Late Holocene sedimentary changes in shallow water settings: the case of the Sele river offshore in the Salerno Gulf (south-eastern Tyrrhenian Sea, Italy)

A complementary data set consisting of sedimentological,petrophysical, geochronologic and seismostratigraphicanalysis was used to detect the sedimentarychanges in the inner shelf record in a mostly stable region,over the last 3 ky cal BP, that is since the sea level attainedits present day position. This study has been carried outwithin the VULCOST project on the Salerno Gulf (southeasternTyrrhenian Sea, Italy), to learn more about theimpact of minor morpho-climatic changes and anthropogenicdisturbances on the shelf sedimentary record. Somedecimeter-thick sandy beds deposited on the inner shelf, offthe Sele river mouth, in the time span corresponding to theLittle Ice Age (LIA), despite the fact that, at the time, thecoastline at that time was farther inland with respect toits present day position. Since the beginning of the 20thcentury, mainly fine grained sediment settled, possiblyowing to the restoration of mild climatic conditions,changes in the rivers’ regime and land-use. The analysis ofthe marine cores, collected off the coast, also reveals alitho-stratigraphic mismatch among coeval intervals,possibly driven by the different response of the catchmentsto the morpho-climatic variations. High resolution seismicdata shows that the sediment bypass area, shaped bywave action, is much deeper than the estimated limit, ifcomputed on the base of fair-weather wave length andsedimentologic analysis. Indeed, toplap terminations ofreflectors are recognizable as deep as 25 m in the southernsector of the Gulf and suggest an intense reworking of theseabed over long periods, much deeper than the outer limitof the beach. This evidence is also supported by the state ofpyroclastic layers in the core record, which proves sedimentreworking in the marine setting, down to 24 m ofdepth. The high resolution sedimentologic and stratigraphicreconstructions point to a non linear relation betweendepth, distance from the coast and sand deposition overthe time. This suggests a complex picture of coastaldynamics within the same basin, with a remarkable outcomeregarding the wave-cut terraces as proxies of sealevel stands.