The Driving Force of Mantle Convection

What drives the motions of mantle convection?

Is it slab suction, subduction, slab-pull and ridge-push, or slab-push and ridge-pull?

Answer:

The slab-pull and ridge-push.

When it comes to the motions of mantle convection, the sinking of cold ocean lithosphere plays a crucial role. This process is primarily driven by the combination of two forces: slab-pull and ridge-push.

Slab-pull: This force occurs as the dense, cold oceanic lithosphere sinks into the mantle at subduction zones. As the lithosphere descends, it exerts a downward force on the rest of the plate, pulling it along. This driving force helps propel the motions of mantle convection, contributing to the overall dynamics of the Earth's geology.

Ridge-push: On the other hand, ridge-push refers to the pressure exerted by the raised mid-ocean ridges. These underwater mountain chains result from the upwelling of magma at divergent plate boundaries. The elevated ridge creates a gravitational force that pushes the rest of the plate away, further influencing mantle convection and tectonic plate movements.

By understanding the interplay between slab-pull and ridge-push, scientists can grasp the fundamental mechanisms driving the motion of Earth's lithosphere and asthenosphere. These forces shape our planet's geological features, from volcanic activity to mountain formation, offering insights into the dynamic processes that shape the Earth's surface.