikkSatellitesASTER , multispectral (launched 1999): 3 VNIR, 6 SWIR, 5 TIRHyperion, hyperspectral (launched 2001): VNIR/SWIRWorldView3, multispectral (launched 2013): 8 VNIR + 8 SWIRPlanned hyperspectral missions: HySpiri (launch > 2015); HISUI (launch > 2015); EnMap (launch > 2017)
4. Spectral resolutionB6B7B8B9a) High-resolution infrared reflectance spectra acquired with Bruker Vertex 70, down sampled to b) HyMap (airborne hyperspectral) and c) ASTER (satellite multispectral) resolution (band widths in grey; B5/B4 in colours). B4B5epidotebasalt + amphibole veinactinolite in calcsilicatetremoliteactinolitecummingtonitetalcbasalt + amphibole veinriebeckiteFe-chlorite2080D2390W2390Dc)b)a)Bruker Vertex 70HyMapASTERmultispectral: mineral groupshyperspectral: mineral species4 |Alteration Spectral Mineral Models
5. Mineral deposits in the Eastern Goldfields, Yilgarn Craton, Western AustraliaGeoscience Australia’spmd*CRC GOCAD modelEastern GoldfieldsEastern GoldfieldsproximaldistalArchaean Au alteration – Mafic/UM Rocks Komatiite associated Fe-Ni sulphide mineralisation Archean Au: structurally controlled syn-gold alteration (Neumayr et al., 2004) reduced pyrrhotite-biotite-amphibole, and oxidised plagioclase-carbonate-pyrite-magnetite-hematite-biotite-chlorite alteration > Au deposited at physicochemical gradientsMg#(modified after Huntington et al., 1999)Magnetite destruction (carbonation)5 |Alteration Spectral Mineral Models
6. Archean Au, Eastern Goldfields, WA – Terrane ScaleRemote SensingGeoscience Australia’spmd*CRC GOCAD modelEastern GoldfieldsBoulder-Lefroy faultSpeedway faultOckerburyfaultKunanalingfaultKanownafaultgranitesKambalda20 km6 |Alteration Spectral Mineral Models
7. Fe2+ ass. with in MgOHhighlowArchean Au, Eastern Goldfields, WA – Terrane ScaleRemote Sensing – Mapping mafic/um rocksSpeedway faultOckerburyfaultKunanalingfaultKanownafaultgranitesBoulder-Lefroy faultNote: open pits:North: phengitic white micasSouth: biotite7 |Alteration Spectral Mineral Models
8. Archean Au, Eastern Goldfields, WA – Camp ScaleRemote Sensing – Mapping mafic/um rocksFe2+ ass. with MgOHhighlowblack below threshold8 |Alteration Spectral Mineral Models
9. Archean Au, Eastern Goldfields, WA – Camp ScaleRemote Sensing, Tramways areaProt. DikeTramways area, imbricate thrust complexTMIMagnetite destruction, due to carbonation?9 |Alteration Spectral Mineral Models
10. Regional/camp scalelithology vs. alteration Fe2+ ass. with MgOHhighlowhighlowTalc-amphibole abundanceTMItalcFe-chlFe-amphiboletalcmodified after Murdie et al. (2010)Black Flag BedsParinga BasaltLunnon BasaltKambalda KomatiiteDevon Consols BasaltDefiance DoleriteProterozoic DykeMagnetite destruction, due to carbonation?10 |Alteration Spectral Mineral Models
11. Camp Scale: Drill Core Archean Au, Eastern Goldfields, WAAmphiboleTalc-AmphiboleCalcite-DolomiteMagnesiteDolomiteCalcite-DolomiteMagnesiteFe-ChlInt-ChlInt-ChlMg-rich to Intermed. ChloriteMg# --- varying amphibole compositions? ---- --- magnesite --- dolomite --- calcite ---Amphibole – Talc abundanceChlorite abundanceCarbonate abundanceFe2+ abundCarb compChl compdepth [m]Au [ppm]main ore zoneFault?proximaldistaldistalMagnetite destruction (carbonation)magnesitedolomitecalcitetalcFe-amphiboleMg-richFe-rich11 |Alteration Spectral Mineral Models
12. Iron-oxide copper-gold deposits (IOCG)IOCG modelP435 Project (1997)12 |Alteration Spectral Mineral Models
13. Alteration Spectral Mineral ModelsPorphyry-epithermal-skarnAlteration ZonationAlteration Zonation (mineralogy)ASTER Geoscience productsExoskarngarnet/pyroxeneMafic indexcalcite/dolomiteCarbonate index, Mafic indexEndoskarn - PorphyryPropyllitic (epidote/chlorite/amphibole)FeOH Group content, Ferrous iron in MgOH; MgOH group content; MgOH group compositionPhyllic (white mica)AlOH Group content, AlOH group compositionPotassic (ferrous silicates: biotite/chlorite/amphibole)Ferrous iron in MgOHEpithermalsilicicQuartz index; Silica index; Advanced Argillic: (alunite/pyrophyllite/kaolinite/dickite/mica)Kaolin indexferric oxides (hematite, goethite, jarosite) Ferric oxide content; ferric oxide composition; FeOH group content; ferrous index 13 |
14. Integrated analysis for mapping and mineralisation+ geochemistry14 |Alteration Spectral Mineral Models
15. Alteration Spectral Mineral ModelsExercise 1Exercise 1: Based on the given reflectance spectra interpret the mineralogy of samples using the USGS library (Appendix 2)Five of the samples stacked in order of their location along a transect. > What can be said about the alteration facies shown by these minerals, including alteration zonation (annotate of the figure) and likely style of mineralisation (see Appendix 1)?Annotate Figures!15 |
16. Thank youCSIRO Mineral ResourcesCarsten LaukampSenior Research Geoscientistt +61 8 6436 8754e carsten.laukamp@csiro.auw http://c3dmm.csiro.au/