Mapping tectonic structures of Kédougou-Kénieba Inlier (Eastern Senegal) from satellite (LANDSAT-7 ETM+ / SRTM) and airborne geophysics imagerie
Résumé
The lineaments of the Kédougou-Kéniéba Inlier (KKI) were mapped from the processing of
severalty pesofimages :(i) various coloured combinations Red-Green-Blue of 1 to 7 bands and the
panchromatic band (8) of a set of images of the matic mapping (Thematic Mapper) of Landsat-7
satellite (ETM7+) ;(ii) SRTM image (Shuttle Radar Topography Mission) or DTM (Digital Terrain
Model) of the Endeavour space shuttle; (iii)as well as the aero magnetic image of the study area.
Five groups of NS,NNE-SSW, NE-SW, EW and NW-SE lineament directions were identified from
these images. The NNE-SSW and NE-SW oriented lineaments are the most frequent. The NS
oriented lineaments often correspond to a straightening of those oriented NNE-SSW. The EW and
NW-SE oriented lineaments are rarely observed andthey often intersect with previous ones. Field
structural data indicate that most of these lineaments correspond to shear and/or thrust faults,orto
dykes. The NE-SW oriented lineaments would be the oldest. They are generally relative to reverse
shear zones and trust faults whichare associated with the D1 Eoeburnean phase of deformation. NS
and NNE-SSW oriented lineaments correspond to faults and shear zones, mainly sinistral, associated with NW-SE oriented lineaments. These three sets of lineamentsforma conjugated
systemfault, associated with the sinistral transpression phase of the D2 Eburnean deformation
phase. The occurrence of all these structures would berelated to the Eoeburnean, Eburnean and
post-Eburnean orogenicevents. Indeed, the doleritic dykes, which have been dated between 1600
Ma and 1100 Ma, show ductile deformation which testify a post-Eburnean tectonicevent (Kibarian
or Hercynian?) subsequently affecting the Paleoproterozoic for mations of the KKI.