After tens of millions of years, the oceanic lithosphere is so cold and dense that it begins to sink into the less-dense mantle. Ocean crust usually subducts when it collides with a continent. ... Older crust subducts very rapidly, so its angle of subduction is lower than that for subduction of younger crust.
How does subduction relate to the age of oceanic crust?
It is due to the process of subduction; oceanic crust tends to get colder and denser with age as it spreads off the mid-ocean ridges .
What effect does lithosphere age have on subduction style?
Our results show that the style of trench migration is strongly controlled by the lithospheric aging. Young slabs, and consequently thin, weak, and light slabs, enhance the retreating style of subduction characterized by trench rollback, low rates of incoming plate velocity, and shallow slab dip (Fig. 2).
What happens to the lithosphere during subduction?
Subduction is a geological process in which the oceanic lithosphere
The subduction zone, accordingly, is the antithesis of the mid-oceanic ridge . ... New seafloor is generated from the upper mantle at the mid-oceanic ridges, spreads laterally outward, and is eventually subducted, or consumed, at the margins of ocean basins.
What are the four major features of a subduction zone?
- Oceanic lithosphere goes under the oceanic plate.
- Scraped sediments accumulate on upper plates.
- Igneous and metamorphic rocks form mountainous topography.
At what boundary type is oceanic lithosphere is destroyed?
At convergent boundaries oceanic lithosphere is always destroyed by descending into a subduction zone. This is because oceanic rock is mafic, and heavy compared to the continents, and sinks easily.
What happens when two oceanic plates collide?
As with oceanic-continental convergence, when two oceanic plates converge, one is usually subducted under the other , and in the process a trench is formed. The Marianas Trench (paralleling the Mariana Islands), for example, marks where the fast-moving Pacific Plate converges against the slower moving Philippine Plate.
Where does flux melting occur?
Flux melting occurs when water or carbon dioxide are added to rock . These compounds cause the rock to melt at lower temperatures. This creates magma in places where it originally maintained a solid structure. Much like heat transfer, flux melting also occurs around subduction zones.
Why do subduction zones produce the largest earthquakes?
Eventually stresses exceed the fault’s strength and it breaks free , releasing the stored energy as seismic (shaking) waves in an earthquake. The massive size of these faults produce the largest earthquakes on Earth.
What is the first step of seafloor spreading?
1. A long crack in the oceanic crust forms at a mid ocean ridge . 2. Molten material rises and erupts along the ridge.
Where does seafloor spreading occur?
Seafloor spreading occurs at divergent plate boundaries . As tectonic plates slowly move away from each other, heat from the mantle’s convection currents makes the crust more plastic and less dense. The less-dense material rises, often forming a mountain or elevated area of the seafloor.
Is the Mariana Trench a divergent boundary?
It is separated from the Philippine Sea Plate
What are the features of a subduction zone?
The main features of subduction zones include ocean trenches, volcanoes, and mountains . Earthquakes also happen as a result of these collisions. When two continental plates collide, the land is broken and pushed upwards, creating mountain ranges.
Is Japan a subduction zone?
Japan has been situated in the convergent plate boundary during long geohistorical ages. This means that the Japanese islands are built under the subduction tectonics. The Japanese islands are characterized as the grown-up continental margin formed by the subduction of the oceanic plate. ...
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.
