Which process involves a tectonic plate being pulled as its edge subducts into the mantle?

Which process involves a tectonic plate being pulled as its edge subducts into the mantle?

• A. Slab Pull
• B. Basal Drag
• C. Asthenosphere
• D. Mantle

Answer: (A)

Slab pull describes the gravitational force that acts on a cold, dense subducting slab as its edge sinks into the mantle, pulling the rest of the plate along with it. When oceanic lithosphere cools and becomes dense enough, it begins to dive at a trench. The sinking slab has downward weight, and that weight effectively pulls the whole plate toward the subduction zone. This is a strong driving force, especially for older, colder oceanic plates. Basal drag is a related concept where mantle convection at the base of the plate exerts shear forces, but it’s a different mechanism from the actual pull caused by the sinking slab. The asthenosphere is the weak, ductile layer the plates glide over, and the mantle is the broader shell within which these processes occur. The question points specifically to the pulling action of the subducting edge, which is why slab pull is the best description.

Slab pull describes the gravitational force that acts on a cold, dense subducting slab as its edge sinks into the mantle, pulling the rest of the plate along with it. When oceanic lithosphere cools and becomes dense enough, it begins to dive at a trench. The sinking slab has downward weight, and that weight effectively pulls the whole plate toward the subduction zone. This is a strong driving force, especially for older, colder oceanic plates.

Basal drag is a related concept where mantle convection at the base of the plate exerts shear forces, but it’s a different mechanism from the actual pull caused by the sinking slab. The asthenosphere is the weak, ductile layer the plates glide over, and the mantle is the broader shell within which these processes occur. The question points specifically to the pulling action of the subducting edge, which is why slab pull is the best description.