Sedimentological and geochemical records of the North Atlantic Glacial Eastern Boundary Current, 50-15 ka BP

The upper branch of the Atlantic Meridional Overturning Circulation (AMOC) plays a critical role in ocean circulation and climate change, yet its variability during the last glacial period is poorly documented. Here, we investigate the northward-flowing Glacial Eastern Boundary Current (GEBC) in the North Atlantic, known today as the European Slope Current, and representing the easternmost portion of the upper branch of the AMOC. Based on flow speed (sortable silt, XRF) and radiogenic/stable isotopic records, we show that Dansgaard-Oeschger (D/O) interstadials (stadials) correspond to a faster (weaker) GEBC during the ~50-15 ka period. This, by analogy to present-day conditions, suggests enhanced (reduced) strength of the subpolar gyre and, by extension, of northern-sourced water production and AMOC during D-O interstadials (stadials). Concomitant fluctuations of both the European Ice Sheet and the GEBC between ~30 and 17 ka suggest an active role of the upper branch of AMOC in the poleward transport of heat and freshwater to the northern North Atlantic, with direct impacts on deep water formation and AMOC strength. Our GEBC reconstruction is the first physical (non-chemical) record documenting dynamic upper AMOC variability at high resolution in the eastern basin of the North Atlantic. Together with the deep North Atlantic records of northern-sourced water export, they confirm the central role of the AMOC in the generation of abrupt climate changes.

The upper branch of the Atlantic Meridional Overturning Circulation (AMOC) plays a critical role in ocean circulation and climate change, yet its variability during the last glacial period is poorly documented. Here, we investigate the northward-flowing Glacial Eastern Boundary Current (GEBC) in the North Atlantic, known today as the European Slope Current, and representing the easternmost portion of the upper branch of the AMOC. Based on flow speed (sortable silt, XRF) and radiogenic/stable isotopic records, we show that Dansgaard-Oeschger (D/O) interstadials (stadials) correspond to a faster (weaker) GEBC during the ~50-15 ka period. This, by analogy to present-day conditions, suggests enhanced (reduced) strength of the subpolar gyre and, by extension, of northern-sourced water production and AMOC during D-O interstadials (stadials). Concomitant fluctuations of both the European Ice Sheet and the GEBC between ~30 and 17 ka suggest an active role of the upper branch of AMOC in the poleward transport of heat and freshwater to the northern North Atlantic, with direct impacts on deep water formation and AMOC strength. Our GEBC reconstruction is the first physical (non-chemical) record documenting dynamic upper AMOC variability at high resolution in the eastern basin of the North Atlantic. Together with the deep North Atlantic records of northern-sourced water export, they confirm the central role of the AMOC in the generation of abrupt climate changes.

Disciplines

Cross-discipline

Keywords

AMOC, last glacial period, Dansgaard-Oeschger, paleoclimate, paleoceanography, eastern boundary current, European Slope Current, contourites

Location

60N, 40S, 0E, -30W

Data

FileSizeFormatProcessingAccess
Radiogenic neodymium isotopic composition (planktic foraminifera), French Atlantic margin
17 KoXLS, XLSXProcessed data
Stable Carbon/Oxygen isotopic composition (benthic foraminifera), French Atlantic margin
44 KoXLS, XLSXProcessed data
Sortable silt and XRF log (Zr/Rb), French Atlantic margin
262 KoXLS, XLSXProcessed data
How to cite
Toucanne Samuel, Soulet Guillaume, Vazquez Riveiros Natalia, Boswell Steven, Dennielou Bernard, Waelbroeck Claire, Bayon Germain, Mojtahid Meryem, Bosq Mathieu, Sabine Marjolaine, Zaragosi Sébastien, Bourillet Jean-Francois, Mercier Herle (2020). Sedimentological and geochemical records of the North Atlantic Glacial Eastern Boundary Current, 50-15 ka BP. SEANOE. https://doi.org/10.17882/77667
In addition to properly cite this dataset, it would be appreciated that the following work(s) be cited too, when using this dataset in a publication :
Toucanne Samuel, Soulet Guillaume, Vazquez Riveiros Natalia, Boswell Steven M., Dennielou Bernard, Waelbroeck Claire, Bayon Germain, Mojtahid Meryem, Bosq Mathieu, Sabine Marjolaine, Zaragosi Sébastien, Bourillet Jean-Francois, Mercier Herle (2021). The North Atlantic Glacial Eastern Boundary Current as a key driver for ice‐sheet – AMOC interactions and climate instability. Paleoceanography And Paleoclimatology. 36 (3). e2020PA004068 (23p.). https://doi.org/10.1029/2020PA004068, https://archimer.ifremer.fr/doc/00683/79488/

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