VonChelsea Dios
Published
A long time ago, the outer shell of the earth split into what we now calltectonic plates. In a new study, scientists have examined the origins of tectonic plates and found that their history is rooted in them.Terra.
Our home planet formed about 4.5 billion years ago, and shortly thereafter, about 3.2 billion years ago, the Earth's shell collapsed into these plates. Now, while scientists know how Earth's tectonic plates shift and move, exactly how they got started remains a mystery.
In a new study led by planetary scientist Alexander Webb of the University of Hong Kong, scientists in collaboration with an international team of researchers have come up with a new idea for explaining why the earth's crust has broken apart.
Related:Plate tectonics may have started a billion years after Earth's birth
According to the study, early Earth's outer layer, or lithosphere, heated up, causing it to expand and crack. This may seem like a simple explanation, but it contradicts many previous theories.
Previous studies have estimated that thermal expansion would be less likely to fracture Earth's surface than thermal contraction, the opposite process in which Earth's outer layer contracts as it cools. Because much of the Earth's internal heatcomes from radioactivity, radioactive decay would cause the planet's interior to cool over time, these studies suggested.
But, according to Webb, the answer to Earth's tectonic origins "lies in considering the major mechanisms of heat loss that may have occurred during Earth's earliest periods."said in a statement. "If volcanic advection, which brings hot material from the depths to the surface, was the main mode of early heat loss, that changes everything."
Here Webb was referring to a method of heat loss involving volcanic advection, or the transfer of heat or matter through the movement of a fluid. In this process, hot volcanic material would erupt and fall back to Earth as heat escapes into space, and the material would cool and press against Earth's young crust, creating a cooling effect. The cooled lithosphere "would have become progressively warmer due to the conduction of hot, deep material underneath," the statement said.
Webb's team used 3D spherical models to simulate how Earth's outer layer might have fractured in response to thermal expansion from heating and cooling during Earth's early years. They found that during global cooling in Earth's early years, the outer layer warmed up at the same time, which is the most likely cause of our planet's crust cracking.
This jobwas released on July 17(opens in new tab)na revista Nature Communications.
Email Chelsea Gohd at cgohd@space.com or follow her on Twitter @chelsea_gohd. Follow us on Twitter @Spacedotcom and on Facebook
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Chelsea Dios
senior writer
Chelsea "Foxanne" Gohd joinedespacio.comin 2018 and is now a senior writer, writing articles and videos for the cameras on everything from climate change to planetary science and human spaceflight. With a degree in Public Health and Life Sciences, Chelsea has written and worked for institutions including the American Museum of Natural History, Scientific American, Discover Magazine Blog, Astronomy Magazine and Live Science. When she's not writing, editing or filming something crazy, Chelsea "Foxanne" Gohd writes music and even performs as Foxannebring a song into space2021 with Inspiration4. You can follow her on Twitter.@chelsea_gohdj@foxannemusic.
9 commentsComment from forums
Fission This new theory about the origins of plate tectonics may have two major flaws. Continental crust only covers 30% of the Earth's surface, and unless you include the crust beneath the oceans, which is regularly recycled in the mantle, it lacks continental crust-like characteristics and is structurally more similar to oceanic crust. If this is not included, then the sparseness of the continental crust must be explained.
My second problem is the claim that we know how continental plates move. As far as I know, only hem chains or hem feathers are considered. However, none of these mechanisms adequately explain the rift that stretches from the North Pole to the South Pole, separating Europe and Africa from the Americas.
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Torbjörn Larsson FissionSaying:
This new theory about the origins of plate tectonics may have two major flaws. Continental crust only covers 30% of the Earth's surface, and unless you include the crust beneath the oceans, which is regularly recycled in the mantle, it lacks continental crust-like characteristics and is structurally more similar to oceanic crust. If this is not included, then the sparseness of the continental crust must be explained.My second problem is the claim that we know how continental plates move. As far as I know, only hem chains or hem feathers are considered. However, none of these mechanisms adequately explain the rift that stretches from the North Pole to the South Pole, separating Europe and Africa from the Americas.
It was intended to explain why plate tectonics began, and it does (as in proposing one of the many explanations above). I agree that the extent of the continental crust and, in particular, its history needs further explanation!
Plate tectonics is mainly based on subduction, which means that gravitational potential energy is responsible for it. I don't know how much of that mechanism is convection or gravity-driven triage and contraction in the mantle, so we have models that cover the complexities, but AFAIK it comes from heat flow into space.
There is no "gap" running between the poles. If we look at a current plate map, we can notice two general properties and one that applies today.
1. Plate boundaries align the plates.
2. There are so-called mid-ocean ridges between the oceanic crusts “in the middle” of the great oceans, where oceanic crust forms when oceanic plates move apart; mainly plaques are formed here. There are also stretches of coastline with volcanic arcs where oceanic plates subduct under continental plates; Here the plates are mostly destroyed.
3. Today, an Antarctic tectonic plate covers the South Pole and an Arctic oceanic plate covers the North Pole, with no polar plate boundaries.https://en.wikipedia.org/wiki/Plate_tectonics:
https://upload.wikimedia.org/wikipedia/commons/a/aa/Tectonic_plates_boundaries_physical_World_map_Wt_180degE_centered-en.svg
responder
Helium Are the fissures along previous volcanic activity? If so, how does this model explain this? Wouldn't advection reduce the volume under the crust and cause more contraction than expansion?
responder
Torbjörn Larsson I should add that the rift between the American and European/Asiatic and African plates has been known for a long time and was one of the first tests of the "continental drift" theory, which later helped spawn the theory of plate tectonics. The reason for the good fit is a large, recent continental gap, so geologists also see matching rocks and fossils.
But the modern biogeographical evidence is also intriguing. New World monkeys and their crocodiles could (originally I think) travel from Africa to South America while the ocean was open, but it was narrower and had more volcanic islands. But apart from traveling from island to island, which would mean several trips, and the resilience of crocodiles, even "pregnant" in salt water, I think floating "islands" are the best option for both cases. Today I was reminded that this is a permanent problem among the lakes in the area, as the waters are regulated and the floating islands rise tens of meters and persist for at least one season (birds use them for nesting and some can enter, although of course which is too risky). A similar thing happens in estuaries when wetlands are flooded.
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Torbjörn Larsson HeliumSaying:
Are the fissures along previous volcanic activity? If so, how does this model explain this? Wouldn't advection reduce the volume under the crust and cause more contraction than expansion?Good question!
I haven't read the full doc, but I think that this or the other article the doc covers discussed both things happening (so there's probably some competition here), but that your model for some parts might lead to what you describe parameters. Space, I'm sure there's a lot to criticize, I look forward to the next series of documents that will or will not accept this model. (Or sometimes people write a specific and immediate review.)
responder
Helium Thanks for your response.
There are many ways to look at this, making it a much more interesting topic.
I'm not a geologist, but my guess is that rock strata are more likely to crack in tension than in compression, so shrinkage, if any, would facilitate cracking. But on the other hand, the contraction wouldn't paint too much of a picture to start a subduction flow.
Another assumption is that we have maps showing the different depths of the mantle, so the thin regions could be the most vulnerable spots, which would certainly affect any model.
responder
Fission Torbjörn LarssonSaying:
It was intended to explain why plate tectonics began, and it does (as in proposing one of the many explanations above). I agree that the extent of the continental crust and, in particular, its history needs further explanation!Plate tectonics is mainly based on subduction, which means that gravitational potential energy is responsible for it. I don't know how much of that mechanism is convection or gravity-driven triage and contraction in the mantle, so we have models that cover the complexities, but AFAIK it comes from heat flow into space.
There is no "gap" running between the poles. If we look at a current plate map, we can notice two general properties and one that applies today.
1. Plate boundaries align the plates.
2. There are so-called mid-ocean ridges between the oceanic crusts “in the middle” of the great oceans, where oceanic crust forms when oceanic plates move apart; mainly plaques are formed here. There are also stretches of coastline with volcanic arcs where oceanic plates subduct under continental plates; Here the plates are mostly destroyed.
3. Today, an Antarctic tectonic plate covers the South Pole and an Arctic oceanic plate covers the North Pole, with no polar plate boundaries.https://en.wikipedia.org/wiki/Plate_tectonics:
(Video) The Plate Tectonics Revolution: Crash Course Geography #19https://upload.wikimedia.org/wikipedia/commons/a/aa/Tectonic_plates_boundaries_physical_World_map_Wt_180degE_centered-en.svg
The description of the Mid-Atlantic Ridge can be confusing. Yes, it's a ridge. However, it is caused by the separation of continents and it is also a rift that opens in the mantle. Magma flowing from the mantle subsequently created the ridge.
responder
Fission Torbjörn LarssonSaying:
It was intended to explain why plate tectonics began, and it does (as in proposing one of the many explanations above). I agree that the extent of the continental crust and, in particular, its history needs further explanation!Plate tectonics is mainly based on subduction, which means that gravitational potential energy is responsible for it. I don't know how much of that mechanism is convection or gravity-driven triage and contraction in the mantle, so we have models that cover the complexities, but AFAIK it comes from heat flow into space.
There is no "gap" running between the poles. If we look at a current plate map, we can notice two general properties and one that applies today.
1. Plate boundaries align the plates.
2. There are so-called mid-ocean ridges between the oceanic crusts “in the middle” of the great oceans, where oceanic crust forms when oceanic plates move apart; mainly plaques are formed here. There are also stretches of coastline with volcanic arcs where oceanic plates subduct under continental plates; Here the plates are mostly destroyed.
3. Today, an Antarctic tectonic plate covers the South Pole and an Arctic oceanic plate covers the North Pole, with no polar plate boundaries.https://en.wikipedia.org/wiki/Plate_tectonics:
https://upload.wikimedia.org/wikipedia/commons/a/aa/Tectonic_plates_boundaries_physical_World_map_Wt_180degE_centered-en.svg
"There is no 'gap' running between the poles."
Torbjörn LarssonSaying:
It was intended to explain why plate tectonics began, and it does (as in proposing one of the many explanations above). I agree that the extent of the continental crust and, in particular, its history needs further explanation!Plate tectonics is mainly based on subduction, which means that gravitational potential energy is responsible for it. I don't know how much of that mechanism is convection or gravity-driven triage and contraction in the mantle, so we have models that cover the complexities, but AFAIK it comes from heat flow into space.
There is no "gap" running between the poles. If we look at a current plate map, we can notice two general properties and one that applies today.
1. Plate boundaries align the plates.
2. There are so-called mid-ocean ridges between the oceanic crusts “in the middle” of the great oceans, where oceanic crust forms when oceanic plates move apart; mainly plaques are formed here. There are also stretches of coastline with volcanic arcs where oceanic plates subduct under continental plates; Here the plates are mostly destroyed.
3. Today, an Antarctic tectonic plate covers the South Pole and an Arctic oceanic plate covers the North Pole, with no polar plate boundaries.https://en.wikipedia.org/wiki/Plate_tectonics:
https://upload.wikimedia.org/wikipedia/commons/a/aa/Tectonic_plates_boundaries_physical_World_map_Wt_180degE_centered-en.svg "There is no 'gap' between the poles." This can be confusing. How can a crevice be the top of a mountain? As Torbjörn Larsson pointed out, the longitudinal ridge is the point where the continental plates pull apart, i.e. a rift. Magma from the mantle rises through fissures, forming the ridge that extends almost the entire distance between the poles. My point is that this structure, which defines the tectonic movement of the continents on both sides, does not conform to mantle flow or mantle plume theory and, as one of the most notable oceanic structures, does not have a good explanation. .
responder
Fission "There is no 'gap' running between the poles." This can be confusing. How can a crevice be the top of a mountain? As Torbjörn Larsson pointed out, the longitudinal ridge is the point where the continental plates pull apart, i.e. a rift. Magma from the mantle rises through fissures, forming the ridge that extends almost the entire distance between the poles. My point is that this structure, which defines the tectonic movement of the continents on both sides, does not conform to mantle flow or mantle plume theory and, as one of the most notable oceanic structures, does not have a good explanation. .
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