| Popis: |
Two-dimensional pseudo-steady-state models of convection in the mantle are investigated by an improved method which yields a much finer resolution near the surface and the ends of the convection cell. The high aspect ratio previously found is confirmed for depth-dependent and non-linear vicosities. These models satisfy most observations: relief, gravity, plate velocity, temperature. A non-linear viscosity model shows a median rift in the mid-ocean ridge and a trench displaced from the continent. So far, no model satisfies the heat-flow data or has a constant surface velocity; these discrepancies are probably connected, but their cause remains speculative. |
