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

Author

Fersi, Wiem, Penaud, Aurélie, Wary, Mélanie, Toucanne, Samuel, Waelbroeck, Claire, Rossignol, Linda, Eynaud, Frédérique, Fersi, Wiem, Penaud, Aurélie, Wary, Mélanie, Toucanne, Samuel, Waelbroeck, Claire, Rossignol, Linda, and Eynaud, Frédérique

Abstract

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.

Published
2021
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2. Sea-surface hydrographical conditions off South Faeroes and within the North- Eastern North Atlantic through MIS 2: the response of dinocysts.

Author

CAULLE, CLÉMENCE, PENAUD, AURÉLIE, EYNAUD, FRÉDÉRIQUE, ZARAGOSI, SÉBASTIEN, ROCHE, DIDIER M., MICHEL, ELIZABETH, BOULAY, SÉBASTIEN, and RICHTER, THOMAS

Abstract

ABSTRACT The last glacial period, showing the progressive development of large boreal ice sheets, was punctuated by large climatic excursions. These excursions were triggered mainly by atmosphere-ocean-ice coupled dynamics and are thus exemplary case studies of natural climate variability. To characterize the sea-surface palaeohydrographical changes accompanying these oscillations along the European margin, we have integrated new palynological data (dinocysts) acquired on core MD99-2281 (60°N, Faeroe Margin) during Marine Isotope Stage 2 in a latitudinal transect including published cores MD95-2002 (47°N, Celtic Margin) and MD95-2010 (66°N, Vöring Plateau). This transect is superimposed on the modern North Atlantic Drift pathway, but also at the outskirts of glacial European ice sheets, thus ideally located to track sea-ice extent and ice-sheet instabilities through time. The results show a coherent and sensitive response of sea-surface environments to the complex chain of abrupt events that punctuated the end of the last glacial period. The Last Glacial Maximum was marked by large seasonal contrasts of temperatures, whereas Heinrich events (HE) were characterized by a sharp cooling and sea-ice development. A tripartite structure is identified within HE1, with indices of melting at 19k cal a BP, followed by a temperate phase synchronous of a relative stability of ice sheets, and a terminal phase (17.5-15k cal a BP) characteristic of the 'conventional Laurentian' HE1. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Published
2013
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3. Imprint of seasonality changes on fluvio-glacial dynamics across Heinrich Stadial 1 (NE Atlantic Ocean)

Author

Samuel Toucanne, Aurélie Penaud, Mélanie Wary, Claire Waelbroeck, Linda Rossignol, Frédérique Eynaud, Wiem Fersi, Laboratoire Géosciences Océan (LGO), Université de Bretagne Sud (UBS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Institut de Ciencia i Tecnologia Ambientals (ICTA), Universitat Autònoma de Barcelona (UAB), Laboratoire Géodynamique et enregistrement Sédimentaire (LGS), Géosciences Marines (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Processus et interactions de fine échelle océanique (PROTEO), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), INSU RISCC, INSU ICE-BIO-RAM, ANR-05-BLAN-0310,IDEGLACE,Impact de Décharges d'Eau douce provenant de la GLace continentale sur le Climat Européen et méditerranéen(2005), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), European Project: 339108,EC:FP7:ERC,ERC-2013-ADG,ACCLIMATE(2014), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Unité de recherche Géosciences Marines (Ifremer) (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Laboratoire Géophysique et Enregistrements Sédimentaires, Centre National de la Recherche Scientifique (CNRS)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Université de Bretagne Sud (UBS), Laboratoire Géophysique et Enregistrements Sédimentaires (IFREMER), Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)

Subjects
010506 paleontology, 010504 meteorology & atmospheric sciences, Pleistocene, [SDE.MCG]Environmental Sciences/Global Changes, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, ‘Fleuve Manche’ paleoriver, Oceanography, 01 natural sciences, 'Fleuve Manche'&nbsp, European ice sheets, Deglaciation, medicine, Dinocyst, Stadial, Glacial period, Meltwater, ComputingMilieux_MISCELLANEOUS, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, northern Bay of Biscay, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, geography, geography.geographical_feature_category, Dinoflagellate cysts, Northern Bay of Biscay, Seasonality, medicine.disease, European Ice Sheets, paleoriver, Heinrich Stadial 1, 13. Climate action, Physical geography, Ice sheet, Geology
Abstract

International audience; 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.

Published
2021
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4. What forced the collapse of European ice sheets during the last two glacial periods (150kaB.P. and 18ka cal B.P.)? Palynological evidence

Author

Penaud, A., Eynaud, F., Turon, J.L., Zaragosi, S., Malaizé, B., Toucanne, S., and Bourillet, J.F.

Subjects
*ICE sheets, *ICE mechanics, *PALYNOLOGY, *RUNOFF, *DINOFLAGELLATE cysts, *SEDIMENTATION & deposition, *PALEOGEOGRAPHY, *GLACIAL Epoch
Abstract

Abstract: We present a new marine palynological record from the temperate North-eastern Atlantic (core MD03-2692, Celtic–Armorican margin) in the area of influence of the ‘Fleuve Manche’ paleoriver during glacial times. The runoff of this paleoriver was connected to the glacial history of European ice sheets (including the British Irish Ice Sheet—BIIS). Our study conducted on dinoflagellate cysts assemblages over the last 200ka, associated with quantification of palynological remains reflecting continental influence (pre-Quaternary dinocysts and micro-algae Pediastrum spp. coenobia), yields detailed insights into the sea-surface paleoenvironments of this sector. More specifically, mechanisms responsible for the origin of unusual deposits of laminated sequences found at the end of Marine Isotope Stage (MIS) 2 and within mid-MIS 6 are here constrained. We provide evidence of genetic similarities between fluvial discharges occurring before and during times of deposition of the laminated deposits. Our study clarifies the causes of the collapse of European glaciated systems. At the end of MIS 2, prior to the deposition of the laminated deposits, pleni-oceanic influence characterized by high concentrations of Quaternary dinocysts prevailed, and a dinocyst species tracing the penetration of the warm North Atlantic Drift into the Bay of Biscay is recorded. However, this scenario did not recur prior to the deposition of laminated sediments of mid-MIS 6. In addition, contrary to the laminated deposits found at the end of MIS 2 and directly associated with Termination I, MIS 6 laminae appeared 20ka earlier than Termination II. Our work shows that, during the penultimate glacial stage, the collapse of mid-latitudes ice sheets around 170kaB.P. may have immediately followed the MIS 6.5 warming phase. Then, the most important melting event around 150kaB.P. may be linked to a peak in insolation at 65°N, though less important than those during MIS 6.5 and Termination II. [Copyright &y& Elsevier]

Published
2009
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5. Land-ocean changes on orbital and millennial time scales and the penultimate glaciation

Author

argari, Vasiliki, Skinner, Luke C., Hodell, David A., Martrat, Belen, Toucanne, Samuel, Grimalt, Joan O., Gibbard, Philip L., Lunkka, Juha Pekka, and Tzedakis, Polychronis Chronis

Subjects
Climate oscillation, Heat transport, sub-01, European ice sheets, Bipolar seesaw, Meridional overturning circulations, Extreme events, Natural experiment, Freshwater discharge
Abstract

Past glacials can be thought of as natural experiments in which variations in boundary conditions influenced the character of climate change. However, beyond the last glacial, an integrated view of orbital- and millennial-scale changes and their relation to the record of glaciation has been lacking. Here, we present a detailed record of variations in the land-ocean system from the Portuguese margin during the penultimate glacial and place it within the framework of ice-volume changes, with particular reference to European ice-sheet dynamics. The interaction of orbital- and millennial-scale variability divides the glacial into an early part with warmer and wetter overall conditions and prominent climate oscillations, a transitional mid-part, and a late part with more subdued changes as the system entered a maximum glacial state. The most extreme event occurred in the mid-part and was associated with melting of the extensive European ice sheet and maximum discharge from the Fleuve Manche river. This led to disruption of the meridional overturning circulation, but not a major activation of the bipolar seesaw. In addition to stadial duration, magnitude of freshwater forcing, and background climate, the evidence also points to the influence of the location of freshwater discharges on the extent of interhemispheric heat transport., a Environmental Change Research Centre, Department of Geography, University College London, London WC1E 6BT, United Kingdom b Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, United Kingdom c Institute of Environmental Assessment and Water Research (IDAEA), Spanish Council for Scientific Research (CSIC), 08034 Barcelona, Spain d IFREMER, Laboratoire Environnements Sédimentaires, F-29280 Plouzané, France e Department of Geography, University of Cambridge, Cambridge CB2 3EN, United Kingdom f Institute of Geosciences, University of Oulu, Oulu, FIN-90014, Finland

Published
2015

6. What forced the collapse of European ice sheets during the last two glacial periods (150 ka BP and 18 ka cal BP)? Palynological evidence

Author

Penaud, A., Eynaud, F., Turon, J. L., Zaragosi, S., Malaize, B., Toucanne, Samuel, Bourillet, Jean-francois, Penaud, A., Eynaud, F., Turon, J. L., Zaragosi, S., Malaize, B., Toucanne, Samuel, and Bourillet, Jean-francois

Abstract

We present a new marine palynological record from the temperate North-eastern Atlantic (core MD03-2692, Celtic-Armorican margin) in the area of influence of the 'Fleuve Manche' paleoriver during glacial times. The runoff of this paleoriver was connected to the glacial history of European ice sheets (including the British Irish Ice Sheet-BIIS). Our study conducted on dinoflagellate cysts assemblages over the last 200 ka, associated with quantification of palynological remains reflecting continental influence (pre-Quaternary dinocysts and micro-algae Pediastrum spp. coenobia), yields detailed insights into the sea-surface paleoenvironments of this sector. More specifically, mechanisms responsible for the origin of unusual deposits of laminated sequences found at the end of Marine Isotope Stage (MIS) 2 and within mid-MIS 6 are here constrained. We provide evidence of genetic similarities between fluvial discharges occurring before and during times of deposition of the laminated deposits. Our study clarifies the causes of the collapse of European glaciated systems. At the end of MIS 2, prior to the deposition of the laminated deposits, plenioceanic influence characterized by high concentrations of Quaternary dinocysts prevailed, and a dinocyst species tracing the penetration of the warm North Atlantic Drift into the Bay of Biscay is recorded. However, this scenario did not recur prior to the deposition of laminated sediments of mid-MIS 6. In addition, contrary to the laminated deposits found at the end of MIS 2 and directly associated with Termination I, MIS 6 laminae appeared 20 ka earlier than Termination II. Our work shows that, during the penultimate glacial stage, the collapse of mid-latitudes ice sheets around 170 ka B.P. may have immediately followed the MIS 6.5 warming phase. Then, the most important melting event around 150 ka B.P. may be linked to a peak in insolation at 65 degrees N, though less important than those during MIS 6.5 and Termination II.

Published
2009
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