New paper argues history, not mantle plume, powers Yellowstone

A now-vanished plate under North America may open the crust below Yellowstone.

See full article...

 

[SomewhereAroundBarstow]

Take a look at what Hawai'i is sitting on.

That's kind of my point though. If you took away all the water and put in a road you could circumnavigate the base of the big island in a couple days. It makes more sense if it's all built by lava coming from a central point than multiple vents wandering around. And that, unless there's been something radical published quite recently, is how we understand the building of the undersea bits as well as the above sea bits.

ETA: And yeah, instabilities from a slab are exactly what I see when I look at the bigger picture.

 

[darphotos]

If you can, go in September. Fewer tourists, so you've practically got the park to yourself. (Summer it is wall-to-wall RVs.) And, if you are lucky, you'll be there for the first snowfall of the year!

Or better, my favorite, May. The weather can be iffy, but the land is just teeming with wildlife.

 

[SomewhereAroundBarstow]

Or better, my favorite, May. The weather can be iffy, but the land is just teeming with wildlife.

And if you're lucky you can still catch a snowfall. We woke up one morning in early June with snow on our tent on the same day Seattle set a new record high.

I think my number one piece of advice about Yellowstone is to go multiple times with significant amounts of time between them. I've been three times and it's a different place every time. The most obvious is how Mammoth Hot Springs, which was an impressive water feature when I was a kid is now dry terraces because in the intervening decades the flow of water has changed due to seismic activity. But then there was the second time I was there when we walked up to an erupting geyser and then when it was done read the sign and discovered it had stopped erupting 20 years before. It's an incredibly dynamic place.

 

[real mikeb_60]

This article really needed some pictures / diagrams. So I went to the wiki for the Farallon Plate and found some. Including a map showing a line of volcanism features that answers the question above. I remember learning that there was a plate being subducted under the North American plate, but I wasn't aware of the "islands and micro-continents accreting to North America basically formed everything west of Utah" part of the theory. That's very interesting.

To restate that: the Farallon plate had islands and micro-continents like those currently in the Pacific, like Hawaii and even the Indonesian archipelago, and over millions of years as the Pacific plate grew and pushed it under the North American plate, it gradually smushed those islands and micro-continents onto the west coast and formed new land.

Edit: I'm picturing a butter knife gliding over the surface of peanut butter or butter and having the top accrete onto the knife. I imagine that's basically what happened here.

That is extremely fascinating and I would LOVE to see a map of what parts of each state can be thought to be a specific pre-historic island. If geologists have researched it enough that they can even get that specific with confidence.

It also leads me to wonder about something else....does this mean that Vancouver island is one of those islands? And it's either still in the process of accreting to North America, or that the process has ended and it stopped where it is without being smushed into Canada?

For the big accretion picture, you might want to check out terranes in N. America:
https://pubs.geoscienceworld.org/gs...nic-model-for-the-Proterozoic-growth-of-North

Crunching things into a smaller continent is, in general, how a big continent grows.

EDIT: the concept carries down to smaller areas, too. A (should be) famous popular adaptation of it is in Assembling California by McPhee. Nice summary of it at https://californiacurated.com/2024/...alifornia-a-journey-through-geology-and-time/. As with most geologic things, it's a concept that doesn't explain all of the details, but explains enough to make useful predictions possible. (Hmmm ... isn't that what a lot of science is about?)

 

[JohnDeL]

That's kind of my point though. If you took away all the water and put in a road you could circumnavigate the base of the big island in a couple days.

I've circumnavigated the region around Yellowstone in a couple of days ( and stopped for core samples while I was at it).

It makes more sense if it's all built by lava coming from a central point than multiple vents wandering around.

Except we are pretty darn sure that Hawai'i is built from a single plume with the plate moving over it, creating multiple vents. So why should Yellowstone, which is roughly on the same scale, be any different?

 

[SomewhereAroundBarstow]

I'm beside myself with disbelief that Ars didn't take this opportunity to evangelize the awesome work on Youtube by Nick Zentner:


View: https://www.youtube.com/watch?v=I9Xk1O17dzg

I hadn't watched this one before. It definitely gets the mind going thinking about what could be going on with the craton moving over vertical ribbons of subducted plates, doesn't it?

But the one thing I know for sure about geology is that anyone who flatly declares that some problem is 100% figured out is almost certainly wrong. If they don't find that out when they're alive, everyone else will find it out after they've died.

I need to track down some maps that go into enough detail in southern Montana to show the Stillwater Complex and see if I can relate it to any of this. My dad theorized based on the mineralogy that it might be an asteroid that had embedded into the mantle several billion years ago and stayed largely intact during multiple orogenic events as the geology of the Beartooths was uncovered and reburied over and over.

 

[SomewhereAroundBarstow]

I've circumnavigated the region around Yellowstone in a couple of days ( and stopped for core samples while I was at it).

Except we are pretty darn sure that Hawai'i is built from a single plume with the plate moving over it, creating multiple vents. So why should Yellowstone, which is roughly on the same scale, be any different?

Yeah, I've circumnavigated Yellowstone a couple times too. But I think we've had a slippage in scale here. I wasn't comparing circumnavigating Hawai'i to Yellowstone. I was comparing it to circumnavigating all the dikes involved in Columbia River Basalt formation, and probably also the Northern Nevada dikes as well. Multiple vents is kind of a given with most magma plumes, but huge dike clusters spread over a very large geographical area is something entirely different.

Did you watch the Nick Zentner video someone embedded above? It doesn't directly address this but his explanation of how he changed how he is teaching the Rocky Mountain orogeny about ten years ago was eye-opening. It's not all sorted out, but I could see how with more work it might actually produce some new models that would explain the scale of the hot spot or even the similarity of the Yakutat/Siletzia chemistry (which I haven't yet read about) to Yellowstone. Not saying it does, but if we get rid of the "long Farallon" model of subduction and instead have North American continental crust being subducted then there's a lot of potential rethinking to come.

 

[SomewhereAroundBarstow]

I've circumnavigated the region around Yellowstone in a couple of days ( and stopped for core samples while I was at it).

Sorry for the double reply but I'm assuming you mean soft earth core samples and you weren't setting up a drill rig while circumnavigating Yellowstone?

 

[JohnDeL]

Sorry for the double reply but I'm assuming you mean soft earth core samples and you weren't setting up a drill rig while circumnavigating Yellowstone?

Paleomag cores. And I had a permit.

 

[SomewhereAroundBarstow]

Paleomag cores. And I had a permit.

A double-o license to core, like James Bond?

This thread is making me want to take a geology road trip. It's been too long.

 

[Thomas Howington]

See my animation, Pangea Yellowstone. Humor me. Thank you

 

[rhgedaly]

I studied geology and geophysics only a decade or so after Plate Tectonics became commonly accepted. My introduction to terranes was in a "sidebar" of a text chapter on plate tectonics where the terranes along the pacific coast of Alaska were featured as something of a mystery yet to be unraveled.

 

[SomewhereAroundBarstow]

I studied geology and geophysics only a decade or so after Plate Tectonics became commonly accepted. My introduction to terranes was in a "sidebar" of a text chapter on plate tectonics where the terranes along the pacific coast of Alaska were featured as something of a mystery yet to be unraveled.

I found a copy of the National Geographic issue on the '64 Alaska earthquake in a stack of magazines being recycled and kept it because the explanation of what causes earthquakes was so unbelievable to me. Plate tectonics was gaining acceptance when I wdas not yet 10 and I remember talking with my dad about it and he said he'd learned about "Wegener's theory of continental drift" as a fringe idea that maybe, just maybe, might lead to something real.

 

[GreyGoshawk]

I'm trying to relate this to the Columbia Basalts and it kind of fits with the model as I understand it (and which could well be decades out of date at this point) of the flows coming out of cracks in the crust rather than volcanic vents as we usually think of them. I'm picturing something almost like a blister on top of the mantle made of subsumed oceanic crust that applies upwards pressure as it moves east.

This is exciting stuff.

Somewhere in all the Nick Zentner videos, a reasonable point was made about the Columbia Basalts and the general flows of that time in Eastern Oregon. They do indeed come from "cracks in the crust rather than volcanic vents." I seem to remember that the cracks pre-dated the outflows, coming from a separate event. (As Siletzia rammed the area?)

The flows to the south do track well with the passage of the Yellowstone hotspot through that area. However, the enormous spread of the flow (through the cracks) northwards into southern Washington raised questions about the completeness of that model.

What some researcher noted was that the spread northward occurred around the time the hotspot reached the ancient continental crust. The thought was that the much-thicker continental crust dammed and/or deflected the hotspot magma such that it 'pooled' underground and emerged further and further north. When the hotspot eventually worked its way under the thicker continental crust, the flows - north and south - ceased. Made sense to me...


Edit 1: I copied SomewhereAroundBarstow's Wikipedia map, as it showed the spread of the cracks/dikes throughout the area. Coincidentally, that roughly matches to the Siletzia-ramming zone. And note that the flood-basalts cut-off at the Cratonic Margin. Much-thicker continental crust to the east of that. (In that map, the plain where "IDAHO" is labeled is where the hotspot came through from the west.)

Edit 2: Map of southern Idaho and the Snake River Plain, showing the eastern (ESRP) and western (WSRP) parts of the geologic province. (Map by Zach Lifton, Idaho Geological Survey.) Note how WSRP follows the old Snake River flood-plain while ESRP direction is likely due to the hotspot 'intervention'.

 

[JohnDeL]

he said he'd learned about "Wegener's theory of continental drift" as a fringe idea that maybe, just maybe, might lead to something real.

One of my (unfortunately many) personal peeves is people confusing Wegener's Continental Drift with Plate Tectonics.

Sure, on the surface they look a lot alike - but then, so do the harmless Indian rat snake and the not-so-harmless spectacled cobra.

Wegener's hypothesis was that the continents move about, ploughing through the oceanic basins. He supposed that this motion was powered by the Earth's rotation as the bits floated on a liquid mantle. And he amassed a crapton of really interesting data that helped bolster up his hypothesis. Not just the gross features of the continents, but exact layers in the rocks that appeared to match between continents and (most importantly) fossils that were common between continents including a worm. (Why is the worm important? Because, generally speaking, worms don't swim and worms don't fly. So for a worm to be present both on South America and on Africa, the two alomost had to be touching at one point.)

Unfortunately for Wegener, while the data was good, the physics of his hypothesis was terrible. Continents are made up of granite, which is (relatively speaking) weak. Ocean basins are made up of basalt, which is (relatively speaking) strong. So a continent couldn't plough through the ocean basin; as one wag of the time put it, "it would be like butter cutting a hot knife". Equally important was the fact that the continents were, by and large, headed away from the equator. But if the motion of the continents was powered by the Earth's rotation, they should have been headed toward it. And then there were the earthquakes which demonstrated pretty conclusively that the mantle was solid (because the mantle propagated shear waves, which is only possible in a solid).

And so Continental Drift failed as a hypothesis and never made it to theory.

It wasn't until WWII, when the oceans were extensively mapped for use in submarine travel, and the 1960s, when the maps were (finally!) declassified and combined with the magnetic readings done during the International Geophysical Year, and some (very primitive) tomography was done on the mantle, showing that it was convecting, and paleomagnetic cores were taken on the various continents proving that they weren't were they used to be, that a bunch of geophysicists collectively slapped their foreheads and said "Eppure si muove!"

They realized that the continents weren't the drivers; they were the passengers, riding along atop of plates that grew at mid-ocean ridges and sank into the mantle at subduction zones. Once that small but essential change was made and the importance of the Earth's internal heat for powering convection was realized, plate tectonics came together as a hypothesis. And in just ten years it was so extensively tested and had so many of its predictions come true that it matured into a theory.

And, while it owes much of its data to Wegener, there is essentially nothing else from Continental Drift in the idea of Plate Tectonics.

My apologies for the tirade, but this is one of my hot buttons...

 

[FranzJoseph]

One of my (unfortunately many) personal peeves is people confusing Wegener's Continental Drift with Plate Tectonics.

Sure, on the surface they look a lot alike - but then, so do the harmless Indian rat snake and the not-so-harmless spectacled cobra.

Wegener's hypothesis was that the continents move about, ploughing through the oceanic basins. He supposed that this motion was powered by the Earth's rotation as the bits floated on a liquid mantle. And he amassed a crapton of really interesting data that helped bolster up his hypothesis. Not just the gross features of the continents, but exact layers in the rocks that appeared to match between continents and (most importantly) fossils that were common between continents including a worm. (Why is the worm important? Because, generally speaking, worms don't swim and worms don't fly. So for a worm to be present both on South America and on Africa, the two alomost had to be touching at one point.)

Unfortunately for Wegener, while the data was good, the physics of his hypothesis was terrible. Continents are made up of granite, which is (relatively speaking) weak. Ocean basins are made up of basalt, which is (relatively speaking) strong. So a continent couldn't plough through the ocean basin; as one wag of the time put it, "it would be like butter cutting a hot knife". Equally important was the fact that the continents were, by and large, headed away from the equator. But if the motion of the continents was powered by the Earth's rotation, they should have been headed toward it. And then there were the earthquakes which demonstrated pretty conclusively that the mantle was solid (because the mantle propagated shear waves, which is only possible in a solid).

And so Continental Drift failed as a hypothesis and never made it to theory.

It wasn't until WWII, when the oceans were extensively mapped for use in submarine travel, and the 1960s, when the maps were (finally!) declassified and combined with the magnetic readings done during the International Geophysical Year, and some (very primitive) tomography was done on the mantle, showing that it was convecting, and paleomagnetic cores were taken on the various continents proving that they weren't were they used to be, that a bunch of geophysicists collectively slapped their foreheads and said "Eppure si muove!"

They realized that the continents weren't the drivers; they were the passengers, riding along atop of plates that grew at mid-ocean ridges and sank into the mantle at subduction zones. Once that small but essential change was made and the importance of the Earth's internal heat for powering convection was realized, plate tectonics came together as a hypothesis. And in just ten years it was so extensively tested and had so many of its predictions come true that it matured into a theory.

And, while it owes much of its data to Wegener, there is essentially nothing else from Continental Drift in the idea of Plate Tectonics.

My apologies for the tirade, but this is one of my hot buttons...

While I do get your pet peeve, I don't think it really reflects badly on Wegener himself. After all, we still acknowledge Hipparchus and Copernicus, even if their models were quite wrong.

Plus, Wegener remains to me much more relevant for his (paleo)climatology work (first Greenland ice coring and pit snow accumulation measurements), and for his heroic mid‑winter rescue of his colleagues in the middle of the Greenland Ice Sheet (where he died on the trip back).

 

[SomewhereAroundBarstow]

One of my (unfortunately many) personal peeves is people confusing Wegener's Continental Drift with Plate Tectonics.

Sure, on the surface they look a lot alike - but then, so do the harmless Indian rat snake and the not-so-harmless spectacled cobra.

Wegener's hypothesis was that the continents move about, ploughing through the oceanic basins. He supposed that this motion was powered by the Earth's rotation as the bits floated on a liquid mantle. And he amassed a crapton of really interesting data that helped bolster up his hypothesis. Not just the gross features of the continents, but exact layers in the rocks that appeared to match between continents and (most importantly) fossils that were common between continents including a worm. (Why is the worm important? Because, generally speaking, worms don't swim and worms don't fly. So for a worm to be present both on South America and on Africa, the two alomost had to be touching at one point.)

Unfortunately for Wegener, while the data was good, the physics of his hypothesis was terrible. Continents are made up of granite, which is (relatively speaking) weak. Ocean basins are made up of basalt, which is (relatively speaking) strong. So a continent couldn't plough through the ocean basin; as one wag of the time put it, "it would be like butter cutting a hot knife". Equally important was the fact that the continents were, by and large, headed away from the equator. But if the motion of the continents was powered by the Earth's rotation, they should have been headed toward it. And then there were the earthquakes which demonstrated pretty conclusively that the mantle was solid (because the mantle propagated shear waves, which is only possible in a solid).

And so Continental Drift failed as a hypothesis and never made it to theory.

It wasn't until WWII, when the oceans were extensively mapped for use in submarine travel, and the 1960s, when the maps were (finally!) declassified and combined with the magnetic readings done during the International Geophysical Year, and some (very primitive) tomography was done on the mantle, showing that it was convecting, and paleomagnetic cores were taken on the various continents proving that they weren't were they used to be, that a bunch of geophysicists collectively slapped their foreheads and said "Eppure si muove!"

They realized that the continents weren't the drivers; they were the passengers, riding along atop of plates that grew at mid-ocean ridges and sank into the mantle at subduction zones. Once that small but essential change was made and the importance of the Earth's internal heat for powering convection was realized, plate tectonics came together as a hypothesis. And in just ten years it was so extensively tested and had so many of its predictions come true that it matured into a theory.

And, while it owes much of its data to Wegener, there is essentially nothing else from Continental Drift in the idea of Plate Tectonics.

My apologies for the tirade, but this is one of my hot buttons...

To be clear I do know they are not the same thing. My point was that in the '50s the orthodox model being taught was "Continents don't move around because that would be crazy; just look at Wegener's wacky ideas!"

 

[JohnDeL]

While I do get your pet peeve, I don't think it really reflects badly on Wegener himself. After all, we still acknowledge Hipparchus and Copernicus, even if their models were quite wrong.

You are right. Wegener had some interesting ideas and the courage to go out and collect the data (which wasn't so easy back in 1910!).

I'm more annoyed at all the folks who think that Plate Tectonics is just Continental Drift under new management. It is like all those folks who say "theory" when they really mean "hypothesis" - it doesn't register with most folks and there are probably some who think I need to start wearing those jackets that tie in back. But, darn it, words mean things and using them right is essential to clear communication!

To be clear I do know they are not the same thing. My point was that in the '50s the orthodox model being taught was "Continents don't move around because that would be crazy; just look at Wegener's wacky ideas!"

Yeah. And then you take a look at geosynclinal "theory" and know what wacky really is!

"The Gulf of Mexico is just a giant geosyncline. In a few million years, it will fill up and then it will evert and make mountains."
"Why does it evert?"
"If there are no further questions, class is dismissed."

 

[Nalyd]

When discussing the differences along the very obviously time-transgressive track of volcanism, it is worth considering that a plume's topographic effects, eruption style, vent locations, and eruption chemistry manifest after interaction with the crust and mantle lithosphere, which can be quite heterogeneous due to tectonic history. The flood basalts and dike swarms are in the Basin and Range, where roughly contemporaneous extension (following Sevier belt mountain building) is creating many aligned pathways through the crust. Get to Yellowstone and any plume would be impinging on Archean cratonic rocks. This changes the magma compositions and chemistry. And yeah interactions with the sinking Farallon could affect the chemistry as well.

Hawaii is a simpler situation because it's only dealing with relatively homogeneous ocean lithosphere and thin, uniform ocean crust. So of course it's a tighter line of very similar volcanoes.

But, while the model is driven by history in the form of the Farallon plate, it is a static picture of the present. The researchers don’t try to trace the history backward to see how these forces could have created the history of eruptions across the Snake River Plain. Nor do they explain why these features developed only at Yellowstone, when portions of the Farallon plate are sliding under most of western North America.

I haven't read the paper yet, but this is a pretty big elephant to pretend isn't in the room.

 

[ridgeguy]

Can recommend John McPhee's Assembling California for anyone interested in the influx of island chains that collided to build California.

https://en.wikipedia.org/wiki/John_McPhee

 

[llanitedave]

True. Which is why some geologists/geophysicist spend their entire careers looking at the data in and around this region.



Yes. And it is also the area that is very hard to create with the alternative hypothesis.



And literally thousands of other formations in the region.

But it all starts with that blowtorch on the bottom of the continent. And the track of that is pretty darn clear.

Exactly. While we look for simplicity, when simplicity fails, you might have to consider complexity. It doesn't have to be alternative hypotheses, it can also be additional hypotheses. That there is a lot of lateral movement going on in the Pacific Northwest that's independent of any underlying hot spot doesn't mean a hot spot can't have passed through it.

 

[JohnDeL]

Exactly. While we look for simplicity, when simplicity fails, you might have to consider complexity. It doesn't have to be alternative hypotheses, it can also be additional hypotheses. That there is a lot of lateral movement going on in the Pacific Northwest that's independent of any underlying hot spot doesn't mean a hot spot can't have passed through it.

What? You mean someone can have a heart attack while they are having a car wreck? Inconcievable!
/joke