|Title||Multiproxy comparison of oceanographic temperature during Heinrich Events in the eastern subtropical Atlantic|
|Publication Type||Journal Article|
|Authors||Patton, GM, Martin, PA, Voelker, AHL, Salgueiro, E|
|Year of Publication||2011|
|Journal||Earth and Planetary Science Letters|
|Pagination||45 - 58|
Abrupt climate change episodes associated with catastrophic calvings of the Laurentide and European Ice Sheets during the last glacial, Heinrich Events (HE), had far-reaching effects in the Atlantic. We have measured minor and trace element concentrations in planktonic foraminiferal calcite in a core from the Iberian Margin (MD95-2040) and a core from the Gulf of Cadiz (MD99-2339) during HE 1, 4 and 5 to explore the use of the Mg‚Äìtemperature proxy for constraining regional temperature changes during these unique periods of ice-rafting. High sedimentation rates throughout the length of both cores allow a detailed reconstruction of temperature during abrupt events. Mg/Ca-derived temperatures reveal ~5‚Äì13 ¬∞C amplitude of cooling during HE1, the largest and most well defined event in this region. The northern site most likely experienced the higher end of this amplitude range. Cooling implied by the Mg/Ca data is within the range of assemblage-derived sea surface temperature (SST) changes from the same cores showing ~ 10 ¬∞C perturbations for each HE but the Mg/Ca data imply smaller changes during HE4 and HE5. Cooling estimated from unsaturated alkenone ratios (~ 3 ¬∞C) represent the smallest changes. The prominence of HE1 in this region is consistent with the changes over the wider North Atlantic that show colder temperatures during HE1 vs. HE4. We use Cd/Ca to reconstruct nutrient concentrations and find very low values (0.02‚Äì0.04 Œºmol/mol) at both locations during HE. These low values are consistent with core top planktonic Cd/Ca from each region suggesting that the cooling during HE was unlikely to be caused by more intense upwelling than in the modern. Temperature comparisons of other proxies, alkenone (U37K‚Ä≤) and assemblage data, from the same core suggest that Mg/Ca paleothermometry is sensitive to the relative size of each HE. This sensitivity is capable of highlighting other variables that influence the impact of Heinrich Events on SST, including the background climate state.
|Short Title||Earth and Planetary Science Letters|