Theses and Dissertations Collection

The Galápagos plume has profoundly affected the development and evolution of the nearby (<250 km) Galápagos Transform Fault (GTF). We present major element, trace element, and radiogenic isotope analyses of samples collected from the GTF during SON0158, EWI0004, and MV1007 cruises. We find that GTF lavas are chemically distinct from nearby axial ridge lavas and off-axis seamounts. The GTF lavas are anomalously depleted in incompatible trace elements (ITEs) and have lower ratios of more incompatible to less incompatible trace elements relative to axial lavas; comparable ITE compositions are only observed >300 km from the plume center. We present a melting model that reproduces GTF lava chemistry from a mixture of melts from a two-component mantle. Model results predict that GTF lavas are produced by a mixture of ~4-5% partial melts of a mantle source that has previously undergone partial melting and is being re-melted beneath the TF.