Depletion of Nb relative to K and La is characteristic of lavas in subduction-related magmatic arcs, as distinct from mid-ocean ridge basalts. Nb depletion is also characteristic of the continental crust. This and other geochemical similarities between the continental crust and high-Mg# andesite magmas found in arcs suggests that the continental crust may have formed by accretion of andesites. ...

[1] The thermal boundary layer beneath continental cratons extends into the Earth’s mantle to depths of at least 200 km. It has been proposed that chemical depletion of the lithospheric mantle during partial melting offsets the effect of increased density from conductive cooling, resulting in neutral buoyancy with respect to the underlying asthenosphere. Mineral compositions of garnet peridotit...

1: Department of Earth and Environmental Sciences, University of Illinois at Chicago, 845 W. Taylor Street, MC186, SES2440, Chicago, IL 60607, U.S.A. 2: Centre de Recherches Pétrographiques et Géochimiques, Nancy Université, CNRS, BP 20, 54501 Vandoeuvre Cedex France 3: Université Européenne de Bretagne, France. 4: Université de Brest ; CNRS ; UMR 6538 Domaines Océaniques; Institut Universitair...