The Upper Miocene evaporite basins in the Mediterranean Region — a study in paleo- oceanography

The Mediterranan Sea is an evaporite basin that compensates its water deficit by inflow through the Straits of Gibraltar and the Bosporus. Excess salinities are discharged through a bottom counter current. In Plio-Pleistocene cooler periods a water surplus produced a surface outflow and a bottom inflow bringing in waters upwelling in the ancestral Canary current. Water circulation in modern evaporite basins can serve as an adequate model to explain ancient evaporites in the Mediterranean region. The last such high-salinity event comprises Upper Miocene evaporites stretching from southeastern Spain to the Caspian Sea, from the Carpathian Foreland to Yemen. They formed in a series of interconnected basins which pre-concentrated or locally diluted circulating bottom currents. Not normal oceanic saltwater but brackish Ponto-Caspian waters were the source of supply during a period when the Straits of Gibraltar were closed.