Lithological Mapping

The Lithological Mapping theme (1984-1988) was devoted to image processing and field control of satellite imagery as part of the GARS Africa Project. improved the interpretation of the lithology, structure and mineralisation of the Kibaran and Ubendian fold belts in Africa using advanced remote sensing technology. The research established a link between fundamental geological investigations and metallogenic research in the Kibaran region. Our understanding of the Kibaran cycle sedimentary formations across the region was greatly improved as a result.

The theme assessed the feasibility of using advanced remote sensing data for detecting mineral assemblages, alteration zones and geobotanical indicators for a range of litho-structural analyses:

  • Discrimination of lithological units within metasedimentary complexes
  • Recognition of different types of intrusive rocks
  • Influence of tropical weathering on characteristic mineral assemblages of rocks and soils
  • Recognition of mineral alteration zones
  • Differentiation of Precambrian and overprinted Cenozoic structures
  • Recognition of structural control on mineralization
  • Determination of spectral properties of geologic materials by radiometric measurements


Methodology

Lithological mapping was performed using a combination of field survey data and spectral analysis of remote sensing data from Landsat MSS, Landsat TM and SPOT for two sites in Africa – the Ubendian fold belt in Tanzania and the Precambrian terranes of the Kibaran fold belt in Burundi. Both sites are dominated by lateritic soils and vegetation that varies from tropical rain forest to savannah. Initial investigations focused on the Ubendian fold belt because it consists of a variety of lithological units covered by a relatively homogeneous vegetation layer. The Kibaran fold belt (Middle Proterozoic) has a more complex character and the research focused on discerning granites, basic rocks and shear zones in northern Burundi, and the use of geobotanical indicators to discern mineral alteration zones in central Burundi.

Results were published in two volumes of the Bulletin (annals) of the Musée Royal de l’Afrique Centrale (MRAC):

  • Volume I (1988): 'Image analysis, geological control and radiometric survey of Landsat TM data in Tanzania'
  • Volume II (1989) 'Spectrométrie à haute résolution in situ et analyse d’image LANDSAT et SPOT au Burundi'


Collaborators

Back to top