10 on what layer do the crustal plates float Ideas

Below is information and knowledge on the topic on what layer do the crustal plates float gather and compiled by the show.vn team. Along with other related topics like: What layer do tectonic plates move upon, Do tectonic plates float on the asthenosphere, The tectonic plates float on which semiliquid layer, Do tectonic plates float on the lithosphere, What is the other term for tectonic plates, how many tectonic plates can be identified on earth today?, What can plate boundaries do when they are near each other, how far do most tectonic plates move in one year?.


onic plates float on

Any geologist will tell you the Earth’s crust is broken into tectonic plates that “float” around like gigantic rafts. But just what these rafts have been floating upon, has been a mystery – until now.

A team of New Zealand scientists detonated tons of dynamite and listened for echoes to reveal the underbelly of the Pacific plate. They found a 10 kilometre thick channel of lubricating jelly-like rock, which they say allows the plate to slide above it, according to a report in Nature.

German meteorologist Alfred Wegener proposed the idea of rafting continents back in 1912 after perusing maps and noticing that the east coast of South America and the west coast of Africa would fit together like jigsaw pieces. But scientists only started taking the idea seriously in 1963 when geophysicists Fred Vine and Drummond Matthews showed that the crust on the ocean floor, on either side of the mid-oceanic ridges, was indeed moving.

These days plate tectonics is “obvious”, says Louis Moresi, a geologist at the University of Melbourne. “You can log on to Google Earth and actually plot the movement.”

The plates themselves are composed of a thick layer of hard rock known as the lithosphere that lies above a softer layer known as the asthenosphere. But no one knew what lay at the lithosphere asthenosphere boundary (LAB).

In the past geologists relied on earthquakes originating on the other side of the planet of the planet to try and find out. Like doctors placing a stethoscope to the Earth’s surface, they detected seismic waves.

The fact these waves move at different speeds through different layers allowed geologists to sketch a coarse picture of the medium through which they travelled. But natural seismic waves are 10-40 kilometres in length – too long to resolve the fine-grained structure below the plates. So the New Zealanders took matters into their own hands.

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“Rather than relying on earthquake waves that come from below we create our own ‘earthquakes’ with dynamite shots,” says Tim Stern at Victoria University, Wellington, who led the project. The resulting waves are about 500 metres long and  able to resolve finer structures. The blast zone was sited on the southern tip of New Zealand’s North Island where the 73-kilometre thick Pacific plate dips beneath the Australian plate at the rate of about 40 millimetres a year.

The team set up 877 Coke can-sized seismometers strung like beads along 85 kilometres. Then from multiple boreholes they detonated half a tonne of TNT in each.

The seismic echoes revealed something unusual stuck to the Pacific plate’s underbelly – a channel of jelly-like rock about 10 kilometres thick.

Tectonic1
Researchers used blast waves to get a view of what lies beneath the Pacific plate as it dives below New Zealand’s North Island. At the base of the plate they found a 10 km thick jelly-like channel, the lithosphere asthenosphere boundary (LAB), which decouples it from the underlying asthenosphere. Credit: Cosmos Magazine

“We always thought the boundary would be gradual and defined by temperature. This study shows it’s an abrupt transition and requires something more than temperature alone to explain it,” says geologist Andrew Gleadow, also at the University of Melbourne.

The New Zealand team suggests the jelly rock gains its consistency from a higher concentration of water or magma than is present in the lithosphere above it. But it would not have to be too high. While the lithosphere contains 0.1% magma, even a 2% concentration of magma might be enough to explain the consistency of the rock in the channel. “On a million-year time scale this would appear weak and jelly-like,” explains Stern.

The finding of the jelly channel might also help resolve a 50-year debate about whether the plates move as a result of being pushed or pulled. An early idea was that magma being extruded from the mid-oceanic ridges was pushing the plates apart. Another pushing force might come from slowly creeping convection currents beneath the plates that act like rollers beneath a conveyer belt.

On the other hand the major force might be a pulling one. As one edge of an oceanic plate dives back into the mantle beneath – as the Pacific one is doing – it pulls the rest of the slab after it. The finding of the jelly layer makes the pushing and rolling mechanisms less likely, says Gleadow. “If the plates are mechanically disconnected from the mantle below, there can’t be good coupling to underlying convection movements.”

On the other hand, the jelly layer adds weight to the idea that gravity is the driving force pulling the plates along. As one edge of the plate is being dragged under, the low friction jelly layer means the rest of the plate just slithers after it like a ski on snow.

The next question is how this channel was formed and if it is present all over the world, says Moresi. Evidence from previous studies hints at a similar structure beneath the coast of Norway and another off Costa Rica. If it is found everywhere, “it would change our understanding of the internal dynamics quite a lot”.

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Additional reporting by Elizabeth Finkel

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Cathal O’Connell

Cathal O’Connell

Cathal O’Connell is a science writer based in Melbourne.

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Extra Information About on what layer do the crustal plates float That You May Find Interested

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What tectonic plates float on – Cosmos Magazine

What tectonic plates float on - Cosmos Magazine

  • Author: cosmosmagazine.com

  • Rating: 4⭐ (357295 rating)

  • Highest Rate: 5⭐

  • Lowest Rate: 2⭐

  • Sumary: Any geologist will tell you the Earth’s crust is broken into tectonic plates that “float” around like gigantic rafts.

  • Matching Result: The plates themselves are composed of a thick layer of hard rock known as the lithosphere that lies above a softer layer known as the …

  • Intro: What tectonic plates float on Any geologist will tell you the Earth’s crust is broken into tectonic plates that “float” around like gigantic rafts. But just what these rafts have been floating upon, has been a mystery – until now. A team of New Zealand scientists detonated tons of dynamite…
  • Source: https://cosmosmagazine.com/earth/earth-sciences/geologists-solve-the-mystery-of-what-tectonic-plates-float-on/

What keeps the continents floating on a sea of molten rock?

What keeps the continents floating on a sea of molten rock?

  • Author: wtamu.edu

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  • Sumary: The continents do not float on a sea of molten rock. The continental and oceanic crusts sit on a thick layer of solid rock known as the mantle. Whi…

  • Matching Result: The continents do not float on a sea of molten rock. The continental and oceanic crusts sit on a thick layer of solid rock known as the mantle.

  • Intro: What keeps the continents floating on a sea of molten rock? Category: Earth Science      Published: July 18, 2013 Under the continents is a layer of solid rock known as the upper mantle or asthenosphere. Though solid, this layer is weak and ductile enough to slowly flow under heat convection, causing…
  • Source: https://wtamu.edu/~cbaird/sq/2013/07/18/what-keeps-the-continents-floating-on-a-sea-of-molten-rock/

Plate Tectonics and the Scientific Method

Plate Tectonics and the Scientific Method

  • Author: academic.brooklyn.cuny.edu

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  • Matching Result: This shell is divided into at least 25 pieces, which are called plates. These plates move very slowing on the partially molten Earth layer (asthenosphere) …

  • Intro: Plate Tectonics – A Scientific Revolution According to the theory of plate tectonics, the outer part of the Earth is a layer of rock about 100 kilometers thick. This shell is very thin compared to the size of the Earth. This shell is divided into at least 25 pieces, which…
  • Source: http://academic.brooklyn.cuny.edu/geology/grocha/plates/platetec10.htm

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Plate Tectonics on the Earth II

Plate Tectonics on the Earth II

  • Author: homework.uoregon.edu

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  • Sumary: The composition of the earth’s interior can be determined as well as distinguishing liquid from solid layers by analyzing the propogation of seismic waves.

  • Matching Result: The earth’s crust is actually a two-component layer. The lithosphere is a thin layer of rock (average density of 2.7 grams per cc) and “floats” on top of a …

  • Intro: Plate Tectonics on the Earth II The composition of the earth’s interior can be determined as well as distinguishing liquid from solid layers by analyzing the propogation of seismic waves. The size of the liquid core is measured by seeing where the S-waves disappear, while the nature of the core…
  • Source: http://homework.uoregon.edu/pub/emj/121/lectures/earthd121.html

Frequently Asked Questions About on what layer do the crustal plates float

If you have questions that need to be answered about the topic on what layer do the crustal plates float, then this section may help you solve it.

The crust floats where, exactly?

the position

The mantle is why do crustal rocks float there.

Oceanic crust is composed of minerals that are generally more dense than continental crust; however, both oceanic and continental crusts are typically less dense than the asthenosphere, which causes the majority of oceanic and continental crusts to float on the asthenosphere.

On what does the mantle float?

Because crustal rocks are lighter (less dense) than mantle rocks, the crust floats on the mantle similarly to how ice floats on water.

The crust floats on water, right?

The basalt of oceanic crust is much less buoyant than continental crust, which “floats” on the mantle and rises above the oceans to form land.

Plates on the mantle do they float?

The thick layer of hot flowing rock that makes up Earth’s mantle is where the thin outer shell, which is broken into large pieces called tectonic plates that fit together like a puzzle, are floating.

Over what does the mantle float?

The Earth’s crust is made up of tectonic plates, which are rocky fragments that float above the mantle, another layer of the planet that lies between the core and the crust and is composed of melted rock.

Is the crust supported by the magma?

The continental and oceanic crusts rest on a substantial layer of solid rock known as the mantle, not on a sea of molten rock on which the continents float.

What is in the asthenospheric space?

The process of plate tectonics, which is connected to continental drift, earthquakes, the formation of mountains, and volcanoes, is caused by lithospheric plates moving very slowly while “floating” on the asthenosphere.

What is the mantle floating with?

The Earth’s crust is divided into numerous pieces called plates, which float on the soft, plastic mantle beneath the crust. Normally, the plates move along smoothly, but occasionally they stick and create pressure.

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