The Southern Tyrrhenian continental margin off Campania: regional seismic stratigraphy and morphobathymetry based on high resolution marine geophysical data

Similarly to other back-arc basins, the Tyrrhenian sea is an area of ongoing extension inside large-scale convergence zone between the continental plates of Europe and Africa. Tyrrhenian extension started about 10 Myr ago, leading to the Pliocene formation of oceanic crust (Patacca et al., 1990). Three passive continental margins, Sardinia, Northern Sicily and Southern Italy border the Southern Tyrrhenian bathyal plain. The area is seismically active and experienced strong horizontal and vertical movements. The Southern Tyrrhenian continental margin off Campania region owes its complex stratigraphic architecture to the interaction between volcanic and sedimentary processes during the Late Quaternary. Multi-channel reflection seismics collected by the CNR-IAMC Institute of Naples, Italy during several oceanographic cruises, starting from the 1996 (Scientific Responsible: dott. Ennio Marsella), coupled to high resolution reflection seismics, Multibeam bathymetry and magnetic profiles contribute to the knowledge of the tectonic setting of the margin, both to a regional and to a local scale. A grid of seismic lines was acquired in the 1999 in the Campania offshore by a joint project between Geomare Sud (Naples), the Marine Geology Group of the University of Palermo and the Department of Tectonics of the Vrije University of Amsterdam, the Netherlands (SISTER 99 oceanographic cruise; Bertotti et al., 1999; Korevaar et al., 2000). The main goal of the cruise (Seismic Investigations in the South Tyrrhenian Extensional Regions) was to acquire data to constrain the kinematics of formation of the Tyrrhenian margin. Regional scale seismic lines have been acquired parallel to and across the continental margin off Campania from Gaeta to Capo Palinuro to the south. Multi-channel profiles clearly document the geometries of normal faults running parallel to the margin. Two major faults defining fault blocks 10-20 km wide and dipping towards the ocean are defined by the interpretation of seismic profiles. The profiles parallel to the margin clearly depict the main extensional regions, as the Salerno graben and the Sapri basin to the south. Shortening related tectonic features also appear, testifying inversion processes at a basin scale. The latter features seem also to indicate a south-westward direction of transport, comparable to that observed in the Cilento region. The Naples Bay represents a half-graben basin controlled by two main normal faults, NE-SW trending, the Phlegrean Fields-Ischia fault and the Capri-Sorrento Peninsula normal fault. Strong downthrows of Meso-Cenozoic sedimentary sequences, representing the acoustic basement, are observed in correspondence to both the faults. The stratigraphic architecture of the Campania margin in the Naples Bay is depicted by the geologic interpretation of the seismic line NAM3 (fig. 1) running from the Ischia and Procida offshore to north-west towards the Dohrn canyon and the Bocca Piccola offshore between the Sorrento Peninsula and the Capri island. Meso-Cenozoic carbonates form a SW-dipping monoclinalic structure downthrown along sets of conjugate normal faults towards the center of the Bay. The bulk of the basin filling is composed of a relic prograding wedge, probably Early Pleistocene in age, unconformably overlain by a syn-tectonic transgressive sequence and then by another thick prograding wedge, supplied by the Sarno river mouth (Aiello et al., 2001; 2004; 2005; Bruno et al., 2002). References Aiello, G., Budillon, F., Cristofalo, G., D'Argenio, B., de Alteriis, G., De Lauro, M., Ferraro, L., Marsella, E., Pelosi, N., Sacchi, M., Tonielli, R., 2001. Marine geology and morphobathymetry in the Bay of Naples. In: Faranda F.M., Guglielmo L. and Spezie G. (Eds.) Structures and Processes of the M