Articles | Volume 13, issue 11
Clim. Past, 13, 1473–1489, 2017

Special issue: Climate–carbon–cryosphere interactions in the...

Clim. Past, 13, 1473–1489, 2017

Research article 03 Nov 2017

Research article | 03 Nov 2017

Central Arctic Ocean paleoceanography from  ∼  50 ka to present, on the basis of ostracode faunal assemblages from the SWERUS 2014 expedition

Laura Gemery1, Thomas M. Cronin1, Robert K. Poirier1,2, Christof Pearce3,4, Natalia Barrientos3, Matt O'Regan3, Carina Johansson3, Andrey Koshurnikov5,6, and Martin Jakobsson3 Laura Gemery et al.
  • 1U.S. Geological Survey, Reston, Virginia, USA
  • 2Rensselaer Polytechnic Institute, Department of Earth & Environmental Sciences, Troy, New York, USA
  • 3Department of Geological Sciences and Bolin Centre for Climate Research, Stockholm University, 10691 Stockholm, Sweden
  • 4Department of Geoscience, Aarhus University, 8000 Aarhus, Denmark
  • 5Tomsk National Research Polytechnic University, Tomsk, Russia
  • 6Department of Geophysics, Moscow State University, Moscow, Russian Federation

Abstract. Late Quaternary paleoceanographic changes at the Lomonosov Ridge, central Arctic Ocean, were reconstructed from a multicore and gravity core recovered during the 2014 SWERUS-C3 Expedition. Ostracode assemblages dated by accelerator mass spectrometry (AMS) indicate changing sea-ice conditions and warm Atlantic Water (AW) inflow to the Arctic Ocean from  ∼  50 ka to present. Key taxa used as environmental indicators include Acetabulastoma arcticum (perennial sea ice), Polycope spp. (variable sea-ice margins, high surface productivity), Krithe hunti (Arctic Ocean deep water), and Rabilimis mirabilis (water mass change/AW inflow). Results indicate periodic seasonally sea-ice-free conditions during Marine Isotope Stage (MIS) 3 ( ∼  57–29 ka), rapid deglacial changes in water mass conditions (15–11 ka), seasonally sea-ice-free conditions during the early Holocene ( ∼  10–7 ka) and perennial sea ice during the late Holocene. Comparisons with faunal records from other cores from the Mendeleev and Lomonosov ridges suggest generally similar patterns, although sea-ice cover during the Last Glacial Maximum may have been less extensive at the new Lomonosov Ridge core site ( ∼  85.15° N, 152° E) than farther north and towards Greenland. The new data provide evidence for abrupt, large-scale shifts in ostracode species depth and geographical distributions during rapid climatic transitions.

Short summary
Continuous, highly abundant and well-preserved fossil ostracodes were studied from radiocarbon-dated sediment cores collected on the Lomonosov Ridge (Arctic Ocean) that indicate varying oceanographic conditions during the last ~50 kyr. Ostracode assemblages from cores taken during the SWERUS-C3 2014 Expedition, Leg 2, reflect paleoenvironmental changes during glacial, deglacial, and interglacial transitions, including changes in sea-ice cover and Atlantic Water inflow into the Eurasian Basin.