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Theses

Dynamique de l'extension continentale - Application au Rift Ouest-Européen par l'étude de la province du Massif Central

Abstract : The first part of this thesis corresponds to a reappraisal of the West European Rift (WER) exemplified by the study of the Massif Central Rift (MCR). In the Massif Central (MC), the distribution of the volcanism associated with the Cenozoic extension allows to separate three episodes: the Pre-rift Volcanism, the Syn-rift Volcanism and the Main Magmatic episodes. The Pre-rift Volcanism (Paleo-Eocene) is associated with a first period of uplift. The syn-rift Volcanism is related to the Eo-Miocene extension and the graben formation. During this period, the chronology of the events is consistent with a passive rifting evolution. The Main Magmatic episode, responsible for the main volcanic provinces, is characterised by two magmatic climax coeval with uplift periods. Such an evolution is consistent with the fust stage of an active rifting. This MCR evolution is common to the whole WER and the spatial distribution of the grabens, which is concentric to the Alps, suggests a close relationship between these two geological systems. The Eo-alpine phase (== 65 Ma) have induced a buckling of the lithosphere ahead of the moutain range and have triggered the Pre-rift Volcanism. The formation of the alpine lithospheric root might explain the passive rifting during the Oligocene, followed by the "active rifting" from the upper Miocene. The second part of this thesis is aimed to study the dynamics of the continental ex~nsion by the means of analogue models. Experiments at crustal scale show the significant role of the extension rate on the structures. Scaling the strength ratio between the brittle and ductile parts makes it possible to show that the geometry of the structures depends on the number of rupture in the brittle part of the mantle lithosphere and the extension rate. These scaled models allow to explain the difference between the Rhinegraben and MCR geometries.
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Submitted on : Tuesday, January 3, 2012 - 2:14:48 PM
Last modification on : Wednesday, November 20, 2019 - 2:50:59 AM
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  • HAL Id : tel-00656029, version 1

Citation

Laurent Michon. Dynamique de l'extension continentale - Application au Rift Ouest-Européen par l'étude de la province du Massif Central. Tectonique. Université Blaise Pascal - Clermont-Ferrand II, 2000. Français. ⟨tel-00656029⟩

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