The Malta-Sicily Escarpment : mass movement dynamics in a sediment-undersupplied margin

Abstract

The Malta-Sicily Escarpment (MSE) is a steep carbonate escarpment that appears to have largely remained isolated from inputs of fluvial and littoral sediments since the Messinian Salinity Crisis. Mass movement activity has so far only been inferred from sediment cores at the base of the MSE. In this study we use geophysical and sedimentological data acquired from the upper MSE and outer Malta Plateau to: (i) map and characterise the dominant forms of mass movements, and (ii) determine the nature and origin of these mass movements, and their role in the evolution of the MSE. We document 67 mass movement scars across 370 km2 of seafloor. Slope instability entailed translational slides, spreads and debris flows that mobilised Plio-Pleistocene outer shelf hemipelagic/pelagic sediments or carbonate sequences across the upper continental slope. Slope failure events are caused by loss of support associated with the formation of channels, gullies, canyon heads and fault-related escarpments. Mass movements play a key role in eroding the seafloor and transferring material to the lower MSE. In particular, they control the extent of headward and lateral extension of submarine canyons, facilitate tributary development, remove material from the continental shelf and slope, and feed sediment and drive its transport across the submarine canyon system.