Extreme marine events revealed by lagoonal sedimentary records in Ghar el Melh during the last 2500 years in the northeast of Tunisia

Abstract

Abstract. The Tunisian coast has been affected in the past by many events of extreme marine submersion (storms and tsunamis). A high-resolution study along two sediment cores GEM3 and GEM4 taken from the lagoon of the Ghar el Melh was performed to identify the different paleo-extreme events and to reconstruct the paleo-environmental changes of the North-eastern part of Tunisia during the Late Holocene. A very high-resolution of analysis (sedimentological, granulometric, and geochemical) was applied on these cores. These cores were also dated with isotopic techniques (137Cs, 210Pbex, 14C) and the outcomes reveal fives phases of paleoenvironmental changes of this lagoonal complex. The first phase dated from −275 to 200 Cal AD characterized by a high percentage of Silt and Clay (fine particles) indicating a protected lagoon. The second phase synchronous with the Dark Age Climatic Period dated from 200 to 1100 Cal AD, is marked by an increase in the coarse sediment and could be explained by a weakening of the sandy barrier due to an increase of storm events. The third phase is characterized by a return to a closed lagoon during the Medieval Warm Period (from 1100 to 1690 Cal AD). The fourth phase dated from 1690 to 1760 Cal AD coincide with the Little Ice Age and is marked by one specific sedimentological layer attributed to a marine submersion event. This layer could be associated to the 1693 tsunami event in southern Italy or an increase of extreme storm events. The fifth phase covering the last 250 years present a reclosing of the lagoon.