Structural controls on stresses and deformations in a large-scale lithospheric shell

It is well-accepted that stresses and deformation are controlled by active forces, such as tractions applied along lateral boundaries and base of the lithosphere and body forces raised from density heterogeneities within or below the lithosphere. Here we analyze how structure, geometry and strength distribution, of the Earth crust and upper mantle can affect the pattern of stresses and deformation. As an application example, we use the North Atlantic realm which characterized by strong topography and rheological variations and subjected to active forces from, e.g., the Iceland hot spot. We conduct a series of numerical experiments modelling the lithosphere as an elastic shell of altering geometries influenced by various mechanisms. The first set of experiments demonstrates that lithosphere, as a part of the spherical Earth, is structurally stronger than the flat lithosphere if boundary moments applied. An application of more realistic, topography derived, geometry of the lithospheric shell in the second set of experiments demonstrates the importance of strong topography changes, for example along continent-ocean transition, as a concentrator of bending stresses and deformations. In the third set, we show how viscous properties of the sub-lithospheric asthenosphere may control the lateral extent of the membrane stresses in the lithosphere.