Title :

Evidence of Dislocation Mixed Climb in Quartz From the Main Central and Moine Thrusts: An Electron Tomography Study

Author(s) :

Weidner, Timmo [Auteur]
Unité Matériaux et Transformations - UMR 8207 [UMET]
Mussi, Alexandre [Auteur]
Unité Matériaux et Transformations (UMET) - UMR 8207
Castelnau, Olivier [Auteur]
Kronenberg, Andreas [Auteur]
Law, Richard [Auteur]
Cordier, Patrick [Auteur]
Unité Matériaux et Transformations (UMET) - UMR 8207

Journal title :

Journal of Geophysical Research : Solid Earth

Abbreviated title :

JGR Solid Earth

Volume number :

129

Pages :

e2024JB029083

Publisher :

American Geophysical Union (AGU)

Publication date :

2024-07-17

ISSN :

2169-9313

HAL domain(s) :

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

English abstract : [en]

In this study we apply electron tomography to characterize 3D dislocation microstructures in two quartz mylonite specimens from the Moine and Main Central Thrusts, both of which accommodated displacements by dislocation ...
Show more >In this study we apply electron tomography to characterize 3D dislocation microstructures in two quartz mylonite specimens from the Moine and Main Central Thrusts, both of which accommodated displacements by dislocation creep in the presence of water. Both specimens show dislocation activity with dislocation densities of the order of 3–4 × 1012 m−2 and evidence of recovery from the presence of subgrain boundaries. ⟨a⟩ slip occurs predominantly on pyramidal and prismatic planes (⟨a⟩ basal glide is not active). [c] Glide is not significant. On the other hand, we observe a very high level of activation of ⟨c + a⟩ glide on the , , (n = 1,2) and even planes. Approximately 60% of all dislocations show evidence of climb with a predominance of mixed climb, a deformation mechanism characterized by dislocations moving in a plane intermediate between the glide and the climb planes. This atypical mode of deformation demonstrates comparable glide and climb efficiency under natural deformation conditions. It promotes dislocation glide in planes not expected for the quartz structure, probably by inhibiting lattice friction. Our quantitative characterization of the microstructure enables us to assess the strain that dislocations can generate. We show that glide systems indicated by the observed dislocations are sufficient to accommodate any arbitrary 3D strain by themselves. Although historically dislocation glide has been regarded as being primarily responsible for producing strain, activation of climb can also directly contribute to the finite strain. On the basis of this characterization, we propose a numerical modeling approach for attempting to characterize the local stress state that gave rise to the observed microstructure.Show less >

Language :

Anglais

Peer reviewed article :

Oui

Audience :

Internationale

Popular science :

Non

European Project :

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

Administrative institution(s) :

Université de Lille
CNRS
INRAE
ENSCL

Collections :

• Unité Matériaux et Transformations (UMET) - UMR 8207

Research team(s) :

Plasticité

Submission date :

2024-07-18T07:39:09Z
2024-08-20T14:07:27Z