Wenk, Linda

The eastern Mediterranean Sea is a complex tectonic area observable from high seismicity and active volcanism. The major tectonic feature in the Eastern Mediterranean is the Hellenic subduction zone where the Nubian Plate dips beneath the Aegean Plate. This process is associated to fault zone activity and numerous earthquakes.
As a consequence of the north-facing subduction a large sedimentary wedge evolved – the Mediterranean Ridge. Here, oceanic sediments deposited since the Mesozoic on the subducting African plate are off-scrapped and accreted to the overriding Eurasian Plate since Miocene .
In accordance to the Critical Taper Theory by DAHLEN et al. (1983), several studies have shown that the physical properties of the basal detachment of such accretionary wedges – the décollement - control their kinematics and mechanics. This also includes their dewatering behaviour and the fluid flow pathways.
Hence, the Mediterranean ridge represents an excellent case study area to investigate the key role of the strength of basal detachment as here the décollement material strongly varies along the subduction zone.
The eastern as well as western part of the Mediterranean wedge is underlying by large evaporite horizons. At some places these accumulated salt reaches a thickness of more than 1.8 - 2 km. These Messinian evaporites act as a weak décollement because of their physical properties. This results in the development of a frontal accreted, thinner wedge with a narrower taper. The taper is the smallest of any accretionary prism documented. Hence, these evaporite deposits have a wide influence on the tectonic behaviour of the wedge.
In addition, the different accretionary modes and therewith fault geometries and activities produce different dewatering behaviour, fluid migration and drainage pathways along the frontal part of the Hellenic subduction zone Hence, numerous fluid venting locations could be recognized by more than hundred mud volcanoes in the Mediterranean Ridge.