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Contents of 12.8 What forces cause plate motions and plumes?

• Plate tectonics, mantle plumes, and superplumes are expressions of convection.
• Subducting lithosphere represents the downwelling process of mantle convection.
• Subducting plates provide nearly all the force required to cause plate motion by slab pull and slab suction.
• Convective upwelling is more diffuse and occurs in the upper mantle at divergent plate boundaries to fill a void, and in the lower mantle as superplumes, which probably connect to at least some hot spots at the surface.

12.8 What forces cause plate motions and plumes?