Evolution of Korba Lagoon (Cap Bon, Tunisia) During the Last Millennia Based on the Analysis of Foraminiferal Assemblages

Abstract

The quantitative study of foraminiferal associations coupled with geochemical and sedimentological proxies, of a 94-cm sediment core from Korba lagoon (Cap Bon, Tunisia), enabled us to better understand the dynamics of depositional environments and identify different stages of evolution of the lagoon. Three major periods were identified. The first revealed high abundance of foraminifera dominated by lagoonal taxa associated with high TOC, TIC and Ca contents. These parameters marked the settlement of a closed lagoon separated from the open ocean by a sandy bar with high foraminiferal productivity in fine sediments. The second period showed the development of estuarine foraminifera coupled with the appearance of charophyte oogonia in addition to planktonic foraminifera, high Ti and Fe concentrations and dominant coarse fraction. These parameters are indicative of an open lagoon environment with the fluvial inputs. The disappearance of charophyte oogonia and planktonic foraminifera coupled with the enrichment of marine taxa marked the opening of our lagoon to the sea. The progressive modification of foraminiferal association revealed by the increase of lagoonal species and the decrease of estuarine taxa prove the settlement of the present-day lagoon conditions.