title: Pure climb creep mechanism drives flow in Earth's lower mantle.
abstract: At high pressure prevailing in the lower mantle, lattice friction opposed to dislocation glide becomes very high, as reported in recent experimental and theoretical studies. We examine the consequences of this high resistance to plastic shear exhibited by ringwoodite and bridgmanite on creep mechanisms under mantle conditions. To evaluate the consequences of this effect, we model dislocation creep by dislocation dynamics. The calculation yields to an original dominant creep behavior for lower mantle silicates where strain is produced by dislocation climb, which is very different from what can be activated under high stresses under laboratory conditions. This mechanism, named pure climb creep, is grain-size-insensitive and produces no crystal preferred orientation. In comparison to the previous considered diffusion creep mechanism, it is also a more efficient strain-producing mechanism for grain sizes larger than ca. 0.1 mm. The specificities of pure climb creep well match the seismic anisotropy observed of Earth's lower mantle.
authors.affiliation: Unité Matériaux et Transformations, UMR CNRS 8207, Université Lille 1, Villeneuve d'Ascq, France.
authors.forename: Francesca
authors.initials: F
authors.lastname: Boioli
authors.affiliation: Unité Matériaux et Transformations, UMR CNRS 8207, Université Lille 1, Villeneuve d'Ascq, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Carrez
authors.affiliation: Unité Matériaux et Transformations, UMR CNRS 8207, Université Lille 1, Villeneuve d'Ascq, France.
authors.forename: Patrick
authors.identifier: 0000-0002-1883-2994
authors.initials: P
authors.lastname: Cordier
authors.affiliation: Laboratoire d'Etude des Microstructures, CNRS-ONERA, Chatillon, France.
authors.forename: Benoit
authors.initials: B
authors.lastname: Devincre
authors.affiliation: Unité Matériaux et Transformations, UMR CNRS 8207, Université Lille 1, Villeneuve d'Ascq, France.
authors.forename: Karine
authors.initials: K
authors.lastname: Gouriet
authors.affiliation: Unité Matériaux et Transformations, UMR CNRS 8207, Université Lille 1, Villeneuve d'Ascq, France.
authors.forename: Pierre
authors.identifier: 0000-0002-7488-8466
authors.initials: P
authors.lastname: Hirel
authors.affiliation: Unité Matériaux et Transformations, UMR CNRS 8207, Université Lille 1, Villeneuve d'Ascq, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Kraych
authors.affiliation: Unité Matériaux et Transformations, UMR CNRS 8207, Université Lille 1, Villeneuve d'Ascq, France.
authors.forename: Sebastian
authors.identifier: 0000-0002-5473-0717
authors.initials: S
authors.lastname: Ritterbex
keywords: Mantle convection Creep mechanism bridgmanite