Was southern Sweden ice free at 19–25 ka, or were the post LGM glacifluvial sediments incompletely bleached?
2007 (English)In: Quaternary Geochronology, ISSN 1871-1014, Vol. 2, no 1-4, 229-236 p.Article in journal (Other (popular science, discussion, etc.)) Published
Glacifluvial deposits along an ice-marginal zone in Småland, southern Sweden, have been dated using post-IR blue OSL. To test for incomplete bleaching, we adopted two strategies: analysis of modern analogues and small-aliquot dose distributions. Samples of modern fluvial sediments show no significant incomplete bleaching; they yield equivalent doses of only 0.5-2 Gy (~0.25-4% of our glacifluvial sediment doses). Small-aliquot dose distributions do not provide any evidence for incomplete bleaching. The sediments are believed to have been deposited during deglaciation and appear to fall into two age groups: 19-25 ka (mainly sandur sediments) and 33-73 ka (mainly deltaic sediments). Compared to the expected ages (13-15 ka), even the younger glacifluvial OSL ages appear up to 10 000 years (~25 Gy) too old. The ages are nevertheless stratigraphically consistent and correspond between sites; we deduce that the 19-25 ka ages are true deposition ages. For glacifluvial sedimentation to take place on the South Swedish Upland at this time either a very early deglaciation is required, or alternatively ice-free conditions just prior to the LGM. The deltaic sediments (33-73 ka) were most likely not significantly bleached during deposition and thus they date events prior to the latest ice advance.
Place, publisher, year, edition, pages
2007. Vol. 2, no 1-4, 229-236 p.
OSL, glacifluvial, Sweden, Weichselian
IdentifiersURN: urn:nbn:se:su:diva-20866DOI: doi:10.1016/j.quageo.2006.05.007ISI: 000247210000038OAI: oai:DiVA.org:su-20866DiVA: diva2:187392