Biostratigraphie de la marge guinéenne : résultats préliminaires de la campagne Equa-marge I (1983)

Preliminary micropaleontological study, principally based on Fora-minifera, of nine deep sea cores taken from the marginal sedimentary Guinean plateau. Early and Middle Eocene, Middle and Late Mioeene, Early Pliocene ana Quaternary microfaunas have been found. The thin and rarely complete Quaternary beds overly various eroded older terms, either (more often) through a hiatus, or through a thin reworked zone. (Biostratigraphy of the Guinean margin : preliminary results from the EQUAMARGE I (1983) cruise.)Etude micropaléontologique préliminaire, essentiellement fondée sur les Foraminifères, de neuf carottes superficielles prélevées en eau profonde sur le plateau marginal sédimentaire de la Guinée. Des niveaux d'âge éocène inférieur, éocène moyen, miocène moyen, miocène terminal, pliocène inférieur et quaternaire ont pu être mis en évidence par les microfaunes. Le Quaternaire, de faible épaisseur et rarement complet, repose sur divers termes antérieurs érodés, soit (le plus souvent) par l'intermédiaire d'un hiatus, soit par une mince zone de remaniement.Marinho M., Mascle Jean, Moullade Michel, Robert Christian M., Saint-Marc Pierre. Biostratigraphie de la marge guinéenne : résultats préliminaires de la campagne Equa-marge I (1983). In: Géologie Méditerranéenne. Tome 11, numéro 1-2, 1984. C.A.M. IXe colloque africain de micropaléontologie. Paris, Museum d'Histoire Naturelle, du 3 au 6 octobre 1983. pp. 59-65

A geological field trip to the Cote d'Ivoire Ghana transform margin

During the Equanaute survey (June 1992), fourteen submersible dives were performed between 4950 and 2250 m water depths across the southern slope of the Cote d'Ivoire-Ghana Marginal Ridge (CIGMR), in the eastern Equatorial Atlantic. The CIGMR, a high-standing topographic marginal ridge along the Cote d'Ivoire-Ghana transform margin, is believed to result from a complex structural evolution due to the specific wrench-related rifting between Western Equatorial Africa and Northeastern Brazil, in Early Cretaceous times. In this paper we report and discuss geological observations made during dives, and sample analyses to resolve the lithology, paleoenvironmental conditions, age and origin of the CIGMR. The data help in better characterizing the different sedimentary and tectonic regimes which successively prevailed during the CIGMR formation and assessing the thermal regime operative during the fabrication and subsequent evolution of the margin. The thick sedimentary pile exposed along the southern CIGMR slope is made up of a repetitive elastic sequence indicative of a deltaic-to-prodeltaic environment. This sedimentary pile, of Early Cretaceous age, has recorded different stages of the transform margin structural evolution. (1) Syn-to post-lithification deformations first record extensional deformations related to the rifting of the adjacent northern divergent; margin segment (the Deep Ivorian Basin). (2) Wrench tectonics has, at a later stage, produced intense fracturing and participated in local folding; chiefly detected upslope. The integrated studies of geological samples and insitu observations obtained during the Equanaute survey support models. for transform margin evolution proposed mainly from geophysicaI data

La campaña Galinaute del sumergible «Nautile»: tres tipos de fondos marinos en la parte profunda del margen de Galicia

In 7986 the french submersible Nautile dived to 3.500 m-5.500 m at Galicia Margin in the area drilled by the JOIDES Resolution 0-V (CDP, Leg 703). Three different kinds of seafloor were investigated: a) the Galicia passive margin (basement and sediments); b) a basaltic seafloor (probably a piece of Cretaceous oceanic crust of the Biscay Bay; c) a 100 km long belt of serpentinized peridotites (ultramafic seafloor) extended between the oceanic and the thinned continental crus