High-resolution onshore–offshore morpho-bathymetric records of modern chalk and granitic shore platforms in NW France

Anne Duperret (1, 2) , Céline Raimbault , Bernard Le Gall (2) , Christine Authemayou (2) , Brigitte van Vliet-Lanoë (2) , Vincent Regard (3) , Elsa Dromelet (4) , Sara Vandycke (5)

1 LOMC - Laboratoire Ondes et Milieux Complexes
2 LDO - Domaines Océaniques
3 GET - Géosciences Environnement Toulouse
4 ULB - Université libre de Bruxelles
5 Faculté Polytechnique

Modern shore platforms developed on rocky coasts are key areas for understanding coastal erosion processes during the Holocene. This contribution offers a detailed picture of two contrasted shore-platform systems, based on new high-resolution shallow-water bathymetry, further coupled with aerial LiDAR topography. Merged land-sea digital elevation models were achieved on two distinct types of rocky coasts along the eastern English Channel in France (Picardy and Upper-Normandy: PUN) and in a NE Atlantic area (SW Brittany: SWB) in NW France. About the PUN case, submarine steps, identified as paleo-shorelines, parallel the actual coastline. Coastal erosive processes appear to be continuous and regular through time, since mid-Holocene at least. In SWB, there is a discrepancy between contemporary coastline orientation and a continuous step extending from inland to offshore, identified as a paleo-shoreline. This illustrates a polyphased and inherited shore platform edification, mainly controlled by tectonic processes.

Mots clés: Rocky coast; Shore platform; Shoreline; Land-sea DEM; Holocene; Bathymetry; Tectonics; Rocky coast

Domaines: Tectonique

Anne Duperret, Céline Raimbault, Bernard Le Gall, Christine Authemayou, Brigitte van Vliet-Lanoë, et al.. High-resolution onshore–offshore morpho-bathymetric records of modern chalk and granitic shore platforms in NW France. Comptes Rendus Géoscience, 2016, 348, pp.422-431. ⟨10.1016/j.crte.2015.06.005⟩. ⟨insu-01185350⟩