Depositional controls on a hypertidal barrier-spit system architecture and evolution,Pointe du Banc spit,north-western France |
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| Authors: | Mikkel Fruergaard Bernadette Tessier Clément Poirier Dominique Mouazé Pierre Weill Suzanne Noël |
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| Institution: | 1. Normandie Université, UNICAEN, UNIROUEN, CNRS, M2C, 14000 Caen, France;2. Normandie Université, UNICAEN, Centre de Recherche d'Histoire Quantitative (CRHQ), 14000 Caen, France |
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| Abstract: | Physical stratigraphy, architecture and evolution of barrier systems in hypertidal environments (tidal range above 6 m) are understudied, and depositional controls are poorly understood compared with wave-dominated barrier systems and barrier spits in microtidal, mesotidal and macrotidal settings. Based on vibracores, ground-penetrating radar, radiocarbon and optically stimulated luminescence age data, the formation and evolution of the hypertidal barrier system of Pointe du Banc, north-western France has been reconstructed. The study shows that the barrier spit has a complex composite sedimentary architecture consisting of wave-dominated and tide-dominated sedimentary bodies. A morpho-sedimentary model is presented that demonstrates how barrier-spit progradation resulting from littoral drift was the main manner of spit elongation, whereas sediment convergence caused by landward migration of swash bars and seaward migration of tidal dunes caused the spit terminus to grow in height and width. These results suggest that long-term accretion rates varied considerably in response to changes in sediment supply. Variations in storminess together with the large-scale topography of the coast controlled the sediment supply and thus the evolution of the barrier system during latest Holocene. Despite architectural complexity, hypertidal barrier systems preserve records of past climate changes. |
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| Keywords: | Coastal evolution depositional controls ground-penetrating radar increased storminess and sediment supply North-West France optically stimulated luminescence dating |
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