Could an external cosmic body have influenced Earth’s geology?

[Dani Rose]

Hello,

I’m currently writing a series of essays on Pangaea, continental drift, and Earth’s geological cycles.
While working on my research, I’ve come across some inconsistencies in the existing theories — for example, why the main pressure seems to have been concentrated in the northern polar regions.

So I’m curious: is there any data or evidence suggesting that an external cosmic body (an asteroid, comet, or another massive object) could have influenced Earth’s geology in the distant past, especially in the polar areas, in a way that might have accelerated or even triggered the breakup of the continents?

I understand that the primary explanation is tectonic plate movement, but could external astronomical events also have played a role?

Thank you for your time and thoughts — they would be very helpful for the development of this essay series.

 

[Borek]

why the main pressure seems to have been concentrated in the northern polar regions.

Just look at the map - most landmass (which is much easier to research and we know about it lot more, than about sea floor) happens to be now in the northern hemisphere. In a way it is purely accidental, it wasn't this way in the past - but at the time there was no civilization capable of research.

 

[fresh_42]

Here is a nice interactive animation website about the continental drift:
https://dinosaurpictures.org/ancient-earth#220

 

[Dani Rose]

Here is a nice interactive animation website about the continental drift:
https://dinosaurpictures.org/ancient-earth#220

It's really nice. Thanks!

 

[Dani Rose]

Just look at the map - most landmass (which is much easier to research and we know about it lot more, than about sea floor) happens to be now in the northern hemisphere. In a way it is purely accidental, it wasn't this way in the past - but at the time there was no civilization capable of research.

This is true, but there are enough remaining traces for us to have an idea of what happened. For example, something disrupted the integrity of Pangaea, and after that began the 'great journey' and rotation of this landmass. If we look at this journey in terms of time, we can at least make assumptions about when similar cataclysms might occur again. The question is whether this is also connected with some cosmic object that influences planet Earth at certain intervals of time.

 

[Baluncore]

I understand that the primary explanation is tectonic plate movement, but could external astronomical events also have played a role?

There must have been some external influences, that have made some difference, but there is no need for an external cosmic body to drive or control plate tectonics. The evolution of circulation within the mantle is sufficient to explain the movements observed.

Ocean seafloor spreading will sweep continental fragments from the area of the oceans, while tending to push the continental fragments into larger supergroups between the oceans.

 

[fresh_42]

I think there is an energy problem in your scenario. Minor asteroids, e.g., the Chicxulub impact, wouldn't have had enough energy to affect tectonics, and a sufficiently large impact gets you to Theia.

Google says, that India weighs about $5\cdot 10^{20}\,\mathrm{kg}.$ Let's say a meteorite is $30\,\mathrm{km/s}$ fast, $20\,\mathrm{km}$ in diameter, and worst case, made out of iron, i.e., has a density of about $8\,\mathrm{g/cm^3}.$ Now you can do the calculations.

 

[Dani Rose]

I think there is an energy problem in your scenario. Minor asteroids, e.g., the Chicxulub impact, wouldn't have had enough energy to affect tectonics, and a sufficiently large impact gets you to Theia.

Google says, that India weighs about $5\cdot 10^{20}\,\mathrm{kg}.$ Let's say a meteorite is $30\,\mathrm{km/s}$ fast, $20\,\mathrm{km}$ in diameter, and worst case, made out of iron, i.e., has a density of about $8\,\mathrm{g/cm^3}.$ Now you can do the calculations.

I don’t mean a direct impact of a cosmic object with Earth, but rather a sufficiently large body passing close by, exerting some kind of gravitational pressure. Otherwise, we are left with the theory that the continents simply ‘decided’ at some point to break apart and start rotating.

 

[fresh_42]

I don’t mean a direct impact of a cosmic object with Earth, but rather a sufficiently large body passing close by, exerting some kind of gravitational pressure. Otherwise, we are left with the theory that the continents simply ‘decided’ at some point to break apart and start rotating.

By decision, you mean such complex phenomena as plumes, subductions, or tensions of a rigid plate swimming on a hot and curved fluid surface. The moon is relatively close and heavy, yet it doesn't impact tectonics. You still have an energy problem in your equations.

 

[Bandersnatch]

but rather a sufficiently large body passing close by, exerting some kind of gravitational pressure

The only interaction available here is tidal deformation. However, it is generally pretty weak, scales only linearly with mass, and very strongly (third power) with the inverse of the distance.
That is a stronger dependence on distance than of the gravitational force.
This makes it very hard to imagine a combination of mass and trajectory of the passing body that would both create crustal deformation significantly larger than the few centimetres we already get from the Moon and the Sun, and not disrupt the Earth-Moon system, Earth's orbit, or the entire solar system - depending on how big we make the passing body. A comet would not cut it. You'd need a planet or a star to make a difference.
The encounter would be rather cataclysmic, whereas the biosphere seems to have enjoyed pretty stable conditions throughout its existence.

 

[Dani Rose]

There must have been some external influences, that have made some difference, but there is no need for an external cosmic body to drive or control plate tectonics. The evolution of circulation within the mantle is sufficient to explain the movements observed.

Ocean seafloor spreading will sweep continental fragments from the area of the oceans, while tending to push the continental fragments into larger supergroups between the oceans.

English (revised version):
I agree that the spreading of the ocean floor pushes the continental fragments, but before that the fragments had already separated from one another. For example, the current expansion of the Atlantic Ocean is exerting pressure on the Pacific Ocean, which is potentially very dangerous for the future activation of the Ring of Fire.

 

[Dani Rose]

By decision, you mean such complex phenomena as plumes, subductions, or tensions of a rigid plate swimming on a hot and curved fluid surface. The moon is relatively close and heavy, yet it doesn't impact tectonics. You still have an energy problem in your equations.

An extremely good example with the Moon, it really does not affect the tectonic plates.
Definitely, the energy problem remains.

 

[Dani Rose]

The only interaction available here is tidal deformation. However, it is generally pretty weak, scales only linearly with mass, and very strongly (third power) with the inverse of the distance.
That is a stronger dependence on distance than of the gravitational force.
This makes it very hard to imagine a combination of mass and trajectory of the passing body that would both create crustal deformation significantly larger than the few centimetres we already get from the Moon and the Sun, and not disrupt the Earth-Moon system, Earth's orbit, or the entire solar system - depending on how big we make the passing body. A comet would not cut it. You'd need a planet or a star to make a difference.
The encounter would be rather cataclysmic, whereas the biosphere seems to have enjoyed pretty stable conditions throughout its existence.

I agree. I have realized that it is unlikely that a cosmic event could have caused the breakup of Pangaea. It certainly could not have been an asteroid impact, since the biosphere was flourishing at that time.

 

[Frabjous]

You might enjoy reading
https://www.nature.com/articles/d41586-024-02602-3

 

[fresh_42]

An extremely good example with the Moon, it really does not affect the tectonic plates.
Definitely, the energy problem remains.

If we look at Jupiter and Saturn, then we see that it is the other way around. We have tidal forces on some of their moons. If we reverse their size ratio, i.e., create a celestial body that can generate tidal forces on the Earth's plates, then we have a bigger problem than tectonics.

 

[Baluncore]

I agree that the spreading of the ocean floor pushes the continental fragments, but before that the fragments had already separated from one another. For example, the current expansion of the Atlantic Ocean is exerting pressure on the Pacific Ocean, which is potentially very dangerous for the future activation of the Ring of Fire.

The Atlantic would stop spreading if the Pacific provided excessive back pressure. There would not be an explosion of the Americas, the process is self limiting. If you squeeze plates together, material will emerge sideways.

A sufficiently large agglomeration of continental plate, must sometime straddle a rising zone between two convection cells, that will partition the continental block with a sea forming, that may develop into an ocean spreading centre. The size of the continents is regulated by the size of the convection cells.

We think we understand plate tectonics, but there are still questions that need answers. Where subduction occurs, why is the trench not over-filled with soft sediment, being scraped off the oceanic plate? Why, when the oceanic plate is being subducted, does it not appear to have different ages along the trench? Why does the thin oceanic plate start to dip and then subduct, without buckling, long before it reaches the foothills of the mountain range on the continent side of the trench? A trench is a tension feature, yet subduction requires a compression of plate boundaries. It would be easy to explain if the Earth was expanding, but there is no acceptable mechanism to drive that expansion.

Plate tectonics is going to get a lot more interesting.

 

[Ken Fabian]

@Dani Rose Seems more likely there is an enduring absence of internal homogeneity that goes way back, possibly to the earliest coalescence of disparate asteroid and cometary materials into this planet. Or arising from subsequent internal circulations and geo-chemical processes that differentiate and separate rather than mix and homogenize. Both?

I don't think there is evidence of close passes by moon/planet sized objects within the much more recent timescales for Pangaea - the orbits of any solar system objects big enough don't appear to be Earth orbit crossing, ie not capable of it.

 

[Frabjous]

This paper talks about transient impact subduction:

Impact-driven subduction on the Hadean Earth
O’Neill, C., Marchi, S., Zhang, S. & Bottke, W. Nature Geosci. 10, 793–797 (2017).

 

[Dani Rose]

You might enjoy reading
https://www.nature.com/articles/d41586-024-02602-3

This article is exceptionally well written and full of valuable information. There is definitely much I can learn from it. Nature publishes only scientists who have truly proven themselves — a dream for anyone devoted to science. My sincere admiration goes to the author, Michael Marshall.

 

[Dani Rose]

If we look at Jupiter and Saturn, then we see that it is the other way around. We have tidal forces on some of their moons. If we reverse their size ratio, i.e., create a celestial body that can generate tidal forces on the Earth's plates, then we have a bigger problem than tectonics.

The problem is definitely not caused by an external body, unless the Earth once had two moons — but that seems rather unlikely.

 

[Dani Rose]

The Atlantic would stop spreading if the Pacific provided excessive back pressure. There would not be an explosion of the Americas, the process is self limiting. If you squeeze plates together, material will emerge sideways.

A sufficiently large agglomeration of continental plate, must sometime straddle a rising zone between two convection cells, that will partition the continental block with a sea forming, that may develop into an ocean spreading centre. The size of the continents is regulated by the size of the convection cells.

We think we understand plate tectonics, but there are still questions that need answers. Where subduction occurs, why is the trench not over-filled with soft sediment, being scraped off the oceanic plate? Why, when the oceanic plate is being subducted, does it not appear to have different ages along the trench? Why does the thin oceanic plate start to dip and then subduct, without buckling, long before it reaches the foothills of the mountain range on the continent side of the trench? A trench is a tension feature, yet subduction requires a compression of plate boundaries. It would be easy to explain if the Earth was expanding, but there is no acceptable mechanism to drive that expansion.

Plate tectonics is going to get a lot more interesting.

Although I am not a physicist, I can logically conclude that the problem is not limited to the idea of an “expanding Earth.” The Pacific Ocean will continue to contract until this process becomes impossible. At that point, a “major change” could indeed follow, along with a renewed awakening of the Ring of Fire. Regarding sediments — while researching the topic, I came across a theory suggesting that much of the material is carried downward with the subducting plate, which is why it does not accumulate in the trenches.

 

[Dani Rose]

@Dani Rose Seems more likely there is an enduring absence of internal homogeneity that goes way back, possibly to the earliest coalescence of disparate asteroid and cometary materials into this planet. Or arising from subsequent internal circulations and geo-chemical processes that differentiate and separate rather than mix and homogenize. Both?

I don't think there is evidence of close passes by moon/planet sized objects within the much more recent timescales for Pangaea - the orbits of any solar system objects big enough don't appear to be Earth orbit crossing, ie not capable of it.

I agree that there is no evidence for passes of moon- or planet-sized bodies within timescales relevant to Pangaea. Nevertheless, important questions remain. I would focus on processes related to the mantle and lithosphere. A significant step forward would be the ability to observe a planet similar to Earth but in its early stage of development — such observations could provide answers to many of these questions.

 

[Dani Rose]

This paper talks about transient impact subduction:

Impact-driven subduction on the Hadean Earth
O’Neill, C., Marchi, S., Zhang, S. & Bottke, W. Nature Geosci. 10, 793–797 (2017).

Thank you sincerely for sharing the article. It raises an important question — if such large impacts could cause transient subduction, wouldn’t they also disturb the early biosphere? As I understand, there was no stable biosphere yet in the Hadean, but even so, such events might have helped life to begin