Africa splitting apart, new ocean forming

[southsider2k5]

http://service.spiegel.de/cache/internatio...,405947,00.html

 

Very Cool stuff.

[WilliamTell]

That was cool to read about.

[NorthSideSox72]

This has an American connection as well.

 

There are two large, classic "rift valleys" in the world - the Great Rift Valley in Africa, which is splitting Africa, is one. The other is the Rio Grande rift valley, running north-south roughly in parallel with the Rio Grande river from southern Colorado, through New Mexico, then turning SE and ending (I think) in the Big Bend area. Central NM has been predicted to experience continued and increased geological activity in rift seperation, and probably some volcanic activity, in the geologically-near future (though I don't think its moving at the staggering pace as the African example).

 

I wonder how the landscape of this country, literally and figuratively, would change if a large lake or sea suddenly opened up in NM and TX.

[RockRaines]

I wonder how the landscape of this country, literally and figuratively, would change if a large lake or sea suddenly opened up in NM and TX.

I dont know, but im sure real estate would be awesome there. It would be the new california.

[NorthSideSox72]

I dont know, but im sure real estate would be awesome there.  It would be the new california.

I guess its time to buy some property in NM then - its dirt cheap right now (except in the richie-rich Santa Fe and Taos areas). Anyone want some desert?

[RockRaines]

I guess its time to buy some property in NM then - its dirt cheap right now (except in the richie-rich Santa Fe and Taos areas).  Anyone want some desert?

You KNOW im in. We can sit on the porch watch the ocean form and discuss the shortcomings of gload and borchard.

[NorthSideSox72]

You KNOW im in.  We can sit on the porch watch the ocean form and discuss the shortcomings of gload and borchard.

[NorthSideSox72]

Looks like Balta has been in mid-post in this thread for quite a while now. Since this is geology, I bet we'll see something cool...

[Balta1701]

This has an American connection as well.

 

There are two large, classic "rift valleys" in the world - the Great Rift Valley in Africa, which is splitting Africa, is one.  The other is the Rio Grande rift valley, running north-south roughly in parallel with the Rio Grande river from southern Colorado, through New Mexico, then turning SE and ending (I think) in the Big Bend area.  Central NM has been predicted to experience continued and increased geological activity in rift seperation, and probably some volcanic activity, in the geologically-near future (though I don't think its moving at the staggering pace as the African example).

 

I wonder how the landscape of this country, literally and figuratively, would change if a large lake or sea suddenly opened up in NM and TX.

I disagree with a significant fraction of this post. The Rio Grande Rift, IMO, is merely a segment of the much larger "Basin & Range" extensional province in Western North America.

 

The uplift of the Rocky Mountains stopped around 40-50 million years ago, as the plate which was subducting under North America (the Farallon plate) basically was completely eaten by North America. At about 28 million years ago, the North American plate came into contact with the Pacific Plate, which was moving parallel to the N.A. plate, thus setting up the incipient transform system which would evolve into the Modern San Andreas.

 

But coeval with this, the large Rocky Mountain area began to break up. There are varying theories as to why this happened, but the whole of the Western U.S. began to be pervasively pulled apart, when only a few million years earlier it was under heavy compression. This created the Basin & Range province...as the areas pulled apart, it created low points in the topography which filled in with sediment to create flat basins, with large mountain ranges inbetween. 30-40 million years ago, Utah was literally 1/2 as wide as it is now.

 

You'll find the best examples of this in Utah, but for a more commonly known one...the Grand Tetons are an example of a Basin & Range extensional Range...there is a large Normal fault on the East Side of that range, and Jackson Hole/Jackson Lake are filling in the basin to the East.

 

Now, as this extension was ripping across the Western U.S., there was one region which for some reason remained a coherent block. That region is the Colorado plateau, which makes up most of Colorado, Arizona, etc. To think about this region...think about the Grand Canyon. That thing's been there for a long time, and the Rocks underneath have not been faulted/tilted in the recent past.

 

Just Southeast of the Colorado Plateau, you'll find the Rio Grande Rift, which is basically coeval with the Basin & Range extension. As far as I know, it's basically viewed as a part of the Basin & Range province. It's connected to this larger picture of pervasive extension in the Western U.S. which has dominated basically since the Miocene...but there's this interesting feature of the Colorado Plateau which seems to disconnect the Rio Grande Rift area from the main Basin & Range province. The Rio Grande Rift then is fundamentally different from what is happening in Africa. While it is a zone of continental extension, it does not seem like it is due to a plate splitting apart, but instead is more due to a plate which is being thinned and spread out.

 

There's naturally more detail than this, but I think that's a good intro.

[NorthSideSox72]

I disagree with a significant fraction of this post.  The Rio Grande Rift, IMO, is merely a segment of the much larger "Basin & Range" extensional province in Western North America.

 

The uplift of the Rocky Mountains stopped around 40-50 million years ago, as the plate which was subducting under North America (the Farallon plate) basically was completely eaten by North America.  At about 28 million years ago, the North American plate came into contact with the Pacific Plate, which was moving parallel to the N.A. plate, thus setting up the incipient transform system which would evolve into the Modern San Andreas.

 

But coeval with this, the large Rocky Mountain area began to break up.  There are varying theories as to why this happened, but the whole of the Western U.S. began to be pervasively pulled apart, when only a few million years earlier it was under heavy compression.  This created the Basin & Range province...as the areas pulled apart, it created low points in the topography which filled in with sediment to create flat basins, with large mountain ranges inbetween.  30-40 million years ago, Utah was literally 1/2 as wide as it is now.

 

You'll find the best examples of this in Utah, but for a more commonly known one...the Grand Tetons are an example of a Basin & Range extensional Range...there is a large Normal fault on the East Side of that range, and Jackson Hole/Jackson Lake are filling in the basin to the East.

 

Now, as this extension was ripping across the Western U.S., there was one region which for some reason remained a coherent block.  That region is the Colorado plateau, which makes up most of Colorado, Arizona, etc.  To think about this region...think about the Grand Canyon.  That thing's been there for a long time, and the Rocks underneath have not been faulted/tilted in the recent past. 

 

Just Southeast of the Colorado Plateau, you'll find the Rio Grande Rift, which is basically coeval with the Basin & Range extension.  As far as I know, it's basically viewed as a part of the Basin & Range province.  It's connected to this larger picture of pervasive extension in the Western U.S. which has dominated basically since the Miocene...but there's this interesting feature of the Colorado Plateau which seems to disconnect the Rio Grande Rift area from the main Basin & Range province.  The Rio Grande Rift then is fundamentally different from what is happening in Africa.  While it is a zone of continental extension, it does not seem like it is due to a plate splitting apart, but instead is more due to a plate which is being thinned and spread out.

 

There's naturally more detail than this, but I think that's a good intro.

 

I knew you'd fill in the holes for me.

 

But answer me this - what is the difference between a plate splitting apart, and one that is being thinned and spread out? Isn't the end result basically the same? I guess I interpereted those as different levels of the same activity, geologically. But then, I am only a novice in this area.

[NorthSideSox72]

Some stuff I found on the RG rift valley, spoken of in the same breath as the GR valley:

 

http://museums.state.nm.us/nmmnh/volcano/volcano.html

 

THis one states further that the Basin and Range province as further west...

 

http://cires.colorado.edu/science/groups/s.../riogrande/faq/

[Balta1701]

I knew you'd fill in the holes for me. 

 

But answer me this - what is the difference between a plate splitting apart, and one that is being thinned and spread out?  Isn't the end result basically the same?  I guess I interpereted those as different levels of the same activity, geologically.  But then, I am only a novice in this area.

It's a function of a couple things...the localization of the extension, and the rate of deformation.

 

The plates are rigid things because they are cool. Underneath the crust, there are hotter rocks that are able to flow, like glaciers. When these things flow, they carry the crust on top of it.

 

However, like i said, they're also hot. Because they're hot, they want to lose heat to colder areas, like the surface. Now, when you have a thick cap of rocks on top, this is a slow process...there's a long diffusion distance with a shallow profile (a steep profile drives faster diffusion).

 

So, if I take a plate which is fairly old, it's going to be rigid fairly deep, becausae its' had a long time to cool by diffusion. If I start pulling apart this plate, it's going to start fracturing...and if I pull it apart fast enough, the deformation is going to become localized in a small area. Why? Because it's easier to thin and break apart one area than it is to thin and break apart a very wide zone. In other words, it's easier to rupture when there's already faults in a place.

 

If you're pulling apart fast enough, you wind up thinning the plate fast enough that diffusion of heat can't keep up with the rate of thinning, so you wind up with hotter material finding itself right up next to the surface and starting to melt to fill in the gaps. If this continues, you'll wind up starting something like the Red Sea...literal sea-floor spreading. It can die off at any point though...you can find failed continental rift systems all over.

 

So, on the other hand, if I slow the deformation down, and have it take place over a wider region for whatever reason (that's tied to the nature of the Basin & Range provine), I'm going to get hotter material moving up, but it's not going to become so strongly localized like it is in Africa. It's going to have time to cool by diffusion, and there should always maintain a rigid layer on top. The African Rift system is a very recent phenomenon...active for the last couple million years at most, while the Basin & Range has been active in places for 40-50 million years. It has a thick crust which has been thinning over a very wide region, and it has gone slowly enough that cooling by diffusion has kept up with the rate of extension, so that it's never become localized into an actual rift.

[Balta1701]

THis one states further that the Basin and Range province as further west...

 

http://cires.colorado.edu/science/groups/s.../riogrande/faq/

The Basin & Range is further west, but that doesn't mean it doesn't have the same driving force. The Colorado Plateau sits inbetween the B&R and the RGR. Think of that like an iceberg, it's floating in there with a thick root, and for some reason the extension never penetrated it. So, the area to the west extended, and some of that extension was transferred through the Colorado Plateau to the East, where the plateau ends and another weak, breakable area was found - the RGR.

[NorthSideSox72]

The Basin & Range is further west, but that doesn't mean it doesn't have the same driving force.  The Colorado Plateau sits inbetween the B&R and the RGR.  Think of that like an iceberg, it's floating in there with a thick root, and for some reason the extension never penetrated it.  So, the area to the west extended, and some of that extension was transferred through the Colorado Plateau to the East, where the plateau ends and another weak, breakable area was found - the RGR.

I see.

 

So really, it is that difference in the rate of deformation and movement that makes the difference; partial tearing of the crust, versus complete severence. Is that about right?

 

So in other words, unless the rate of rift speeds up a lot, the valley won't open up enough to form an oceanic area? It is already filled with water of sorts - the Rio Grande. So wouldn't it still be an eventuality, even at a slower rate, that the valley will deepen, take on more drainage and fill with wider bodies of water?

 

I've spent a lot of time in NM, and I always took the basin/range area (west central and SW NM, SE AZ) as being seperate from the rift valley. I guess they are connected (although in that second article, the authors seem to seperate them somewhat).

 

New Mexico is a geologist's dream, I would think. Like a giant text book for volcanism and tectonics. I think I read somewhere that you can find virtually every kind of volcano there is somewhere in NM.

[YASNY]

This has an American connection as well.

 

There are two large, classic "rift valleys" in the world - the Great Rift Valley in Africa, which is splitting Africa, is one.  The other is the Rio Grande rift valley, running north-south roughly in parallel with the Rio Grande river from southern Colorado, through New Mexico, then turning SE and ending (I think) in the Big Bend area.  Central NM has been predicted to experience continued and increased geological activity in rift seperation, and probably some volcanic activity, in the geologically-near future (though I don't think its moving at the staggering pace as the African example).

 

I wonder how the landscape of this country, literally and figuratively, would change if a large lake or sea suddenly opened up in NM and TX.

 

This might reduce our illegal immigration problem.

[NorthSideSox72]

This might reduce our illegal immigration problem.

 

They'd just use boats. Think Cuban refugees.

[YASNY]

They'd just use boats.  Think Cuban refugees.

 

Actually. I apologize for that post. It was completely out of place. I should have read the entire thread first.

[Balta1701]

I see.

 

So really, it is that difference in the rate of deformation and movement that makes the difference; partial tearing of the crust, versus complete severence.  Is that about right?

 

So in other words, unless the rate of rift speeds up a lot, the valley won't open up enough to form an oceanic area?  It is already filled with water of sorts - the Rio Grande.  So wouldn't it still be an eventuality, even at a slower rate, that the valley will deepen, take on more drainage and fill with wider bodies of water?

 

I've spent a lot of time in NM, and I always took the basin/range area (west central and SW NM, SE AZ) as being seperate from the rift valley.  I guess they are connected (although in that second article, the authors seem to seperate them somewhat).

 

New Mexico is a geologist's dream, I would think.  Like a giant text book for volcanism and tectonics.  I think I read somewhere that you can find virtually every kind of volcano there is somewhere in NM.

What happens when you pull something apart slowly is that yes, you do get fracturing and the formation of basins as things pull apart. But if you're pulling it apart slowly enough, those basins are able to fill in with sediment. Yes you do get lakes, but lakes are basically just inland-sediment-traps. At some point, those lakes fill in, and you get some sort of equlibrium level. When things speed up, you get lakes like Jackson Hole. When things slow down, you get flatlands, like some of the Basins in Utah.

 

I think this is a decent picture of how to think of areas like the western U.S. This is much easier when you have textbooks.

 

 

Notice how the sediments shed off of the ranges wind up filling in the basins, to create a flat base level. Eventually, if you keep pulling apart slowly enough, you wind up just going through cycle after cycle of breaking apart the stuff which was already there and filling in the basins that form inbetween, while nothing ever localizes enough to form an acutal spreading center.

[NorthSideSox72]

What happens when you pull something apart slowly is that yes, you do get fracturing and the formation of basins as things pull apart.  But if you're pulling it apart slowly enough, those basins are able to fill in with sediment.  Yes you do get lakes, but lakes are basically just inland-sediment-traps.  At some point, those lakes fill in, and you get some sort of equlibrium level.  When things speed up, you get lakes like Jackson Hole.  When things slow down, you get flatlands, like some of the Basins in Utah.

 

I think this is a decent picture of how to think of areas like the western U.S.  This is much easier when you have textbooks.

 

 

Notice how the sediments shed off of the ranges wind up filling in the basins, to create a flat base level.  Eventually, if you keep pulling apart slowly enough, you wind up just going through cycle after cycle of breaking apart the stuff which was already there and filling in the basins that form inbetween, while nothing ever localizes enough to form an acutal spreading center.

 

OK. So in conclusion, there isn't likely to be any ocean-front property in New Mexico any time soon. Lake-front maybe. But accompanied by earthquakes and possibly volcanoes and fissures.

 

Eh, maybe I'll pass on the real estate.

[Balta1701]

OK.  So in conclusion, there isn't likely to be any ocean-front property in New Mexico any time soon.  Lake-front maybe.  But accompanied by earthquakes and possibly volcanoes and fissures.

 

Eh, maybe I'll pass on the real estate. 

Lake front property is possible within the next few thousand years...but a lot of that depends on what all that CO2 we've given the atmosphere actually does.

[knightni]

A little something that I just threw together.

[NorthSideSox72]

A little something that I just threw together.

 

I also like how the subtitle for the thread changed.

[SleepyWhiteSox]

This might reduce our illegal immigration problem.

 

[Heads22]

 

I also like how the subtitle for the thread changed.

 

No idea how that happened....

[kapkomet]

You know what this really is? It's not an ocean forming, it's Haliburton putting a gigantic oil pipe underneath Africa so we can tap all that oil. Come on people! Get it right!