Figure 1. Schematic illustration of the mechanical model, used for the calculation of the stress state of lithosphere, and the method of parametrization of a 3-D model, used for the conversion of variations in density boundaries into density variations in relatively thin plane-parallel layers. Here r _stand - density according to the reference model (depth dependent only). Deviations of the constructed 3D density model of the lithosphere from the reference values are used in the calculations.