Helena Alexanderson

Waxing and waning ice sheets and changing sea levels have been interpreted from the Quaternary stratigraphic record at Leinstranda, Broggerhalvoya in NW Svalbard. We have identified seven high relative sea-level events, related to glacio-isostatic loading, and separated by at least four glacial events. To establish a chronology for the high sea-level events (interstadials and interglacials) and the intervening glaciations, we have used three different absolute dating methods: optically stimulated luminescence (OSL) of shallow marine deposits, and electron spin resonance (ESR) and radiocarbon (AMS-C-14) dating of fossils contained in these sediments. Of the absolute dating methods, OSL has provided the stratigraphically most consistent dataset and which also matches a biostratigraphically inferred interglacial. The ESR ages of mollusc shells suffer from low precision due to unusually large uranium content in most dated shell samples, which in turn is most likely a result of significant recent uranium enrichment of the sediments. Most radiocarbon ages are non-finite. The results show that the high relative sea-level events range in age from the Saalian sensu lato (>= Marine Isotope Stage, MIS, 6) to the early Holocene (MIS 1), and include events OSL-dated to 185 +/- 8 ka, 129 +/- 10 ka, 99 +/- 8 ka and 36 +/- 3 ka. The methods used by us and by previous investigators of the same site are compared and assessed, and sources of error, accuracy and precision of ages are discussed. (C) 2011 Elsevier B.V. All rights reserved.