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|Title: ||MAPPING HYDROTHERMALLY ALTERED ROCKS AND LINEAMENT ANALYSIS THROUGH DIGITAL ENHANCEMENT OF ASTER DATA CASE STUDY: KEMASHI AREA, WESTERN ETHIOPIA|
|Authors: ||ABERA, FANTAYE WELDEMARIAM|
|Advisors: ||Dr. Dagnachew Legesse|
digital elevation model
|Copyright: ||Jul-2009 |
|Date Added: ||3-May-2012 |
|Abstract: ||Hydrothermal alteration, structure and geology of the Kemashi area, western Ethiopia
have been studied by means of remote sensing techniques and limited field data.
Advanced Spaceborn Thermal Emission and Reflection Radiometer (ASTER) reflectance
data have been processed and interpreted with the production of geological map,
lineament map and some hydrothermal alteration minerals abundance maps at a scale
Statistically selected and enhanced 3-bands color composite image of raw ASTER data
and images resulted from principal component transformation (PCA) produced
substantial spectral contrast between different lithology and enable to interpret the
Spatial enhancement of ASTER data using convolution filters and digital elevation
model (DEM) extracted from the Shuttle Radar Topographic Mission (SRTM) have been
used for lineament manual extraction. Hill-shading techniques are applied to SRTM
DEMs to enhance terrain perspective views and to extract morphologically defined
structures. Foliations, folds, different set of fractures are major structural elements
recognized from the image processing and hill-shading techniques.
For regional mapping of some hydrothermal alteration minerals “Feature oriented
Principal Component Analysis (FPCA)” and band rationing and threshold image
processing methods were applied. For both methods application subset of the ASTER
bands were selected according to the position of characteristics spectral features of the
alteration minerals in the VNIR and SWIR portion of the spectrum.
Hydrothermal alteration in the study area mainly consist argillic-altered rocks and iron
oxide/hydroxide altered rocks and mapped across various lithologic units.
The overall result of this study demonstrates the usefulness of remote sensing method
and ASTER multi-spectral data for alteration, structure and lithologic mapping.|
|Appears in:||Thesis - Earth Sciences|
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