Recycling of oceanic crust

In plate tectonics, there are three categories of volcanism: ocean ridge, arc and intraplate. While the origins of ocean ridge and arc volcanism are readily explained by plate tectonics, intraplate volcanism (IPV) is not. The dominant hypothesis for the origins of IPV is by mantle plumes from deep within the interior of the earth.

The plume model arose from the assertion of Wilson that the source of Hawiian lavas was a thermal anomaly or hotspot. And proposed they were conduits of upwelling lower mantle, thus formulating the concepts of plumes. The modern incarnation of the plume model can be attributed to Hofmann and White who proposed plumes were composed of recycled oceanic crust. 

The concept of storing subducted oceanic crust in thermal boundary layers which is based on the Hofmann and White mode had been proposed by Dickinson and Luth as an alternative to models in which subducted oceanic crust was recycled back toward mid-ocean ridge systems by convection within the upper mantle. 

A. D. Smith (2013) Recycling of oceanic crust and the origin of intraplate volcanism, Australian Journal of Earth Sciences, 60:6-7, 675-680.