A new Holocene relative sea-level curve for western Brittany (France): Insights on isostatic dynamics along the Atlantic coasts of north-western Europe

• Published in: Quaternary Science Reviews
• Main Authors: Goslin, Jérôme, Van Vliet-Lanoë, Brigitte, Spada, Giorgio, Bradley, Sarah, Tarasov, Lev, Neill, Simon, Suanez, Serge
• Other Authors: Littoral, Environnement, Télédétection, Géomatique (LETG - Brest), Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Université d'Angers (UA)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Caen Normandie (UNICAEN), Université de Nantes (UN)-Université de Nantes (UN), Domaines Océaniques (LDO), Centre National de la Recherche Scientifique (CNRS)-Institut d'écologie et environnement-Observatoire des Sciences de l'Univers-Université de Brest (UBO)-Institut national des sciences de l'Univers (INSU - CNRS), Dipartimento di Scienze di Base e Fondamenti, Università degli Studi di Urbino 'Carlo Bo', Institute for Marine and Atmospheric Research Utrecht (IMAU), Utrecht University Utrecht, Department of Physics and Physical Oceanography, Memorial University of Newfoundland St. John's, School of Ocean Sciences Menai Bridge, Bangor University, ANR-10-CEPL-0001 - COCORISCO - COnnaissance, COmpréhension et gestion des RIsques COtiers (2010), ANR-10-CEPL-0001,COCORISCO,COnnaissance, COmpréhension et gestion des RIsques COtiers(2010)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2015
• Subjects: Earth structure; Brittany; Relative sea-level; Holocene; Isostasy; GIA models; Tidal-range modelling; [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology; [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry; [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph]; Antarctic; Briggs; Peltier; Antarc*; Fennoscandian; Ice Sheet
• Online Access: https://hal.archives-ouvertes.fr/hal-01225416; https://doi.org/10.1016/j.quascirev.2015.10.029

International audience This study presents new Relative Sea Level (RSL) data that were obtained in the Finistère region (Western tip of Brittany, France) and the implications those data have for the understanding of the isostatic dynamics across north-western Europe, and more specifically along the Atlantic and Channel coasts. New stratigraphic sequences were obtained and analyzed to derive 24 new Sea-level Index Points, in which 6 are basal. These new data considerably increase the knowledge we have of the RSL evolution along the coasts of Western Brittany since the last 8 kyr B.P. From this new dataset, RSL was estimated to rise continuously over the last 8 kyr with a major inflection at ca. 6 kyr cal. BP. Our results show large vertical discrepancies between the RSL records of Brittany and South-Western UK, with the latter plotting several meters below the new data. From this comparison we suggest that the two regions underwent a very different pattern and/or amplitude of subsidence during the last 8 kyr which has implications for the spatial and temporal pattern of the peripheral bulge of the European ice sheets. We compared our data against predictions from Glacio-Isostatic Adjustment models (GIA models). There are large misfits between RSL observations and the predictions of the global (ICE-5G (VM2a) – Peltier, 2004, GLAC1-b – Tarasov and Peltier, 2002; Tarasov et al., 2012, Briggs et al., 2014) and regional UK models (“BIIS” – Bradley et al., 2009; Bradley et al., 2011; “Kuchar”- Kuchar et al., 2012), which can't be resolved through significant changes to the deglaciation history and size of the British–Irish Ice sheet. Paleo-tidal modelling corrections indicate regional changes in the tidal ranges played a negligible role in the data-model misfits. Hence, we propose that the misfits are due to some combination of: (i) unaccounted mass-loss of far-field ice-sheets (Antarctic ice-Sheet or Laurentide Ice-Sheet), (ii) unresolved differences in the deglaciation history and size of the Fennoscandian Ice ...