What is subduction and where does it occur?
Subduction is a geological process that takes place at convergent boundaries of tectonic plates where one plate moves under another and is forced or sinks due to gravity into the mantle. Regions where this process occurs are known as subduction zones.
Subduction zones circle the Pacific Ocean, forming the Ring of Fire. A subduction zone is the biggest crash scene on Earth. These boundaries mark the collision between two of the planet's tectonic plates. The plates are pieces of crust that slowly move across the planet's surface over millions of years.
- What happens when two continental plates collide? Instead, a collision between two continental plates crunches and folds the rock at the boundary, lifting it up and leading to the formation of mountains and mountain ranges.
- Tectonic plates can transport both continental crust and oceanic crust, or they may be made of only one kind of crust. Oceanic crust is denser than continental crust. At a subduction zone, the oceanic crust usually sinks into the mantle beneath lighter continental crust.
- Movements of tectonic plates create volcanoes along the plate boundaries, which erupt and form mountains. A volcanic arc system is a series of volcanoes that form near a subduction zone where the crust of a sinking oceanic plate melts and drags water down with the subducting crust.
Plate subduction occurs when two tectonic plates converge and at least one of them is an oceanic plate. Oceanic plates are formed at divergent plate boundaries from dense basaltic magma. This magma originates from the mantle beneath and fills the gap between the spreading plates.
- This rock (basalt) becomes a new part of Earth's crust. Seafloor spreading occurs along mid-ocean ridges—large mountain ranges rising from the ocean floor. The Mid-Atlantic Ridge, for instance, separates the North American plate from the Eurasian plate, and the South American plate from the African plate.
- Pacific Ocean
- about 200 million years
An oceanic plate can descend beneath another oceanic plate - Japan, Indonesia, and the Aleutian Islands are examples of this type of subduction. Alternately, an oceanic plate can descend beneath a continental plate - South America, Central America, and the Cascade Volcanoes are an example of this type of subduction.
- Continental lithosphere tends to be lighter and more buoyant (it literally floats on top of the magma). Thus, the initial buoyancy of the continental plate relative to the oceanic plate not only caused the oceanic plate to subduct, but further added to the size of the continental plate in the process.
- subduction (n.) a geological process in which one edge of a crustal plate is forced sideways and downward into the mantle below another plate. Synonyms: geological process. geologic process.
- A volcanic neck or lava neck, is a volcanic land form created when magma hardens within a active volcano. When present, a plug can cause an extreme build-up of pressure if rising volatile-charged magma is trapped beneath it, and this can sometimes lead to an explosive eruption.
Updated: 28th November 2019