Collaborative Research: The Origin and Evolution of the Galapagos Lithosphere, Floreana Volcano
Floreana Island is the most distinctive volcano of the Galapagos hotspot system. Unlike other Galapagos Islands, Floreana experienced extensive explosive activity, and its alkalic lavas are anomalously enriched in incompatible trace elements, exhibit evidence of metasomatism, have unique isotopic compositions, and contain abundant mantle xenoliths. The fundamental goal of the proposed project is to use Floreana's unique features to elucidate the magmatic processes that construct and modify the lithosphere forming the Galapagos Platform, which will be accomplished through a detailed volcanologic, petrologic, and geochemical study. Determining the volcanic history and compositional evolution of Floreana volcano will permit estimation of variations in the depths and extents of melt production through analysis of major and trace element variations and how those change with time. These results will be applied to questions about Floreana's volcanic evolution, including: a) the relationship between the different eruptive sequences; b) apparent shallow depths of melting, which may contradict a deep plume origin; c) compositional variations within single eruptive episodes; d) the relationship between Floreana lavas and the giant volcanic terraces which underlie the southern Galapagos Platform; and e) the origins of the xenoliths and their relationship to Floreana lavas and other parts of the Galapagos lithosphere. The powerful combination of high precision geochemical and petrologic analysis coupled with detailed field observations will provide a rare opportunity to gain insight into elusive questions about plume-lithosphere interaction, ocean-island magmatism, and, ultimately, mantle evolution.