Spatio-temporal variations on the vertical deformation rate of the NW Anatolian Block: Luminescence chronology of the Sakarya River terraces

The study area (40-40.45°N and 30-32.15° E) exhibits a high topography (1200-1800 m elevation) and bounded by the Galatean Massif at east, Pontide Mountain Range to the north, the Central Anatolian Plateau to the south and the Marmara Sea to the west. The region is actively been deformed and dissected by the active branches of the dextral strike slip North Anatolian Fault Zone (NAFZ) and the Sakarya River (SR) system. We have investigated the depositional terraces formed along the main course and the major tributaries of the SR to reveal the dynamics of the terrace formation by climate, sea level changes and also to quantify the variations in rate of vertical deformation within the current geodynamics of the NW Anatolian Block. The geometry of the main river (1) and its tributaries (4) allow us to determine the spatio-temporal variations in four vertical (100 km) and three along fault sections (200 km) since the last ~150 ka.

Up to date, we have mapped 23 distinct evenly scattered multi-step terrace staircases along the main river course and its 6 major tributaries. Mapping is aided with high precision rtk-GPS profiling and SfM photogrammetry using UAV. The dating is carried by luminescence geochronology (OSL and p-IRIR) to constrain the timing of the formation and also abandonment of each depositional terrace step.

The results show that the focus region is under control of vertical deformation at a rate of 0.6-0.7 mm/year regardless from the distance to the main strand of the NAFZ. There is also evidence that this rate has been decelerated from ~1.0-1.1 mm/year since the last 100 ka. The distinct variations in the calculated uplift rates along the profiles reveal apperant southwards tilting in between the active branches of the NAFZ and also within the block.

This study is funded by TUBITAK 117Y426 project grant.