Data/hora: 14/06/2024 05:50:55

Provedor de dados: | 5
País: | France

Título:

Dynamique sédimentaire et évolution holocène d'un système macrotidal semi-fermé : l'exemple de la rade de Brest

Sediment dynamics and Holocene evolution of a semi-closed macrotidal system : the example of the bay of Brest

Autores: | Gregoire, Gwendoline.
Data: | 2016-12-08
Ano: | 2016
Palavras-chave: | Dynamique sédimentaire; Holocène; Paléo-vallée; Estuaire; Système côtier; Rade de Brest; Carottages; Sismique-réflexion; Imagerie; Bathymétrie; Seismic reflection; Coastal system; Bay of Brest; Coring; Paleo-valley; Estuary; Sedimentary dynamic; Backscatter imagery; Bathymetry.
Resumo: | The bay of Brest is a tide-dominated, semi-enclosed coastal basin, which is connected with two rivers (Aulne and Elorn). Its jagged shoreline and seabed morphology constitute an ideal setting to understand sedimentary transfer at the land-sea interface. In this aim, this study is divided in two different time scale. The first (a) focuses on the present-day sedimentary bedload dynamic and the second (b) on the reconstruction of the Holocene infilling, during the last marine transgression. (a) A analyse combining a sedimentology approach and numerical has highlighted the major control of the tidal currents. Swells and rivers have a minor impact, because the inherited morphology accentuates and promotes tidal currents. There are responsible of a shelly sandy exchange between the oceanic domain (Iroise Sea) and confined (bay of Brest). At present, the bay of Brest suffers from an imbalance of shelly sand. Fine sediments are eroded and redistributed in the shallow parts of the bay. In ideal conditions (strong tidal current) they can be exported.(b) From the stratigraphic and chronostratigraphic analyses, the successive landward retreat of estuarine processes, during the last marine transgression, has been observed. The sea level acts as the major factor control of the sedimentary geometry deposits. However, the morphological particularity of the bay of Brest influenced their preservation and it is possible to determinate the longitudinal and transversal asymmetry. After the sea level stabilisation (3 000 BP), the Holocene climatic variations and anthropic activities have disturbed the suspension dynamic.The bay of Brest had a different impact on the sedimentary transfer during the last marine transgression. At present, it acts as a « sediment trap » for the fine particles and has not enough sandy sediment. This configuration tends to an erosion of the system.
Tipo: | Text
Idioma: | Francês

Identificador:

https://archimer.ifremer.fr/doc/00498/60920/64282.pdf

https://archimer.ifremer.fr/doc/00498/60920/

Editor: | Université de Bretagne occidentale
Formato: | application/pdf

Fonte:

info:eu-repo/semantics/openAccess

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