The Messinian Guadalhorce corridor: the last northern, Atlantic–Mediterranean gateway

Messinian marine deposits of the Guadalhorce River valley in southern Spain record evidence of the last northern gateway that existed between the Mediterranean and the Atlantic. They comprise sandstones and conglomerates with unidirectional cross-bed sets up to nearly 1 km long in their down-sedimentary-dip direction. These cross-bed sets relate to extremely fast (1.0–1.5 m s⁻¹) bottom currents flowing from the Mediterranean into the Atlantic. The Guadalhorce gateway (which had a maximum width of 5 km and a maximum water depth of 120 m) was an important element controlling the Messinian pre-evaporitic oceanic circulation in the Mediterranean Sea, as it acted as a major outflow channel. Its closure limited the exchange of water between the Atlantic and the Mediterranean to the Rifian corridors of Morocco, inducing water-mass restriction and stratification in the western Mediterranean immediately prior to the `Messinian Salinity Crisis'.