Holocene Chronology of the Brattforsheden Delta and Inland Dune Field, Sw Sweden

Abstract

Abstract Brattforsheden is a large glacifluvial deposit in southwestern Sweden and associated with it is one of Sweden’s largest inland dune fields. Although the relative ages of the Brattforsheden depos-its are well known, absolute ages from the area are few. In this study we have used optically stimulat-ed luminescence (OSL), surface exposure (10Be) and radiocarbon (14C) dating to provide an absolute chronology for the deglaciation and for the Holocene development of the aeolian dunes. Our data show that the deglaciation took place just before 11 ka (11.5 ± 0.6 ka OSL, 11.3 ± 0.8 ka 10Be), in line with the 14C-based regional deglaciation age. Aeolian dunes started forming immediately after degla-ciation and were active for at least 2000 years, well after vegetation had established. Renewed aeolian activity occurred 270-180 years ago, resulting in the deposition of sand sheets. Comparison between dating methods and studies of OSL dose distributions show that glacial, glacifluvial and littoral sedi-ments suffer from incomplete bleaching and thus that mean OSL ages from such deposits overesti-mate the true depositional age. By using small aliquots and statistical age models, this effect can part-ly be countered. Also, some of the 10Be ages appear too old, which may be due to previous exposure.