Active deformation of a segment of arc: the strait of Kythira,Hellenic arc,Greece

A field analysis of Late Cenozoic faults has been carried out in the southwest Hellenic arc, on the islands of Kythira and Antikythira as well as on both sides of the strait, in southeast Peloponnisos and western Crete. The previously unknown geological structure of Antikythira is briefly described. Together with accurate bathymetric data obtained using a multi-beam echo sounder on submarine fault scarps, the results of studies on land lead to a new interpretation of the neotectonic deformation of this segment of the Hellenic arc. The submersion of the strait is a consequence of extension related to normal faulting, the extension rate being faster than in adjacent segments of the arc. The direction of extension related to Late Pliocene-Quaternary normal faulting is determined from on-land information. The existence of oblique en échelon normal faults indicates that dextral deformation plays a role within the Kythira strait, in connection with the opening of the adjacent Cretan Sea triggered by subduction beneath the Hellenic arc. The whole pattern of fault systems in southeast Peloponnisos, as inferred from teledetection and field studies, is consistent with the clockwise rotation that has been independently proposed and verified by palaeomagnetic studies. The Kythira strait thus provides an example of a complex transform-extensional deformation and rotation between two major segments of external arc.