Why Do Mantle Plumes Rise?

Plumes are postulated to rise as the base of the mantle becomes hotter and more buoyant. Plumes are postulated to rise through the mantle and begin to partially melt on reaching shallow depths in the asthenosphere by decompression melting. This would create large volumes of magma.

What can a rising column of mantle plume cause?

A mantle plume is a large column of hot rock rising through the mantle. The heat from the plume causes rocks in the lower lithosphere to melt.

Why are mantle plumes stationary?

Mantle plumes appear to be largely unaffected by plate motions. While a plume that feeds hot spot volcanoes remains stationary relative to the mantle, the plate above it usually moves. The result is that a chain of progressively older volcanoes are created on the overlying plate.