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
John Berry Assocs.5000 Beverly Hills Dr.AUSTIN, TX 78731+1- 512 - 452 - [email protected]
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.
John Berry Assocs.5000 Beverly Hills Dr.AUSTIN, TX 78731+1- 512 - 452 - [email protected]
Landsat TM and ASTER SWIR Band Coverage of Clay Mineral Spectra. ASTER can resolve
Kaolinite, Alunite, Illite, etc..
John Berry Assocs.5000 Beverly Hills Dr.AUSTIN, TX 78731+1- 512 - 452 - [email protected]
John Berry Assocs.5000 Beverly Hills Dr.AUSTIN, TX 78731+1- 512 - 452 - [email protected]
John Berry Assocs.5000 Beverly Hills Dr.AUSTIN, TX 78731+1- 512 - 452 - [email protected]
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)
John Berry Assocs.5000 Beverly Hills Dr.AUSTIN, TX 78731+1- 512 - 452 - [email protected]
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
John Berry Assocs.5000 Beverly Hills Dr.AUSTIN, TX 78731+1- 512 - 452 - [email protected]
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.
John Berry Assocs.5000 Beverly Hills Dr.AUSTIN, TX 78731+1- 512 - 452 - [email protected]
ASTER THERMAL Band 12 vs Band 13
0.800
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.
John Berry Assocs.5000 Beverly Hills Dr.AUSTIN, TX 78731+1- 512 - 452 - [email protected]
ASTER Thermal IR Mineral Signatures: Band 13/Band 14
Dunite
Calcite
Muscovite
KaoliniteMagnetite
Albite
Quartz
0.800
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
John Berry Assocs.5000 Beverly Hills Dr.AUSTIN, TX 78731+1- 512 - 452 - [email protected]
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
John Berry Assocs.5000 Beverly Hills Dr.AUSTIN, TX 78731+1- 512 - 452 - [email protected]
John Berry Assocs.5000 Beverly Hills Dr.AUSTIN, TX 78731+1- 512 - 452 - [email protected]
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
John Berry Assocs.5000 Beverly Hills Dr.AUSTIN, TX 78731+1- 512 - 452 - [email protected]
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
John Berry Assocs.5000 Beverly Hills Dr.AUSTIN, TX 78731+1- 512 - 452 - [email protected]
John Berry Assocs.5000 Beverly Hills Dr.AUSTIN, TX 78731+1- 512 - 452 - [email protected]
KHOY, IRAN: 7-3-1 Composite, showing Tectonic Windows and Related Folds
John Berry Assocs.5000 Beverly Hills Dr.AUSTIN, TX 78731+1- 512 - 452 - [email protected]
John Berry Assocs.5000 Beverly Hills Dr.AUSTIN, TX 78731+1- 512 - 452 - [email protected]
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