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Hyperspectral remote sensing of evaporate minerals and associated sediments in Lake Magadi area, Kenya |
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| Authors: | Gayantha RL Kodikara Tsehaie WoldaiFrank JA van Ruitenbeek Zack KuriaFreek van der Meer Keith D ShepherdGJ van Hummel |
| Institution: | a Department of Oceanography and Marine Geology, Faculty of Fisheries & Marine Science and Technology, University of Ruhuna, Sri Lanka b University of Twente, Faculty of Geo-information Science and Earth Observation (ITC), Hengelosesestraat 99, P.O. Box 6, 7500AA Enschede, The Netherlands c Department of Geology, University of Nairobi, Nairobi, Kenya d World Agroforestry Centre (ICRAF), P.O. Box 30677-00100, Nairobi, Kenya e Institute for Nanotechnology (MESA+), University of Twente, The Netherlands |
| Abstract: | Pleistocene to present evaporitic lacustrine sediments in Lake Magadi, East African Rift Valley, Kenya were studied and mapped using spectral remote sensing methods. This approach incorporated surface mineral mapping using space-borne hyperspectral Hyperion imagery together with laboratory analysis, including visible, near-infrared diffuse reflectance spectroscopy (VNIR) measurements and X-ray diffraction for selected rock and soil samples of the study area. The spectral signatures of Magadiite and Kenyaite, which have not been previously reported, were established and the spectral signatures of trona, chert series, volcanic tuff and the High Magadi bed were also analyzed.Image processing techniques, MNF (Minimum Noise Fraction) and MTMF (Mixture Tuned Matched Filtering) using a stratified approach (image analysis with and without the lake area), were used to enhance the mapping of evaporates. High Magadi beds, chert series and volcanic tuff were identified from the Hyperion image with an overall mapping accuracy of 84.3%. Even though, the spatial distribution of evaporites and sediments in Lake Magadi area change in response to climate variations, the mineralogy of this area has not been mapped recently. The results of this study shows the usefulness of the hypersspectral remote sensing to map the surface geology of this kind of environment and to locate promising sites for industrial open-pit trona mining in a qualitative and quantitative manner. |
| Keywords: | Hyperion Lake Magadi MTMF Surface mineral mapping Magadiite Kenyaite |
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