The Modern and Ancient Central-Mediterranean Gateways

Gateways, seaways and straits are physical elements of sedimentary basins that are hierarchically distinguished based on their dimensions and temporal persistence. The term ‘gateway’ applies to any oceanographic or marine connection, regardless of its size (width and length), duration and depth (shallow v. deep water). Seaways are broad marine passages, spanning from hundreds to thousands of kilometres in width, and active in the range from hundreds of years to tens of kiloyears in geological time. Straits are narrower passageways, connecting sub-basins within larger marine areas, persisting for no longer than 10 kyr and producing distinct sedimentary records as individual depositional systems. In this paper, we focus on the Modern Central-Mediterranean Gateway, now represented by the coalescent Strait of Sicily, the Egadi Islands and the Messina Strait. These connections, linking the western with the eastern Mediterranean sub-basins, drive continuous tidally modulated water exchange and sediment transport, representing an example of a modern gateway. We then provide field-based examples of the sedimentary record of the former gateway, referred to as the Ancient Central-Mediterranean Gateway, here represented by four major straits that developed during the Pliocene epoch and Quaternary period along localized graben dissecting the southernmost edge of the Italian peninsula. We discuss the geological features of each of these straits, along with their depositional architectures and facies. These elements record the initiation of specific depositional processes, possibly enhanced by a stronger penetration of the Atlantic water inflow from the Gibraltar Strait, reinforced by the onset of the Northern Hemisphere glaciation.