On the occurrence of the Neapolitan Yellow Tuff tephra as a stratigraphic marker in the southern Gaeta Bay (Eastern Tyrrhenian margin; Italy)

A main volcanic marker has been identified for the first time on the continental shelf of the northernPhlegraean Fields in the Gaeta Gulf (Campania region, eastern Tyrrhenian margin, Italy) by meansof Subbottom Chirp profile grid and stratigraphic analysis of a core collected on the slope. In theseismic sections, the core bottom corresponds to the top of a continuous and parallel reflector (V)interbedded within the transgressive deposits of the Late Quaternary-Holocene depositionalsequence. The Transgressive System Tract deposits are particularly thick compared to the majorityof the transgressive deposits of other shelf settings. This might be due to the input of pyroclasticand volcanoclastic deposits related to the intense eruptive activity of the Campania Plain during theLate Pleistocene-Holocene time span. Undulations and pockmarks are the main morphologicalfeatures of the sea floor and they might be linked to gas uprising, widely detected in the study area.The V reflector is located on the shelf from northeast to southwest at different depths, ranging from10 ms (about 8 m) to 30 ms (about 25 m) below sea floor and it can be mapped down to thecontinental slope. The geological calibration of this continuous reflector coupled withtephrostratigraphic analysis, allowed to correlate it with the Neapolitan Yellow Tuff depositsemplaced at Phlegraean Fields at ca. 15 ka.