APPLYING PALEOMAGNETIC CONSTRAINTS ON ROTATION AND DEFORMATION OF THE ARABIAN PLATE SINCE THE EOCENE IN SOUTHEAST TURKEY

In the Eastern Mediterranean, convergence of the Afro-Arabian and the Eurasian Plates led to the closure of the Neotethys Ocean and to continent - continent collision by the Miocene. The ongoing convergence gave way to the development of the North and East Anatolian fault zones resulting in westwards extrusion of the Anatolian Plate.

To quantify and determine temporal constraints on the vertical axis rotations of the Arabian Plate and the deformation related to collision, we performed a paleomagnetic study at the northern tip of the Arabian Plate in SE Turkey. Such a study is crucial for both establishing a reference frame for the deformation that took place from Eocene onwards in Turkey, and to further constrain Arabian Plate rotation relative to Africa, caused by the opening of the Red Sea.

We collected 851 sedimentary cores from 78 sites from the northern part of the Arabian Plate ranging from the Eocene to Miocene. The sediments consist of limestones and marls which form a key horizon on the Arabian Plate. A field area comprising the entire northern tip of Arabian Plate was covered.

Relatively small and hardly significant counter-clockwise rotations are observed from the north-western part of the Arabian Plate around Gaziantep, which are in line with previously published results from volcanics in this region. Towards the central northern part near Urfa, Diyarbakır and Mardin, however, the results show no rotation on either side of the Bozova Fault and the Akçakale Graben. Further to the east, in the Şırnak, Siirt, Hakkari regions, mixed local clockwise and counterclockwise rotations up to 15° are observed likely to be caused by thin-skinned thrusting and deformation of the northern tip of the Arabian Plate.

We therefore suggest that the rotations observed in the western part and northeastern edges of the Arabian Plate represent local fault block rotations and do not represent the rotation of the entire plate. The Urfa, Kocak and Mardin regions, however, show no rotations since the Eocene, and were likely part of the rigid Arabian Plate.

Considering the counter-clockwise rotations in the west and no rotations in the east, we speculate that the opening of the Akçakale Graben is related to these differential block rotations.