Once subducted oceanic crustal material has been processed in the subduction zone environment (see the preceding paragraph), it is likely subducted into the deeper, convecting mantle as eclogite, the high-pressure form of basalt.

Eventually this material may be incorporated into the mantle source regions of some erupted magmas.

For example the geochemistry of some oceanic island basalts has been interpreted to suggest that discrete bodies of eclogite or pyroxenite in peridotite-dominated mantle, partially melted at high pressures and contributed to the lavas that erupted at the surface.