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| Titel |
Evolutionary models of the Earth with a grain size-dependent rheology: diffusion versus dislocation creep |
| VerfasserIn |
Antoine Rozel, Gregor Golabek, Marcel Thielmann, Jana Schierjott, Paul Tackley |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250134189
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| Publikation (Nr.) |
 EGU/EGU2016-14887.pdf |
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| Zusammenfassung |
| We present a set of 2D numerical simulations of mantle convection considering grain size
evolution and a composite visco-plastic rheology including diffusion and dislocation
creep. A 1D parameterization allows us to anticipate the stress conditions for the
present-day temperature profile in a convection cell. We are therefore able to obtain
self-consistent 2D convecion models together with non-equilibrium grain size for
present-day conditions, controlling the partitioning between diffusion and dislocation
creep.
However, the internal temperature of the mantle is thought to have significantly
evolved throughout the history of the Earth. Using a higher internal temperature
is usually believed to decrease both viscosity and internal stresses. In our case,
a high temperature potentially increases the grain size, which tends to increase
the viscosity: the temperature and grain size-dependence of the viscosity are in
competition.
We study the evolution of the diffusion-dislocation partitioning throughout the
history of the Earth. We report the evolution of grain size and stress over time in our
simulations.
Several complex processes are included in our models. Grain size evolution is a sum of
grain growth and dynamic recrystallization. All our simulations consider thermochemical
convection in a compressible mantle with melting producting basaltic crust and depleted
mantle. Close to the surface, melting produces basaltic material which is erupted or intruded
at the base of the crust. Phase transitions reset the grain size to a low value, which influences
the whole dynamics of the mantle. |
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