Investigation of compressional tectonism of Western Blacksea Region (Sarıyer-Şile) through calcite and illite geochronology.

The Western Black Sea region is an important region for the study of the Alpine orogenic belt that developed as a result of the closure of the Neo-Tetis ocean, as it contains records of the evolutionary history of entire Alpine orogeny from subduction to oceanic closure and collision, however the final closure age and the effects of this to the Black sea is still disputed. Debates continue about whether the Black Sea is under an extension or compression regime nowadays, what type of tectonic regime prevails along the Black Sea coast, and the past-to-present activity of faults along its shores. In the scope of the study we investigate syn-collisional faulting events near the Sarıyer-Şile in the western Black Sea region.Within our study area, investigating the evolution of the faults and dating them using geochronological methods will shed light on both the region's history and potential recent active tectonics. We collected some samples of syn-tectonic calcites and illite-bearing fault clay from observed faults. These samples underwent age determination through K-Ar (illite) and U-Pb (calcite) dating methods. The aim is to obtain data on whether the Black Sea is still undergoing extension or, as suggested in some studies, whether the extension regime has ended and a compression regime has resumed. In order to solve this problem, U-Pb age data were obtained for the first time on faults in the region. These ages range from 48 to 55 My, indicating that the reverse faulting associated with the closure of the Intra-Pontid Ocean occurred in Early Eocene times. Samples of injection clay containing illite were also collected from the field using a K-Ar method, and ages ranging 70-140 Ma.