Helena Alexanderson

Recent OSL dating of various Late Quaternary deposits in Sweden has resulted in several sets of ages that appear inconsistent with geological interpretation; they usually overestimate the expected age. We explore the problems and potential of OSL-dating in Sweden by analysing quartz-OSL-ages from several known-age sites in Sweden and by investigating their luminescence properties. Two difficulties in obtaining accurate and precise ages are incomplete bleaching and low-sensitivity quartz. Incomplete bleaching can give rise to age overestimation, but the importance of this effect can be minimised by selecting suitable sediment facies, although for some settings unexplained overestimates still remain. Low quartz OSL sensitivity leads to practical problems in measurements and larger uncertainties in dose estimates, but not necessarily to systematic age overestimation. Sites that contain Dala sandstone clasts and/or sediments that may have had extensive reworking during the Quaternary seem to provide high-sensitivity quartz. We consider such sites to show the most potential for accurate and precise OSL-dating in Sweden.