Sediment drifts and erosional surfaces in the central Mediterranean: seismic evidence of bottom-current activity

Abstract

We present evidence, based on seismic reflection profiles, of sediment drift accumulation and deep submarine erosion driven by bottom currents in different physiographic settings of the central Mediterranean. The study shows that significant bottom-current activity is enhanced by the focussing effects of particular sea-floor morphologies where these interact with the established deep circulation. We cite occurrences from the Corsica Channel, the eastern Tyrrhenian slope basins, the Sicily Channel, the eastern flank of the Apulian swell and the deep Ionian Basin at the foot of the Malta Escarpment. Examples range from asymmetric, convex upwards sediment drift accumulation associated with a lateral moat, as in the Tyrrhenian slope basins or the Sicily Channel (600/800 m depth), to the large-scale bedforms at 2000 m depth in the Ionian Basin. A more complex upslope-migrating sediment drift sequence, bounded by diverse unconformities occurs in the Corsica Channel (300 m depth). The identified features occur in the uppermost portion of the sediment column and commonly control the present-day sea-bottom morphology. Bottom-current-related sedimentary processes seem to be more widespread than previously thought in the Mediterranean. These processes make a significant contribution to sediment accumulation of Quaternary age in marginal basin settings and their potential for generating unconformities of various magnitudes should be taken into account when inferring depositional histories.