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Abstract

A number of samples have been dredged from the upper parts of Amanay and El Banquete Seamounts, yet volcanic materials have been collected only in Amanay. Based on the textural features and the presence or absence of kaersutite, two main types of olivine pyroxene basaltic rocks have been identified. From a compositional point of view, they are basanites with high enrichment in the most incompatible elements, similar to that displayed by Ocean Island Basalts. Samples from Amanay seamount would have been formed due to a low degree of melting of an enriched mantle, very similar to that which probably caused the Miocene volcanic activity of Fuerteventura. The age of Amanay volcanic rocks, 15.3 ± 0.4 and 13.1 ± 0.3 Ma, is similar to those of the old volcanic units exposed in the nearby islands (Gran Canaria, Fuerteventura and Lanzarote). This proves the formation of a separate submarine volcanic edifice coeval with the other edifices of the Eastern Canarian Volcanic Ridge. Volcanic activity on the submarine edifice is thought to have ceased at about 13 Ma, simultaneous with the adjacent main volcanic construction.