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Impact of the overriding plate crustal rheology on convergence zones dynamics

Abstract : Most of deformation at the Earth’s surface is localized at plate boundaries. This deformation can be accommodated in very different ways depending on the tectonic setting. In the case of the convergence zones, the deformation is classically classified as follows: i) intra-oceanic convergence (when convergence involves two oceanic lithospheres), which generally leads to the subduction/ obduction initiation and to the formation of an island arc, ii) convergence between an oceanic and a continental lithosphere, which is generally accommodated by subduction and can also lead to the formation of a mountains range at the plate boundary and iii) convergence between two continental lithospheres leading to the formation of a collisional mountain range formed by the stacking of crustal slices. Hence, different materials (i.e., oceanic crust, continental crust, sediments) evolving in different contexts (i.e., oceanic subduction, continental subduction, obduction) result in the formation of contrasted structures in terms of units size, morphology and metamorphism. In addition, some convergent zones from a similar tectonic context (e.g., ocean/continent convergence) can produce mountains ranges presenting very different characteristics (e.g., characterized by extension as in the Aegean or, at the opposite, by significant shortening, as in the Andes). Although the mechanism of plate convergence appears to be the same, the structures obtained at the surface (e.g., Alpes, Andes, Aegean, Himalayas) seem then to be unique. Rheology of both the lower subducting plate and of the plates interface is known to influence the convergence zones dynamics. However, very few studies have addressed the role of the overriding plate rheology in details, while it may also exert a large control on the deformation style at plate boundaries. In this study, we therefore focus on the influence of the overriding plate rheology on the convergence zones dynamics and, more precisely, on the role of the crustal part. For this, we use both 2D thermo-mechanical numerical models and 3D analogue models, in which the rheological property of the crust of the upper plate is tested vertically but also laterally. This complementary approach allows us to test the effect of numerous parameters controlling the rheological structure (e.g., nature of the material, thickness, convergence velocity, initial thermal structure) on the convergence zone dynamics and on the deformation style occurring at plate boundaries
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Conference papers
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Contributor : Isabelle Dubigeon <>
Submitted on : Wednesday, October 26, 2016 - 3:45:30 PM
Last modification on : Friday, April 5, 2019 - 8:17:50 PM

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Solenn Hertgen, Philippe Yamato, Benjamin Guillaume. Impact of the overriding plate crustal rheology on convergence zones dynamics. 25 ème Réunion des sciences de la Terre (RST 2016), Société Géologique de France, Oct 2016, Caen, France. pp.159. ⟨insu-01388167⟩

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