<p>When the subducted oceanic plate slides beneath the continental crust, it causes crustal thickening and sometimes crustal folding. In addition to this, rising plumes of magma are created when the oceanic plate is forced down into the mantle. These are all orogenic (mountain building) processes. We also have mountains built by volcanoes.</p>

<p>The friction created by the subducted plate scraping the bottom of the plate above as it is being forced into the hot mantle, plus the fact that it carries water with it, causes partial melting of the plate and the rising of magma plumes, which also have a lifting effect. Water mixing with the magma makes it more fluid and more easily melted. These plumes often force their way through the upper plate and erupt as volcanoes, which is why volcanic arcs are created near subduction zones. The classic example of volcanic arcs is found around the Pacific rim, where subduction zones abound.</p>

CC BY-SA 4.0
2019-11-23T09:28:34.200Z
2019-11-23T09:28:34.200Z
Michael Walsby
<p>When an oceanic plate goes under a continental plate are the resulting mountains a result of the melting and then rising of the oceanic plate or are the mountains formed by the continental plate being pushed up by the collision with the oceanic plate?</p>

CC BY-SA 4.0
2019-11-23T12:01:56.703Z
Note that it is generally not the oceanic plate itself that melts to generate subduction arc magmas, although it can happen (adakites for example). It is the mantle wedge between the subducting plate and the crust that melts, because it has been hydrated (thus has a lower temperature solidus) by the release of fluids from the subducting plate (a process called metasomatism).
Jean-Marie Prival
CC BY-SA 4.0
2019-11-23T12:23:40.203Z
What is a mantle wedge?
Brinn Belyea
CC BY-SA 4.0
2019-11-23T13:17:35.947Z
Picture the traditional 2D-view of a subduction zone, with a horizontal crust and an inclined oceanic plate. The mantle wedge is the triangle-shaped area in between. It is this hydrated mantle that (partially) melts.
Jean-Marie Prival
CC BY-SA 4.0
2019-12-05T13:28:39.827Z
Short answer, yes.
John
<plate-tectonics><subduction><mountain-building>
How does a subduction zone form mountains?
Brinn Belyea
# How does a subduction zone form mountains?

(Asked by: username_0 on 2019-11-23)

When an oceanic plate goes under a continental plate are the resulting mountains a result of the melting and then rising of the oceanic plate or are the mountains formed by the continental plate being pushed up by the collision with the oceanic plate?

**Tags:** plate-tectonics, subduction, mountain-building

> **Comments:**
> **username_1**: Note that it is generally not the oceanic plate itself that melts to generate subduction arc magmas, although it can happen (adakites for example). It is the mantle wedge between the subducting plate and the crust that melts, because it has been hydrated (thus has a lower temperature solidus) by the release of fluids from the subducting plate (a process called metasomatism).  
> **username_0**: What is a mantle wedge?  
> **username_1**: Picture the traditional 2D-view of a subduction zone, with a horizontal crust and an inclined oceanic plate. The mantle wedge is the triangle-shaped area in between. It is this hydrated mantle that (partially) melts.  
> **username_2**: Short answer, yes.  

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## 1 answers

### Answer by username_3 on 2019-11-23. Score: 5

When the subducted oceanic plate slides beneath the continental crust, it causes crustal thickening and sometimes crustal folding. In addition to this, rising plumes of magma are created when the oceanic plate is forced down into the mantle. These are all orogenic (mountain building) processes. We also have mountains built by volcanoes.

The friction created by the subducted plate scraping the bottom of the plate above as it is being forced into the hot mantle, plus the fact that it carries water with it, causes partial melting of the plate and the rising of magma plumes, which also have a lifting effect. Water mixing with the magma makes it more fluid and more easily melted. These plumes often force their way through the upper plate and erupt as volcanoes, which is why volcanic arcs are created near subduction zones. The classic example of volcanic arcs is found around the Pacific rim, where subduction zones abound.


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