Relative sea level changes and paleogeographical evolution of the southern Sele plain (Italy) during the Holocene

Abstract

Several boreholes were studied in detail through different analytical methods in order to highlight the Holocene relative sea-level changes and the paleogeographical evolution of the southern sector of the Sele river coastal plain (Tyrrhenian Sea, southern Italy). Stratigraphic and paleontological analyses identified a transition from floodplain strata to brackish water, lagoon and upper shoreface deposits. The present setting of the outermost plain strip was interpreted as the result of a barrier-lagoon system which first migrated landward and then seaward during the Holocene. After being exposed to continental conditions during the Last Glacial regression, the study area gradually reached brackish water conditions at the beginning of the Holocene. Shortly before 6.7 ka cal BP the coastline reached its maximum retreat, reaching 1.6 km inland from the present shore. Subsequently, the barrier-lagoon system mainly prograded until marshy conditions were established, which partially persisted until very recent times. Four biological sea-level markers were sampled, and their ages, constrained by AMS 14C dating, span between 6.77 and 7.98 ka cal BP. Altitudes (m above mean sea level) of the collected samples were corrected taking into account the uncertainties of the vertical position with respect to the palaeo sea level. Vertical tectonic displacements were evaluated through the comparison between relative sea-level data and the Holocene predicted sea-level curve, as well as with the available morphotectonic and stratigraphic data. The results suggest negligible rates of vertical tectonic displacements during the Holocene, at least along the southern sector of the Sele river coastal plain.