During a continent-continent collision, such as the India-Asia or the Europe-Adria collision, some areas of the continental lithosphere are shortened. This shortening can cause three main deformation styles in the continental lithosphere: (1) brittle faulting, (2) heterogeneous ductile folding or (3) homogeneous ductile thickening.
We apply basic continuum mechanical models to better understand which parameters control the deformation style of the lithosphere. Furthermore, we study how the integrated strength on the continental lithosphere varies during shortening.
Figure 1: Basic 2D thermo-mechanical models of the continental lithosphere with different rheological flow law for the lower crust, crustal thickness and basal temperature.
Figure 2: Finite element simulations of lithospheric shortening. Depending on the rheology of the lower crust, shortening of the continental lithosphere is dominated by either folding (left) or thrusting (right).
Figure 3: 3D finite element model to study the fundamentals of continental indentation. The continental lithosphere is modeled as a power-law fluid with four layers of different effective viscosity representing (1) strong upper crust, (2) weak lower crust, (3) strong upper mantle and (4) weak upper mantle. With such models we study the relative importance of the three deformation styles (1) thickening, (2) folding and (3) lower crustal flow. The model has a free surface and includes gravity.
Figure 4: Set-up for a full 3D model to study the velocity and deformation field resulting from the collision of India and Asia. The set-up is based on latest topographic, gravity and seismic data (left). Map view of surface velocity field together with velocity field determined from GPS data (right).