Sedimentological and palynological records since 10 ka BP along a proximal-distal gradient on the Armorican shelf (NW France)

• Published in: Quaternary Science Reviews
• Main Authors: David, Ophélie, Penaud, Aurélie, Vidal, Muriel, Fersi, Wiem, Lambert, Clément, Goubert, Evelyne, Herlédan, Maiwenn, Stéphan, Pierre, Pailler, Yvan, Bourillet, Jean-François, Baltzer, Agnès
• Other Authors: Geo-Ocean (GEO-OCEAN), Université de Bretagne Sud (UBS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Geo-Instituut, Catholic University of Leuven = Katholieke Universiteit Leuven (KU Leuven), Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD France-Nord ), Littoral, Environnement, Télédétection, Géomatique (LETG - Brest), Université de Brest (UBO)-Université de Rennes 2 (UR2)-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)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), Université de Brest (UBO)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (Nantes Univ - IGARUN), Nantes Université - pôle Humanités, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Nantes Université - pôle Humanités, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (Nantes Univ - IGARUN), Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Littoral, Environnement, Télédétection, Géomatique (LETG - Nantes ), Université de Brest (UBO)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2022
• Subjects: Fluvial discharge; Holocene; South Brittany; Pollen; Dinoflagellate cysts; Paleoenvironmental changes; Turritella layer; Anthropogenic pollen indicators (API); [SDU]Sciences of the Universe [physics]; North Atlantic
• Online Access: https://insu.hal.science/insu-03824739; https://insu.hal.science/insu-03824739/document; https://insu.hal.science/insu-03824739/file/96146.pdf; https://doi.org/10.1016/j.quascirev.2022.107678

International audience New findings acquired in Armorican shelf (core MD08-3204 CQ: Bay of Quiberon and core VK03-58bis: South Glénan islands) depict Holocene paleoenvironmental changes since 10 ka BP through a multi-proxy dataset including sedimentological and palynological data. First, grain-size analyses and AMS- 14 C dates show a common sedimentary history for both study cores. The slowdown of the relative sea level (RSL) rise was accompanied by a drop of the sedimentation rates between ∼8.3 and 5.7 ka BP; the rates had been relatively higher at the onset of the Holocene. This interval led to the establishment of a shell-condensed level, identified in core VK03-58bis by the "Turritella layer" and interpreted as a marker for the Maximum Flooding Surface. Palynological data (pollen and dinoflagellate cyst assemblages) acquired in core MD08-3204 CQ argue for an amplification of the fluvial influence since 5.7 ka BP; the establishment of the Highstand System Tract (i.e., mixed marine and fluviatile influences on the platform) then accompanied the slowdown of the RSL rise rates. On the shelf, the amplification of Anthropogenic Pollen Indicators (API) has been better detected since 4.2 ka BP, due not only to the increase of human impact but also due to a stronger fluvial influence on the shelf during the Late Holocene. Palynological data, recorded on the 8.5-8.3 ka BP interval along an inshore-offshore gradient, also demonstrate the complexity of the palynological signals such as i) the fluvial influence that promotes some pollen taxa (Alnus and Corylus) from proximal areas and ii) the macro-regionalization of palynomorph sources in distal cores. In addition, the comparison of palynological tracers, including API, over the last 7 kyrs BP, with South Brittany coastal and mid-shelf sites subject to northern vs. southern Loire catchment areas, shows a major hydro-climatic effect on the reconstructed palynological signals. Strengthened subpolar gyre (SPG) dynamics, combined with recurrent positive North Atlantic ...