Optically stimulated luminescence dating of Holocene alluvial fans, East Anatolian Fault System, Turkey

Abstract

In this study, the optically stimulated luminescence dating technique was used to determine the time of deposition of alluvial sediment samples from the Turkoglu-Antakya segment of the East Anatolian Fault System (EAFS) in Turkey. The double-single aliquot regenerative dose protocol on fine grain samples was used to estimate equivalent doses ( De). Annual dose rate was computed using elemental concentration of uranium ( U) and thorium ( Th) determined by using thick-source alpha counting and potassium (K) concentrations using X-ray fluorescence and/or atomic absorption spectroscopy. The environmental dose was measured in situ using alpha- Al(2)O3: C chips inside plastic tubes for a year. The two different bulk sediment samples collected from the Islahiye trench yielded ages of 4.54 +/- 0.28 and 2.91 +/- 0.23 ka. We also obtained a 2.60 +/- 0.18 ka age for the alluvial deposit in the Kiranyurdu trench and 2.31 +/- 0.14 ka age for an excavation area called Malzeme Ocagi. These ages were consistent with the corresponding calibrated Carbon- 14 ( 14C) ages of the region. The differences between the determined ages were insufficient to clearly distinguish the disturbance event from the effects of bioturbation, biological mixing, or other sources of De variation in the region. They provide a record of alluvial aggradation in the region and may determine undocumented historical earthquake events.