Effects of the Africa-Europe collision on the seafloor morphology in eastern Mediterranean after the data of the PRISMED II Survey

Abstract

The main physiographic features of the Eastern Mediterranean basin result a long evolution presently marked by the convergence of the African and Eurasian plates which tend to reduce and close the oceanic space. Since the Messinian salinity crisis, about 5 My BP, the eastern basin has separated from the Central Mediterranean domain by an orographic axis linking the Nile delta to the Cyprus island through a prominent submarine relief, the Eratosthenes seamount which reaches a water depth of 810 m and towers the surrounding basins of about 2000 m depth. The present configuration of the seafloor of this area is under a tight control of two major factors active during the Pliocene-Quaternary and even now. It is firstly, the influence of tectonics related to the convergence of the African/Eurasian blocks which generates important scarps on the Eratosthenes seamount. The second factor corresponds to the sedimentary transfer and accumulation through the Nile deep sea fan which spreads largely northward wrapping the Eratosthenes seamount. A major consequence of this important sedimentary accumulation is the remobilization of the Messinian evaporitic layer, buried under the Nile sediments, which tends to upraise as diapiric structures resulting in a rugged morphology of the seafloor.