A balance of heating and cooling

Mantle convection is the main mechanism by which heat is removed from the earth’s interior. The mantle is heated by small concentrations of radioactive elements. We can estimate the rates of heating and cooling and use these to calculate how mantle temperature has changed over the eons.

Slow cooling

The picture shows an example of such a calculation. The upper panel shows how the temperature of the core, the upper mantle and the lower mantle would vary with time before present (shown as Age). The lower panel shows the rate of heat generation, the rate of heat removal by plates and the rate at which heat from the core rises in plumes.

Such long-term changes in the temperature of the mantle could have caused changes in the tectonic regime operating at the surface: see tectonic evolution and episodic tectonics.

See:
Davies, G. F., Cooling the core and mantle by plume and plate flows, Geophys. J. Int., 115, 132-146 (1993)