Depositional controls on a hypertidal barrier-spit system architecture and evolution, Pointe du Banc spit, north-western France

TY - JOUR

T1 - Depositional controls on a hypertidal barrier-spit system architecture and evolution, Pointe du Banc spit, north-western France

AU - Fruergaard, Mikkel

AU - Tessier, Bernadette

AU - Poirier, Clement

AU - Mouaze, Dominique

AU - Weill, Pierre

AU - Noel, Suzanne

PY - 2020/1/1

Y1 - 2020/1/1

N2 - 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.

AB - 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.

KW - Coastal evolution

KW - depositional controls

KW - ground-penetrating radar

KW - increased storminess and sediment supply

KW - North-West France

KW - optically stimulated luminescence dating

U2 - 10.1111/sed.12652

DO - 10.1111/sed.12652

M3 - Journal article

SN - 0037-0746

JO - Sedimentology

JF - Sedimentology

ER -