THE MEDITERRANEAN LOWER CRETACEOUS

2.2. Continental Margin of Northwestern Africa
This vast area covered by the waters of the Atlantic Ocean includes the Continental
Margin of Northwestern Africa from Senegal to Gibraltar, with the Cape Verde
Islands, the Canary Islands and Madeira. The ocean bottom is with strongly differentiated
relief (U с h u p i et al., 1976) (Fig. 16).
Fig. 16. Schematic section of the Continental Margin of Northwestern Africa (according to data
of deep-sea drilling and seismic investigations). Init. Rep. DSDP, 47, 1, 1977)
The oldest sedimentary rocks are the Upper Jurassic-Lower Cretaceous limestones
and siliceous rocks discovered on Maio Island (Cape Verde Islands). The Lower
Cretaceous starts with the Berriasian which lies with a gradual lithological transition
over Tithonian cherty limestones. The Berriasian, Valanginian and Hauterivian
are represented by slightly metamorphosed limestones, 200 m thick, covered
by basalt lava which spread at the end of the Hauterivian. The Berriasian-Hauterivian
part is dated by scanty foraminifera. The Barremian is represented on top
by bituminous marls with Crioceratites emerici L é v., Heteroceras giraudi К i I.,
Lytoceras subfimbriatum d'O г b., bivalvs and fish remains.
The Aptian-Albian section is built of variegated clayey shales, slightly metamorphosed
limestones and basalts. Pbylloceras guettardi (Ras p.), Parahoplites
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