Geologic evolution of Izmir-Balikesir transfer zone: A crustal-scale structure reorganizing extensional tectonics in Western Anatolia

This thesis attempts to expose the structural implication of a crustal scale zone of weakness, the İzmir?Balıkesir transfer zone (İBTZ) which is a recently recognized as strike-slip dominated shear zone that accommodates the differential deformation between the Cycladic and Menderes core complexes within the Aegean Extensional System. Here, I present new stratigraphic, structural, paleomagnetic, geochronologic and kinematic data and 1/25,000 scale mapping of Miocene to Recent rock units within the İBTZ. The results point out that the İBTZ is a transtensional brittle shear zone that deforms the pre-Neogene basement rock units, the early-middle Miocene volcano-sedimentary units and the Plio?Quaternary continental units. The analysis of large-scale structures and fault kinematic data indicate that three different deformation phases prevailed in the İBTZ 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 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 İzmir 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 core complex. 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 extensional deformation. During Phase 3, the İBTZ 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. With respect to new paleomagnetic data, İBTZ is a clockwise rotated structural shear zone that separated two counterclockwise rotated rigid blocks; the Menderes and Cycladic complexes, and can be interpreted as the surface reflection of the teared part of the subduction beneath the Anatolian plate. Keywords: paleomagnetism, block rotation, geochronology, kinematic analysis, Izmir-Balıkesir Transfer Zone, western Anatolia.