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La modélisation expérimentale tridimensionnelle thermomécanique de la subduction continentale et l'exhumation des roches de ultra haute pression/basse température

Abstract : Spatial distribution of UHP/LT terrains evidences that their exhumation is essentially a 3-D process that takes place in specific sites of the mountain belt characterised by structural and/or geometrical complexities. In 2-D thermo-mechanical laboratory experiments of continental subduction in the low compressional regime, we ob-tained exhumation of HP rocks from depth limited by the overriding plate thickness (~70 km). Deeper subducted crust becomes too hot and hence weak. It flows up and underplates the overriding lithosphere. In 2-D experi-ments corresponding to highly compressional regime, the continental margin subduction causes failure of the overriding plate resulting in subduction of the fore-arc block or arc plate. The continental crust subducts to more than 200 km-depth, being sandwiched between the subducting “cold” block/plate and the subducted continental mantle. This crust thus meets UHP/LT conditions. It is still very weak but cannot flow up in this 2-D context, being blocked between the indicated rigid units. We show numerically that subduction along a convex plate boundary generates locally within the overriding plate along-boundary extension that produces local retreat of this plate front and thereby reduction of interplate pressure. Such a reduction is necessary to allow exhumation. By applying this extension to the overriding plate in a 3-D thermo mechanical model we do obtained local ex-humation of UHP/LT and investigated in detail its mechanism.
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https://tel.archives-ouvertes.fr/tel-00005197
Contributor : David Boutelier <>
Submitted on : Wednesday, March 3, 2004 - 11:12:46 AM
Last modification on : Thursday, March 5, 2020 - 12:20:31 PM
Document(s) archivé(s) le : Friday, April 2, 2010 - 8:11:21 PM

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  • HAL Id : tel-00005197, version 1

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David Boutelier. La modélisation expérimentale tridimensionnelle thermomécanique de la subduction continentale et l'exhumation des roches de ultra haute pression/basse température. Géologie appliquée. Université Nice Sophia Antipolis, 2004. Français. ⟨tel-00005197⟩

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