Petrology and Geochemistry of lavas from Sal Island: Implications for the variability of the Cape Verde magmatism

sal island (cape verde archipelago) preserves a magmatic history ranging from ≈ 25.6 ma to ≈ 0.6 ma. the chemistry of magmatism varies from hy-normative (serra negra basalts: ≈ 5 ma) to highly sio2 undersaturated (nephelinites and melilitites). the calculated temperatures of magmatic segregation are higher than those usually considered for the asthenosphere, thus endorsing the role of a mantle plume to the origin of cape verde magmatism. nephelinites and melilitites are characterized by pronounced k negative anomalies which are interpreted as reflecting the interaction of plume magmas with the lithosphere. some of the sal lavas are characterized by low 143nd/144nd (down to 0.512577) - when compared with the himu component. these values are similar to those usually reported for the southern cape verde islands. this suggest the role of a em1-type end-member to the magma sources of the sal, which is for the first time evidenced from the whole rock composition of one of the northern cape verde islands.