Mapping evaporite minerals and associated sediments in Lake Magadi, Kenya, using Hyperspectral Hyperion data

Gayantha R.L. Kodikara, Tsehaie Woldai, Frank J.A. van Ruitenbeek, Zack Kuria, Freek van der Meer, Keith D. Shepherd, G.J. van Hummel

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Abstract

Pleistocene to present evaporitic lacustrine sediments in Lake Magadi, eastern branch of East African Rift Valley, Kenya was mapped by using space-borne hyperspectral Hyperion image. Mapping was coupled with laboratory analysis, including visible, near-infrared diffuse reflectance spectroscopy (VNIR) measurements & X-ray diffraction for selected rock and soil samples that were collected in
field. The spectral responses of 92 rock and soil samples were studied and identified including the spectral signatures of Magadiite and Kenyaite, which have not been previously reported from the Lake Magadi, Kenya, were established in this research. In addition to that, spectral signatures of trona, chert series, volcanic tuff and High Magadi bed were studied and identified.
Mapping of evaporite series, High Magadi beds, chert series, volcanic tuff and high vegetation using Hyperion image facilitated by different types of mapping techniques including MNF (Minimum Noise Fraction) and MTMF(Mixture Tuned Matched Filtering) with stratified approach (Image analysis with and without lake area) substantially improved the existing knowledge of the geology of the area. Although, all the ground mineralogy that was identified by reflectance spectra could not be mapped according to the spectral resolution of the image, spectral resolution of diagnostic absorption feature of the field reflectance spectra, noise of the image, spatial extend of ground target, spatial resolution of the image and accuracy of image prepossessing stages, we came up our image classification with overall accuracy of 84.3%. The producer accuracies of trona, High Magadi bed and the chert were reasonably high satisfying the primary purpose of this research concluding that the mapping capability of evaporite minerals and associated sediments in lacustrine environment using space-borne remote sensing techniques. The mapping output can be used successfully to understand the recent geologic history and to assist in locating promising sites for industrial open-pit mine in a qualitative and quantitative manner.
Original languageEnglish
Number of pages16
Publication statusPublished - 2010
Event7th Academic Session University of Ruhuna 2010 - Matara, Sri Lanka
Duration: 18 Mar 201018 Mar 2010
Conference number: 7

Conference

Conference7th Academic Session University of Ruhuna 2010
Country/TerritorySri Lanka
CityMatara
Period18/03/1018/03/10

Keywords

  • Hyperion
  • Lake Magadi
  • Reflectance and emittance spectroscopy
  • X‐ray diffraction
  • Surface mineral mapping
  • Magadiite
  • Kenyaite

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