View article

Some of Earth’s largest magmatic provinces result from the interaction between mid-ocean ridges and near-ridge hotspots, which are hypothesized to overlie plumes of upwelling mantle. Geodynamic models predict that upwelling plumes are sheared by the motion of the overlying tectonic plates and can connect to a nearby mid-ocean ridge by shallow flow beneath thin, young lithosphere. Here we present seismic tomographic images of the upper 300 km of the mantle beneath the Galápagos Archipelago in the eastern Pacific Ocean. We observe a low-velocity anomaly, indicative of an upwelling plume, that is not deflected in the direction of plate motion. Instead, the anomaly tilts towards the mid-ocean ridge at depths well below the lithosphere. These characteristics of the plume–ridge connection beneath the Galápagos Archipelago are consistent with the presence of multiple stages of partial melting, melt …