High resolution seismic stratigraphy of the Gulf of Pozzuoli (Naples Bay) and relationships with submarine volcanic setting of the Phlegrean Fields volcanic complex

High resolution seismic stratigraphy of the Gulf of Pozzuoli has been studied to discuss volcanological implications on geological evolution of the Phlegrean Fields volcanic complex. A new seismo-stratigraphic framework of the Gulf of Pozzuoli is provided based on the geological interpretation of Sparker profiles, showing thirteen seismic units. The seismo-stratigraphic analysis has evidenced that the marine units prevail in the eastern Pozzuoli offshore (Baia town) while the volcanic units prevail in the western Pozzuoli offshore (Pozzuoli town). Two deep volcaniclastic units appear to be related to the northern margin of the Pentapalummo Bank, a relict volcanic edifice located in the outer Pozzuoli shelf. The Pozzuoli basin filling is made up of five seismic units, marine in origin, whose internal configuration is mostly characterized by parallel reflectors. The marine units are overlain by three volcanic units, whose origin is probably pyroclastic, both due to their seismic facies and to their deposition in palaeo-morphological depressions. A wedge-shaped seismic unit, acoustically transparent, has been interpreted in the Gulf of Pozzuoli as the Neapolitan Yellow Tuff deposits. Lowstand and highstand deposits, pertaining to the Late Quaternary depositional sequence are respectively characterized by progradational and parallel seismic reflectors, located in the Gulf of Pozzuoli. Different models on the geological structure of the Phlegrean caldera and its present-day unrest state have been taken into account to improve the discussion of the volcanological aspects related with the seismo-stratigraphic setting of the Gulf of Pozzuoli, representing the submerged border of the caldera itself.