Two-way exchange between the Easter mantle plume and the Easter microplate spreading axis

Abstract

THE conventional model whereby plume volcanism forms linear age-progressive volcanic chains, with the youngest activity occurring nearest a spreading axis (at a 'hotspot'), has been challenged for the Easter seamount chain1–4. Whereas early work suggested the existence of a linear melting anomaly (a 'hotline')1,2, more recent studies3,4 have proposed a hotspot near Salas y Gomez island, connected with the Easter microplate spreading system by an ∼800-km-long, volcanically active plume channel. Here we use geochemical, geological and geochronological data to argue that the hotspot lies close to Easter Island. Moreover, new isotopic data for lavas from the seamount chain provide evidence for bidirectional flow between the spreading axis and the plume, thus supporting geophysical and fluid-dynamical models of mantle flow in a plume/spreading axis system5–7. Material balance and flux considerations show the Easter plume to be weak and cool compared with those beneath larger features such as Iceland, Hawaii and the Galapagos islands.