Parameters that control lithospheric‐scale thermal localization on terrestrial planets

Abstract

Shear‐heating induced localization has been suggested as a potentially important mechanism for breaking the lithosphere. Yet, the physical parameters that control the onset of this instability remain unclear. We therefore performed systematic 2‐D simulations of visco‐elasto‐plastic lithospheric deformation in which we addressed the effects of various parameters and we found that a sharp transition exists between localizing and non‐localizing regimes. In a next step we develop a semi‐analytical model that combines scaling laws with a 1‐D lithospheric deformation model. We show that the 1‐D model successfully predicts the occurrence of shear localization in 2‐D models, if the thickness of the plastically deforming part of the (lower) lithosphere is employed as characteristic length‐scale. An application of the 1‐D model to the terrestrial planets shows that this type of shear‐localization is expected to occur most readily on Earth.