Imprint of seasonality changes on fluvio-glacial dynamics across Heinrich Stadial 1 (NE Atlantic Ocean)

Type Article
Date 2021-09
Language English
Author(s) Fersi Wiem1, Penaud Aurélie1, Wary Mélanie2, Toucanne SamuelORCID3, Waelbroeck Claire4, Rossignol Linda5, Eynaud Frédérique5
Affiliation(s) 1 : Univ Brest (UBO), CNRS, UMR 6538 Laboratoire Géosciences Océan (LGO), F-29280 Plouzané, France
2 : Institut de Ciència i Tecnologia Ambientals (ICTA-UAB), Universitat Autònoma de Barcelona, Bellaterra, Catalonia, Spain
3 : Ifremer, Laboratoire Géophysique et environnements Sédimentaires, F-29280 Plouzané, France
4 : LOCEAN/IPSL, Sorbonne Université-CNRS-IRD-MNHN, UMR7159, Paris, France
5 : Univ Bordeaux, CNRS, UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), F-33405 Talence, France
Source Global And Planetary Change (0921-8181) (Elsevier BV), 2021-09 , Vol. 204 , P. 103552 (18p.)
DOI 10.1016/j.gloplacha.2021.103552
Keyword(s) Heinrich Stadial 1, Dinoflagellate cysts, Northern Bay of Biscay, European ice sheets, 'Fleuve Manche'&nbsp, paleoriver

The northern Bay of Biscay has previously proven its great potential for recording the ‘Fleuve Manche’ paleoriver (i.e., the largest Pleistocene river in Europe) fluvio-glacial activity. In this study, new dinoflagellate cyst (dinocyst) analyses have been carried out at sub-centennial resolution in core MD13–3438 to reconstruct the deglacial history of the ‘Fleuve Manche’ paleoriver runoff coupled with European Ice Sheets (EIS) fluctuations across Heinrich Stadial 1 (HS1: 18.2–14.6 ka BP), a key extreme climatic event of the last glacial period. Prior to Heinrich Event (HE) 1 (16.7–14.6 ka BP), the onset of HS1 (18.2–16.7 ka BP) appears here marked by enhanced ‘Fleuve Manche’ paleoriver runoff, materialized by laminated deposits. Our work suggests a novel sub-centennial scale subdivision of the early HS1 (laminated) interval into 5 sub-phases when episodes of substantial fluvio-glacial delivery concomitant with warm summers alternate with episodes of moderate runoff associated with extended cold winters. We argue that multidecadal seasonal changes played a key role in the hydrological regime of western Europe during this HS1 interval, with the retreat of the southern limb of the EIS, and associated influx of meltwater and fluvio-glacial delivery, which were strongly influenced by those multidecadal changes in seasonality. Interestingly, our paleoclimatic record not only evidences the crucial role of seasonality in controlling climate and hydrological variations during HS1 but also shows a remarkable echo with reconstructions from the western Mediterranean Basin, highlighting common climate forcings at regional scale during the last deglaciation.

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