subductionzonetype

Subductionzone type refers to the classification of convergent plate boundaries where one tectonic plate sinks into the mantle beneath another. Subduction zones recycle oceanic lithosphere and drive major geologic processes, including earthquakes, volcanism, and mountain building. They are commonly marked by deep seismicity in a Wadati-Benioff zone, a surface trench, an accretionary wedge, forearc and backarc basins, and, in many cases, a volcanic arc.

There are three broad subduction-zone types based on the interacting plates. Oceanic-continental subduction occurs when an oceanic plate subducts beneath a continental plate; it typically produces a continental volcanic arc, an adjacent forearc basin, and related seismicity. Oceanic-oceanic subduction involves one oceanic plate subducting beneath another, yielding island arcs and deep trenches. Continental-continental subduction is less common today because large continental plates resist subduction; when it occurs, it tends to produce crustal thickening and high-grade metamorphism rather than a long-lived volcanic arc, and it is often associated with large mountain belts rather than active arc volcanism. In modern Earth, most subduction zones involve at least one oceanic plate.

Subduction-zone geometry also varies. Slabs may descend at steep angles or at shallow, flat angles, and they can undergo rollback, tearing, or complex deformation. These geometries influence surface volcanism, backarc spreading, mantle flow, and patterns of earthquakes. The depth extent of the descending slab, traced by seismicity, helps define the subduction regime.

Subduction zones have major implications for hazards, resource formation, and Earth's evolution. They host powerful earthquakes and volcanoes, create ore deposits, and contribute to crustal growth and recycling. Notable examples include the Cascadia subduction zone, the Peru-Chile trench with the Andean arc, and the Arcs of Japan, the Aleutians, and Indonesia.