mineral exploration using modern remote sensing techniques by john l. berry john berry assocs. 5000...

Mineral Exploration Using Mineral Exploration Using Modern Remote Sensing Modern Remote Sensing

TechniquesTechniquesby

John L. Berry

John Berry Assocs.5000 Beverly Hills Dr.AUSTIN, TX 78731+1- 512 - 452 - [email protected]

ASTER DEM & Draped Image


Bands 1,2,3 Composite ASTER DEM ASTER DEM with Contours

Oblique View of Band 1,2,3 composite draped over DEM

Comparison of ASTER Bands (bottom) with TM bands Comparison of ASTER Bands (bottom) with TM bands (top). Note multiple narrow ASTER bands where TM (top). Note multiple narrow ASTER bands where TM has one broad band in SWIR and TIR.has one broad band in SWIR and TIR.


Landsat TM and ASTER SWIR Band Coverage of Clay Mineral Spectra. ASTER can resolve

Kaolinite, Alunite, Illite, etc..



Standard USGS reference spectra for Na-Sericite, K-sericite, phengite and Mg/Fe phengite in the SWIR region, showing the progressive shift of the absorption band position to longer wavelengths (left). The same spectra convolved to the ASTER band configuration showing the variation in the shape of the 2209 nm absorption band for the same minerals (right) (Courtesy AD, Inc., website)


Emissivity Spectra of Common Rocks showing shift in emissivity low from 8.6 um(ASTER Band 11) for granite to 10.7 um(ASTER Band 13) for dunite.

This shift forms the basis for using the thermal bands of ASTER to map lithology


ASTER Mineral Emissivity Spectra - Superimposed

0.800

0.900

1.000

1.100

10 11 12 13 14

ASTER Thermal IR Band No.

Em

iss

ivit

y.

Va

lue

1.0

at

8.3

mic

ron

s

Dunite

Kaolinite

Calcite

Muscovite

Albite

Quartz

Magnetite

Thermal emissivity spectra of some important minerals convolved with the ASTER thermal bands,superimposed on each other by normal-izing to a value of 1.0at 8.0 um (Band 10).

The spectral curvesdiffer even more than those for rocks. Thus alteration zones char-acterized by these minerals can be map-ped using ASTER TIR.


ASTER THERMAL Band 12 vs Band 13

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0.900

1.000

1.100

0.800 0.900 1.000 1.100Band 12

Ba

nd

13

Dunite

Kaolinite

Calcite

Muscovite

Albite

Quartz

Magnetite

Green

RedMinerals are widely separated on this plot, and would show up as green (Dunite) to orange (Albite) if Band 13 were assigned to Greeen and Band 12 to Red.


ASTER Thermal IR Mineral Signatures: Band 13/Band 14

Dunite

Calcite

Muscovite

KaoliniteMagnetite

Albite

Quartz

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0.900

1.000

1.100

1.200

0.800 0.900 1.000 1.100 1.200

Band 13

Ban

d 1

4

The linear distribution shows that there is a strong correlation between the emisssivity spectra of different minerals in bands 13 and 14, a phen-omenon that is also seen in the SWIR region, but for vegetation spectra.

This means that in an image, dunite(olivine) would be dark and quartz would be bright, but they would have the same color. This is therefore NOT a good band combination

Using ratio composites (next slide)helps to spread the data points out in color space, giving better discrimination


Ternary Diagram of ASTER Ratios 10/11, 12/13, 13/14

Calcite

Quartz

Albite

MagnetiteKaolin

Dunite

Muscovite

0.250

0.260

0.270

0.280

0.290

0.300

0.310

0.320

0.330

0.450 0.460 0.470 0.480 0.490 0.500 0.510 0.520 0.530

Ratio Band 13/Band 14

Rat

io B

and

12/B

and

13

This is actually an enlarged section of a ternary diagram,but Excel will not display it as such. It shows that good separation of the minerals in color space can be achieved using Thermal band ratios.

This image shows different ages of lava flow - the youngest being the whitest. The overall variation in the image is from red to green, with little blue: this reflects the linearity of the distribution of points on the previous slide. The N-S dark line on the east edge appears to be a fault in alluvium.

John Berry Assocs.5000 Beverly Hills Dr.AUSTIN, TX 78731+1- 512 - 452 - [email protected] Rift Valley Thermal image

Khoy Ophiolite, NW Iran.ASTER Bands 3,2,1 draped over DEM

Ophiolite nappes are at left



Bands 7,3,1, ASTER Composite

Khoy Area: 7-3-1 ASTER composite compared to Geological Map. Note the greater amount of detail on the image in the Ultramafics at lower left


3 NW-trending Nappes

Basalts

Ultramafic Rocks

Khoy

Tectonic Mélanges

Left: 7,3,1 Composite. Red Box outlines area of next 2 slides. Blue Box outlines the slide after that

Right: 4/7-3/4-2/1 Abram Band Ratio Composite



KHOY, IRAN: 7-3-1 Composite, showing Tectonic Windows and Related Folds



KHOY, IRAN:

ASTER Band Ratios, showing Tectonic winows and related Folds

E-MORB

OIB

Band Ratio 4/7-3/4-2/1

composite distinguishes Ocean Island Basalt (OIB)

from mid-Ocean Ridge (MORB) Basalt

mineral exploration using modern remote sensing techniques by john l. berry john berry assocs. 5000...

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