Strain Partitioning Between the Izmir-Balikesir Transfer Zone and the North Anatolian Fault Zone, NW Turkey

The present tectonic framework of the Western Anatolia has been dominated by two major deformations. The first one is the product of the slab-edge processes related to the convergence between Eurasian and African plates along with the Aegean-Cyprean subduction system since the Oligocene, and the second one is the westwards escape of Anatolian Block along the North Anatolian Fault Zone (NAFZ) since the late Miocene. The first one resulted in a widespread extensional deformation in the Western Anatolia and the Aegean region and is associated with slab-detachment and slab-tear processes that gave rise to the development of dynamic topography and various core-complexes (e.g., Cyclades and Menderes). Recent studies have shown that the deferential extensional strain between the core complexes in the region has been accommodated by strike-slip dominated transfer zones, the İzmir-Balıkesir Transfer Zone (İBTZ), which developed (sub)parallel to the extension direction and accommodate differential extension and rotational deformation in the region. The second one gave way to the development of a complex strike-slip deformation pattern and an array of pull-apart basin complexes throughout the northern margin of the Anatolian Block. The NAFZ and İBTZ interact around the Balıkesir-Bursa region resulting in a very peculiar deformation style due to partitioning of strain between these major structures.
This study aims at unraveling how the strain partitioning operates between İBTZ and NAFZ and to reveal the kinematic constraints that produced the present tectonic scheme in the region. The geometry and kinematics of the faults are determined by analyzing 2773 fault slip data obtained from 49 sites evenly distributed throughout the study area. The preliminary results show that the İzmir-Balıkesir Transfer Zone localized after Miocene with the decoupling of strike-slip faults, and to the episodic exhumation of the metamorphic core complexes. The focal mechanism solutions of the recent earthquakes support this decoupling and manifest the seismic activity of the İBTZ. This study is supported by a Tübitak Project, Grant Number of 117R011.