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View Full Version : 20 Ancient Supervolcanoes Discovered in Utah and Nevada



Squink
2013-Dec-24, 12:13 AM
East central Nevada and southwest Utah (http://www.sci-news.com/geology/science-supervolcanoes-utah-nevada-01612.html)


The newly discovered supervolcanoes aren’t active today, but 30 million years ago more than 5,500 cubic km of magma erupted during a one-week period near a place called Wah Wah Springs.

“In southern Utah, deposits from this single eruption are 4 km thick.
...
These supervolcanoes have diameters up to 60 km and are filled with intracaldera tuff and breccias. They have been hidden in plain sight for millions of years despite their enormous size.The Huckleberry Ridge eruption at Yellowstone only ejected half that volume of rock (http://en.wikipedia.org/wiki/Supervolcano).

Having driven through the area in 2011, I must say, I did not notice any supervolcanoes dotting the landscape.

grapes
2013-Dec-24, 12:28 AM
Thread moved, at OP request

You don't see them when you drive through Yellowstone, either. These super volcanos are not your typical cinder cones at all. And the eruption is over a very long period of time.

dgavin
2013-Dec-25, 06:12 PM
Nice find, that chain of hot spots is on the southern edge of the great elliptical basin complex, which also holds the Yellowstone hotspot, Newberry hotspot and the Long Valley Hotspot.

http://www.mantleplumes.org/images3/CRBEllipseFig2_600.jpg

Source article for that image here: http://www.mantleplumes.org/CRBEllipse.html

In it's own right the Great Ellipse is looking like a giant form of a volcanic caldera, with a number of hotspots (super volcanos) around it's rim. Evidence is still piling up that the Great Ellipse is not a mantle plume origin, but it's more like a rocky form something akin to Jupiter's red spot (Drixoral Torsion). Just a very slowly moving one.

The following article just gives you an idea of the magma distribution in the snake river plain. http://oregonstate.edu/terra/2013/04/rethinking-yellowstone/ Most notable is the image I'll link to below, where the black circle is Yellowstone's caldera. Basically more evidence that the entire area below the Great Ellipse has a huge abundance of magma in the upper crustal regions.

http://oregonstate.edu/terra/wp-content/uploads/2013/04/YellowstoneFigure1.jpg

The Great Ellipse is so large, it can only be noticed from orbit or on terrain feature maps.

BigDon
2013-Dec-28, 10:25 PM
I'm still trying to wrap my head around the Siberian and the smaller Deccan traps. (For the folks at home the word trap in this case denotes massive basalt flood plains, like the maria on the Moon.)

During the laying down of the Deccan traps in India at the end of the Cretaceous there was the equivalent of a Mt. Saint Helens eruption weekly for a *million* years! That's fifty two million large scale eruptions in a terribly short span of time.

The Chixilub impact event merely put the non-avian dinosaurs out of their misery.

THAT is/was the reason so many paleontologist felt the dinosaurs were already on the way out at the time of the impact. That would be bad even on a human time scale if it were to start up again tomorrow.

A whole bunch of people have a hard time grasping that the Earth is even capable of that level of violence.

Like finding out your sweet ol' grandma used to be an axe murderer.

HenrikOlsen
2013-Dec-29, 09:55 PM
And one of the really interesting things about the Deccan traps is that they were actually antipodal to the Chicxulub impact when it happened.

It's entirely possible that this was what really set them off, antipodal focusing of impact shock waves which shatter surface features is a quite well documented effect.

So we get the Death of Dinosaurs walking the lands, fire in one hand, ice in the other.

HenrikOlsen
2013-Dec-29, 10:01 PM
Oh, and I read that an antipodal-at-the-time impact crater has been found for the Siberian Traps as well, suggesting a similar dual-cause reason for the Permian-Triassic transition.

dgavin
2013-Dec-30, 03:12 PM
I've been looking for a possible antipodal source for the great elliptical basin, as it's only 17-30 million years old. Anyway while it does correspond to an extreme low spot in the ocean on other side of the planet, I don't think that's from an impact.

Squink
2013-Dec-30, 10:49 PM
I've been looking for a possible antipodal source for the great elliptical basin, as it's only 17-30 million years old.Did the same, also came up empty. The area's pretty remote (http://www.findlatitudeandlongitude.com/antipode-map/#.UsH4u_aj2WZ), so may not have been well studied.

BrentArsement
2013-Dec-31, 05:21 PM
Just visited Pagosa Springs, Colorado for a week. Never realized how hydrothermal it is. Any geological works on whether its part of an ancient volcanic network? Thanks.

Brent

dgavin
2013-Dec-31, 08:05 PM
Brent, Origianly it was felt the Rockies were once a subduction chain, before part of the Fallon Plate was entirely subducted. And they likely were.

However the Great Elliptical Basin, basically borders almost all of the rocky montains. http://www.mantleplumes.org/images3/CRBEllipseFig2_600.jpg

As such, while Colorado may no longer have subduction vulcanism, like it did some 50 million years ago or so. It /is/ in the Great Elliptical Basin, if you look at that image I reposted in this reply above, basically, any area that highlight in green is capable of hot spot/dixtoral torsion driven volcanoes. SO in the simplest form Yes, it is part of a volcanic network. Achient? yes and no. The subduction volcanoes all are. however the Basin is only 17-30 million years old, and there are more resent volcanoes in Colorado driven by that process now. They main reson there is not the activty there, you see in the cascade range, is here we have both subduction and dixtoral processes, and a crust thats about 20-40km thinner then in colorado. It takes vulcanism a lot longer to get to the surface in Colorado, so it's now very rare. But it's still a part of the basin's rim volcanic systems, which is an active process.

BrentArsement
2014-Jan-01, 03:12 AM
Wonderful description, dgavin. Thank you. I have always loved the volcanic process. As a young 2nd Lieutenant, our Commander organized a hike to the top of Mt. Rainier near Fort Lewis, Washington. It was a remarkable experience for a young Texan man. Pagosa Springs stirred my interest, such as did Yellowstone and Rainier. Thanks again for taking the time for such a wonderful explanation.

Brent

MickLinux
2014-Jul-07, 02:34 AM
I think that at the time of the Permian extinction and the splitting of Pangea, antipodal to the Siberian Traps was the Scotia Plate. Now, as Ieremember the Smithsonian's lead paleogeologist looked for an asteroid strike at the antipodal point, and found nothing. However, I'm not sure I agree. If you look at the depths of the Wadell Sea, you will see the southern end of Africa echoed there. Look again, and you will see that the Scotia plate appears to have slid out from a section that corresponds to the sill-depleted area of the African karoo.

Also, the structure of kimberlites around the world matches two patterns: a chipping structure centered on the scotia/karoo, and concentric rings and radii centered on the Hudson bay.

Here's what I think happened: look up de Meijer /van Westrenen explosion for reference. I think there was a collection of Ca/U bergs in the mantle beneath the Afircan Vredefort site. An asteroid struck obliquely into the mantle, and drove one of the bergs in close enough to the center that the whole collection went supercritical and blew out there.

The pressure shock waves in the mantle also triggered another ca/U berg collection under the hudson, and caused it to blow, leaveing a shattered glass effect. The combination of the two also caused the initial split of the atlantic, after which thermodynamic processes caused additional rifting. There was another small such blowout in the region of China.
The whole thing also caused the permian extinction. It was much more sudden than fungal growth fossils in the Karoo indicate, for the reason that radioactive contamination messed with the pb-pb dating.

the blowout area of the karoo matches the scotia plate, because the scotia plate is the mantle remains of the blowout path. As such, it is lighter and stronger and more stable than other plates. the sill depletion came from a collapse of the entire region, causing the breakup of the sills and erosion of the land.

MickLinux
2014-Jul-07, 02:41 AM
Also, has anyone noticed that if you look at a whole week's worth of quakes, 1+ magnitude, that they surround the great elliptical basin, and then make radial forays inwards? And the sierra Nevada is rising significantly fast. They say that it is due to draining aquifers, but I wonder if perhaps it may be instead due to a major adjustment of the basin, or perhaps due to magma movement below.

geonuc
2014-Jul-07, 11:04 PM
Also, has anyone noticed that if you look at a whole week's worth of quakes, 1+ magnitude, that they surround the great elliptical basin, and then make radial forays inwards? And the sierra Nevada is rising significantly fast. They say that it is due to draining aquifers, but I wonder if perhaps it may be instead due to a major adjustment of the basin, or perhaps due to magma movement below.

What? The Sierra Nevada uplift is due to draining aquifers? I don't even know what that means. Please explain.

dgavin
2014-Jul-08, 04:57 AM
Mick. The Magma in the Elliptical Basin is thought to be dextral torsion driven, and not mantle plume driven. Basically for all intensive purposes, it is a single mega-volcanic region that actually did uplift and break out about 17mil years ago, and spawned fissure eruptions for close to a million years, during which the basin subsided in a very slow form of a million year long caldera collapse. The left over magma has since erupted in a number of area's as super volcanoes typically along the edge of the basin. The exception to that is the Newberry, Yellowstone, and Long Valley hot spots, which are the remnants of the three original mega volcano's fissures, which migrated towards the edge as well. And yes, both the sierra's and the steen's mountains are raising fast, mostly because as the Rockies and then cascades formed, mountain ranges tend to spread out from erosion, but also a little from gravity, and gravities spreading effects go deeper into the lithosphere. To the basin is actually being compressed on all sides. Add to that the addition force of the pressure from seduction zone too, and it's enough to cause area's with large faults, to uplift.