Analysis and modeling of contourite drifts and contour currents off promontories in the Italian Seas (Mediterranean Sea)

The complex relationship between currents flowing around capes and their related contourite deposits is still an interesting topic to confront, both from a sedimentologic and oceanographic perspective. We analyze here recent observations of contourite drifts, located at intermediate depths off promontories in the southern Tyrrhenian and in the southern Adriatic Sea. These contourites are located slightly upstream from the cape tip of Cape Vaticano, while they occur both upstream and downstream, in the lee wave region, of the Gargano Promontory. We therefore analyze and discuss tank and numerical simulations of contour-following flows, with particular attention to the presence of turbulent phenomena occurring in the lee region. Discussing the classical stream-tube model (i.e., a thin vein of dense water flowing around a cape) we moreover provide physical justification for some aspects we recognized in the study experiments. The comparison between bathymetric-stratigraphic data and numerical, tank and analytic results, allows investigation of the possible occurrence of sediment drifts around capes. We found that the presence of turbulence, and thus of erosive conditions for sediments in the lee of a cape, can be detected by using dimensionless numbers related to cape dimension and ocean current features. This work can be seen as a new approach to bridge the gap between marine sedimentology and physical oceanography.