Kohn, Marion; Steinke, Stephan; Baumann, Karl-Heinz; Donner, Barbara; Meggers, Helge; Zonneveld, Karin A F (2009): Age model and stable oxygen isotope analyses of sediment core GeoB8507-3. PANGAEA, https://doi.pangaea.de/10.1594/PANGAEA.729703 (unpublished dataset), Supplement to: Kohn, M et al. (2011): Stable oxygen isotopes from the calcareous-walled dinoflagellate Thoracosphaera heimii as a proxy for changes in mixed layer temperatures off NW Africa during the last 45,000 yr. Palaeogeography, Palaeoclimatology, Palaeoecology, 302(3-4), 311-322, https://doi.org/10.1016/j.palaeo.2011.01.019
The present study is the first study on the stable oxygen isotope composition of the photosynthetic calcareous-walled dinoflagellate species Thoracosphaera heimii off NW Africa during the last 45,000 yr. T. heimii based temperature estimates of sediment core GeoB 8507-3 were compared with those obtained from the stable oxygen isotopes of the planktic foraminifera Globigerina bulloides and Globigerinoides ruber (pink), and the Mg/Ca ratio of G. ruber (pink).
We show that the isotopic composition of T. heimii and the temperature estimates based on the equation for inorganically precipitated calcite provide comparable results to those obtained from G. ruber (pink) isotopes and Mg/Ca ratios with exception of the Early Holocene and the Younger Dryas. The recently proposed palaeotemperature equation of Zonneveld et al. (2007), however, provides unrealistic temperature reconstructions that are about 16 °C lower than those based on planktic foraminifera. Thus, this equation needs to be revised. The difference between T. heimii and G. bulloides isotopic and temperature reconstructions can be ascribed to differences in the ecology of both species, especially with regard to their depth habitat and/or seasonal production in the research area.
All temperature proxies suggest comparable conditions during the last glacial and Holocene. Small differences between the reconstructed temperature values of T. heimii and the other proxies can be explained by differences in seasonal production of the individual species. The relatively low temperatures recorded by T. heimii at about 15,000 to 8,000 yr BP are interpreted to reflect an increase in duration and/or intensity of the upwelling in the vicinity of the core site in comparison to the last glacial, with an abrupt and strong decrease of upwelling intensity and/or duration during the Early Holocene and the Younger Dryas.
Kohn, Marion (2009): The stable oxygen isotope signal of the calcareous-walled dinoflagellate Thoracosphaera heimii as a new proxy for sea-surface temperature. PhD Thesis, Elektronische Dissertationen an der Staats- und Universitätsbibliothek Bremen, Germany, urn:nbn:de:gbv:46-diss000117626
Latitude: 19.475000 * Longitude: -18.099500
Date/Time Start: 2003-04-27T14:05:00 * Date/Time End: 2003-04-27T14:05:00
Minimum DEPTH, sediment/rock: 0.05 m * Maximum DEPTH, sediment/rock: 8.10 m
|#||Name||Short Name||Unit||Principal Investigator||Method/Device||Comment|
|2||Age model||Age model||ka||Kohn, Marion||Age, 14C AMS|
|3||Age, standard deviation||Age std dev||±||Kohn, Marion|
|4||Globigerina bulloides, δ18O||G. bulloides δ18O||‰ PDB||Kohn, Marion||Mass spectrometer Finnigan MAT 251|
|5||Thoracosphaera heimii, δ18O||T. heimii δ18O||‰ PDB||Kohn, Marion||Mass spectrometer Finnigan MAT 251|
|6||Globigerinoides ruber pink, δ18O||G. ruber p δ18O||‰ PDB||Kohn, Marion||Mass spectrometer Finnigan MAT 251|
385 data points