Submarine canyon morphology and evolution along the Western and Southern margins of Sardinia

Abstract

Recent high-resolution and older medium-resolution seismic profiles, together with bathymetric data, have been integrated for a detailed investigation of the western and southern Sardinian margins. This study analyzes the trigger mechanism, morphologies, spatial distribution and temporal evolution of submarine canyon systems. The origin of these canyons is primarily influenced by the interplay between slope gradient, crustal vertical movements and sea-level changes, which destabilize the slopes and trigger retrogressive erosion. The canyon evolution, instead, is determined by the interaction between erosive processes, gravitational mass movements and bottom currents. Their path and sinuosity are influenced by the large amount of magmatic structures present on the western margin and by the structural highs on the southern margin. We classify the submarine canyons of Western and Southern Sardinia as type 2, i.e. they cut the shelf edge without connecting to large fluvial systems. Indeed, Sardinian canyons are primarily shaped not by major river systems, but by mass flow events and bottom currents, which act as primary mechanisms of sediment transport and incision. Ultimately, we conclude that the origin of the canyons is post-Messinian, resulting from more recent glacio-eustatic variations that occurred during the Quaternary, thus challenging earlier hypotheses that associated their formation with the Messinian Salinity Crisis.