Kinematics of the Havran-Balıkesir Fault Zone and its implication on geodynamic evolution of the Southern Marmara Region, NW Anatolia

Cenozoic convergence, collision and subsequent subduction between African and Eurasian plates are accommodating in overriding Eurasian plate both forming the Aegean extension and the North & East Anatolian fault zones. To understand the kinematic evolution of upper crust, here we provide new paleostress data from the Havran-Balıkesir Fault Zone located at the interaction area between the North Anatolian Fault Zone (NAFZ) and west Anatolian extensional structures. Paleostress reconstructions of fault-slip data reveal that three distinct deformation phases have been experienced in the region. Phase 1 is represented by left-lateral strike-slip faulting with reverse component in the pre-Pliocene period. The Phase 2 is characterized by approximately N–S trending contraction and associated E–W trending extension in Plio–Quaternary, which is spatiotemporally linked to the initiation of NAFZ through the area. The youngest deformation, Phase 3 is attributed to NE–SW trending extension and NW-SE-trending contraction commenced by the Quaternary transpressional tectonics in Southern Marmara Region. These results show that the main contraction axes have been experienced a spectacular anticlockwise rotation (from NW-SE to E-W), which is associated with; (i)the propagation geometry of the NAFZ into the region (ii)slab roll-back and retreat and tearing process on the Aegean subduction system, and (iii)the existence of inherited structures of the İzmir-Balıkesir Transfer Zone