The Superiority of Using the ESR Dating Method in Mollusc Shells Compared to 14C and 230Th/234U: A Case Study at the Eastern Part of Konya Closed Basin, Central Turkiye

Abstract

The Konya Closed Basin in central Anatolia preserves Quaternary lacustrine sediments, providing critical evidence for regional paleoclimatic reconstructions. Accurate dating of these is essential for understanding Quaternary climate evolution in the area. In this study, fossil mollusc shells systematically collected from the eastern part of the basin were dated for the first time using ESR spectroscopy. Prior to dating analyses, comprehensive geological investigations and paleontological classifications were conducted. ESR spectra recorded at room temperature on both natural and gamma-irradiated samples revealed freely rotated CO2- radical signals at g = 2.0007. Kinetic studies confirmed the long-term stability of the CO2- radical, with high activation energies (similar to 1.3 eV) and thermal lifetimes exceeding similar to 10(6) years, reconfirming its reliability as a dating signal throughout the Quaternary period. Most ESR ages were derived from the 2.0007 signal, while the signal of the orthorhombic CO2- radical at g = 1.9973 was utilized for a few samples. Dose-response curves were best fitted to a single exponential saturation function and equivalent doses were calculated accordingly. ESR ages ranged from 138 to 6 ka, showing stratigraphic consistency with the sedimentary record. Comparative dating using C-14 AMS and Th-230/U-234 techniques demonstrated general agreement with ESR ages, although minor discrepancies were observed due to the open-system behavior of mollusc shells. Overall, the results support the chronological reconstruction of Holocene to Middle Pleistocene paleoenvironmental events in the Konya Closed Basin.