Rapid Deep Water Changes during Abrupt Climate Transitions in Glacial and Interglacial Periods

• Joan O. Grimalt ^[1] ; Belen Martrat ^[1] ; Isabel Cacho ^[2] ; Miquel Canals ^[2]
  1. [1] Instituto de Diagnóstico Ambiental y Estudios del Agua

     Instituto de Diagnóstico Ambiental y Estudios del Agua

     Barcelona, España

     
  2. [2] Universitat de Barcelona

     Universitat de Barcelona

     Barcelona, España

     
• Localización: Geotemas (Madrid), ISSN 1576-5172, Nº. 11, 2010 (Ejemplar dedicado a: Deep-Water Circulation: Processes & Products. International Congress. Baitona, Pontevedra, Spain. 16 & 17 June 2010), págs. 57-58
• Idioma: inglés
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• Resumen

  • The present contribution reports several examples of abrupt climate changes recorded in open marine sites in which comprehensive examination of the proxies available for surface (e.g. SST, δ18O and δ13C in planktonic foraminifera) and bottom (e.g. n-hexacosan-1-ol index, δ18O and δ13C in benthic foraminifera) seawaters show that these rapid transitions involved processes occurring both at upper and deep ocean levels. Thus, in the Shackleton site (Iberian Margin) a close correspondence between abrupt SST changes and deep water currents is observed. Accordingly, in both the glacial and interglacial periods each abrupt cooling is paralleled by a strong current increase involving a deep water change from predominance of North Atlantic Deep Water to Antarctic Bottom Water. Similarly, in the Alboran Sea, during marine isotope stage 3, each rapid SST drop occurred in parallel to an improvement in deep water ventilation that reflected enhanced formation of Western Mediterranean Deep Water.Combined examination of these proxies shows that the oceans were not only passive recorders of abrupt climate changes but active agents involving strong reorganizations of the marine and ocean water masses and circulation