Mediterranean Seafloor Features: Overview and Assessment

Abstract

This paper focuses on Mediterranean seafloor features in view of refining interpretations of the seabed that formed in an interplate-intercontinental system. This survey takes into account maps prepared for the International Bathymetric Chart of the Mediterranean (IBCM) and other recent investigations using various technologies (conventional and multinarrow beam bathymetry, sonograph, seismic, side-scan sonar, and dive surveys). The study assesses the geomorphology in light of plate tectonic considerations developed during the past 15 years. Mediterranean features result essentially from (I) the long-term succession of tectonic displacement induced by continuous motion of Africa towards Europe, and (2) progressive closure of the sea involving a series of submarine-insular sills that played a significant role during the Messinian salinity crisis, climatic-eustatic changes, and erosional events. The Mediterranean area can be subdivided into three geomorphic settings. (1) The relatively stable margins, from off Tunisia to the Middle East, correspond to the submarine prolongation of the African plate (includes the Pelagian Sea and Gulf of Sirte). The eastern sectors were influenced by Nile-derived deposition. (2) Unstable convergent (subducted) regions include compressive margins and associated deep-sea floor (i.e., Mediterranean Ridge, Arc-Trench systems, Aegean Sea, and Adriatic Sea) where the seafloor commonly includes a structurally broken, complex topography. (3) Rifted regions formed recently as a result of extension and foundering (i.e., Western Mediterranean Basin, Tyrrhenian Sea). The central part of latter sectors, particularly in the Western Basin, is occupied by bathyal plains bordered by large deep-sea fans formed by gravity depositional processes. The seafloor in such regions is locally modified by piercement features of volcanic or salt diapirism origin.