What geographic feature is associated with an ocean plate going under a continental plate?

Plate subduction.

Explanation:

When an ocean plate goes under a continental plate the process is called plate subduction. Since we know that density of oceanic plates are higher in density (heavier) than continental plates so in case of collision ocean plate goes below and form trenches. Continental plates are made up of Silicon and aluminium (SIAL) and oceanic plates are made up of silicon and manganese (SIMA).