What is subduction zone magmatism?
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Magma formed above a subducting plate slowly rise into the overriding crust and finally to the surface forming a volcanic arc, a chain of active volcanoes which parallels the deep ocean trench. They occur down to depths of around 670 km at some subduction zones.
What causes magmatism above subduction zones?
In contrast to mid-ocean ridge magmatism, where upwelling and adiabatic decompression of the mantle is the primary cause of melt generation, subduction zone magmatism is triggered by the depression of the mantle solidus due to influx of volatiles (dominantly H2O) from the dehydrating subducting slab (Grove et al.
What is island arc magmatism?
Island arcs are long chains of active volcanoes with intense seismic activity found along convergent tectonic plate boundaries (such as the Ring of Fire). Most island arcs originate on oceanic crust and have resulted from the descent of the lithosphere into the mantle along the subduction zone.
Where is the magmatic arc?
Continental magmatic arcs form above subduction zones where the upper plate is continental lithosphere and/or accreted transitional lithosphere. The best-studied examples are found along the western margin of the Americas. They are Earth’s largest sites of intermediate magmatism.
What is an example of a subduction zone?
Examples of Subduction Zones An example of a series of islands that formed from a genuine subduction zone is the Aleutian Islands, positioned near the border between two oceanic plates. Another example of a subduction zone would be the one that formed the Cascade Volcanoes in Oregon, Washington, and Western Canada.
What is meant by a subduction zone?
The subduction zone is the place where two lithospheric plates come together, one riding over the other. Most volcanoes on land occur parallel to and inland from the boundary between the two plates.
How do subduction zones create volcanoes?
A subduction volcano forms when continental and oceanic crust collide. The oceanic crust melts and migrates upwards until it erupts on the surface, creating a volcano.
Which types of boundaries produce subduction?
1. Convergent boundaries: where two plates are colliding. Subduction zones occur when one or both of the tectonic plates are composed of oceanic crust. The denser plate is subducted underneath the less dense plate.
What are subduction zones?
What is volcanism process?
Volcanism is the eruption of molten rock from inside the Earth to the surface. Volcanism occurs because of Earth’s internal heat, and is associated with tectonic processes and a part of the rock cycle. Volcanic eruptions occur when molten lava reaches the surface of the Earth.
Is Hawaii a volcanic island arc?
The Hawaiian Islands were formed by volcanic activity. The Hawaiian Emperor seamount chain is a well-known example of a large seamount and island chain created by hot-spot volcanism. Each island or submerged seamount in the chain is successively older toward the northwest.
Is Aleutian Islands subduction zone?
Part of Hall of Planet Earth. The Aleutian Trench, extending 2,900 kilometers from the Gulf of Alaska to Kamchatka, marks the place where the Pacific plate is being subducted beneath the North American plate.
What is the significance of magmatism in subduction zones?
Magmatism in subduction zones builds continental crust and causes most of Earth’s subaerial volcanism. The production rate and composition of magmas are controlled by the thermal structure of subduction zones.
How is the thermal structure of a subduction zone calculated?
In canonical models, the thermal structure of subduction zones is calculated as a balance between thermal diffusion and advection. Heat is advected by the creeping solid mantle flow within the wedge-shaped region between the subducting slab and overriding lithosphere ( McKenzie, 1969 ).
How is subduction initiated in the Neotethys?
Subduction initiation in the Neotethys is recorded by supra–subduction zone ophiolites containing hydrous arc tholeiites and boninites, greenschist- to granulite-facies metamorphic soles, and/or evidence of forearc extension coupled to long-lived arc magmatism (e.g., Maffione et al., 2017; Shervais, 2001) ( Fig. 2 ).
Does melt migration predict arc heat flow in subduction zones?
Predicted arc heat flow in subduction zones associated with melt migration compared with observed, global ranges. The ranges shown are based on the global compilation of Stein (2003), as presented by Manga et al. (2012).