Interaction of down-slope and along-slope processes off Capo Vaticano (southern Tyrrhenian Sea, Italy), with particular reference to contourite-related landslides

Abstract

The Late Quaternary architecture of the upper slope-shelf sector of the Calabro-Tyrrhenian continental margin off Capo Vaticano was reconstructed to decipher the interaction of along-slope and down-slope sedimentary processes, based on the analysis of very high-resolution single-channel seismic profiles and multibeam bathymetry. Both along-slope bottom currents and downslope gravity processes influenced the stratigraphic architecture of the margin during the last eustatic cycle, locally forming a mixed turbidite and contourite system. Along-slope processes formed elongated drifts located on the upper continental slope and outer shelf, while gravity-driven down-slope processes formed mass-transport deposits and turbidite systems with erosive channels, locally indenting the present-day shelf. Several slide events affected the elongated drifts and failure processes appear to be dominated by translational sliding that affect the upper 10–20m of the stratigraphic record, with glide plains developed within contourite deposits. The most striking feature is the Capo Vaticano slide complex, which displays a large spatial coverage (area of about 18km2), between ca −190m and −500m and is composed of several intersecting slide scars and overlapping deposits. These characteristics are peculiar for the Tyrrhenian continental margins, where slide events developed in open-slope areas are usually less complex and smaller in size. This would indicate that high sedimentation rates and occurrence of contourite deposits can represent a preconditioning factor for medium-large scale slope instability on the Tyrrhenian margins.