Sanaga Fault: Evidence of Neotectonics and Landscape Evolution in Edéa Region (Cameroon, Centre-Africa)

Morphometric parameters extracted fromDEM (90 m) combined with field and literature data of Edéa region, a portion of Cameroonian passive margin located between 3°43’ - 4°00 ’N and 10°00’ - 10°15’E, were used to constraint the present day landscape and forces that have acted and is currently acting on its evolving topography. The obtained results show that the Sanaga Fault is one of the main driver forces responsible for this evolution. Set up during the Pan-African orogeny, this fault which affects a good part of the Proterozoic basement and Tertiary sedimentary cover has developed two systems of secondary active faults different by their nature and characteristics, quite visible in the Edéa region- the Ekitté System, shearing normal faults with a N-S to NNE-SSW strike and the Sanaga-Batignol System shearing directional faults with a NW-SE strike. Most of these faults constitute the river beds and play iteratively, deeply affecting both the drainage system and the landscape. Morphometric indices used reveal that the landscape has been rejuvenated and experiences uplifts and tiltings to present-day due to these reactivations. Structural and petrographical analyses confirm the current role played by the Sanaga Fault and its systems in the segmentation of the region into block tectonics and the occurrence of pseudotachylites and tectonic breccia. Block tectonics, pseudotachylites, tectonic breccias are accompanied with the recent earth tremors with magnitudes comprised between 2.6 and 4.0 on the Richter scale highlighting the neotectonics in this region.