The first independent chronology for Middle and Late Weichselian sediments from southern Sweden and the Island of Bornholm

Conventional Optically Stimulated Luminescence (OSL) dating using the equivalent dose distributions of 8 mm aliquots have been extended to key stratigraphical sites in southernmost Sweden and the island of Bornholm. The objective has been to bridge the lack of an independent chronology, which might catalyze a new understanding of the ice flow patterns related to the initiation of the Last Glacial Maximum, and the stratigraphical development during the deglaciation sequence. Sediments from proximal environments are usually 10-15 kyr older than expected from regional stratigraphical correlations and radiocarbon dates of mammoth tusks. We propose that OSL signals are inherited from reworked sediments that were sufficiently bleached prior to glacial or glaciofluvial transportation and deposition. Sediments from distal and beach environments seem to indicate proper depositional ages. Thus, the main Weichselian stadial was preceded by almost 20 kyr of ice free conditions, succeeded by an ice advance from south-southeast before northeasterly ice flow predominated. Major inconsistencies still exists for the final deglaciation. Two distinct environmental reconstructions of the uppermost diamict at two separate sites, both superimposed on a periglacial surface, predict either deposition during subaquatic conditions associated with drifting icebergs after 16 kyr or subglacial sedimentation associated with an ice advance in Oresund. It remains unsolved whether the periglacial surface at the two sites can be correlated or if they represent two different stratigraphical levels. In perspective, the introduction of OSL dates in Skane has identified the periglacial marker horizon or horizons as targets for future intensive dating