Last interglacial coastal environments in the Mediterranean–Saharan transition zone

The coast of Tunisia stretches from the western Mediterranean climate belt in the north to the Saharan desert climate belt in the south. The sediments of this coastal strip provide a record of sea level change if an accurate chronology of the coastal deposits is available. We have here surveyed and analysed coastal sites and established a chronology based on optical dating techniques. The optical ages range from 156 ka to 62 ka (2σ level) and cluster around the last interglacial period (~ 125–75 ka). Our study shows that sea level rose after Termination II for about 25 ka leading to a transgressive deposit at ~ 120 ka. A disconformity shown by some deposits suggests a brief drop of sea level during this transgressional phase. Subsequently, for around 40 ka the coastal area became covered by soils, colluvia and aeolian sediments indicating a slowly falling sea level. While the composition of sediments at the north coast did not change, the deposits at the central and south coast experienced a drastic change from a quartz- to a carbonate-dominated sedimentation sometime during the last interglacial. Littoral sedimentation ceased at ~ 70 ka when the coast became sediment starved in the course of the falling sea level.