PALEOMAGNETIC RESULTS OF NEOGENE VOLCANIC ROCKS IN EASTERN ANATOLIA; EVIDENCE OF BLOCK ROTATIONS ALONG THE EAST AND NORTH ANATOLIAN FAULTS

Paleomagnetic studies of Anatolia on the Neogene rocks have been interpreted mostly with the westards excursion of Anatolia due to the collision between the Arabian plate and the Eurasian plate. However, inside the collision zone in East Anatolia, no paleomagnetic data are available. In order to describe the deformational history of Eastern Anatolia during the Neotectonic period we carried out a palaeomagnetic study on Miocene to Quaternary volcanic rocks at 100 different sites on the basis of their geographical position and avaliable ages.

The results indicate that the study area could be divided into four main crustal blocks during the Neotectonic period. These blocks are termed by the Van Block (VB), Kars Block (KB) the Pontide Block (PB) and the Anatolian Block (AB). Close to the collision zone in the AB, counterclockwise rotation of -37.0°±9.6° is obtained in Late Miocene, while clockwise rotation of 21.3°±8.4° is obtained in the VB during the same time. Further north, however, a region with no significant rotation is defined, during Late Miocene-Quaternary in the KB. The differences in rotations between these blocks are observed across the NE-SW trending East Anatolian and NE Anatolian Fault Zones. The significant differences in the amount of rotation between the AB, PB and the VB indicate that most of the deformation occurred during the Upper Miocene and Pliocene time. Our results are in good agreement with seismological and GPS data obtained in East Anatolia.