Data/hora: 07/06/2024 00:47:53

Provedor de dados: 	5	
País: 	France	
Título: 	Holocene coastal changes and infilling of the La Perroche marsh (French Atlantic coast)	
Autores: 	Clave, B; Masse, L; Carbonel, P; Tastet, Jp.	
Data: 	2001-07	
Ano: 	2001	
Palavras-chave: 	Changements côtiers; Marais maritime; Holocène; Ostracodes; Sédiments; Coastal changes; Coastal salt marsh; Holocene; Ostracods; Sediments.	
Resumo: 	The La Perroche marsh is a small Holocene marsh on the south-western coast of the Oleron island (Bay of Biscay, France) presently occupied by a freshwater swamp and separated from the ocean by a continuous sand dune ridge. The study of its infill shows first basal conglomeratic deposits with calcareous pebbles on a Cenomanian rough substrate. The Holocene infill since 6000 years BP begins with a very fast sedimentation of sands. Then, the sedimentation becomes finer, with lagoonal to freshwater influences recorded by ostracods. The distribution of these deposits inside the marsh is asymmetric, with a thick sandy-gravely layer in the eastern part and a succession of sands, clays and organic layers in the western part. Communication with the sea is episodic, and the sedimentation is controlled by an active channel, as shown by the presence of displaced coastal-marine faunas at some sites. Around 5000 years BP, a coastal marsh began to develop with high organic matter contents. These organic deposits presently outcrop on the beach, suggesting a more seaward location of the shoreline at that time. Generally, these sediments are azoic. When fauna is present, it indicates brackish to freshwater environments showing a progressive isolation of the system. A second phase of terrigenous sedimentation occurred after a transgressive event around 2800-2500 years BP, but the communication with the sea was then very reduced, as indicated by mainly freshwater faunas. This transgressive event appears to be synchronous with a positive sea-level tendency recorded, throughout north-western European coasts, between 3000 and 2000 years BP. The definitive closing of the marsh occurred around 2100 years BP, after a second phase of freshwater marsh. (	
Tipo: 	Text	
Idioma: 	Inglês	
Identificador: 	http://archimer.ifremer.fr/doc/00322/43349/42877.pdf

DOI:10.1016/S0399-1784(01)01153-7

http://archimer.ifremer.fr/doc/00322/43349/	
Editor: 	Gauthier-villars/editions Elsevier	
Formato: 	application/pdf	
Fonte: 	Oceanologica Acta (0399-1784) (Gauthier-villars/editions Elsevier), 2001-07 , Vol. 24 , N. 4 , P. 377-389	
Fonte: 	2001 Ifremer/CNRS/IRD/Éditions scientifiques et médicales Elsevier SAS

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