Local and regional controls on Holocene sea ice dynamics and oceanography in Nares Strait, Northwest Greenland

Research output: Contribution to journalJournal articleResearchpeer-review

Documents

Nares Strait is one of three channels that connect the Arctic Ocean to Baffin Bay. Unique sea-ice conditions in the strait lead to the formation of landfast ice arches at its northern and southern ends. These ice arches regulate Arctic sea-ice and freshwater export through the strait and promote the opening of the North Water polynya. The present study addresses the paucity of pre-satellite records of environmental conditions in the Nares Strait area, and aims at reconstructing Holocene sea-ice conditions and ocean circulation in the strait. The investigation is based on a marine sediment core strategically retrieved from under the current ice arch in Kane Basin to the south of Nares Strait, and provides a continuous record spanning the past ca 9 kyrs. We use benthic foraminiferal assemblages and sea-ice biomarkers to infer changes in Holocene ocean circulation and sea-ice conditions in Kane Basin. The establishment of the modern ocean circulation in Kane Basin is related to ice sheet retreat and postglacial rebound, while changes in sea-ice cover concur with major shifts in the Arctic Oscillation (AO). Our results suggest that sea-ice cover in Kane Basin was highly variable between ca 9.0 and 8.3 cal. ka BP, before increasing, probably in link with the 8.2 cold event and the opening of Nares Strait. A short period of minimum sea-ice cover and maximum Atlantic bottom water influence occurred between ca 8.1 and 7.5 cal. ka BP, when Kane Basin was deeper than for the remaining of the Holocene. As atmospheric temperatures dropped, sea-ice cover intensified in Kane Basin between ca 7.5 and 5.5 cal. ka BP, but strong winds under prevailing positive-like AO conditions likely prevented the formation of ice arches in Nares Strait. During this time, our micropaleontological data show that Atlantic water was progressively excluded from Kane Basin by the postglacial isostatic rebound. Increasingly cooler atmospheric temperatures and a shift towards more negative phases of the AO may have promoted the establishment of ice arches in Nares Strait between ca 5.5 and 3.0 cal. ka BP. Instabilities in the Kane Basin ice arch ca 3.0 cal. ka BP coincide with a shift towards prevailing positive phases of the AO, while a brief recovery of the ice arch occurred during more negative-like AO conditions between ca 1.2 and 0.2 cal. ka BP.

Original languageEnglish
Article number106115
JournalMarine Geology
Volume422
Number of pages11
ISSN0025-3227
DOIs
Publication statusPublished - 2020
Externally publishedYes

Bibliographical note

Funding Information:
Eleanor Georgiadis' studentship is funded by the Iniative d'Excellece (IdEx) programme of the University of Bordeaux , and the Natural Science and Engineering Research Council of Canada (NSERC). We warmly thank Benoit Lecavalier for constructive conversations, and for having shared with us the Agassiz ice core temperature record and simulations of sea level change in Nares Strait. Our gratitude is also extended to Naima El Bani Altuna, Frédérique Eynaud and Jérôme Bonnin for discussions concerning foraminifera, and Caroline Guilmette for analytical support for HBI measurements. We thank the editor, Adina Paytan, for entrusting our original manuscript to both a paleoceanographer and a physical oceanographer in the reviewing process. The manuscript was greatly improved thanks to both reviewers' comments. This work is supported by the Fondation Total , the French Agence Nationale de la Recherche (GreenEdge project), the Network of Centres of Excellence ArcticNet , and the European Research Council (StG IceProxy). Finally, we wish to thank the CCGS Amundsen captain, officers and crew for their support during the 2014 ArcticNet cruise.

Publisher Copyright:
© 2020 Elsevier B.V.

    Research areas

  • Arctic Ocean and adjacent high latitudes, Glacial sediments, Micropaleontology (forams), Paleoceanography, Sea-ice biomarkers

ID: 362325185