Large meteorite impacts drove plate-tectonic processes on the early Earth

September 26, 2017
Large meteorite impacts drove plate-tectonic processes on the early Earth
Figure: Geodynamic simulation of the early Earth, showing a global subduction event driven by a giant (1700km diameter) impactor 4 million years into the simulation’s evolution. Dark colours indicate subducting crust and lithosphere, hot colours indicate upwelling mantle which drives volcanic activity at the surface. Credit: Macquarie University

An international study led by researchers at Macquarie University has uncovered the ways in which giant meteorite impacts may have helped to kick-start our planet's global tectonic processes and magnetic field. The study, being published in the premier journal Nature Geoscience, explores the effect of meteorite bombardment, in geodynamic simulations of the early Earth.

"Our results indicate that giant in the past could have triggered events where the solid outer section of the Earth sinks into the deeper mantle at ocean trenches – a process known as subduction. This would have effectively recycled large portions of the Earth's surface, drastically changing the geography of the planet," explained lead author Associate Professor Craig O'Neill from Macquarie University.

"Large impact events may have also kick-started the Earth's by triggering the planet's cold outer crust to suddenly move downward and interact with the Earth's outer core. This affects convection in the core, and thus the geodynamo – the process that creates the Earth's magnetic field," he added.

To date, there is still not clear evidence to show whether plate tectonics operated in Earth's early history, with the first 500 million years of our planet's life, called the Hadean, often being dubbed as Earth's geological dark ages. The little crust that has been preserved from this elusive period – mostly single grains of a mineral called zircon – has been used to argue for early tectonic activity. However, this is at odds with geochemical data and geodynamic simulations, which suggest that the Earth may instead have had a motionless 'lid' on its surface – in contrast to the actively moving combination of plates we see today.

"We know that meteorite impacts had a huge effect on the inner solar system at this time," says Associate Professor O'Neill, "you only need to look at the Moon to see that. What isn't clear was how our own history might have affected the planet's evolution."

"We've seen evidence of some geological activity that suggests something like subduction acted on the early Earth – but this is hard to reconcile with other geodynamic simulations. But if we consider Earth as part of an evolving early solar system, as opposed to only looking at the planet in isolation, then this evolution starts to make more sense," he added.

O'Neill also notes that while the magnetic field for much of Earth's ancient history has been quite low, but recent work has suggested field strengths up to present-day values existed between around 4.0-4.1 billion years ago.

"This is a really important age in the inner solar system. Impacting studies have suggested a big disturbance in the asteroid populations at this time, with perhaps a big upswing in impacts on the Earth. Our simulations show that larger amounts of meteorite collisions with the planet around this time could have driven the subduction process, explaining the formation of many zircons around this period, as well as the increase in magnetic field strength."

Overall, the study adds evidence towards the fact that impacts likely had a role in the formation of the Earth that we know today.

"This work shows there is a strong connection between impacts and geophysical evolution capable of drastically altering a planet's evolution," said coauthor Dr Simone Marchi from the Southwest Research Institute in the USA.

"One has to wonder, how much of the current Earth, and other terrestrial , is the result of collisions that took place eons ago?" Dr Marchi concluded.

Explore further: Unravelling Earth's magnetic field

More information: C. O'Neill et al. Impact-driven subduction on the Hadean Earth, Nature Geoscience (2017). DOI: 10.1038/ngeo3029

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Semmster
1.2 / 5 (6) Sep 26, 2017
On that note, is it conceivable that nuclear events have an effect on the planet's tectonics?
Solon
2.1 / 5 (11) Sep 26, 2017
"We know that meteorite impacts had a huge effect on the inner solar system at this time," says Associate Professor O'Neill, "you only need to look at the Moon to see that. What isn't clear was how our own impact history might have affected the planet's evolution."

They know nothing of the sort. It is only an assumption that anything at all has hit the moon or Earth, or any other cratered body ever observed. Zircons can be formed by electrical processes, as can craters. Is there a way to disprove that discharges were the cause?
Cusco
4.5 / 5 (8) Sep 26, 2017
Nuclear events, such as man-made explosions? Any effect would be extremely minor, a small earthquake has multiple times as much energy as even the Tsar Bomba. There was speculation that some of the Nevada underground testing may have triggered an earthquake in a stressed fault in California, but I don't believe even that was ever conclusively proven. Outside of the movies the actual likelihood of nuclear weapons causing tectonic plate events is pretty miniscule.
Osiris1
1 / 5 (2) Sep 26, 2017
We were proposing using a noted scientist like Dr Freeman Dyson who led the research, to use a large spacecraft with a strong and heavy 'pusherplate' against the rear of which nuclear bombs would explode to drive the craft onward...... just ONE ship. Forget the 'nuclear fission' idea when scaling to planetary.

That said, we will find that large impacts and resulting 'plate tectonics' from the resultant fractured surfaces will be the mundane finds among rocky inner heavy planets in inner solar systems. That Venus does not appear to have one is likely because the impact was at a tangential angle retrograde to Venus' rotation, almost stopping it; letting solar tidal forces to lock what was left. Mercury, a heavy planet core with the outer layers vaporized away and tidally locked because of its solar proximity, is also to be expected. Venus HAD a chance, but a large 'accident' took it away. What hit US may have 'speeded' our rotation.. opposite tangential angle. A Casino!
rrwillsj
4 / 5 (8) Sep 26, 2017
Sorry Solon. But if you expect me to believe that Zeus' thunder-bolts cratered the moon? Sprinkling zircons around as souvenirs? A few thousand years ago?

I'm going to find it a lot more believable that it was Hera. Throwing thunder-mugs at the head of Zeus for all his forays into adultery!
krzychu01230
1 / 5 (5) Sep 27, 2017
Most observable features on rocky bodies, especially in case of small objects [most probably Martian moons were born from 'gods thunderbolt'], are unexplainable by nonelectric hypothesis. All rocky bodies poses indication of electrical scarring what is reproducible by lab experiments.
Schumacher levy 9, deep impact, chelyabinsk meteor, clearly indicate that 'impact' hypothesis is not purely mechanical and electrical energy must be considered.
Kalopin
1 / 5 (4) Sep 27, 2017
...well?, finally looking into 'shock dynamics'? ...wait 'til you see what really happened- https://www.linke...ny-hood/

[...the Moon impacted the Tethys sea 13kya, art the YDB...a comet struck the Hudson bay, ending the Clovis 10.5kya and, more recently a meteor impact restructured the entire Mississippi river valley just a couple hundred years ago...this is what happened to science, history, technologies,... and yes, there is absolute proof for each scenario!;-]
rrwillsj
4.2 / 5 (5) Sep 27, 2017
krzychu01230, correct me if I misunderstand your opinion. Electrical events of undetermined causation that cause cratering on an airless body? As often as I have looked at the Moon through a telescope... I have never seen any lightning strikes... or heard any thunder!

However, are you denying that with all the tetra-tonnage of debris flying all around the Solar System? For billions of years. That none of that celestial avalanche ever impacted the Moon with sufficient energy to leave craters?

Maybe it was some combination of rockfalls and electrical bolts and still to be discovered phenomena?

Uhh Kalopin, dear fellow, if you are going to make such absolutist demands ? Commanding the Cosmos how it must act within your belief system. "Commanding the tide to cease and desist!"

You really need to rethink your statement. "...there is absolute proof for each scenario!..."

Cause that is a contradiction that implies that your posted opinion us hypothetical and speculative.
Kalopin
1 / 5 (5) Sep 27, 2017
@rrwillsj, yes, I accept that it may sound like an outrageous statement to anyone who has not put in the study...but, once the evidence has been investigated, it will speak for itself...

...there is an entire city buried beneath limestone, melt rock on the Yucatan, along with all the other cities buried globally, this is proof that the Moon impacted the Tethys at the YDB, as there would be no other way to put them there-physics...
...the magnetic anomaly, scattered islands, how Greenland was pushed to the northeast, the emptying out of lake Agassiz,...are all strong evidence a comet hit the Hudson 10.5kya, as this would describe every detail...
...historical accounts, satellite views, impactites and, along with several artifacts- man-made iron objects taken to the point of melt and fused with ejecta rock and vitrified sand are proof that a meteor coming from the debris trail of comet c/1811f1 was what had actually caused what is known as the New Madrid earthquakes of 1811-1812..
Caliban
5 / 5 (3) Sep 27, 2017
What these researchers propose is almost certainly correct, but would still only account for a _part_ of tectonic activity.

The heat of formation and radiological decay would have been quite large in the Earth's interior from the outset, which would have inevitably created convection currents in the plastic material beneath the solid crust, along with vulcanism on a very large, global, scale, which -alone- would have been sufficient to start tectonic processes, as any pairs of convection cells in close enough proximity would provide the impetus necessary to begin the subduction process on a local basis, which would gradually have linked to other zones of actiivity, eventually linking up to the stitched-together network of interacting plates we find currently. Impactors of any origin or description would only have modified those processes over time.

Plate Tectonics are not driven -primarily- by planetary rotation.
Maggnus
5 / 5 (3) Sep 27, 2017
Most observable features on rocky bodies, especially in case of small objects [most probably Martian moons were born from 'gods thunderbolt'], are unexplainable by nonelectric hypothesis. All rocky bodies poses indication of electrical scarring what is reproducible by lab experiments.
Schumacher levy 9, deep impact, chelyabinsk meteor, clearly indicate that 'impact' hypothesis is not purely mechanical and electrical energy must be considered.

Bullshit.
Maggnus
5 / 5 (3) Sep 27, 2017
...well?, finally looking into 'shock dynamics'? ...wait 'til you see what really happened- https://www.linke...ny-hood/

[...the Moon impacted the Tethys sea 13kya, art the YDB...a comet struck the Hudson bay, ending the Clovis 10.5kya and, more recently a meteor impact restructured the entire Mississippi river valley just a couple hundred years ago...this is what happened to science, history, technologies,... and yes, there is absolute proof for each scenario!;-]

"absolute proof!?! HAHAHAHAHAHAHAHAHAHA
Maggnus
5 / 5 (3) Sep 27, 2017
@rrwillsj, yes, I accept that it may sound like an outrageous statement to anyone who has not put in the study...but, once the evidence has been investigated, it will speak for itself...

...there is an entire city buried beneath limestone, melt rock on the Yucatan, along with all the other cities buried globally, this is proof that the Moon impacted the Tethys at the YDB, as there would be no other way to put them there-physics...
...the magnetic anomaly, scattered islands, how Greenland was pushed to the northeast, the emptying out of lake Agassiz,...are all strong evidence a comet hit the Hudson 10.5kya, as this would describe every detail...
...historical accounts, satellite views, impactites and, along with several artifacts- man-made iron objects taken to the point of melt and fused with ejecta rock and vitrified sand are proof that a meteor coming from the debris trail of comet ..
Wow. Quack. Ignored.
john berry_hobbes
4 / 5 (4) Sep 28, 2017
About every 6 months something pops up from this site and I start reading it again for a few minutes until I inevitably get a malodorous whiff of the Thunderbutts clones and remember why I read serious sites. You know, like banning socks, removing agenda based pseudo-science that has been thoroughly debunked, etc.

I really had to hold my nose back in August on my visit to Arizona, but the research was worth it. Maybe it was good to see this. Motivates me to use that intel. Thanks to AGW for the suggestion! Definitely beats feeding them on here.
Kalopin
1 / 5 (4) Sep 28, 2017
well, the price of ignorance is high... all I can do is present the truth, whether or not you all have enough intelligence to study and understand will be your prerogative...

...the facts are that Pangaea was intact during the Pleistocene, highly advanced civilizations and including [yes!] dinosaurs also thrived in lesser gravity, less electromagnetism, less ground-level radiation and shorter days...
...there are plenty cities buried globally to give proof [bay of Cambay, off the coasts of Japan, Yucatan,...and on land in Bosnia, China, Alaska, Antarctica,...] that were all lost from this event-YDB...

...when the Moon impacted it slowed the lithosphere further inn relation to the faster spinning inner core, increasing the dynamo effect...making it impossible for the megafauna to exist...causing mass extinctions, loss of technologies, science, history,... leaving a world full of cluelessness-devolution!

...victims of mistranslations and misinterpretations!
Kalopin
1 / 5 (4) Sep 28, 2017
...should I have to explain?-
...that limestone forms at the bottom of seas?...and that the massive amount of limestone covering the many pyramids and temples on Yucatan had originally formed at the bottom of the Tethys?...so, how would so many tonnes of a type rock that forms on sea-beds end up covering a city? ...and, btw, this is the very same limestone to form the Ozarks, Betic Cordilleras, rock of Gibraltar, most all the mountainous anomalies throughout the southwest U.S.,...

...the ONLY object containing enough mass, weight, volume, density, electromagnetic repulsion, and in orbit [very important] would be the Moon... there is no other option- physics!

...you see, all the effects have been proven [pole reversal, mass extinctions, buried cities, smaller plants and animals, loss of technologies, loss of history,...] ...and must find a mechanism, so, what was it? ...what force could have produced this outcome? well, guess what?,...
krzychu01230
1 / 5 (1) Sep 28, 2017
Rrwillsj, check https://www.youtu...ypC3jsHI and how many this kinds of craters have You seen on Moon? Released energy of deep impact and levy 9 was puzzling to mainstream; deep imp double flash and radial discharge was mainly electrical [question is about potential difference]. So I think that impact of larger object would look like a mythological 'gods thunderbolt' and geological consequences would be profound and not necessarily long term [and so mechanical] . Electrode process on planetary scale – hemispheric dichotomy, spiders –Mars; hexagonal, bull eye and chain of crater; archetypes and mythology; mega fauna and fossilization/mineralization problems explained.
So I think that Your electro-rocky concept is good one; terrella kind of experiments in dusty plasma on micro grav condition should be made.
Kalopin
1 / 5 (1) Sep 28, 2017
...so, to sum up- besides spin force, tidal motion, convection,... the main driving force for plate tectonics would come from an extraterrestrial source- impacts... [shock dynamics]

...once the spin force congeals another supercontinent, producing an imbalance, this will cause another Lunar-Earth encounter, once again, breaking apart the supercontinent into separate smaller plates, scattering them and leaving a better balanced planet...

Earth's moon is a left-over, crystalized iron, inner planetary core, a ball-bearing, a terraforming-harmonic balancer, as this action is commonplace throughout the universe. once a supernova explodes, sending out shrapnel and these left-over cores, they find attraction to other stars and inner planets, and begin the start of another newly forming habitable world...
[see, this is simple!;-]
rrwillsj
4 / 5 (4) Sep 28, 2017
Okay, I give up. The simpletons have won this battle. Ignorance and primitive stuporstitions are victorious for the comments on this article.

If any real scientists actually read these paeans to gibberish? I'm certain they are rolling around their floors, laughing loudly!
Aroryborealis
5 / 5 (1) Sep 28, 2017
rrwillsj, you need not surrender. You have lost nothing, especially your dignity.
Consider the context of "their" argument.
Instead of providing a framework of rational concepts, that make sense in an ascending order of understanding, leading to a logical epiphany, tactics are employed, like taking your pre-acceptance of ambiguous clauses for granted, because they did. You are then demanded to do all the research, and interpret it exactly as they did, on a subject you oppose in the first place, in order to satisfy their opinion of what constitutes proof.
This forum is used to launch a thinly veiled mockery of established Science.
That is not an attitude of constructive debate.
Fear not, dear rr'. Since Empirical Method is irrelevant to their belief, they'll continue to remain in the fringes, where Pseudo-Science depends on undisciplined, impressionable minds, to advance it's jealous agendas.
Kalopin
1 / 5 (2) Sep 29, 2017
[...word salad, much?!]
...'the proof is in the pudding', do you expect me to put all the satellite views?, every historical account?, every site on every buried city? all the scientific and observational data? on this page for you to give a closer study? [cause, guess what-it all adds up!]
"ignorance and primitive superstition" are more reasons [besides pride, greed,...] so much stupidity is currently being forced on innocence...
...for our ancestors to see their pyramids buried in caves, would be the equivalent of landing on the beach and seeing the statue of liberty, bent over and up to her neck in rock and sand, what part would you all be playin'? ;-]]]]]]]
...time to rid the current outdated paradigm, put some uncertainty within textbooks and teach the facts!

[oh, waiting for you all to show me exactly were I am mistaken!, for future presentations, thanks ;-]

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