ИСТИНА

In numerical two-dimensional experiments we investigate the spatial field of overlithostatic horizontal stresses in the mantle and in moving continent and its evolution. A continent moves self-consistently with changing mantle flows. Velocity of a continent in the process of movement varies in accordance with time-dependent forces which act from underlying viscous mantle as well as with mantle forces acting on the end faces of continent (i.e., the thickness of a continent is taken into account). This model is described in [Bobrov, Trubitsyn, 2008]. Continent viscosity is equal to 105 with respect to average viscosity of the mantle. We consider two model laws for viscosity: isoviscous mantle case ν = const; and p,T-dependent viscosity case ν = 30 • exp [-9.2T + 2.3(1-z)] (z – depth from the surface). For these two models we analyze how a form of viscosity law can change the horizontal stress fields in the mantle and continent. We research what model law gives the results more close to actual data. In our statement, both cases should give approximately equal Nusselt number (i.e., should have the same heat transfer). For this reason, the computational Rayleigh numbers were different (for exponential viscosity case - Ra = 10e7 ; for isoviscous model, where the heat transfer is more effective owing to the absence of high-viscosity layer at the surface - Ra = 10e6 ).