Luminescence Surface Exposure Dating and Paleoseismic Insights from the Kuşadası Fault Zone, Western Türkiye

Exposure dating has become a critical tool in addressing specific geoscientific challenges, including glaciology, active fault studies, and environmental reconstructions. Cosmogenic exposure dating (e.g., ³⁶Cl) and luminescence surface exposure dating are widely used techniques, often complementing each other. In active tectonic studies across Türkiye, cosmogenic ³⁶Cl dating has been applied extensively to active faults to elucidate paleoseismic histories and slip rates. Although luminescence surface exposure dating is relatively new in this context, its initial applications along the Manisa Fault in Western Türkiye have shown promising results. In this study, we focus on the Kalafat and Yavansu faults within the Kuşadası Fault Zone, which is considered the eastern continuation of the Samos Fault that ruptured during the 30 October 2020 earthquake. This region, characterized by N-S extensional tectonics with horst-graben structures and normal faulting, offers well-preserved fault scarps that serve as natural laboratories for exposure dating.

Preliminary luminescence depth profiling of scarp samples and optically stimulated luminescence (OSL) dating of associated colluvial wedges provide valuable insights into the paleoseismic history of these faults: (i) Luminescence profiling revealed stable signal limits at ~6 mm, with intensity increasing with depth; (ii) Calibration against prior cosmogenic dating yielded uppermost ages of ~15 ka for KF and ~8 ka for YF; (iii) OSL dating of colluvial wedge bases produced ages of 16.56 ± 1.77 ka for KF and 14.45 ± 0.74 ka for YF. These results indicate significant seismic activity along both faults during the Late Pleistocene, consistent with regional tectonic processes. This research underscores the utility of integrating luminescence surface exposure techniques with cosmogenic methods for refining paleoseismic chronologies. This study is fully supported by the Dokuz Eylül University Scientific Research Project (Project No. FBA-2023-3042).