The oceanic crust is primarily destroyed at subduction zones. These zones are areas where one tectonic plate is forced beneath another into the Earth’s mantle. This process occurs at convergent plate boundaries, where two plates move towards each other.
When an oceanic plate converges with a continental plate, the denser oceanic plate is subducted beneath the less dense continental plate. As the oceanic plate descends into the mantle, it begins to melt due to the increasing temperature and pressure. This melting process recycles the oceanic crust back into the mantle, effectively destroying it.
Subduction zones are also associated with deep ocean trenches, volcanic activity, and earthquakes. The most well-known subduction zones include the Pacific Ring of Fire, where the Pacific Plate is subducting beneath several continental plates, leading to frequent volcanic eruptions and seismic activity.
In summary, the oceanic crust is destroyed at subduction zones, where it is recycled back into the Earth’s mantle through the process of plate tectonics.