The initial growth stage of the Fuerteventura Island is represented by submarine, transitional and subaerial volcanics. Among the submarine types, two can be distinguished: a basaltic (s.l.) one, and a basanitic one. The latter is characterized by the presence of hydrous ferromagnesian minerals (kaersutite, phlogopite) and a more alkaline character, whereas the former shows a less alkaline character that brings it closer to the subaerial group. All these groups would be generated from different partial melt degrees of a garnetbearing mantle source. However, for the basanitic group, also a shallower (oceanic lithosphere) melting and an amphibole-bearing source have to be invoked