Holocene variability of the North Atlantic Irminger current on the south- and northwest shelf of Iceland

Sædís Ólafsdóttir, Anne E. Jennings, Aslaug Geirsdóttir, John Andrews, Gifford H. Miller

Research output: Contribution to journalArticlepeer-review

60 Scopus citations

Abstract

The Irminger Current (IC) transports heat and nutrients to the Icelandic shelf and its fluctuations are strongly linked to variations in the strength of the North Atlantic surface flow from the south. By using benthic foraminiferal assemblages and their stable isotopic composition in two marine sediment cores located in the pathway of the IC on the West Iceland shelf we were able to derive bottom water temperature estimates at a ~100year resolution and define the temperature difference between the core sites throughout the Holocene. These are the first transfer function bottom water temperatures presented from the Icelandic shelf based on benthic foraminiferal assemblages. Our findings demonstrate a delayed Holocene Thermal Maximum in the marine current system around Iceland compared to the Northern Hemisphere summer insolation receipts. The maximum heat transport in the IC occurred between 8 and 4kayears, later than some previous records report. A reconstruction of the ambient seawater δ18O based on paired samples of C2 transfer function temperature estimates and oxygen isotopic composition indicates repeated freshwater input to the N-Atlantic inflow in the early Holocene impacting the current system before 8ka. Two fundamental regime shifts are evident in the paleoceanography and foraminiferal properties during the Holocene, occurring around 8ka towards more stable conditions and again around 4ka towards more unstable conditions. Increasing fluctuation with similarities to the Great Salinity Anomaly in the 1970s occur after 4ka.

Original languageEnglish (US)
Pages (from-to)101-118
Number of pages18
JournalMarine Micropaleontology
Volume77
Issue number3-4
DOIs
StatePublished - Dec 2010

Bibliographical note

Funding Information:
The research has been supported by grants of excellence from the Icelandic Centre for Research ( 022160004 and 070272013 ) and a research grant (040233021) awarded to Á. Geirsdóttir (University of Iceland) and G.H. Miller (INSTAAR) and a NFS grant ( 0823535 ) to A. Jennings (INSTAAR). RANNÍS Graduate Student Grant was awarded to the senior author as well as the Eimskip University Fund of the University of Iceland . Dating of MD99-2263 and four of the MD99-2264 came from NSF grant ATM-0502515 to J.T. Andrews (INSTAAR). We thank D. Klitgaard Kristensen (Norwegian Polar Institute) for her work on improving the RBF database for the C2 transfer function program. The crew and scientists on IMAGES V cruises in 1999 are also thanked. D. Thornalley (Cardiff University), K.L. Knudsen (Aarhus University) and R.E. Came (Massachusetts Institute of Technology/Woods Hole Oceanographic Institution) are acknowledged for sharing data. Two anonymous reviewers are thanked for constructive comments. Appendix A

Copyright:
Copyright 2011 Elsevier B.V., All rights reserved.

Keywords

  • Foraminifera
  • Holocene
  • Iceland
  • Irminger Current
  • Stable isotopes
  • Temperature

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