Problems and potential of OSL dating Weichselian and Holocene sediments in Sweden
2010 (English)In: Abstracts and Proceedings of the Geological Society of Norway, NGF Number 1, 2010, 2010, 3-4 p.Conference paper (Other academic)
Recent OSL dating of various Late Quaternary deposits in Sweden has resulted in several sets of ages that appear inconsistent with geological interpretation; they usually overestimate the expected age. We explore the problems and potential of OSL dating in Sweden by analysing quartz OSL-ages from several known-age sites in Sweden and by investigating their luminescence properties. Two difficulties in obtaining accurate and precise ages are incomplete bleaching and low-sensitivity quartz. Incomplete bleaching can give rise to age overestimation, but the importance of this effect can be minimised by selecting suitable sediment facies, although for some settings unexplained overestimates still remain. Low quartz OSL sensitivity leads to practical problems in measurements and larger uncertainties in dose estimates, but not necessarily to systematic age overestimation. Sites that contain Dala sandstone clasts and/or sediments that may have had extensive reworking during the Quaternary seem to provide high-sensitivity quartz. We consider such sites to show the most potential for accurate and precise OSL-dating in Sweden.
For typical Swedish material, the scatter in doses makes OSL-ages less precise and the method cannot usually compete with radiocarbon dating for young (Late Weichselian-Holocene) sediments unless the deposits simply lack organic material. The lowest overall uncertainty for the samples in this study is 4% of the age (average is 7%) and we expect that OSL ages from Sweden cannot be much better known than this. A 5-10% precision in age is, however, usually not a problem for older sediments and OSL can advantageously be used to date for example interstadial deposits. Nevertheless, given the Swedish record of OSL-difficulties it is important to work with multiple samples and adapt analytical protocols to each site or sample to give credibility to the results.
Place, publisher, year, edition, pages
2010. 3-4 p.
IdentifiersURN: urn:nbn:se:su:diva-50713OAI: oai:DiVA.org:su-50713DiVA: diva2:382298
29th Nordic Geological Winter Meeting, Oslo, Norway, 11-13 January 2010.