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Des contraintes pour les zones de convergence: Confrontation des données du métamorphisme et des modélisations numériques thermomécaniques - Application aux Alpes et à l'Oman.

Abstract : What are the mechanisms controlling the exhumation of HP(UHP)-LT metamorphic rocks in the different types of convergence zones? What are the conditions required to obtain this exhumation? Are these mechanisms different according to the nature of the rocks involved? These questions have already been the subject of numerous studies but are still not completely resolved.

Numerical models constitute the ideal tool for such studies. It permits to carry out parametric studies whose results can be tested against natural data. The comparison of synthetic P-T-t paths, obtained from the experiments conducted using the thermomechanical numerical code PARA(O)VOZ, with natural ones inferred from Alpine metamorphism allowed to study the processes of exhumation during convergence in the context of both oceanic and continental subduction. The particular case of obduction was addressed in the case of Oman, for which additional high-resolution P-T estimates were specifically realized.

The numerical experimental part of this study clarifies the influence of parameters such as the convergence rate, the erosion rate, or the nature of the lithospheres involved and the density of sediments, on the exhumation processes. It demonstrates good correlations between the results of the numerical experiments and the field observations (topography, morphology, P-T-t shape, exhumation rates).

This study reveals the importance of the buoyancy forces responsible for the initially fast exhumation stages, both in the accretionary wedge and within the entire subduction channel and intraplate contact zone. It also confirms that erosion and surface tectonic processes control the exhumation rates at the slower, final stages. Finally, this study allows to characterize more precisely the exhumation mechanisms of oceanic crust which, once eclogitized, can be exhumed only with the help of less dense materials such as serpentinite or continental crust.

Finally, an assessment of exhumation paths and mechanisms for sedimentary, oceanic and continental material in convergence zones is proposed.
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https://tel.archives-ouvertes.fr/tel-00134728
Contributor : Philippe Yamato <>
Submitted on : Monday, March 5, 2007 - 10:55:45 AM
Last modification on : Wednesday, December 9, 2020 - 3:13:56 PM
Long-term archiving on: : Tuesday, June 15, 2010 - 4:40:33 PM

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  • HAL Id : tel-00134728, version 1

Citation

Philippe Yamato. Des contraintes pour les zones de convergence: Confrontation des données du métamorphisme et des modélisations numériques thermomécaniques - Application aux Alpes et à l'Oman.. Sciences de la Terre. Université Pierre et Marie Curie - Paris VI, 2006. Français. ⟨tel-00134728⟩

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