PALAEOMAGNETIC ANALYSIS OF DISTRIBUTED NEOTECTONIC DEFORMATION AND BLOCK DEFINITION IN THE ANATOLIDES OF TURKEY

Since final closure of the Neotethyan Ocean in the Eastern Mediterranean with sealing of the Bitlis Suture bordering the Arabian Shield, two forces comprising the continuing northward motion of Arabia into the Neotethyan accretionary collage and westward suction towards the retreating Hellenic Arc have operated during the Neotectonic phase of deformation. Initially post-collisional forces accompanied the uplift of the Anatolian Plateau. Subsequently establishment of the intracontinental transforms comprising the North and East Anatolian Fault zones (NAFZ and EAFZ) by Early Pliocene times has permitted extrusion and rotation of blocks away from the Arabian Syntaxis. We produce an updated summary of Cenozoic palaeomagnetic results from this region which show that deformation has been distributed across the zone between the two transforms. This is expressed by block rotations that vary systematically across Anatolia and range from strongly CCW in the zone of high strain north of the Arabian indenter to near zero in central Anatolia, and then become successively CW in western Anatolia. New palaeomagnetic results from the Cappadocian Ignimbrite Province help to establish the chronology of rotation and permit a comparison with the Sivas Basin to the east where rotation appears to have been concentrated during the Quaternary. The transition of tectonic regimes from compression in the east to extension in the west involves the expulsion of blocks and their rotation along arcuate strike slip faults. In pre-collisional rocks this has compounded earlier rotations imparted during indentation with later rotations linked to tectonic escape. Regional resolution of neotectonic rotation between the Central Anatolian Thrust Zone and the EAFZ identifies comparable rotation across a zone ~200 km wide and suggests that blocks involved in rotation are relatively large away from the influence of the transforms. The weak collage of accretionary terranes sandwiched between the Arabian Indenter and the Eurasian margin appears to have taken up the bulk of the strain imparted by the continuing northward motion of Arabia. This effect has been to expand the radius of the Tauride Arc and the perimeter of extruded crust bordering the limit of the extensional province in western Turkey. The distributed character of neotectonic deformation is illustrated by equivalent polar distributions: both palaeotectonic and neotectonic palaeomagnetic poles show arcuate distributions with poles to best-fitting small circles focussed close to the study area. Differences between the distributed neotectonic deformation resolved from palaeomagnetism and the contemporary GPS record reflect the contrasting time periods being evaluated: the palaeomagnetic record incorporates evolving and changing tectonic regimes whereas the GPS signature has no long term validity within the Anatolian collage; hence the full spectrum of techniques for resolving neotectonic deformation is relevant to unravelling deformation in such regions.