Chronostratigraphy of the Late Glacial Żabinko site (western Poland) and investigation of the dose rate variability

The Żabinko exposure (western Poland) reveals the classic fluvio-aeolian succession known from studies in the European Sand Belt. Previous chronostratigraphic studies were mainly based on uncalibrated radiocarbon dates from organic sediments and thermoluminescence dating. The picture visible from these studies indicated a number of discrepancies between these methods. The new research in this exposure was based on optically stimulated luminescence (OSL) dating and calibrated radiocarbon dates. The results obtained indicate a general discrepancy between the results achieved by these two methods. While the radiocarbon dates provide some meaningful picture and allow correlation with previous studies, the results of OSL dating do not allow for a chronological model of sedimentary processes. The OSL dates show large inversions of the results and are clearly younger than the other dating results. Detailed analysis of OSL measurements shows radioactive disequilibrium and variability linked to differential stratification of sediments, significantly impacting the assessment of environmental dose rates. We believe that this atypical variability is presumably the result of postdepositional processes, such as changes in groundwater levels, chemical weathering and radionuclide migration.