Jean-Pierre André

Mixed siliciclastic–cool-water carbonate deposits over a tide-dominated epeiric platform: the Faluns of l’Anjou formation (Miocene, W. France)

Abstract 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.

Une plate-forme ouverte à faciès bryomol: Le bassin Miocène supérieur de Charf El Akab (Maroc atlantique)

Abstract Along the northwestern coast of Morocco, near Tangier, Late Tortonian-Messinian carbonate and clastic deposits constitute the filling of a subsident open shelf. The carbonate rocks are mainly medium to coarse bryozoan skeletal grains with molluscs and red algae (bryomol facies). The sedimentation was mainly controlled first by wave and swell energy, and then by tidal currents. These characters give evidence of a marine temperate water; however, some genera and species of bryozoans found in the sediments may indicate a tropical environment.