Adding another piece to NE European Aeolian Sand Belt puzzles: a sedimentary age case study of Pērtupe site, eastern Latvia

The NE European Sand Belt spreads over three Baltic States and consists of dunefields usually lying directly atop former glacial lakes. Some of these dunefields have so far been investigated in terms of their sediment properties and chronology. Nevertheless, there is a limited number of profiles where both glaciolacustrine and aeolian sediments co-occur and thus provide a unique environmental record where wet and dry conditions alternate. In this study, we investigated the Pērtupe profile, eastern Latvia, that represents sediment transition from glaciolacustrine silt to aeolian sand and along with a few known profiles helps to distinguish three sediment units as glaciolacustrine, transitional, and aeolian. This is most likely typical of the sediments of the NE European Sand Belt. A microstudy of sediments revealed that both aeolian and periglacial conditions alternated. However, this seems to be better expressed through prevalence of weathered quartz grains with some fracturing in the transitional unit. Aeolian deposition did take place in drier conditions, but micaceous interlayers argue for occasional watertable-controlled events. This study provides one more support regarding a start of aeolian deposition at ca. 11.3 ka in the NE European Sand Belt, which took place instantly after deglaciation rather than after a few-thousand-year hiatus. Enhanced aeolian activity is known from the region at a similar time frame, but mostly as its maximum or termination, meaning that aeolian activity must had been asynchronous.