How does overriding plate control convergence zone dynamics?
| Autor: | Hertgen, Solenn, Yamato, Philippe, Guillaume, Benjamin, Schliffke, Nicholas, Magni, Valentina, van Hunen, Jeroen |
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| Přispěvatelé: | Géosciences Rennes (GR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS), Department of Earth Sciences [Durham], Durham University, Centre for Earth Evolution and Dynamics [Oslo] (CEED), Department of Geosciences [Oslo], Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO)-Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Dubigeon, Isabelle, Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS) |
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: | |
| Zdroj: | European Geosciences Union General Assembly 2018 European Geosciences Union General Assembly 2018, Apr 2018, Vienne, Austria. Geophysical Research Abstracts, 20, pp.EGU2018-12948, 2018 |
| Popis: | International audience; In convergence zones, oceanic or continental subduction/collision can form mountain belts presenting contrastedunit sizes, morphologies and metamorphisms sequences (e.g., Andes vs., Alps). Hence, some convergent zonesevolving in a similar geodynamic framework (e.g., continent-continent convergence) exhibit very different deformationstyles, with either very localized deformation (e.g., in the Alps) or deformation distributed over thousandsof kilometers (e.g., in the Himalayas/Tibetan Plateau). On the other hand, other convergent zones share similarstructures despite their different tectonic settings (e.g., Tibetan and Altiplano/Puma plateaus). Many studies alreadyexist on the important role played by the subducting plate and the mantle flow on the convergence zone dynamicsand the variability of the structures observed within the overriding plate. However, the influence of the overridingplate itself on the subduction system, and especially, the importance of its rheology, remains poorly understood.In this study, we therefore present 3D thermo-mechanical numerical models of oceanic subduction followedby continental subduction/collision, where the rheological properties of the overriding plate are varied. Forthis, we systematically modified the crustal thickness of the overriding lithosphere (from 20 to 40 km) and thetemperature at the Moho (between 300 and 800C). These ranges of values correspond to thermal thicknesses forthe overriding lithosphere ranging from 80 km to 265 km.While all models share a common global evolution (i.e. slab sinking, slab interacting with the 660-km discontinuityand slab detachment after continental subduction and subduction cessation), our study highlightsstriking differences arising from the variation in overriding plate strength, both in terms of geometry and timing:- The overriding plate rheology controls the subduction mode during oceanic subduction. With a thin, weakoverriding plate (i.e. lithospheric thermal thickness < 150 km) the slab rolls back, while with a thick, strongoverriding plate (i.e. lithospheric thermal thickness > 150 km) the slab folds forward.- Mantle flow is impacted by the overriding plate rheology. With a strong overriding plate, the mantle flow is lessvigorous and more localized around the slab.- The location and the amount of strain within the overriding plate after continental subduction initiation varybetween the two end-members. The weak model shows a diffuse deformation in the whole overriding plate whilein the strong model the deformation is localized close to the trench.- The trench has a higher curvature (convex toward the overriding plate) in models with strong overridinglithosphere.- The slab break-off following continental subduction occurs earlier in the models involving a weak overridingplate than in the models with a "strong" overriding plate. The difference can be as much as 25 Ma within the rangeof tested parameters.Our results evidence the first-order role played by the rheology of the overriding plate on the convergencezone dynamics. Studies focusing on the subduction dynamics should therefore no longer neglect it |
| Databáze: | OpenAIRE |
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