Review of the Senegalo-Malian shear zone system – Timing, kinematics and implications for possible Au mineralisation styles
The Kédougou Kénieba Inlier (KKI) of eastern Senegal forms a typical Paleoproterozoic greenstone belt
characterised by low-metamorphic sequences of volcanic rocks and volcano-sediments that have been
intruded at various stages by gabbroic suites and calc-alkaline granitoids. The main structures of the
KKI comprise two anastomosing structures about N–S trending shear belts that are distinguished into
the western Main Transcurrent Zone (MTZ) and the eastern Senegalo-Malian shear zone system
(SMSZ). These shear belts are taken to define the limits between the western Mako, the central
Diale-Kéniebandi and the eastern Daléma-Kofi domains even though transitions exist between their
characteristic deposition sequences.
Remote sensing analysis of airborne geophysics and satellite data (Landsat, ENVI, SRTM) in combination
with geological field mapping, structural analysis and geochronology suggests that the SMSZ
represents a Birimian structure that records a main stage of deformation that could characterise the
major transcurrent Eburnean tectonics (D2) dated from 2105 Ma (Feybesse et al., 2006a–e). This sinistral
transpressive deformation marked by a major constraint oriented NNW–SSE, is accompanied by a NNE–
SSW extension leading to the opening of dilational areas such as small pull-apart basins marked by local
calk-alkaline volcanic sequences and several coeval intrusions of the Boboti Suite dated 2080 ± 0.9 Ma
(Hirdes and Davis, 2002). A post-Birimian to pre-Neoproterozoic deformation post dates the transcurrent
phase and is marked by regional N–S extension.
Review of the existing Au-mineralisation models in combination with the spatial analysis of soil geochemical
data suggest seven possible mineralisation styles that are related to the transpressional tectonics
and coeval magmatism.
Auteur(s) : - Diène M., Fullgraf, T., Diatta, F, Gloaguen, E., Gueye, M.,Ndiaye, P.M (2015).
Année de publication : 2015
Revue : Journal of African earth Sciences
Type : Article
Mise en ligne par : DIENE Mahamadane