Physical properties and state of the crust and upper mantle of the Eastern Mediterranean Sea deduced from geophysical data

Abstract

By evaluating the geophysical information available for the Eastern Mediterranean Sea (EMS), a crustal thickness map and some conclusions as to the nature of the crustal type were drawn. It was found that the Ionian Abyssal Plain is floored by an oceanic type of crust which is 14 km thick and covered by sediments of the order of 8 km thick. The Herodotus Abyssal Plain in the Levantine Sea is floored by a crust 22 km thick and covered by sediments ranging between 10 and 15 km thick. The Eastern Mediterranean Rise, extending more or less continuously from the Apulian Plateau to Rhodes and the south of the Antalya Basin, is of a thickness ranging between 28 and 34 km. The thickness of its sedimentary cover is of the order of 10 km. The borders of the Eastern Mediterranean Sea are built up of thick continental crust. For example the Hellenides of Western Greece range between 40 and 44 km thick and Western Turkey has a similar crustal thickness. The crust of Sicily also exceeds 40 km whereas the southern and eastern borders of the EMS are approximately 30–32 km thick. Tectonically the northern border of the EMS is built up of active continental margins defined by the Calabrian, Hellenic and Cyprus—Antalya Arcs, whereas the southern border represents a passive continental margin controlled mainly by subsidence and stretching. To the east, the Dead Sea Megashear limits the area. The deep basins of the Eastern Mediterranean Sea are tectonically controlled by subsidence and partial stretching. The Mediterranean Ridge or Rise is still an area of dispute, regarded by some authors as a subsiding continental fragment and separated from the Hellenic Arc by the Hellenic Trench, whereas others consider it to be a zone of crustal shortening, thickened mainly by thrusting. Both the western and southwestern borders of the Mediterranean Rise and the Hellenides are controlled by compressional processes similar to those deforming the Calabrian Arc. The Stravo and Pliny trenches to the east-southeast border of the Hellenic Arc are partly affected by strike-slip movements. Various plate-tectonic models of the area have been proposed by several authors, though the complexity of the deformation hardly permits reliable reconstructions. The lack of reliable paleomagnetic information and the absence of linear magnetic anomalies do not favour the application of plate tectonic concepts. Vertical processes due to the uprising of lithothermal systems below the Hellenic and Calabrian arcs may also be regarded as the driving force controlling the present-day deformation.