Spectral Geology

2 June 2009

Lecture series presented by the UWA Student Chapter

of the Society of Economic Geologists

Objective

• Asking the right questions!

• Mineral system analysis

• Integration with geophysical and geochemical data

To show how remote (airborne and satellite imagery) and

field/drill-core (e.g. ASD™, microFTIR™ and Hylogger™)

spectral data can be applied for exploration and research.

Outline9:00 - 9:15: Introduction to spectral geology and the available

technologies - Carsten Laukamp (CET)

9:15 - 10:00: Is spectral geology complementary to current geophysics? - Rob Hewson (CSIRO)

10:00 - 10:20: The application of ASTER and ASD data at Pataz Goldfields, Northern Peru - Wally Witt (CET)

10:20 - 10:35: Coffee break

10:35 - 11:20: Mine scale spectral geology - Ore characterisation using "HyLogging Systems” - Erick Ramanaidou (CSIRO)

11:20 - 12:05: 3D spectral geology - mineral systems, exploration targeting and C3DMM - Tom Cudahy (CSIRO)

12:05 - 12:30: QandA - led by SEG Student Chapter and Carsten Laukamp

Mineral Mapping Theory

Mineral Mapping Theory

Mineral Mapping Theory

Mineral Mapping Theory• Diagnostic absorption features of hydroxyl mineral groups in the SWIR

– Al(OH): 2170 - 2210 nm

•Topaz, Pyrophyllite, Kaolinite, Montmorillonite, Muscovite, Illite

– “Mg(OH)”: 2300 - 2400 nm•Chlorite, Talc, Epidote, Amphibole, Antigorite, Biotite, Phlogopite

– “Fe(OH)”: 2250 - 2300 nm•Jarosite, Nontronite,

Saponite, Hectorite

– Si(OH): 2240 nm (broad)•Opaline silica

Composition of Minerals

Muscovite

PhengitePhengite

(Mg,Fe)(Mg,Fe)octoct Si Sitettet = Al = Aloctoct Al Al tettet

From Scott and Yang, 1997

mineralminers.com/html/musmins.stm

Al, Fe, Mg, Cr, V

Si, Al

K, Na, Ca

octahedral

tetrahedral

interlayer

• white mica composition

• crystallinity of white micas or clay minerals

• Mg# of chlorites

• carbonate composition

• …

Spectral-Mineral Wavelength Regions

-12

13.5

39

64.5

90

115.5

0.35 0.85 1.35 1.85 2.35

-12

13.5

39

64.5

90

115.5

7.35 8.35 9.35 10.35 11.35 12.35

Electro-Magnetic Spectrum - Wavelength in Micrometer

Gro

und

Ref

lectanc

e (offse

t fo

r clarit

y)

Gro

und

Em

issivity (o

ffse

t fo

r clarit

y)

dark soil

green vegetation

green vegetation

dark soil

limestone

limestone

sandstone

sandstone

dry vegetationdry vegetation

ARGUS

Hymap

Aster

Landsat TM

From Peter Hausknecht

VNIR

iron oxidesREEs

vegetation

SWIR

OH-bearing hydroxyls(kaolin, chlorite, mica, amphibole)

sulphatescarbonates

Thermal Infrared

Non-OH-bearing silicates(quartz, feldspars, pyroxene, garnet)

sulphatescarbonates

Visible Near Infrared Short Wave Infrared

0.45

0.65

0.85

1.05

1.25

1.45

1.65

1.9 2.1 2.3 2.5

Wavelength (micrometer) =>

Laboratory

ARGUS / AVIRIS

HYMAP

ASTER

Landsat TM

Spectral Resolution

Available Technologies(examples)

• Field spectral devices:

• PIMA

• Fieldspec Pro

• TERRASPEC

• microFTIR

• Hylogger system:

• HyLogger™

• HyChips™

• TIR-Logger™

• Remote sensing devices:

• airborne (e.g.HyMap)

• satellite (e.g. ASTER)

Field Spectral DevicesAnayltical spectral devices (ASD, http://www.asdi.com)• Fieldspec Pro

•350-2500 nm•10 nm spectral

resolution @ SWIR •~AUD$100K

• TERRASPEC•More robust fibre•contact

TERRASPEC

Integrated Spectronics (ISPL, http://www.intspec.com)• PIMA (Portable Infrared Mineral Analyser)

• 1300-2500 nm• 8 nm resolution• contact• ~AUD$40K

Fieldspec Pro

Hylogging Suite• HyLogger™

• 0.4-2.5 m • FTIR (D&P)• diamond drill core logging• ~700m / day

• 1 cm line-profile footprint

• HyChips™• 0.4-2.5 m • ASD based• RAB/RC drill chip tray logging• 45 trays / hour (up to 3000 * 1 m samples p/d)

• TIR-Logger™• 2.5 -20 m• FTIR (D&P) • Diamond drill (and Chips)• ~700m / day • 1 cm line-profile footprint

Remote Sensing Spectral Devices

Airborne HyMap

Spectral Configuration – 128 channels

Module Spectral range Bandwidthacross module

Average spectralsampling interval

VIS 0.45 – 0.89 um 15 – 16 nm 15 nmNIR 0.89 – 1.35 um 15 – 16 nm 15 nm

SWIR1 1.40 – 1.80 um 15 – 16 nm 13 nmSWIR2 1.95 – 2.48 um 18 – 20 nm 17 nm

www.hyvista.com

• Australian sensor• Sydney-based• NASA-approved• high SNR• 126 bands• 0.4-2.5 m• 3-30 m pixel• 512 pixel swath• whiskbroom• fully calibrated

Airborne HyMapHyMap products delivered for the Qld Next Generation Mineral Mapping Project (excerpt) (http://www.em.csiro.au/NGMM/):

• Natural colour basemap;• False colour basemap; • Green vegetation content;• Dry vegetation content;• Iron oxide content;• Hematite/Goethite ratio;• Ferrous iron content; • Kaolin content;• Kaolin crystallinity;• Al-smectite content;• Al-smectite composition;• White mica (paragonite-muscovite-phengite)

content;• White mica composition;• White mica crystallinity;• MgOH (cc/dol/chl/ep/amph) content;• MgOH (cc/dol/chl/ep/amph) composition;• Ferric iron and MgOH;• Ferrous iron and MgOH;• Chlorite-Epidote content;• Epidote content;• Opaques;• Hydrated silica

false colour white mica composition

2190 nm

2215nmAl-rich Al-poor

5kmBlock H

ASTER

(Advanced Spaceborne Thermal Emission and Reflective Radiometer)

• “Next generation” geology-tuned satellite sensor:

• 14 spectral bands including 6 SWIR and 5 TIR geological bands (+ DEM)

• 15 m VNIR• 30 m SWIR• 90 m TIR

• Pushbroom for VNIR and SWIR

• Whiskbroom for TIR

• Significant Instrument/Data Issues• atmospheric correction, SWIR X-talk, TES

www.asterweb.jpl.nasa.govwww.science.aster.ersdac.or.jp

Software• TSG (the Spectral Geologist)

–Field and core spectra

• TSA (the Spectral Assistant)

• TSG-Core Distributed through Ausspec (www.ausspec.com)

• ENVI (Environment for Visualising Images) (www.ittvis.com)

–Hyperspectral images

–Field spectra

• ERMapper (www.ermapper.com)

–ASTER wizard

• CSIRO/HyVista Suite

–ASTER and hyperspectral multi-scene processing

• C-HyperMAP

• C-SatMAP

–IDL based

Outline9:00 - 9:15: Introduction to spectral geology and the available

technologies - Carsten Laukamp (CET)

9:15 - 10:00: Is spectral geology complementary to current geophysics? - Rob Hewson (CSIRO)

10:00 - 10:20: The application of ASTER and ASD data at Pataz Goldfields, Northern Peru - Wally Witt (CET)

10:20 - 10:35: Coffee break

10:35 - 11:20: Mine scale spectral geology - Ore characterisation using "HyLogging Systems” - Erick Ramanaidou (CSIRO)

11:20 - 12:05: 3D spectral geology - mineral systems, exploration targeting and C3DMM - Tom Cudahy (CSIRO)

12:05 - 12:30: QandA - led by SEG Student Chapter and Carsten Laukamp