Authigenic 10Be/9Be ratios and 10Be-fluxes (230Thxs-normalized) in central Baffin Bay sediments during the last glacial cycle: Paleoenvironmental implications

• Main Authors: Simon, Quentin, Thouveny, Nicolas, Bourlès, Didier, Nuttin, Laurence, Hillaire-Marcel, Claude
• Other Authors: Centre Européen de Recherche et d'Enseignement des Géosciences de l'Environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre de recherche en géochimie et géodynamique (GEOTOP ), Université du Québec à Montréal = University of Québec in Montréal (UQAM)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: [SDU]Sciences of the Universe [physics]; [SDE]Environmental Sciences; Arctic; Baffin Bay; Baffin; North Atlantic
• Online Access: https://hal.science/hal-01456980; https://hal.science/hal-01456980/document; https://hal.science/hal-01456980/file/SIMONetal2016-QSR-BAFFIN-version-auteur.pdf; https://doi.org/10.1016/j.quascirev.2016.03.0270277-3791

International audience Authigenic 10Be/9Be ratios and 10Be-fluxes reconstructed using the 230Thxs normalization, proxies of thecosmogenic radionuclide 10Be production rate in the atmosphere, have been measured in a sedimentarycore from Baffin Bay (North Atlantic) spanning the last 136 ka BP. The normalization applied on theexchangeable (authigenic) 10Be concentrations using the authigenic 9Be isotope and 230Thxs methodsyield equivalent results strongly correlated with sedimentological parameters (grain-size and mineralogy).Lower authigenic beryllium (Be) concentrations and 10Be/9Be ratios are associated with coarsegrainedcarbonate-rich layers, while higher authigenic Be values are related to fine-grained felsparrichsediments. This variability is due to: i) sediment composition control over beryllium-scavengingefficiency and, ii) glacial history that contributed to modify the 10Be concentration in Baffin Bay byinput and boundary scavenging condition changes. Most paleo-denudation rates inferred from the10Be/9Be ratio vary weakly around 220 ± 76 tons.km2.yr1 (0.09 ± 0.03 mm.yr1) corresponding torelatively steady weathering fluxes over the last glacial cycle except for six brief intervals characterizedby sharp increases of the denudation rate. These intervals are related to ice-surging episodes coeval withHeinrich events and the last deglaciation period. An average freshwater flux of 180.6 km3.yr1 (0.006 Sv),consistent with recent models, has been calculated in order to sustain glacially-derived 10Be inputs intoBaffin Bay. It is concluded that in such environments, the authigenic 10Be measured mainly depends onclimatic effects related to the glacial dynamics, which masks the 10Be production variation modulated bygeomagnetic field changes. Altogether, these results challenge the simple interpretation of 10Be-concentrationvariation as a proxy of Interglacial/Glacial (interstadial/stadial) cycles in Arctic and sub-Arcticregions. They rather suggest the effect of higher-frequency paleoclimatic changes and local ...