Mediterranean Sea: An overview of the spatial distribution of surficial sediment in relation to their origin, seabed relief and water circulation patterns

The present paper provides a conclusive picture of the origin and spatial distribution of terrigenous versus biogenic carbonate material in the surficial unconsolidated seafloor sediments of the Mediterranean Sea, considering the different sources of inorganic and organic material, the seafloor relief and water circulation patterns. Terrigenous material dominates about three quarters of the Mediterranean seafloor, mainly in the central Mediterranean and the northern parts of the western and eastern Mediterranean. This dominance is attributed to significant riverine inputs and the generally oligotrophic nature of Mediterranean waters. Conversely, biogenic carbonate-rich sediments are more prevalent in the southern parts of the central and eastern Mediterranean where, despite the oligotrophic conditions, the presence of biogenic carbonate is maintained by minimal terrestrial contributions, mainly from Saharan dust deposition. Surface water circulation, although less important than riverine fluxes and primary production in shelf waters, plays an important role in sedimentation processes beyond the shelf break and is responsible for localized open sea sediment distribution patterns. Finally, anthropogenic interventions and expressions of ongoing climate change are discussed in relation to the production, transfer and deposition of both terrigenous and biogenic sediments.