Where is oceanic lithosphere thickest and why?
The thickest oceanic lithosphere can be up to a hundred kilometers thick, where the upper mantle has cooled underneath a comparatively thin, old layer of oceanic crust. Continental lithosphere is thinnest where it overlies the very hot, viscous upper mantle at the thinnest fringes of active continental rifts.
What happens to oceanic lithosphere as you move away from a mid-ocean ridge quizlet?
As lithospheric plates move away from midocean ridges, they cool and become denser. They eventually become more dense than the underlying hot mantle. After subducted, cool, dense lithosphere sinks into the mantle under its own weight. This helps to pull the rest of the plate down with it.
What does oceanic lithosphere consist of and how thick is it?
Oceanic lithosphere consists mainly of mafic crust and ultramafic mantle (peridotite) and is denser than continental lithosphere. Young oceanic lithosphere, found at mid-ocean ridges, is no thicker than the crust, but oceanic lithosphere thickens as it ages and moves away from the mid-ocean ridge.
Why does the lithosphere get thicker?
As the oceanic lithosphere cools, undepleted mantle becomes part of the lithospheric column and its thickness increases with age.
Why does the lithosphere thicken as it moves away from the ridge as a result of seafloor spreading?
Why does the lithosphere thicken as it moves away from the ridge as a result of seafloor spreading? Because it is capped by large outpourings of basaltic lava or other crustal fragments.
What happens to oceanic lithosphere as you move away from a mid-ocean ridge?
The oceanic lithosphere thickens as it ages and moves away from the mid-ocean ridge. This thickening occurs by conductive cooling, which converts hot asthenosphere into the lithospheric mantle, and causes the oceanic lithosphere to become increasingly dense with age.
What happens to the oceanic crust when it moves away slowly from the ridge?
As oceanic crust moves away from the shallow mid-ocean ridges, it cools and sinks as it becomes more dense. This increases the volume of the ocean basin and decreases the sea level.
What is the primary reason for the elevated position of the oceanic ridge system?
The primary reason for the elevated position of the ridge system is that newly created oceanic lithosphere is hot and therefore less dense than cooler rocks of the deep-ocean basin.
How does the seafloor change as you move away from the mid-ocean ridge?
Mid-ocean ridges and seafloor spreading can also influence sea levels. As oceanic crust moves away from the shallow mid-ocean ridges, it cools and sinks as it becomes more dense. This increases the volume of the ocean basin and decreases the sea level.
What causes the seafloor to spread apart at mid-ocean ridges?
Sea-floor spreading is what happens at the mid-oceanic ridge where a divergent boundary is causing two plates to move away from one another resulting in spreading of the sea floor. As the plates move apart, new material wells up and cools onto the edge of the plates.
What causes the motion of oceanic oceanic divergent boundary?
Divergent boundaries occur along spreading centers where plates are moving apart and new crust is created by magma pushing up from the mantle. Picture two giant conveyor belts, facing each other but slowly moving in opposite directions as they transport newly formed oceanic crust away from the ridge crest.
How mid-oceanic ridges are formed?
Mid-ocean ridges occur along divergent plate boundaries, where new ocean floor is created as the Earth's tectonic plates spread apart. As the plates separate, molten rock rises to the seafloor, producing enormous volcanic eruptions of basalt.
Which type of boundaries movement causing the formation of oceanic ridges?
When two plates are moving away from each other, we call this a divergent plate boundary. Along these boundaries, magma rises from deep within the Earth and erupts to form new crust on the lithosphere. Most divergent plate boundaries are underwater and form submarine mountain ranges called oceanic spreading ridges.
What happens to new oceanic crust at a mid-ocean ridge quizlet?
New oceanic crust is hot. As it moves away from the mid-ocean ridge toward a deep ocean trench it cools and becomes more dense. What happens as subduction occurs? As subduction occurs, crust closer to a mid-ocean ridge moves away from the ridge and toward a deep-ocean trench.
What boundary causes mid-ocean ridges?
divergent plate boundaries Mid-ocean ridges occur along divergent plate boundaries, where new ocean floor is created as the Earth's tectonic plates spread apart. As the plates separate, molten rock rises to the seafloor, producing enormous volcanic eruptions of basalt.
How does oceanic crust move along mid-ocean ridges?
Mid-ocean ridges and seafloor spreading can also influence sea levels. As oceanic crust moves away from the shallow mid-ocean ridges, it cools and sinks as it becomes more dense. This increases the volume of the ocean basin and decreases the sea level.
How mid oceanic ridges are formed?
Mid-ocean ridges occur along divergent plate boundaries, where new ocean floor is created as the Earth's tectonic plates spread apart. As the plates separate, molten rock rises to the seafloor, producing enormous volcanic eruptions of basalt.
What happens as newly formed oceanic crust moves away from the mid-ocean ridge?
As oceanic crust moves away from the shallow mid-ocean ridges, it cools and sinks as it becomes more dense. This increases the volume of the ocean basin and decreases the sea level.
What happens to new oceanic crust at mid-ocean ridges?
New oceanic crust is formed at mid-ocean ridges. This happens through the process of seafloor spreading. Mid-ocean ridges are divergent plate boundaries. At mid-ocean ridges, tectonic plates move apart and seafloor spreading occurs.
What causes the mid-ocean ridges to form?
Mid-ocean ridges occur along divergent plate boundaries, where new ocean floor is created as the Earth's tectonic plates spread apart. As the plates separate, molten rock rises to the seafloor, producing enormous volcanic eruptions of basalt.
Why do plates move away from the mid-ocean ridges?
As some magma erupts out through the crust, the magma which does not erupt continues to move under the crust with the current away from the ridge crest. These continual convection currents, called convection cells, help to move the plates away from each other to allow more crust to be created and the sea floor to grow.
What happens to the oceanic plate as it moves away from the spreading ridge?
Mid-ocean ridges and seafloor spreading can also influence sea levels. As oceanic crust moves away from the shallow mid-ocean ridges, it cools and sinks as it becomes more dense. This increases the volume of the ocean basin and decreases the sea level.
Which boundary movement causes the formation of oceanic ridge?
When two plates are moving away from each other, we call this a divergent plate boundary. Along these boundaries, magma rises from deep within the Earth and erupts to form new crust on the lithosphere. Most divergent plate boundaries are underwater and form submarine mountain ranges called oceanic spreading ridges.
Which of the following causes the plates to move away from each other?
The heat from radioactive processes within the planet's interior causes the plates to move, sometimes toward and sometimes away from each other. This movement is called plate motion, or tectonic shift.
What causes the plates to separate?
Convection currents drive the movement of Earth's rigid tectonic plates in the planet's fluid molten mantle. In places where convection currents rise up towards the crust's surface, tectonic plates move away from each other in a process known as seafloor spreading (Fig. 7.21).
How are oceanic ridges formed?
What causes mid-ocean ridges to form? Mid-ocean ridges form at divergent plate boundaries, where seafloor spreading leads to the production of new ocean crust. This new crust is formed due to igneous intrusions and extrusions as magma either cools beneath the Earth's surface or erupts as lava above the Earth's surface.
What makes lithospheric plates move?
The heat from radioactive processes within the planet's interior causes the plates to move, sometimes toward and sometimes away from each other. This movement is called plate motion, or tectonic shift.
What causes the motion of lithosphere and tectonic plates?
The force that causes most of the plate movement is thermal convection, where heat from the Earth's interior causes currents of hot rising magma and cooler sinking magma to flow, moving the plates of the crust along with them.
What layer causes the lithosphere to move?
1 Answer. The theory of plate tectonics suggests that the lithospheric plates move because of convection currents in the semi molten mantle.
Why do plates move away from the mid ocean ridges?
As some magma erupts out through the crust, the magma which does not erupt continues to move under the crust with the current away from the ridge crest. These continual convection currents, called convection cells, help to move the plates away from each other to allow more crust to be created and the sea floor to grow.