Title :

Stress-induced amorphization triggers deformation in the lithospheric mantle

Author(s) :

Samae, Vahid [Auteur]
Electron Microscopy for Materials Science - EMAT (Antwerp, Belgium)
Cordier, Patrick [Auteur]
Unité Matériaux et Transformations - UMR 8207 [UMET]
Demouchy, Sylvie [Auteur]
Géosciences Montpellier
Bollinger, Caroline [Auteur]
Bavarian Research Institute of Experimental Geochemistry and Geophysics [Bayerisches Geoinstitut]
Gasc, Julien [Auteur]
Géosciences Montpellier
Koizumi, Sanae [Auteur]
Earthquake Research Institute [Tokyo]
Mussi, Alexandre [Auteur]
Unité Matériaux et Transformations - UMR 8207 [UMET]
Schryvers, Dominique [Auteur]
Electron Microscopy for Materials Science - EMAT (Antwerp, Belgium)
Idrissi, Hosni [Auteur]
Electron Microscopy for Materials Science - EMAT (Antwerp, Belgium)
Institute of Mechanics, Materials and Civil Engineering [Louvain] [IMMC]

Journal title :

Nature

Abbreviated title :

Nature

Volume number :

591

Pages :

82-86

Publisher :

Springer Science and Business Media LLC

Publication date :

2021-03-03

Article status :

Publié

English keyword(s) :

Olivine
Lithosphere Asthenosphere Boundary
Shear amorphization
Grain boundary sliding

HAL domain(s) :

Planète et Univers [physics]/Sciences de la Terre/Géophysique [physics.geo-ph]
Physique [physics]/Matière Condensée [cond-mat]/Science des matériaux [cond-mat.mtrl-sci]

English abstract : [en]

The mechanical properties of olivine-rich rocks are key to determining the mechanical coupling between Earth’s lithosphere and asthenosphere. In crystalline materials, the motion of crystal defects is fundamental to plastic ...
Show more >The mechanical properties of olivine-rich rocks are key to determining the mechanical coupling between Earth’s lithosphere and asthenosphere. In crystalline materials, the motion of crystal defects is fundamental to plastic flow. However, because the main constituent of olivine-rich rocks does not have enough slip systems, additional deformation mechanisms are needed to satisfy strain conditions. Experimental studies have suggested a non-Newtonian, grain-size-sensitive mechanism in olivine involving grain-boundary sliding. However, very few microstructural investigations have been conducted on grain-boundary sliding, and there is no consensus on whether a single or multiple physical mechanisms are at play. Most importantly, there are no theoretical frameworks for incorporating the mechanics of grain boundaries in polycrystalline plasticity models. Here we identify a mechanism for deformation at grain boundaries in olivine-rich rocks. We show that, in forsterite, amorphization takes place at grain boundaries under stress and that the onset of ductility of olivine-rich rocks is due to the activation of grain-boundary mobility in these amorphous layers. This mechanism could trigger plastic processes in the deep Earth, where high-stress conditions are encountered (for example, at the brittle–plastic transition). Our proposed mechanism is especially relevant at the lithosphere–asthenosphere boundary, where olivine reaches the glass transition temperature, triggering a decrease in its viscosity and thus promoting grain-boundary sliding.Show less >

Language :

Anglais

Peer reviewed article :

Oui

Audience :

Non spécifiée

European Project :

Rheology of Earth materials: closing the gap between TIMEscales in the laboratory and in the MANtle

ANR Project :

Incorporation et diffusion des gaz rares dans les joints de grain.

Administrative institution(s) :

Université de Lille
CNRS
INRA
ENSCL

Collections :

• Unité Matériaux et Transformations (UMET) - UMR 8207

Research team(s) :

Plasticité

Submission date :

2021-03-05T06:38:06Z
2021-03-05T07:29:12Z