Anastasia Poliakova, Antony G Brown, David C. W. Sanderson, Alan G Cresswell, Lena G Håkansson, Tomas Goslar, Inger Alsos

A small Arctic floodplain-lake (Tendammen, Colesdalen valley) in Svalbard revealed a laminated sediment sequence with numerous 14C AMS age-depth reversals in its 800 year history. In order to test the hypothesis that the anomalous dates result from catchment erosion and the deposition of reworked sediment and macrofossils, we applied luminescence profiling and flood-sensitive biological proxies. This revealed that many of the dates levels have high portable and laboratory-verified optically and infra-red stimulated luminescence (OSL/IRSL). This is interpreted as resulting from floods delivering partially unbleached sediment-aggregates along with plant macrofossils into the lake. This confirms that luminescence from lake cores can be used to identify flood events from lake sediments, which may often be associated with old carbon from the catchment depending upon catchment history. The flood record generated using a composite age-depth model (SCPs, uplift and selected 14C dates) is compared with other climate records and supports an increasing climatic variability over the last millennia as rapid warming proceeds in the High Arctic.