accretionary tectonics

Accretionary tectonics refers to the process where crustal fragments, known as terranes, are scraped off a descending oceanic plate and added to a continental margin. This occurs at convergent plate boundaries, where tectonic plates collide. As an oceanic plate subducts beneath another plate, these fragments, which can include oceanic crust, island arcs, or other geological features, are essentially "glued" onto the overriding plate.1

This process is a significant mechanism for the growth of continents and the building of mountain ranges. Over time, the accumulation of these accreted terranes can substantially widen continental margins and contribute to the formation of complex mountain belts, such as the Cordilleran ranges in North America. The study of these accreted fragments, particularly oceanic crustal slices called ophiolites, provides valuable insights into the composition and processes of oceanic domains and their interaction with subduction zones.1