Role of mantle indentation in collisional deformation evidenced by deep geophysical imaging of Western Alps
Résumé
In collision belts, the first-order role of the mantle in localizing deformation has remainedelusive, as the resolution of geophysical imaging remains too low to constrain crustal geometry.To address this issue, we geologically interpret a recent high-resolution shear-wavevelocity model from ambient-noise tomography of Western Alps. We show that the lowercrustal Alpine geometry is highly variable at depth, evolving from a preserved Europeancrustal slab in the South to a smooth crustal root in the North. Moho morphology is controlledby numerous pre-existing major faults reactivated during the Alpine orogeny. Twomantle indenters located above the subducted European plate at different depths appear tocontrol the locus of active deformation. The rigid nature of Adria mantle explains the localizationof brittle deformation that is transferred towards the upper crust. The strain-fieldpartitioning results in a combination of strike-slip with either shortening or extension controlledby the anticlockwise rotation of Adria.
Domaines
Planète et Univers [physics]Origine | Fichiers éditeurs autorisés sur une archive ouverte |
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