Heat and gravity are fundamental to the process
Lithospheric plates are part of a planetary scale thermal convection system. The energy source for plate tectonics is Earth’s internal heat while the forces moving the plates are the “ridge push” and “slab pull” gravity forces.
It was once thought that mantle convection could drive plate motions. Early textbooks showed mantle convection cells, like in a beaker of hot liquid on a Bunson burner, pushing plates along from below. Convection in the mantle, certainly plays a role, but doesn’t explain how some plates move faster than the convective currents beneath them. What would cause that? Current dynamic models have plates moving as part of a gravity-driven convection system that pushes young hot plates away from spreading ridges and pulls old cold plates down into subduction zones.
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The forces that drive Plate Tectonics include:
- Convection in the Mantle (heat driven)
- Ridge push (gravitational force at the spreading ridges)
- Slab pull (gravitational force in subduction zones)