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Interactions mécaniques entre la tectonique compressive et le magmatisme : expériences analogiques et exemple naturel

Abstract : The magmatism takes place mainly in extreme cases of the plates lithospheric, where the tectonic deformation can be important. In order to study the mechanical interactions between compressive tectonics and the magmatism, we developed a new experimental technique, into which a fluid (simulating the magmas) is injected into silica powder (simulating the crust) in shortening. A first series of experiments, in which the silica powder is homogeneous, shows that the presence of magmas induces the formation of arched overlappings and a plate not deformed. Conversely, the deformation supports the horizontal installation of the magmas, and controls their relatively passive installation in a space adapted by the tectonic uplift of the plate. Into one second series of experiments, we introduced heterogeneities into the silica powder, in order to simulate a stratification. We show that heterogeneities can control the installation of the magmas to the interface between the levels of different behaviors. In order to validate our experimental results, the experiments are compared with a natural example, the Tromen volcano in Argentina. During three missions on the ground, we carried out a cartographic, structural and geochronologic study of Tromen. We show that the tectonic context of Tromen for its volcanic working life was compressive. Moreover, the results obtained show similarities between the structures observed on Tromen and those obtained in our experiments (arched overlappings, little deformed plate) thus validating our experimental results. Lastly, the structures obtained in our experiments also show similarities with the structures observed in the Andes Centrales on a crustal scale. This comparison enables us to propose a new model of formation of the high plateaus, such Altiplano and Tibet, which remain great geological enigmas.
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https://tel.archives-ouvertes.fr/tel-00008498
Contributor : Alain-Hervé Le Gall <>
Submitted on : Tuesday, March 15, 2005 - 3:35:18 PM
Last modification on : Thursday, January 14, 2021 - 11:41:14 AM
Long-term archiving on: : Friday, April 2, 2010 - 9:06:15 PM

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  • HAL Id : tel-00008498, version 1

Citation

Olivier Galland. Interactions mécaniques entre la tectonique compressive et le magmatisme : expériences analogiques et exemple naturel. Géologie appliquée. Université Rennes 1, 2004. Français. ⟨tel-00008498⟩

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