Morphology of a Pre-collisional, Salt-bearing, Accretionary Complex: The Mediterranean Ridge (Eastern Mediterranean)

Abstract

The Eastern Mediterranean Sea is a remnant of a deep Mesozoic oceanic basin, now almost totally consumed as a result of long-term plate convergence between Eurasia and Africa. The present-day surface morphology of the Eastern Mediterranean relates both to the early history of formation of the deep basins and the recent geodynamic interactions between interfering microplates. Among the most conspicuous morphologic features of the basin is an arc-shape, elongated and wide, bathymetric swell bisecting the entire basin from the Ionian to Levantine areas, known as the Mediterranean Ridge. During the last decade this tectono-sedimentary accretionary prism, which results from the Hellenic subduction, has been intensively surveyed by swath mapping, multichannel seismic profiling and deep dives. We present here, and briefly discuss, the main morphological characteristics of this feature as derived from swath bathymetric data that considerably help to better assess the lateral and north-south morphostructural variability of the Mediterranean Ridge. This study reveals that the characteristics and morphostructural variability of the Mediterranean Ridge are related to: (1) a specific incipient collision geodynamic setting south of Crete, where the African and Aegean continental margins are nearly in contact, (2) a unique regional kinematics, controlled by frontal convergence south of Crete (central Mediterranean Ridge) and oblique subduction with opposite sense of shear for the western (Ionian) and eastern (Levantine) domains of the Mediterranean Ridge, that explain the lateral variations of deformation and (3) particularities of its sedimentary cover, which includes massive salt layers within the outer Mediterranean Ridge and local salt deposits within the inner domains, that control the north-south morphostructural variability of the sedimentary wedge.

Two-stage growth of the Calabrian accretionary wedge in the Ionian Sea (Central Mediterranean): Constraints from depth‐migrated multichannel seismic data

“…4 to 8). As already identified for the Western Mediterranean Ridge, the distribution of Messinian evaporites is quite heterogeneous, as a result of the complex configuration of the basins in the foreland at the time of deposition (Chaumillon et al, 1996;Reston et al, 2002b;Huguen et al, 2006). Our depth seismic reveals that beneath the center of the IAP, the thickness of Messinian Mobile and Upper Units reaches 1.2 km (Fig.…”

“…We suggest that the 1.2 km thick Messinian section (de Voogd et al, 1992;Minelli and Faccenna, 2010;Polonia et al, 2011), actually imaged beneath the center of the Ionian Abyssal Plain is not representative of the average thickness deposited in the entire Ionian basin, 5 Ma ago. We propose that this thicker Messinian section was deposited in sub-basins of the Ionian Abyssal Plain (Huguen et al, 2006), that formed by the activity of the NW vergent reverse faults during the pre-Messinian times (Fig. 3) (Hieke et al, 2005;Gallais et al, 2011).…”

“…et al, 1996Chaumillon and Mascle, 1997;Reston et al, 2002aReston et al, , 2002bKopf et al, 2003;Huguen et al, 2006):…”

Constraints on fluid flow processes in the Hellenic Accretionary Complex (eastern Mediterranean Sea) from numerical modeling

“…(c) Sample region of the gravity cores taken by Kopf et al [2012], which were used for the geotechnical analysis in this study. Bathymetric chart from Huguen et al [2006]. has evolved since approximately 19 Ma (million years before present) .…”

The Hellenic deep sea observatory: Science objectives and implementation

“…The characteristics and morphostructural variability of the Mediterranean Ridge are related to: (1) incipient collision south of Crete, where the African and Aegean continental margins are nearly in contact; (2) unique regional kinematics, controlled by frontal convergence south of Crete (central Mediterranean Ridge) and oblique subduction with an opposing sense of lateral shear for the western (Ionian -dextral shear) and eastern (Levantinesinistral shear) domains of the Mediterranean Ridge; and (3) peculiarities of its sedimentary cover, which includes massive salt layers within the outer Mediterranean Ridge and local salt deposits within the inner domains, both of them controlling the north-south morphostructural variability of the sedimentary wedge (Huguen et al, 2006). The Western Hellenic Trench particularly displays a tectonically complex, largely compressive setting, related to (i) the northeastward underplating and subduction of the Ionian oceanic lithosphere below the overriding Aegean microplate and (ii) the "escape tectonics"regime accommodated by dextral strike slip along the trench, at the interface between the deformed sediments of the East Mediterranean Ridge and the rigid backstop of the Aegean microplate (McKenzie, 1978;Le Pichon et al, 1995;Kreemer and Chamot-Rooke, 2004).…”