Características composicionaies y procesos de evolución magmàtica en el complejo volcánico Sur - II de Fuerteventura (Islas Canarias)

Abstract

The Southern Volcanic Complex II consists mainly of basalts with some trachybasalls and basaltic trachyandesltes. Its lower sequence is formed by middle alkaline rocks whilst in the upper one only m ild ly alk ali H y + O I -n o rm a tive rocks are found. The variations in com positio n are largely explained by similar crystal fractionation models for both the lower and the upper sequences. The variation among d iffe re nt basaltic types is due to d iffe re n t extractio n rates o f ab out 10-15%, o liv in e being th e domin ant phase, followed, in a lesser proportion, by dinopyroxene. The difference between the most differentiated basalts and trachybasalts or basaltic trachyandesiles could be explained by extraction of dominant clinopyroxene with plagioclase and Fe-Ti oxide