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Effects of composite rheology on plate-like behavior in global-scale mantle convection
  • Maelis Arnould,
  • Tobias Rolf,
  • Antonio Manjón-Cabeza Córdoba
Maelis Arnould
Université Claude Bernard Lyon 1

Corresponding Author:maelis.arnould@univ-lyon1.fr

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Tobias Rolf
University of Oslo
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Antonio Manjón-Cabeza Córdoba
University College London
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Abstract

Earthâ\euro™s upper mantle rheology controls lithosphere-asthenosphere coupling and thus surface tectonics. Rock deformation experiments and seismic anisotropy measurements indicate that composite rheology (co-existing diffusion and dislocation creep) occurs in the Earth’s uppermost mantle, potentially affecting convection and surface tectonics. Here, we investigate how the spatio-temporal distribution of dislocation creep in an otherwise diffusion-creep-controlled mantle impacts the planform of convection and the planetary tectonic regime as a function of the lithospheric yield strength in numerical models of mantle convection self-generating plate-like tectonics. The low upper-mantle viscosities caused by zones of substantial dislocation creep produce contrasting effects on surface dynamics. For strong lithosphere (yield strength $>$35 MPa), the large lithosphere-asthenosphere viscosity contrasts promote stagnant-lid convection. In contrast, the increase of upper mantle convective vigor enhances plate mobility for lithospheric strength $<$35 MPa. For the here-used model assumptions, composite rheology does not facilitate the onset of plate-like behavior at large lithospheric strength.
02 May 2023Submitted to ESS Open Archive
04 May 2023Published in ESS Open Archive