Collaborative Research: Volcanic Evolution in the Galapagos: A Geological, Petrological, and Geochemical Investigation of Volcan Ecuador

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9612110 Geist This project is an integrated field, petrological, and geochemical study of Volcan Ecuador, Isla Isabela, Galapagos. The immediate objectives of this study are as follows: 1. Determine the eruptive and structural history of the volcano through field studies and K-Ar dating. 2. Obtain a sufficiently complete suite of chemical data so that the liquid line of descent can be determined and the nature of the parental magmas constrained. 3. Identify any temporal trends in composition, through analysis of suites of samples whose ages are constrained by a combination of stratigraphy and K-Ar dating. For this purpose, samples will be taken from stratigraphic sections exposed in fault scarps and caldera walls. Determine what, if any, effect has the apparent faulting on Ecuador had on magma composition? Laboratory based work will include major element analyses, petrographic studies, electron microprobe analyses of mineral phases, Sr, Nd, Pb, and Hf isotopic analyses, and trace element analyses. The results obtained will be used, along with thermodynamic models of magmas, to model magma generation and evolution. These will be compared with the results of studies of other volcanoes in the Galapagos. This in turn will be used to address the problem of how the Galapagos mantle plume interacts with lithosphere and asthenosphere at shallow levels in the mantle beneath the Galapagos. The proposed study is a joint Franco-American project involving a collaboration between Francis Albarede of the Ecole Normale Superieure de Lyon, Dennis Geist of the University of Idaho, and William White of Cornell University.