Abstract

In this thesis we calculate the effect of small-scale convection on the thickness and temperature structure of the lithosphere for three cases where geophysical and geological data may allow us to see these effects. The problems are: (1) the cooling of the oceanic lithosphere; (2) the cooling of a passive rift temperature structure; and (3) the rate of thinning of lithosphere which has been thickened in a continental convergence zone. In all these cases the convection is driven by the temperature gradients at the base of the lithosphere and the key to the interaction between the lithosphere and the flow in the asthenosphere is the viscosity relation we assume. It is very likely that the viscosity of the mantle depends on temperature and we take that to be the case. Viscosity which also depends on pressure and stress is