Paleomagnetism of the Miocene Soma basin and its structural implications on the central sector of a crustal-scale transfer zone in western Anatolia (Turkey)

The Izmir-Balikesir Transfer Zone (IBTZ) is a crustal-scale major tectonic feature in western Anatolia accommodating differential extension between the Menderes (MCC) and Cycladic (CCC) core complexes. The kinematics and evolution of the southern part of the IBTZ are well constrained, but its northern continuation remains unstudied. This part is crucial in understanding the complete evolution of western Anatolian tectonics, as well as a possible link between the IBTZ and North Anatolian Fault Zone (NAFZ). In this study, new and extensive paleomagnetic, structural, and stratigraphic data were collected from the Soma basin. These results show that the basin evolved as a part of the IBTZ, including two separate rotational phases. During the first (middle Miocene) phase, deformation was characterized by transcurrent tectonics and associated block rotations as much as similar to 50 degrees clockwise, during which the IBTZ evolved as a wide dextral shear zone. During the second (late Miocene - recent) phase, the mode of deformation in the Aegean region switched from localized to distributed extension, related to the acceleration of the tearing-off of the African Oceanic slab below the Aegean region. This led to the narrowing of the IBTZ as a discrete brittle shear around the Soma basin, manifested by decoupling of dextral strike-slip and normal faulting. In this period, the Soma basin underwent around -21 degrees counter-clockwise rotation. Based on our new results, the IBTZ extends further to the north and possibly interacts with the southern branch of the NAFZ since the late Miocene