Multiproxy approach for Holocene paleoenvironmental reconstructions from microorganisms (testate amoebae and foraminifera) and sediment analyses: The infilling of the Loire Valley in Nantes (France)

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TitreMultiproxy approach for Holocene paleoenvironmental reconstructions from microorganisms (testate amoebae and foraminifera) and sediment analyses: The infilling of the Loire Valley in Nantes (France)
Type de publicationJournal Article
Year of Publication2015
AuteursDelaine M, Chatelet EArmynot du, Bout-Roumazeilles V, Goubert E, Le Cadre V, Recourt P, Trentesaux A, Arthuis R
JournalHOLOCENE
Volume25
Pagination407-420
Date PublishedMAR
Type of ArticleArticle
ISSN0959-6836
Mots-clésforaminifera, Holocene, paleoenvironmental reconstructions, sediment infilling, testate amoebae
Résumé

Foraminifera and testate amoebae are jointly used with sediment characteristics (sediment size, calcium carbonate, C, H, N and S proportions, and clay mineralogy) to reconstruct the Holocene sediment infilling of the Loire estuary (Nantes, France). The results reveal the infilling of the Loire Valley during the Holocene. Deposited on the Hercynian substratum, the first deposits are made of gravels with rare associated fauna. This corresponds to the gravel lag usually present as basal deposits in the river course. The clay mineralogy indicates an erosion of the substratum. Then, from 8850 to 5850cal. yr BP, estuarine fauna settled in a laminated sediment that alternates between clay and sand. The smectite associated with kaolinite and illite suggests increased input from the Sevre Nantaise River. The fauna progressively shifts from estuarine to marine, indicating a rise in the sea level. From 5850cal. yr BP, the pace of the sea level rise slowed and channels migrated, implying intense erosion. After 2100cal. yr BP, the fauna was dominated by testate amoebae, indicating a continentalization of the environment. The top samples reflect recent human activity and urbanization.

DOI10.1177/0959683614561883