Fig. 8: Deformation of the models with a flat Moho topography and a laterally varying surface elevation (non-uniform distribution of gravitational body forces) and a flat Moho topography and a flat surface elevation (uniform distribution of gravitational body forces) since 30 Ma under the influence of left side velocity boundary condition and equal pressure at the base.

a–c The evolution of crustal structure together with the magnitude of the plastic strain (failure) for the brittle upper crust at 20 Ma, 10 Ma, and end of the simulation at 0 Ma, respectively. Vectors represent the flow field through time. d–f The evolution of finite strain (values represent second invariant of strain tensor) magnitude at the brittle and ductile zones of the crust at 20 Ma, 10 Ma, and end of the simulation at 0 Ma, respectively. Note that in the experiment with a flat Moho topography and a laterally varying surface elevation the weakening and damage of the brittle upper crust and the resulting accumulated plastic strain and plastic shear zones produce basins and ranges and symmetric dome-like structures in the crust. The right limb of active shear zones remain at high-angle dips and the left limb evolves into a low-angle detachment fault, but without metamorphic core complex formation. g, h Similar to a–c but at 12 and 0 Ma, respectively. i, j Similar to d–f but at 12 and 0 Ma, respectively. Note that in the experiment with a uniform thickness crust and flat Moho topography the weakening and damage of the brittle upper crust and the resulting accumulated plastic strain and plastic shear zones produce basins and ranges, but no doming or metamorphic core complex formation. Necking centers in the crust remain active, and the conjugate shear zones are diffuse or distributed throughout. Dips of the active shear zones remain high and no low-angle detachment fault forms. Experiments start at 30 Ma and evolve to 0 Ma. Stages of evolution are given in Ma.