Segmentation of the Hellenides recorded by Pliocene initiation of clockwise block rotation in Central Greece

New paleomagnetic data from Early Miocene to Pliocene terrestrial sedimentary and volcanic rocks in Central Greece constrain the history of vertical-axis rotation along the central part of the western limb of the Aegean arc. The present-day pattern of rapid block rotation within a broad zone of distributed deformation linking the right-lateral North Anatolian and Kephalonia continental transform faults initiated after Early Pliocene time, resulting in a uniform clockwise rotation of 24.3 +/- 6.5 degrees over a region > 250 km long and > 150 km wide encompassing Central Greece and the western Cycladic archipelago. Because the published paleomagnetic dataset requires clockwise rotations of > 50 degrees in Western Greece after similar to 17 Ma, while our measurements resolve no vertical-axis rotation of Central Greece between similar to 15 Ma and post-Early Pliocene time, a large part of the clockwise rotation of Western Greece must have occurred during the main period of contraction within the external thrust belt of the Ionian Zone between similar to 17 and similar to 15 Ma. Pliocene initiation of rapid clockwise rotation in Central and Western Greece reflects the development of the North Anatolia-Kephalonia Fault system within the previously extended Aegean Sea region, possibly in response to entry of dense oceanic lithosphere of the Ionian Sea into the Hellenic subduction zone and consequent accelerated slab rollback. The development of the Aegean geometric arc therefore occurred in two short-duration pulses characterized by rapid rotation and strong regional deformation. (C) 2012 Elsevier B.V. All rights reserved.