New data on the evolution of the Sele river coastal plain (southern Italy) during the holocene

Abstract

New data on the evolution of the Sele River coastal plain (Southern Italy) during the Holocene. - In order to reconstruct the evolution of the Sele River coastal plain beginning with the Last Postglacial transgression, its outermost strip (limited inland by remnants of a Last Interglacial coastal ridge) was geomorphologically and geologically surveyed. Surface data were integrated with those coming from three proposedly drilled bore-holes which allowed detailed litho-stratigraphic observations, ostracod and pollen analyses and C14 datings. Furthermore, a great number of pre-existing well logs and the results of 15 new vertical electrical soundings were considered to depict the three-dimensional stratigraphic architecture of the area. The Holocene portion of the plain includes a composite sandy ridge which is partly exposed along the present coast and disappears inland under a muddy, substantially flat depression that reaches up to the base of the Tyrrhenian coastal ridges. The stratigraphic, palaeo-environmental and chronological data obtained allow to interpret the present setting of the Sele Plain's outer strip as the result of a barrier-lagoon system that migrated alternatively landward and seaward during the Holocene. After being exposed to subaerial conditions during the Last Glacial regression with a seaward pro-gradation of the shoreline up to 15 km, the study area gradually entered brackish water conditions at the beginning of the Holocene. Shortly before 8,400 yrs BP the coastline experienced its maximum retrogradation, reaching 1.6 km inland from the present shore. Subsequently, the barrier-lagoon system entered a period of prevailing progradation. The inversion of tendency, from retrogradational to progradationai, most probably can be ascribed to a decline of the rate of sea level rise under the threshold of balance with the pro-gradation due to fluvial sedimentation. The progradation was interrupted by at least three minor transgressive phases occurred between 8,400 and 2,000 yrs BP. About 5,500 years BP the lagoon was largely gained by palustrine conditions which persisted partially until very recent times.