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RHEOLOGY OF EARTH MATERIALS: CLOSING THE GAP BETWEEN TIMESCALES IN THE LABORATORY AND IN THE MANTLE

Objective

Most large-scale geological process such as plate tectonics or mantle convection involve plastic deformation of rocks. With most recent developments, constraining their rheological properties at natural strain-rates is something we can really achieve in the decade to come.
Presently, these theological properties are described with empirical equations which are fitted on macroscopic, average properties, obtained in laboratory experiments performed at human timescales. Their extrapolation to Earth’s conditions over several orders of magnitude is highly questionable as demonstrated by recent comparison with surface geophysical observables.
Strain rates couple space and time. We cannot expand time, but we can now reduce length scales. By using the new generation of nanomechanical testing machines in transmission electron microscopes, we can have access to elementary deformation mechanisms and, more importantly, we can measure the key physical parameters which control their dynamics. At this scale, we can have access to very slow mechanisms which were previously out of reach. This approach can be complemented by numerical modelling. By using the recent developments in modelling the so-called “rare events”, we will be able to model mechanisms in the same timescales as nanomechanical testing.
By combining, nanomechanical testing and advanced numerical modelling of elementary processes I propose to elaborate a new generation of rheological laws, based on the physics of deformation, which will explicitly involve time (i.e. strain rate) and will require no extrapolation to be applied to natural processes.
Applied to olivine, the main constituent of the upper mantle, this will provide the first robust, physics-based rheological laws for the lithospheric and asthenospheric mantle to be compared with surface observables and incorporated in geophysical convection models.

Host institution

UNIVERSITE DE LILLE
Net EU contribution
€ 1 784 400,00
Address
42 Rue Paul Duez
59000 Lille
France

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Region
Hauts-de-France Nord-Pas de Calais Nord
Activity type
Higher or Secondary Education Establishments
Non-EU contribution
€ 0,00

Beneficiaries (3)

UNIVERSITE DE LILLE
France
Net EU contribution
€ 1 784 400,00
Address
42 Rue Paul Duez
59000 Lille

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Region
Hauts-de-France Nord-Pas de Calais Nord
Activity type
Higher or Secondary Education Establishments
Non-EU contribution
€ 0,00
UNIVERSITE CATHOLIQUE DE LOUVAIN
Belgium
Net EU contribution
€ 200 000,00
Address
Place De L Universite 1
1348 Louvain La Neuve

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Region
Région wallonne Prov. Brabant Wallon Arr. Nivelles
Activity type
Higher or Secondary Education Establishments
Non-EU contribution
€ 0,00
UNIVERSITEIT ANTWERPEN
Belgium
Net EU contribution
€ 515 000,00
Address
Prinsstraat 13
2000 Antwerpen

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Region
Vlaams Gewest Prov. Antwerpen Arr. Antwerpen
Activity type
Higher or Secondary Education Establishments
Non-EU contribution
€ 0,00