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Old 02-13-2019, 11:45 AM
Northern Piper is offline
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Why no "Ring of Fire" around the Atlantic?


So, there's the ring of fire around the Pacific Ocean.

Why no ring of fire around the Atlantic? What's the difference ?
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Old 02-13-2019, 11:53 AM
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The Pacific Plate is a large tectonic plate whose edges are the Ring of Fire - that's where the magma comes up, more or less.

The Atlantic is instead characterized by a large Mid-Atlantic Ridge in the middle between the North American and Eurasian Plates, so the magma comes up in the middle instead of around the edges.
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Old 02-13-2019, 11:56 AM
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Quote:
Originally Posted by wevets View Post
The Pacific Plate is a large tectonic plate whose edges are the Ring of Fire - that's where the magma comes up, more or less.

The Atlantic is instead characterized by a large Mid-Atlantic Ridge in the middle between the North American and Eurasian Plates, so the magma comes up in the middle instead of around the edges.
Just to elaborate - the Pacific is shrinking as the plates around it come together - the Ring of Fire is where the collision is happening. The Atlantic is growing - and the mid-Atlantic ridge is where the expansion is happening.

Note that the east coast of North America has a large continental shelf, while the west coast doesn't.

Last edited by Andy L; 02-13-2019 at 11:57 AM.
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Old 02-13-2019, 11:59 AM
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Of course, just as I was going to post the first response, SDMB goes down.

In addition to what's already been posted, note that there is volcanic activity; for example, in Iceland and Italy.
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Old 02-13-2019, 12:03 PM
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Originally Posted by Johnny L.A. View Post
Of course, just as I was going to post the first response, SDMB goes down.

In addition to what's already been posted, note that there is volcanic activity; for example, in Iceland and Italy.
And Iceland is on the Mid-Atlantic Ridge (Italy is in the area affected by the collision of the European and African plates)
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Old 02-13-2019, 01:47 PM
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There are volcanoes in the Caribbean, but that is down to the interaction of the Caribbean plate and the South American plate.
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Old 02-13-2019, 02:07 PM
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Originally Posted by Andy L View Post
And Iceland is on the Mid-Atlantic Ridge (Italy is in the area affected by the collision of the European and African plates)
Iceland is a hotspot, similar to the Hawaiian islands. Hotspots are something different than plate tectonics as far as where the volcanism comes from.
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Old 02-13-2019, 02:26 PM
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Originally Posted by bump View Post
Iceland is a hotspot, similar to the Hawaiian islands. Hotspots are something different than plate tectonics as far as where the volcanism comes from.
Nope, sorry. It's smack dab on the Mid-Atlantic Ridge. Go look at an undersea map of the Atlantic.

The Ridge, by the way, is not fixed over a single area on the Earth as hotspots are. There was one (perhaps more) hot spot that started on North America and now is on the other side of the Ridge. This is because the Ridge drifts somewhat to the west. I forget the name of it off-hand, but it came up in a thread not too long ago.
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Old 02-13-2019, 02:36 PM
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This site has a map of the Ridge https://en.wikipedia.org/wiki/Mid-Atlantic_Ridge - it goes through the middle of Iceland.
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Old 02-13-2019, 02:58 PM
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Originally Posted by dtilque View Post
I forget the name of it off-hand, but it came up in a thread not too long ago.
The Great Meteor/New England hotspot track.
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Old 02-13-2019, 03:23 PM
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No reason it can't be both... but Iceland is definitely over a hot spot- what we see there isn't normal mid-oceanic ridge behavior.

http://geologymatters.org.uk/2011/08...land-hot-spot/

https://www.sciencedaily.com/release...1024142011.htm

and the most interesting ("Our model suggests that the initiation of the Iceland hotspot predates the opening of the North Atlantic by at least 70 m.y.")

https://www.researchgate.net/publica..._hotspot_track

Last edited by bump; 02-13-2019 at 03:25 PM.
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Old 02-13-2019, 07:56 PM
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Originally Posted by Andy L View Post
Just to elaborate - the Pacific is shrinking as the plates around it come together - the Ring of Fire is where the collision is happening. The Atlantic is growing - and the mid-Atlantic ridge is where the expansion is happening.

So was the Pacific once much bigger?
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Old 02-13-2019, 08:33 PM
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Iceland is essentially in the (long, drawn-out) process of being created by volcanic activity. There's a very nice graphic in (IIRC) the Volcano Museum in Reykjavik of the two sides of the island being ripped apart form each other and filled in up the middle by successive eruptions.

If it keeps going at the current rate, it'll end up as wide as Australia some day. In ... oooh ... just about a hundred million years or so
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Old 02-13-2019, 08:36 PM
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Quote:
Originally Posted by Northern Piper View Post
So was the Pacific once much bigger?
In some ways of looking at it, you could say that the Pacific was nearly the whole deal.

https://en.m.wikipedia.org/wiki/Panthalassa

Last edited by Pork Rind; 02-13-2019 at 08:37 PM.
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Old 02-13-2019, 08:59 PM
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Quote:
Originally Posted by bump View Post
No reason it can't be both... but Iceland is definitely over a hot spot- what we see there isn't normal mid-oceanic ridge behavior.

http://geologymatters.org.uk/2011/08...land-hot-spot/

https://www.sciencedaily.com/release...1024142011.htm

and the most interesting ("Our model suggests that the initiation of the Iceland hotspot predates the opening of the North Atlantic by at least 70 m.y.")

https://www.researchgate.net/publica..._hotspot_track
Thanks. Learn something new everyday.

Quote:
Originally Posted by Northern Piper View Post
So was the Pacific once much bigger?
Oh, yes.
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Old 02-14-2019, 06:55 PM
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Quote:
Originally Posted by bump View Post
No reason it can't be both... but Iceland is definitely over a hot spot- what we see there isn't normal mid-oceanic ridge behavior.

http://geologymatters.org.uk/2011/08...land-hot-spot/

https://www.sciencedaily.com/release...1024142011.htm

and the most interesting ("Our model suggests that the initiation of the Iceland hotspot predates the opening of the North Atlantic by at least 70 m.y.")

https://www.researchgate.net/publica..._hotspot_track
Quote:
Originally Posted by Andy L View Post
Thanks. Learn something new everyday.
From the first cite:
Quote:
The North American Plate and the Eurasian Plate are moving away from one another at a rate of 10km every million years; about the same rate as your fingernails grow.
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Old 02-17-2019, 02:16 PM
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Quote:
Originally Posted by Northern Piper View Post
So was the Pacific once much bigger?
Well depending on how you define "The Pacific" it was once all the ocean that was.

Quote:
The Pacific Ocean was born 750 million years ago at the breakup of Rodinia, although it is generally called the Panthalassic Ocean until the breakup of Pangea, about 200 million years ago. The oldest Pacific Ocean floor is only around 180 Ma old, with older crust subducted by now.
https://en.wikipedia.org/wiki/Pacific_Ocean
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Old 02-18-2019, 11:21 AM
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Nope, sorry. It's smack dab on the Mid-Atlantic Ridge. Go look at an undersea map of the Atlantic.
I remember a photo from last year where a Doper was diving off the coast of Iceland and had his hands touching the two different plates, which I thought was incredibly cool. Certainly put my touching the Vishnu schist when I took a mule to the bottom of Grand Canyon into the shade.
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