This process, called subduction , occurs at the oceanic trenches (figure 6). The entire region is known as a subduction zone. Subduction zones have a lot of intense earthquakes and volcanic eruptions. The subducting plate causes melting in the mantle.
What is it called when oceanic crust sinks back into the mantle?
Where two tectonic plates converge, if one or both of the plates is oceanic lithosphere, a subduction zone will form. An oceanic plate will sink back into the mantle.
When the crust sinks down into the mantle What happens to it?
At depths of 100-250 km the oceanic crust begins to melt . The resulting magma, along with the water mentioned earlier, rises up into the wedge of mantle above. This rising material then lowers the melting point of the hot mantle wedge, so in turn parts of that melt.
What happens when two oceanic plates collide?
A subduction zone is also generated when two oceanic plates collide — the older plate is forced under the younger one — and it leads to the formation of chains of volcanic islands known as island arcs. ... Earthquakes generated in a subduction zone can also give rise to tsunamis.
What happens to old oceanic crust as new molten material rises from the mantle?
What happens to old oceanic crust as new molten material rises from the mantle? The molten material spreads out, pushing older rock to both sides of the ridge . It sinks down due to density. ... The Earth’s ocean floors move like conveyor belts, carrying the continents along with them, as they move.
What word best describes the lower mantle?
The lower mantle, historically also known as the mesosphere , represents approximately 56% of Earth’s total volume, and is the region from 660 to 2900 km below Earth’s surface; between the transition zone and the outer core.
What do you know about mantle?
The mantle is the mostly-solid bulk of Earth’s interior . The mantle lies between Earth’s dense, super-heated core and its thin outer layer, the crust. The mantle is about 2,900 kilometers (1,802 miles) thick, and makes up a whopping 84% of Earth’s total volume.
What causes slab pull?
What is Slab Pull? Slab pull is the pulling force exerted by a cold, dense oceanic plate plunging into the mantle due to its own weight . The theory is that because the oceanic plate is denser than the hotter mantle beneath it, this contrast in density causes the plate to sink into the mantle.
Can two oceanic plates converge?
Convergence can occur between an oceanic and a largely continental plate , or between two largely oceanic plates, or between two largely continental plates.
What happens when two oceanic plates collide quizlet?
When two oceanic plates collide, the denser plate is subducted and some material rises upward and forms an ISLAND . ... Ocean floor is pushed away from a midocean ridge to form new sea floor.
What is the difference between continental and oceanic plates?
Oceanic plates are much thinner than the continental plates . ... At the convergent boundaries the continental plates are pushed upward and gain thickness. The rocks and geological layers are much older on continental plates than in the oceanic plates. The Continental plates are much less dense than the Oceanic plates.
What will happen to the old oceanic crust materials?
Oceanic crust slowly moves away from mid-ocean ridges and sites of seafloor spreading. As it moves, it becomes cooler, more dense, and more thick. Eventually, older oceanic crust encounters a tectonic boundary with continental crust .
Is it true that a deep ocean trench is an underwater mountain?
A deep-ocean trench is an underwater MOUNTAIN . Molten material erupts INSIDE the central valley of mid-ocean ridges. The farther from a mid-ocean ridge a rock sample is taken, the YOUNGER the rock is. Sea-floor spreading occurs at MID-OCEAN RIDGES.
Is a deep valley along the ocean floor beneath which oceanic crust slowly sinks toward the mantle?
deep ocean trench – a deep valley along the ocean floor through which oceanic crust slowly sink toward the mantle.
Is lower mantle solid or liquid?
The lower mantle is the liquid inner layer of the earth from 400 to 1,800 miles below the surface. The lower mantle has temperatures over 7,000 degrees Fahrenheit and pressures up to 1.3 million times that of the surface near the outer core.
Does heat churns through the mantle?
Mantle convection is the slow, churning motion of Earth’s mantle. ... 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.
