Towards robust and predictive geodynamic modelling: the way forward in frictional plasticity

Thibault Duretz (1) , René de Borst (2) , Philippe Yamato (1) , Laetitia Le Pourhiet (3)

1 GR - Géosciences Rennes
2 University of Sheffield [Sheffield]
3 iSTeP - Institut des Sciences de la Terre de Paris

Strain localization is a fundamental characteristic of plate tectonics. The resulting deformation structures shape the margins of continents and the internal structure of tectonic plates. To model the occurrence of faulting, geodynamic models generally rely on frictional plasticity. Frictional plasticity is normally embedded in visco‐plastic (V‐P) or visco‐elasto‐plastic (V‐E‐P) rheologies. This poses some fundamental issues, such as the difficulty, or often inability, to obtain a converged equilibrium state, and a severe grid sensitivity. Here, we study shear banding at crustal‐scale using a visco‐elasto‐viscoplastic (V‐E‐VP) model. We show that this rheology allows to accurately satisfy equilibrium, leads to shear band patterns that converge upon mesh refinement and preserves characteristic shear band angles. Moreover a comparison with analytic models and laboratory data reveals that V‐E‐VP rheology captures first order characteristics of frictional plasticity. V‐E‐VP models thus overcomes limitations of V‐P and V‐E‐P models and appears as an attractive alternative for geodynamic modeling.

Keywords: tectonics; numerical modeling; faulting; plasticity; rheology; geodynamics

Domains: Tectonics

Thibault Duretz, René de Borst, Philippe Yamato, Laetitia Le Pourhiet. Towards robust and predictive geodynamic modelling: the way forward in frictional plasticity. Geophysical Research Letters, 2020, 47 (5), pp.e2019GL086027. ⟨10.1029/2019GL086027⟩. ⟨insu-02498077⟩