Potential Cyclic Steps in a Gully System of the Gulf of Palermo (Southern Tyrrhenian Sea)

Multibeam bathymetric data revealed the occurrence of a train of bedforms along a gully system in the Gulf of Palermo, southern Tyrrhenian Sea. The observed gullies, located in the westernmost sector of the Gulf of Palermo, incise the outer shelf at a depth of 120 m and converge at the Zafferano Canyon, connecting to the Palermo Basin at a depth of 1300 m. Bedforms develop along these gullies and along the thalweg of the canyon, displaying an average wavelength of 200 m, with maximum values of 340 m. Their gully floor location combined with their wave length, upslope asymmetry and crescent shape point to a possible cyclic step origin of these bedforms. Preliminary numerical modelling suggests that, assuming that these bedforms were formed by cyclic steps in turbidity currents, these flows might have been few meters thick and have had velocities in the range of 0.2–1.5 m/s.