Britannica Sources used in this answer

What is obduction and how does it preserve oceanic crust?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Earth's lithosphere and upper mantle — oceanic crust A cross section of Earth's outer layers, from the crust through the lower mantle.

Obduction is a geological process occurring at convergent plate boundaries where, instead of being subducted into the mantle, a slice of oceanic crust breaks away from the descending slab and is thrust over the overriding plate.1

This process is the primary mechanism by which oceanic crust is preserved on land. When these crustal slices are emplaced onto the continental margin, they are known as ophiolites. Because the vast majority of oceanic crust is typically recycled into the mantle during subduction, the preservation of these ophiolite complexes is rare and geologically significant. They serve as essential natural laboratories that allow scientists to study the composition of the ocean floor and the complex tectonic mechanisms involved in their emplacement.1