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The Tortonian bioclastic sands of Anjou (W France) are weakly cemented mixed siliciclastic–carbonate deposits. The carbonate fraction can reach up to 90%, and is irregularly spread over the area of the original depositional platform. The temperate marine water character is demonstrated by the lack of ooids, green algae, and biohermal scleractinians, and is dominated by numerous species of bryozoans and bivalves, associated with red algae, barnacles, and echinoderms (bryomol facies; Heterozoan association). Skeletal grains are weakly cemented. The presence of large submarine dunes indicates a platform bounded by a tide-domination of a succession that developed rapidly under highstand and shelf margin wedge system tracts. The tide-dominated “Faluns de l’Anjou” provides a model different from many other examples of temperate carbonate settings, which are often wave-dominated. |
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