Skip to Main content Skip to Navigation
Journal articles

Evolution of a Holocene banner bank controlled by morphodynamics and structural setting of a macrotidal coast: Saint-Brieuc Bay (NW-Europe)

Abstract : The morphology and internal structure of the Horaine Bank (Bay of Saint-Brieuc, NW France) are described based on multibeam echosounder and high-resolution seismic datasets coupled with vibro-core data. The Horaine Bank shows large-scale bedforms in the lee of a submerged rocky shoal, which allowed defining it as a Banner Bank. The internal structure of the sandbank reveals four seismic units (U1-U4) on a Cambrian basement (U0). The basal unit U1 is interpreted as reworked lowstand fluvial sediments those infilled micro incised valleys during a rise in sea level. This unit is overlain by paleo-coastal barrier sand-spit (U2) whose development was controlled by swell in the context of a rapid rise in sea level. The successive prograding unit (U3) is interpreted as flooding deposits in continuity with unit U2. The unit U4 is characterized by oblique reflectors oriented in two opposite directions. This last unit, dated post 3500 yr BP, corresponds to migrating dunes superimposed on the bank and observable in the high-resolution bathymetric data. The strong correlation between tidal currents and the apparent clockwise migration of dune crests suggests the presence of a tidal gyre controlling the present-day dynamics of most of the Horaine bank dunes. This study proposes a new model for the construction of banner banks characterized by the gradual transition of a sand spit to a banner bank during marine transgression and ensuing hydrodynamic variability.
Document type :
Journal articles
Complete list of metadata

https://hal.archives-ouvertes.fr/hal-03186763
Contributor : David Menier <>
Submitted on : Wednesday, March 31, 2021 - 4:18:53 PM
Last modification on : Tuesday, May 11, 2021 - 4:20:01 PM

File

1-s2.0-S1674987121000475-main....
Publication funded by an institution

Licence


Distributed under a Creative Commons Attribution - NoDerivatives 4.0 International License

Identifiers

Citation

Kalil Traoré, David Menier, Erwan Gensac, Pascal Le Roy, Clément Lambert, et al.. Evolution of a Holocene banner bank controlled by morphodynamics and structural setting of a macrotidal coast: Saint-Brieuc Bay (NW-Europe). Geoscience Frontiers, Elsevier, 2021, 12 (5), pp.101183. ⟨10.1016/j.gsf.2021.101183⟩. ⟨hal-03186763⟩

Share

Metrics

Record views

58

Files downloads

40