Structural evidence for strike-slip deformation in the İzmir-Balıkesir transfer zone and consequences for late Cenozoic evolution of western Anatolia (Turkey)

The analysis of large-scale structures and fault kinematic data indicate that three different deformation phases prevailed in the Ä°zmir Bay region during the late Cenozoic. The first phase (Phase 1) is characterized by N-S directed extension and E-W contraction that gave way to the development of strike-slip faults with normal components and likely took place during the early (?) to late Miocene. This transtensional phase, forming the volcano-sedimentary basin of deposition was overprinted by the second phase (Phase 2) which is characterized by variable extension and contraction directions indicating wrench- to extension-dominated transtension. The structures related to Phase 2 are observed all around the Ä°zmir Bay and indicate a distributed nature of the deformation that probably took place during the early Pliocene, coeval with the end of the activity of the Mid-Cycladic Lineament and the last exhumation of the central Menderes Massif. The latest deformation phase (Phase 3) is characterized by an association of NW-SE trending left-lateral and NE-SW trending right-lateral strike-slip faults and E-W trending normal faults forming transtensional deformation. During Phase 3, the Ä°BTZ evolved from a wider shear zone into a relatively narrow discrete fault zone by the late Pliocene, during which the strike-slip and extensional deformation were completely decoupled from each other. The field-based evidence for strike-slip deformation from the region has only recently been recognized, but has very important implications for understanding the deformation styles and coupling of Aegean-West Anatolian extensional deformation system along the Ä°BTZ. We conclude that the Ä°zmir Bay Basin developed during the Plio-Quaternary within the dextral Ä°BTZ.