Testing the potential of luminescence dating of high-alpine lake sediments

The potential of luminescence dating of high-alpine lacustrine sediments is tested on samples taken from three high-altitude moraine-bounded lakes in the Swiss Alps. Independent age control is provided by radiocarbon ages and detailed palynological data in all cases. All samples show good luminescence characteristics (no thermal transfer, good dose recovery and recycling), but two samples show rather low quartz signals. Radioactive disequilibria in the uranium decay chain observed in one sample are accounted for by using a dynamic modelling approach. Because all cores had largely dried out and water content had not been measured after sampling, we developed a modern limnological approach to retrospectively establish palaeo-water content. Applying average water content values from a dataset of modern sediments with similar characteristics to the samples investigated here we obtained ages that match the independent age control. Whereas the low-signal quartz separates consistently underestimate these ages, the polymineral samples more accurately match them, do not suffer from anomalous fading and are thus considered reliable. This study demonstrates for the first time that applying luminescence dating to high-alpine, ice-proximal lacustrine sediments is a promising avenue to obtain a chronology for such depositional environments.

► Establishing water content is a key issue in Luminescence dating of subaqueous sediments. ► We have developed a method to do this for dried-up samples. ► We apply this method to proximal glaciolacustrine sediments. ► Feldspar ages match, while quartz underestimates, independent age control. ► Fine-grain dating is a promising avenue of dating proximal glaciolacustrine sediments.