Evolution of the Bababurnu Basin and shelf of the Biga Peninsula: Western extension of the middle strand of the North Anatolian Fault Zone, Northeast Aegean Sea, Turkey

The generally transpressional character of the North Anatolian Fault Zone in western Turkey implies a transtensional character in the Northern Aegean Sea. The geological evolution of the basins lying above and immediately adjacent to this fault zone is still poorly understood. Similarly little information exists regarding the tectonic configurations created by the westerly and southerly extension of the middle and southern strands of the North Anatolian Fault Zone into the Northern Aegean Sea, other than what has been inferred using somewhat speculative maps onland. This study combines ∼1600 km of single-channel seismic reflection profiles and piston-core data with detailed land mapping to develop a comprehensive evolutionary model. We suggest that the tectonic system of the Biga Peninsula and the northeastern Aegean Sea are characterized by transpressional broken-slat geometry onland and transtensional broken-slat geometry at sea. The system includes a set of prominent NE-SW-striking faults with considerable strike-slip component in the east (northwestern Turkey and eastern Aegean Sea) and a second set of major NW-SE-striking extensional faults in the west (eastern Greece). We further suggest that rotational wedges form the link between the NE-SW- and NW-SE-striking faults. Detailed mapping of the seismic data and fault linkages with the onland geology demonstrate that the middle strand of the North Anatolian Fault Zone exits into the Aegean Sea near the town of Behramkale and that it extends into the Bababurnu pull-apart basin in the northeastern Aegean Sea as a right-releasing step-over active during the Quaternary.