Évolution sédimentaire comparée des marges armoricaines et de Blake-Bahama depuis le Crétacé supérieur, d'après les résultats des Legs 48 et 44 du Glomar Challenger

We compare the post-lower Cretaceous sedimentary evolution on the Armorican and Blake Plateau continental margins. This comparison is based on lithological studies made on sediments from legs 44 and 48 of D.V. Glomar Challenger. These studies (mineralogy, textures, coarse fraction observation) and the consideration of the accumulation rates for each components, allow us to establish the similarity between the sedimentary regime on both margins. We notice particulary the simultaneous occurrence of a lowermost upper Cretaceous hiatus, reduced accumulation rates during Late Cretaceous and Paleocene ; the instauration of an active bottom current regime during Paleocene and its strengthening during Eocene and Oligocene ; a drastic incrcase of the accumulation rate during Miocene and Pliocene (terrigenous and biogenous supplies) contemporaneous of the alpine orogenic phases and of the global climatic deterioration. The similarity observed in both evolution appears as a consequence of the control exerced by sea-floor spreading processes and the related hydrological and climatic changes that occurred as a consequence of the newly created oceanic basins. [NOT CONTROLLED OCR]