Beryllium isotope variations in sediment cores from the Alpha Ridge, Arctic Ocean
2008 (English)In: Arctic Palaeoclimate and its Extremes (APEX): second international conference and workshop, 2008, 92- p.Conference paper (Other academic)
The Healy-Oden Trans-Arctic Expedition 2005 (HOTRAX) recovered cores along a transect across the Arctic Ocean. Here we present results from measurements of seawater-derived beryllium isotopes in cores HLY0503-09JPC and HLY0503-14JPC from the Alpha-Mendeleev Ridge. The intention of measuring beryllium (Be) isotopes is to establish a chronostratigraphy as the decrease of 10Be concentration (half-life = 1.51 Million years) with depth in the cores may provide first order sedimentation rates. The isotopes 10Be and 9Be were extracted simultaneously from sample aliquots by using a leaching procedure. To eliminate the dilution effect of beryllium caused by short-term changes in sedimentation rate and grain size variability, the 10Be concentration was normalized to the stable isotope 9Be. The results show low downcore 10Be concentrations and subsequently sedimentation rates on the order of mm/ka in both cores from the Alpha Ridge. However, we note two indications suggesting that our calculated sedimentation rates from the beryllium results may not be valid and requires further analysis: 1) the decrease of 10Be down core does not follow a well defined trend; 2) a comparison with preliminary results from nannofossil studies of cores HLY0503-14JPC and HLY0503-08JPC located nearby HLY0503-09JPC indicates much higher sedimentation rates than we obtained from the 10Be data (Backman and Fornaciari pers. comm.). The pronounced decrease of 10Be with core depth may imply a stronger effect of sea ice shielding of atmospheric inputs, whereas the 9Be increase with depth may point to a stronger continental input of 9Be.
Place, publisher, year, edition, pages
2008. 92- p.
IdentifiersURN: urn:nbn:se:su:diva-13601OAI: oai:DiVA.org:su-13601DiVA: diva2:180121