Alteration Spectral Mineral Models Geological models Mineral Systems

Alteration Spectral Mineral Models

Geological models – “Mineral Systems” • 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 questions after Kelley et al. , 2006 2 | Alteration Spectral Mineral Models

Technologies Geoscience-tuned VIRS systems Proximal (hyperspectral) VNIR &/or SWIR: PIMA, Field. Spec/Terra. Spec (ASD) handheld FTIRs Drill core: Hy. Logging (CSIRO, FLSmidth), HCI-3 (Corescan), HCIS (Terracore) Airborne (hyperspectral) Hy. Map , Hy. Vista corporation SEBASS , Aerospace Corporation CASI-SASI-MASI-TADI , ITRES aisa. FENIX, aisa. OWL, Specim Hy. Spex, Norsk Elektro Optikk Satellites ASTER , multispectral (launched 1999): 3 VNIR, 6 SWIR, 5 TIR Hyperion, hyperspectral (launched 2001): VNIR/SWIR World. View 3, multispectral (launched 2013): 8 VNIR + 8 SWIR Planned hyperspectral missions: Hy. Spiri (launch > 2015); HISUI (launch > 2015); En. Map (launch > 2017) 3 | Alteration Spectral Mineral Models

Spectral resolution multispectral: mineral groups hyperspectral: mineral species Bruker Vertex 70 Hy. Map ASTER B 4 a) b) B 5 B 7 B 9 B 6 B 8 c) riebeckite Fe-chlorite epidote basalt + amphibole vein actinolite in calcsilicate basalt + amphibole vein tremolite actinolite cummingtonite 2080 D 2390 D talc 2390 W 4 a) High-resolution infrared reflectance spectra acquired with Bruker Vertex 70, down sampled to b) Hy. Map (airborne hyperspectral) and c) ASTER (satellite multispectral) resolution (band widths in grey; B 5/B 4 in colours). | Alteration Spectral Mineral Models

Mineral deposits in the Eastern Goldfields, Yilgarn Craton, Western Australia • Komatiite associated Fe-Ni sulphide mineralisation • Archean Au: Geoscience Australia’s • structurally controlled pmd*CRC GOCAD model • syn-gold alteration (Neumayr et al. , 2004) Eastern Goldfields • reduced pyrrhotite-biotite-amphibole, and • oxidised plagioclase-carbonate-pyrite-magnetitehematite-biotite-chlorite alteration > Au deposited at physicochemical gradients Eastern Goldfields Archaean Au alteration – Mafic/UM Rocks Magnetite destruction (carbonation) Mg# distal 5 | Alteration Spectral Mineral Models proximal (modified after Huntington et al. , 1999)

Archean Au, Eastern Goldfields, WA – Terrane Scale Remote Sensing Geoscience Australia’s pmd*CRC GOCAD model Eastern Goldfields Kanowna fault Kambalda Ockerbury fault granites Kunanaling fault 20 km Speedway fault 6 | Alteration Spectral Mineral Models Boulder-Lefroy fault

Archean Au, Eastern Goldfields, WA – Terrane Scale Remote Sensing – Mapping mafic/um rocks Kanowna fault Fe 2+ ass. with in Mg. OH low Note: open pits: North: phengitic white micas high South: biotite Ockerbury fault granites Kunanaling fault Speedway fault 7 | Alteration Spectral Mineral Models Boulder-Lefroy fault

Archean Au, Eastern Goldfields, WA – Camp Scale Remote Sensing – Mapping mafic/um rocks Fe 2+ ass. with Mg. OH low black below threshold 8 | Alteration Spectral Mineral Models high

Archean Au, Eastern Goldfields, WA – Camp Scale Remote Sensing, Tramways area Prot. Dike Tramways area, imbricate thrust complex Magnetite destruction, due to carbonation? TMI 9 | Alteration Spectral Mineral Models

Regional/camp scale Proterozoic Dyke Paringa Basalt Defiance Dolerite Lunnon lithology vs. alteration Black Flag Beds Devon Consols Basalt Kambalda Komatiite Basalt low high talc Fe 2+ ass. with Mg. OH Fe-amphibole Magnetite destruction, due to carbonation? low TMI 10 | Alteration Spectral Mineral Models Fe-chl high Talc-amphibole abundance modified after Murdie et al. (2010) talc

Au [ppm] Fault? Camp Scale: Drill Core Archean Au, Eastern Goldfields, WA main ore zone --- varying amphibole compositions? ---Magnetite destruction (carbonation) --- magnesite --- dolomite --- calcite --- Mg# Int-Chl Fe-Chl comp Int-Chl Chlorite abundance Mg-rich to Intermed. Chlorite Fe-rich Carbonate abundance Mg-rich Carb comp Calcite. Dolomite calcite Magnesite Dolomite Calcite. Dolomite dolomite Magnesite Amphibole – Talc abundance magnesite Fe 2+ abund Fe-amphibole Amphibole Talc-Amphibole distal 11 | Alteration Spectral Mineral Models proximal distal talc depth [m]

Iron-oxide copper-gold deposits (IOCG) IOCG model P 435 Project (1997) 12 | Alteration Spectral Mineral Models

Porphyry-epithermal-skarn Alteration Zonation (mineralogy) ASTER Geoscience products Exoskarn garnet/pyroxene Mafic index calcite/dolomite Carbonate index, Mafic index Propyllitic (epidote/chlorite/amphibole) Fe. OH Group content, Ferrous iron in Mg. OH; Mg. OH group content; Mg. OH group composition Phyllic (white mica) Al. OH Group content, Al. OH group composition Potassic (ferrous silicates: biotite/chlorite/amphibole) Ferrous iron in Mg. OH Endoskarn Porphyry Epithermal silicic Quartz index; Silica index; Advanced Argillic: (alunite/pyrophyllite/kaolinite/dickite/ mica) Kaolin index ferric oxides (hematite, goethite, jarosite) Ferric oxide content; ferric oxide composition; Fe. OH group content; ferrous index 13 | Alteration Spectral Mineral Models

Integrated analysis for mapping and mineralisation + geochemistry 14 | Alteration Spectral Mineral Models

Exercise 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)? igures! F Annotate 15 | Alteration Spectral Mineral Models

Thank you CSIRO Mineral Resources Carsten Laukamp Senior Research Geoscientist t +61 8 6436 8754 e carsten. laukamp@csiro. au w http: //c 3 dmm. csiro. au/