Fission-track chronology of the North Anatolian fault zone

The North Anatolian fault zone is one of the most prominent features of Neogene tectonics within the whole Mediterranean region, but has never been investigated by means of apatite fission-track thermochronology. During the last decades, seismicity and GPS velocity fields of the Aegean-Anatolian area have been well investigated and yielded a consistent picture of present-day plate motions. The Anatolian microplate of central and western Turkey is characterized by a coherent motion with counterclockwise rotation. Its westward displacement along the arcuate North Anatolian fault zone is slightly less than 30 mm/a. The Aegean region is subjected to N-S extension in addition to the rotation with Anatolia. Compressional strain occurs perpendicular to the Hellenic arc. However, our understanding of the transitional period between the Mesohellenic orogeny (Eocene-Oligocene) and the establishment of the modern plate-tectonical configuration is rather poor. The onset of subduction of the Mediterranean slab under the continental Aegean region, and the plate-tectonical individualization of the Aegean- Anatolian microplate have probably not occurred at the same time. It is very likely that the complete mechanical separation of the Aegean-Anatolian microplate from main Eurasia occurred later, in consequence of a gradual or stepwise development. The western prolongation of the North Anatolian fault zone consists of two main branches of transtensional fault zones which delimit the so-called Marmara block of northwestern Turkey and the northern Aegean sea. The northern branch comprises the pull-apart basins of the Marmara sea and the North Aegean trough. The present research proposal is designed for a better understanding of the exhumation histories, vertical kinematics and geomorphological developments of the tilted shoulders adjacent to these young pull-apart basins. Fission-track thermochronology of pre-Neogene basement rocks should help to answer the following questions: 1. What is the maximum age of extension and dip-slip tectonics along the quoted pull-apart basins? 2. How was the cooling and exhumation history, as well as the vertical kinematic development of tilted blocks adjacent to the main fault planes? 3. What was the influence of dip-slip tectonics, uplift and tilting upon the development of coastal morphologies and subaerial drainage pattern? 4. Does the improved knowledge of extensional tectonics, exhumation histories and geomorphology yield a better understanding of east Mediterranean plate tectonics?

The North Anatolian fault zone is one of the most prominent features of Neogene tectonics within the whole Mediterranean region, but has never been investigated by means of apatite fission-track thermochronology. During the last decades, seismicity and GPS velocity fields of the Aegean-Anatolian area have been well investigated and yielded a consistent picture of present-day plate motions. The Anatolian microplate of central and western Turkey is characterized by a coherent motion with counterclockwise rotation. Its westward displacement along the arcuate North Anatolian fault zone is slightly less than 30 mm/a. The Aegean region is subjected to N-S extension in addition to the rotation with Anatolia. Compressional strain occurs perpendicular to the Hellenic arc. However, our understanding of the transitional period between the Mesohellenic orogeny (Eocene-Oligocene) and the establishment of the modern plate-tectonical configuration is rather poor. The onset of subduction of the Mediterranean slab under the continental Aegean region, and the plate-tectonical individualization of the Aegean- Anatolian microplate have probably not occurred at the same time. It is very likely that the complete mechanical separation of the Aegean-Anatolian microplate from main Eurasia occurred later, in consequence of a gradual or stepwise development. The western prolongation of the North Anatolian fault zone consists of two main branches of transtensional fault zones which delimit the so-called Marmara block of northwestern Turkey and the northern Aegean sea. The northern branch comprises the pull-apart basins of the Marmara sea and the North Aegean trough. The present research proposal is designed for a better understanding of the exhumation histories, vertical kinematics and geomorphological developments of the tilted shoulders adjacent to these young pull-apart basins. Fission-track thermochronology of pre-Neogene basement rocks should help to answer the following questions: 1. What is the maximum age of extension and dip-slip tectonics along the quoted pull-apart basins? 2. How was the cooling and exhumation history, as well as the vertical kinematic development of tilted blocks adjacent to the main fault planes? 3. What was the influence of dip-slip tectonics, uplift and tilting upon the development of coastal morphologies and subaerial drainage pattern? 4. Does the improved knowledge of extensional tectonics, exhumation histories and geomorphology yield a better understanding of east Mediterranean plate tectonics?