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La localisation de la déformation dans le manteau sous-continental:
origine à travers l'étude du massif de Ronda (Espagne) et implications sur la résistance de la lithosphère.

Abstract : The predicted rheology for the sub-continental mantle does not account for both the weak mantle strength beneath deforming regions and processes of lithosphere-scale strain localization. In order to better constrain this rheology, we used structural geology, tectonics and numerical modeling through the study of the Ronda peridotites. The structural study of these peridotites shows that their deformations were formed beneath a back-arc continental rift, before they were inserted into the internal Betics at the early Miocene. Just below the extending crust, a ductile strain gradient occurs in response to a process that implies the dominance of the dryGBS creep during dynamic olivine grain size reduction. Numerical quantifications demonstrate that this ductile process can trigger large strain localization and a drop of strength for the highly deformed peridotites at low temperature (< 800 °C). At larger scale, the results of a 2-D numerical model show also that such a weakening process promotes high strain localization in the sub-continental mantle, which leads to trigger continental necking. This strain localization provokes consistently an important drop of strength in the sub-continental mantle, as observed beneath deforming regions. Based on this “localizing” rheology, our results allow us to propose a new definition of the mantle rheology that accounts for the evolution of the mantle strength during the deformation of the lithosphere.
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https://tel.archives-ouvertes.fr/tel-00365303
Contributor : Jacques Precigout <>
Submitted on : Monday, March 2, 2009 - 10:12:07 PM
Last modification on : Friday, April 5, 2019 - 8:03:15 PM
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Jacques Précigout. La localisation de la déformation dans le manteau sous-continental:
origine à travers l'étude du massif de Ronda (Espagne) et implications sur la résistance de la lithosphère.. Tectonique. Université Rennes 1, 2008. Français. ⟨tel-00365303⟩

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