Aarhus Universitets segl

Northeast Greenland: ice-free shelf edge at 79.4 degrees N around the Last Glacial Maximum 25.5-17.5 ka

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The size of the last glacial ice sheet on the Northeast (NE) Greenland shelf and its interaction with ocean circulation have been the subject of debate. Here we provide insights into the extent of the ice sheet around the Last Glacial Maximum (LGM) and investigate timing and strength of changes in the flow of Atlantic Water. The study is based on a multiproxy investigation of a marine sediment core, gravity core DA17-NG-ST01-019G, from 323-m water depth at the NE Greenland shelf edge at 79.4°N. We present benthic and planktic foraminiferal distribution data, AMS-14C dates, sedimentological (ice-rafted debris (IRD) and grain sizes), and geochemical (XRF) data in combination with geophysical (sub-bottom profiler) data. The oldest sediments at the study site are dated to 25.5–17.5 ka, encompassing the time frame from the beginning of the LGM to the early deglaciation. This part is overlain by sediments from the late deglaciation and Holocene. The deposits dating from the LGM are very rich in both planktic and benthic foraminifera and macrofossils of excellent preservation. The faunas show that the site generally was affected by a strong flow of relatively warm subsurface Atlantic Water during the LGM and Early Holocene. Conditions turned more polar with cold bottom water flow in the Middle–Late Holocene (c. 7.5 ka to Recent) with presence of mainly agglutinated benthic foraminiferal species. Our data from the LGM also indicate that the deposits were mixed by iceberg scouring, confirmed by the geophysical data showing extensive ploughing of the sediments on the outer shelf area. The results further indicate that the Greenland Ice Sheet did not reach to the edge of the NE Greenland shelf at 79.4°N during the LGM 24–18 ka.

OriginalsprogEngelsk
TidsskriftBoreas
Vol/bind51
Nummer4
Sider (fra-til)759-775
Antal sider17
ISSN0300-9483
DOI
StatusUdgivet - okt. 2022

Bibliografisk note

Funding Information:
We thank the captain, crew and scientific party on board RV ‘Dana’. We warmly thank Søren Rysgaard, Arctic Climate Centre, Aarhus University and Jørgen Bendtsen, ClimateLab, Copenhagen, for the CTD data from the core location. We also wish to thank Trine Ravn‐Jonsen for composing the X‐ray fluorescence data set, Mimi Oksman, then Aarhus University, now Geological Survey of Denmark and Greenland, Copenhagen, and Mériadec Le Pabic, Aarhus University for their assistance in opening and sampling of the core. We thank IHS Markit for granting an academic licence to the Kingdom seismic interpretation software for SeisLab Aarhus. We are also grateful to Jesper Olsen and Marie Kanstrup from the Aarhus AMS Centre, Aarhus University and to Mériadec Le Pabic for carrying out the C measurements. Finally, we thank the two reviewers Anne Jennings and an anonymous reviewer for their very constructive and helpful suggestions to improve the manuscript. The NorthGreen17 expedition was funded by the Danish Centre for Marine Research and the Natural Science and Engineering Research Council of Canada. The research was funded by the Danish Council for Independent Research (grant no. 7014‐00113B G‐Ice project and 0135‐00165B (GreenShelf), both to MSS) with additional funding from the European Union’s Horizon 2020 research and innovation program under Grant Agreement No. 869383 (ECOTIP; MSS). The research also received support from the Research Council of Norway through its Centers of Excellence funding scheme, grant number 223259, and UiT the Arctic University of Norway, Tromsø, Norway (TLR). GEUS granted time for TN to join the NorthGreen2017 Expedition. The authors declare no conflict of interests. 14

Publisher Copyright:
© 2022 The Authors. Boreas published by John Wiley & Sons Ltd on behalf of The Boreas Collegium.

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