Radiocarbon dating versus volcanic event stratigraphy: Age modelling of Quaternary marine sequences in the coastal region of the Eastern Tyrrhenian Sea

We present the results of an integrated stratigraphic study conducted on eight marine sediment cores collected in the Naples and Salerno Bays, Eastern Tyrrhenian Sea. The aim of the study is the understanding of the timing and the impacts on the sedimentary environment of explosive volcanic events that occurred over the coastal zone of the Campania region during the latest Quaternary. Accurate dating and correlation have been essential for the construction of reliable models of the sediment architecture and influx rates in this area, as well as for establishing the links between changes in sedimentation and palaeoenvironmental events. While in case of deep marine sequences distal ash layers usually offer a significant potential for accurate geochronology, in the case of shallow marine sequences (continental shelf to upper slope) radiocarbon dating revealed to be essential in order to refine correlation among clusters of marine tephra layers with the equivalent proximal pyroclastic deposit onland, particularly where depositional rates are high and the chemistry and age of tephra layers display little variability. The integrated use of AMS 14C dating on marine materials and the tephrostratigraphic approach based on reconstructions of historical volcanic events is fundamental in order to minimize the uncertainties that affect chronologic constraints derived from radiocarbon-based age models.