Is crust created or destroyed at the trenches?

Is crust created or destroyed at the trenches?

Seafloor spreading processes create new oceanic crust at mid-ocean ridges and destroy older crust at deep sea trenches.

Why does the crust sink at a trench?

Subduction zones, usually associated with deep ocean trenches, are found around the world. As it moves down into the subduction zone, our crust is pushed down under another plate. It bends down and starts to sink into the mantle – the older the crust, the steeper the angle.

What process causes oceanic crust to sink beneath a deep ocean trench?

Ocean trenches are long, narrow depressions on the seafloor. At many convergent plate boundaries, dense lithosphere melts or slides beneath less-dense lithosphere in a process called subduction, creating a trench.

Does seafloor spreading create new crust?

The denser lithospheric material then melts back into the Earth’s mantle. Seafloor spreading creates new crust. Subduction destroys old crust. The two forces roughly balance each other, so the shape and diameter of the Earth remain constant.

Are deep ocean trenches stable?

They are not geologically very stable because volcanic activity and earthquakes are always associated with deep-ocean trenches.

How are trenches formed in the deep ocean?

While divergent plates create crust by sea floor spreading, another process, such as the convergence of plates, destroys some of the Earth’s crust. The process by which the Earth’s crust is destroyed is called subduction, and it most commonly occurs at the deep ocean regions of the world, where ocean trenches are formed.

How does the oceanic crust move away from the ridge?

As oceanic crust forms and spreads, moving away from the ridge crest, it pushes the continent away from the ridge axis. If the oceanic crust reaches a deep sea trench, it sinks into the trench and is lost into the mantle.

What do you call a partially infilled trench?

Trenches that are partially infilled are known as “troughs” and sometimes they are completely buried and lack bathymetric expression, but the fundamental plate tectonics structures that these represent mean that the great name should also be applied here. This applies to the Cascadia, Makran, southern Lesser Antilles, and Calabrian trenches.

What does the inner trench wall consist of?

The inner trench wall marks the edge of the overriding plate and the outermost forearc. The forearc consists of igneous and metamorphic crust, and this crust may act as buttress to a growing accretionary wedge (formed from sediments scraped off the top of the downgoing plate).