Holocene evolution of the coastal system of Sfax (SE Tunisia)

This study aims to identify the depositional environments along the Tunisian coastal system
and to follow their evolution over the Holocene. The material consists in three marine
sediment cores retrieved at 3 meter depth from the Northern coastal system of Sfax
(«Société d'Étude et d'Aménagement des Côtes Nord de la Ville de Sfax", site
TAPARURA). The identification of the different depositional paleoenvironments was
mainly based on field campaigns and laboratory mineralogical and sedimentological analyses
of sediments. The vertical succession analysis of depositional facies allows to identify 2
main environments. First a fluviatile depositional environment (coastal plain) is
characterized by fluviatile channels facies and inundation plains at the bottom of the cores.
Second, at the top of the cores, we observed a marine sandy sedimentation with numerous
bioclasts of gasteropods, lamellibranches and algae. This facies evolution is consistent with a
relative sea level rise, responsible for the flooding of the fluviatile system at the level of
the coastal plain. The main factor controlling the facies evolution and the sediment thickness
variation is the local sea-floor morphology. The Holocene seabed is mainly inherited from
the last glacial maximum morphology. Resulting from an important fluviatile digging that
occurred, the relative sea-level fluctuations, the hydro-isostatic rebound and the climate.