Geology of Santa Fe island: The oldest galapagos volcano

Abstract

Santa Fe Island was a volcanic center when it emerged 3.9 ± 0.6 m.y. ago. Later upfaulting of a horst along the central axis of the island dominates its present morphology. Santa Fe is made up of evolved transitional lavas that are not related by fractional crystallization alone. Source heterogeneties, differing degrees of melting, or open-system magma chambers may explain the observed trace element variations. Santa Fe, Baltra, and Española make up a geologic subprovince in the central Galapagos: they are older than the other islands, and their lavas are compositionally similar. At the time of their emergence, the three islands were in a tectonic setting similar to that of the young western and central Galapagos Island. © 1985.