Testing OSL failures against a regional Weichselian glaciation chronology from southern Scandinavia


  • Michael Houmark-Nielsen (e-mail: michaelh@geo.ku.dk), Institute of Geography and Geology, University of Copenhagen, Øster Voldgade 10, DK-1350, Copenhagen K, Denmark


Optically stimulated luminescence (OSL) is used extensively for dating Quaternary sediments. In stratigraphic successions, inter-till beds dated by OSL constrain ages of periglacial or interglacial episodes, while till testifies to ice-sheet oscillations. The majority of OSL results from southern Scandinavia agree with the glaciation chronology predicted by numerical and relative ages, but not all. Overestimation of the expected timing seems to arise from an inherited signal acquired prior to the latest depositional episode. Here, the geological context is examined for solifluction deposits that cap Middle Weichselian periglacial strata and Last Glacial Maximum (LGM) ice proximal deposits showing pre-LGM ages. Suggestions are given as to how the depositional environment may influence the dating results. Even though independent dating anchors the marine Cyprina clay and last interglacial peat bogs to the Eemian interglacial, OSL ages show underestimation by up to 60%. It is discussed whether variations in dose rates after burial could be responsible for this discrepancy. Despite these failures, OSL ranks among the most qualified methods for dating Quaternary sedimentary successions.