The heat driving mantle convection primarily comes from three sources:
- Primordial heat : This is heat left over from the Earth's formation, including the accretion and differentiation processes that created the core. It accounts for about 20 to 50% of the heat in the mantle.
- Radioactive decay : The decay of radioactive isotopes such as uranium, thorium, and potassium within the mantle and core generates significant heat, contributing about 50 to 80% of the total heat driving convection.
- Tidal friction : The gravitational pull of the Moon on the Earth causes tidal friction, which may contribute up to about 10% of the heat.
This internal heat causes the mantle material near the core to become hot and less dense, leading it to rise, while cooler, denser material sinks, creating convection currents that drive plate tectonics and mantle dynamics
. In summary, mantle convection is fueled mainly by the combination of primordial heat and radioactive decay, with a smaller contribution from tidal forces
