Mining Goes Digital – Mueller et al. (Eds)
© 2019 Taylor & Francis Group, London, ISBN 978-0-367-33604-2
86
Application of ASTER multispectral data and hyperspectral
spectroscopy for phosphate exploration
N. Mezned
Mineral Resources and Environment Laboratory, Department of Geology, Faculty of Science of Tunis,
University of Tunis El Manar, Tunisia
Higher Institute for Preparatory Studies in Biology and Geology Soukra, Institution of Agricultural
Research and Higher Education, Tunisia
A. Fatnassi & S. Abdeljaouad
Mineral Resources and Environment Laboratory, Department of Geology, Faculty of Science of Tunis,
University of Tunis El Manar, Tunisia
ABSTRACT: Reflectance spectroscopy and ASTER data have proven their capabilities
for remote mineralogical mapping and ore exploration. In this context, a new methodology
based on the use of ASD hyperspectral spectroscopy and ASTER multispectral data is proposed for the exploration of phosphates in a specific geological and abruptly topographical
context in Tunisia. The contribution of this study consists in mapping sedimentary phosphates in the Chaketma mine site in the Centre West of Tunisia using all ASTER VNIR,
SWIR and TIR data. Resulting maps from the processing of ASTER data using MF method
highlighted already delimited phosphate perspectives as well as other no prospected phosphate outcrops. XRD analysis results as well as ASD hyperspectral spectra were used for the
validation purposes. Given the abrupt landscape of the site, the contribution of this approach
is well highlighted. Moreover, these results allow to better mark out phosphates and minimize the impact of their exploitation on environment.
1 INTRODUCTION
Phosphate constitutes an important and a necessary resource for the development in Tunisia, as it is very considered in worldwide. Due to the inaccessibility of the most mineral
deposits, prospecting has completed only 14% of basic investigations. In addition, laboratory analyzes as well as the field work are cumbersome, punctual and costly. Therefore, the
remote sensing technique becomes very useful for the rapid detection and mapping of different surface states, especially mineralization. Remote sensing at moderate cost facilitates
the observation, analysis and management of natural resources. It shows a considerable
contribution compared to traditional techniques which always remain complementary.
Particularly, reflectance spectroscopy has proven its capabilities for remote mineralogical identification. Indeed, due to their absorption features in the Short Waves InfraRed SWIR region, carbonates were identified and quantified in several previous studies
(Clarck, 1999; Gomez et al., 2008; Alayet et al., 2017). Moreover, Aster VNIR (Visible
and Near InfraRed) and SWIR multispectral satellite images have been widely used for
mineral mapping and ore exploration such us bauxite, iron oxides, gold (Houssainjani
et al., 2015). Aster SWIR data have been recently used for targeting rock phosphate (Guha
et al., 2018). Aster derived emissivity and temperature has however been used for quartz
and igneous rock mapping (Pasricha et al, 2018). Testing the ability of ASTER VNIR,
SWIR and particularly TIR data for sedimentary phosphate exploration and mapping is
absent in the literatures.
© 2019 Taylor & Francis Group, London, ISBN 978-0-367-33604-2
86
Application of ASTER multispectral data and hyperspectral
spectroscopy for phosphate exploration
N. Mezned
Mineral Resources and Environment Laboratory, Department of Geology, Faculty of Science of Tunis,
University of Tunis El Manar, Tunisia
Higher Institute for Preparatory Studies in Biology and Geology Soukra, Institution of Agricultural
Research and Higher Education, Tunisia
A. Fatnassi & S. Abdeljaouad
Mineral Resources and Environment Laboratory, Department of Geology, Faculty of Science of Tunis,
University of Tunis El Manar, Tunisia
ABSTRACT: Reflectance spectroscopy and ASTER data have proven their capabilities
for remote mineralogical mapping and ore exploration. In this context, a new methodology
based on the use of ASD hyperspectral spectroscopy and ASTER multispectral data is proposed for the exploration of phosphates in a specific geological and abruptly topographical
context in Tunisia. The contribution of this study consists in mapping sedimentary phosphates in the Chaketma mine site in the Centre West of Tunisia using all ASTER VNIR,
SWIR and TIR data. Resulting maps from the processing of ASTER data using MF method
highlighted already delimited phosphate perspectives as well as other no prospected phosphate outcrops. XRD analysis results as well as ASD hyperspectral spectra were used for the
validation purposes. Given the abrupt landscape of the site, the contribution of this approach
is well highlighted. Moreover, these results allow to better mark out phosphates and minimize the impact of their exploitation on environment.
1 INTRODUCTION
Phosphate constitutes an important and a necessary resource for the development in Tunisia, as it is very considered in worldwide. Due to the inaccessibility of the most mineral
deposits, prospecting has completed only 14% of basic investigations. In addition, laboratory analyzes as well as the field work are cumbersome, punctual and costly. Therefore, the
remote sensing technique becomes very useful for the rapid detection and mapping of different surface states, especially mineralization. Remote sensing at moderate cost facilitates
the observation, analysis and management of natural resources. It shows a considerable
contribution compared to traditional techniques which always remain complementary.
Particularly, reflectance spectroscopy has proven its capabilities for remote mineralogical identification. Indeed, due to their absorption features in the Short Waves InfraRed SWIR region, carbonates were identified and quantified in several previous studies
(Clarck, 1999; Gomez et al., 2008; Alayet et al., 2017). Moreover, Aster VNIR (Visible
and Near InfraRed) and SWIR multispectral satellite images have been widely used for
mineral mapping and ore exploration such us bauxite, iron oxides, gold (Houssainjani
et al., 2015). Aster SWIR data have been recently used for targeting rock phosphate (Guha
et al., 2018). Aster derived emissivity and temperature has however been used for quartz
and igneous rock mapping (Pasricha et al, 2018). Testing the ability of ASTER VNIR,
SWIR and particularly TIR data for sedimentary phosphate exploration and mapping is
absent in the literatures.