Climatefluctuations during the Holocene in NWIberia: High and low latitude linkages

High resolution benthic foraminiferal stable isotopes (δ18O, δ13C) and molecular biomarkers in the sediments are used here to infer rapid climatic changes for the last 8200 years in the Ría de Muros (NW Iberian Margin). Benthic foraminiferal δ18O and δ13C potentially register migrations in the position of the hydrographic front formed between two different intermediate water masses: Eastern North Atlantic Central Water of subpolar origin (ENACWsp) and subtropical origin (ENACWst). The molecular biomarkers in the sediment show a strong coupling between continental organic matter inputs and negative δ13C values in benthic foraminifera. The rapid centennial and millennial events registered in these records have been compared with two well known North Atlantic Holocene records from the subtropical Atlantic sea surface temperatures (SST) anomalies off Cape Blanc, NW Africa and the subpolar Atlantic (Hematite Stained Grains percentage, subpolar North Atlantic). Comparison supports a strong link between high- and low-latitude climatic perturbations at centennial–millennial time scales during the Holocene. Spectral analyses also points to a pole-to-equator propagation of the so-called 1500 yr cycles. Our results demonstrate that during the Holocene, the NW Iberian Margin has undergone a series of rapid events which are likely triggered at high latitudes in the North Atlantic and are rapidly propagated towards lower latitudes. Conceivably, the propagation of these rapid climatic changes involves a shift in atmospheric and oceanic circulatory systems.The authors acknowledge to the EU project HOLSMEER: Holocene Shallow Marine Environments of Europe (EVK2-CT-2000-00060) for providing samples and financial support, GRACCIE (Consolider-Ingenio, CDS 2007-00067); CONTOURIBER (CTM 2008-06399-C04-01/MAR) y Proxecto 08MDS036000PR (Xunta de Galicia). L.P. and P.D. also thank the EU Acces to Research Infrastructures Paleostudies Program (Geosciences Faculty, Bremen University, Germany) for providing us with analytical facilities, and to F. Lamy for all the help provided. L.P. acknowledges a fellowship from the Comer Abrupt Climate Change Foundation (USA). Thoughtful comments and discussion provided by P.G. Mortyn are greatly thanked. Also thanks to Antje Volker and an anonymous reviewer for very insightful comments that helped to improve the quality of this paper. This is LDEO contribution 7352.Peer reviewe

Climatefluctuations during the Holocene in NWIberia: High and low latitude linkages

High resolution benthic foraminiferal stable isotopes (δ18O, δ13C) and molecular biomarkers in the sediments are used here to infer rapid climatic changes for the last 8200 years in the Ría de Muros (NW Iberian Margin). Benthic foraminiferal δ18O and δ13C potentially register migrations in the position of the hydrographic front formed between two different intermediate water masses: Eastern North Atlantic Central Water of subpolar origin (ENACWsp) and subtropical origin (ENACWst). The molecular biomarkers in the sediment show a strong coupling between continental organic matter inputs and negative δ13C values in benthic foraminifera. The rapid centennial and millennial events registered in these records have been compared with two well known North Atlantic Holocene records from the subtropical Atlantic sea surface temperatures (SST) anomalies off Cape Blanc, NW Africa and the subpolar Atlantic (Hematite Stained Grains percentage, subpolar North Atlantic). Comparison supports a strong link between high- and low-latitude climatic perturbations at centennial–millennial time scales during the Holocene. Spectral analyses also points to a pole-to-equator propagation of the so-called 1500 yr cycles. Our results demonstrate that during the Holocene, the NW Iberian Margin has undergone a series of rapid events which are likely triggered at high latitudes in the North Atlantic and are rapidly propagated towards lower latitudes. Conceivably, the propagation of these rapid climatic changes involves a shift in atmospheric and oceanic circulatory systems.The authors acknowledge to the EU project HOLSMEER: Holocene Shallow Marine Environments of Europe (EVK2-CT-2000-00060) for providing samples and financial support, GRACCIE (Consolider-Ingenio, CDS 2007-00067); CONTOURIBER (CTM 2008-06399-C04-01/MAR) y Proxecto 08MDS036000PR (Xunta de Galicia). L.P. and P.D. also thank the EU Acces to Research Infrastructures Paleostudies Program (Geosciences Faculty, Bremen University, Germany) for providing us with analytical facilities, and to F. Lamy for all the help provided. L.P. acknowledges a fellowship from the Comer Abrupt Climate Change Foundation (USA). Thoughtful comments and discussion provided by P.G. Mortyn are greatly thanked. Also thanks to Antje Volker and an anonymous reviewer for very insightful comments that helped to improve the quality of this paper. This is LDEO contribution 7352.Peer reviewe