Impacts of Relative Sea Level Change and Sedimentary Dynamic on an Historic Site Expansion Along the Coast Between Sfax and Jebeniena, Tunisia

Abstract

New data evaluating the relative sea level changes and sedimentary dynamics along the coast of Tunisia are presented. Data are inferred from archaeological sites of Punic-Roman age located between Ras Boutria (Jebeniena) and El Awebed (Sfax). New results are based on high-resolution micropalaeontological, sedimentological and geochemical analyses of several sediments cores coupled to new 14C datings. The coast of Jebeniana (Ras Boutria historic site) recorded the first marine transgression, overlying the quartz sand Tyrrhenian deposits, 2210 a BP in age. This transgression, also recognized in Sfax coast, revealed by the dominance of lagoonal ostracod associated to coastal and marine taxa, allows the settlement of an open lagoon. It reveals also, a high value of species number and a reduced density. The pelagic influences are augmented by the high marine geochemical elements concentrations such as the chloride (Cl) and the sulfur (S). The increase of the brackish ostracod mark the settlement of a closed lagoon toward 768 a BP. The enrichment of the sediment in quartz grains coupled with the action of the current drift authorized the build-up of sandy spits and the genesis of the lagoon that preserve a rich assemblage of euryhaline ostracods and mollusks species. This process was probably responsible of the obstruction of the historic Boutria harbor and the abandon of the historic city.