The tectonics of Cyprus Arc: a model of complex continental collision

Cyprus Arc is an arcuate depression that wraps the southern reaches of Cyprus in the easternmost Mediterranean Sea. The tectonic regime that constrains Cyprus Arc is generally considered to be that of collision between northward moving Africa and southward moving Eurasia, and the Arc is the site where a Tethyan lithospheric toe off NE Africa is being subducted northward under the Anatolian sub-plate. Evidence to this process is the subduction of Eratosthenes Seamount, located 100 km south of Cyprus, the northern section of which is down-faulted as it subsides toward the Arc. Since Eratosthenes Seamount is rooted in continental lithosphere, and the Troodos ophiolite in southern Cyprus is an oceanic crust, the convergence of Africa and Anatolia along Cyprus Arc was considered a prime example of ongoing obduction. However, abundant GPS evidence shows that Anatolia is moving not southwards but westwards, and the rate of displacement exceeds 20 mm/yr, which is approximately 20 times faster than the rate of the northwards motion of Africa. Earthquakes reflect that composite dynamic model along Cyprus Arc, and compressional, extensional and strike-slip crustal motion co-occur along Cyprus Arc. Seismic reflection profiles show that the structural layout of the eastern segment of Cyprus Arc, from Hecataeus Plateau to Hatay region, is transtensional, emphasizing the prominence of the westwards motion of Anatolia. This composite pattern of the motion of the tectonic plates in the easternmost Mediterranean suggests that the slow northward motion of Africa leads indeed to subduction along Cyprus Arc, but this subduction is not counteracted, because Anatolia is moving much faster westwards. This dynamic setup of plate motion accounts for the composite pattern of earthquake distribution, and is compatible with large lateral displacements along strike of subduction zones and collisional fronts.