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Earth's Volcanism Linked To Meteorite Impacts
New Scientist ^ | 12-13-2002 | Kate Ravilious

Posted on 12/13/2002 8:36:39 AM PST by blam

Earth's volcanism linked to meteorite impacts

14:31 13 December 02

Exclusive from New Scientist Print Edition

Space rocks are blamed for violent eruptions (Image: GETTY)

Large meteorite impacts may not just throw up huge dust clouds but also punch right through the Earth's crust, triggering gigantic volcanic eruptions.

The idea is controversial, but evidence is mounting that the Earth's geology has largely been driven by such events. This would also explain why our planet has so few impact crater remnants.

Counting the number of asteroids we see in the sky suggests that over the past 250 million years, Earth should have been hit around 440 times by asteroids larger than one kilometre across. But scientists have found only 38 large impact craters from this period.

Dallas Abbott from Columbia University and her colleague Ann Isley from the State University of New York studied the timing of these 38 impacts and found that they correlate strongly with eruptions of "mantle-plume" volcanoes during the same period.

Deep impact

Most volcanoes come from small amounts of the Earth's upper mantle boiling over, but mantle-plume volcanoes happen when hot rock from deep within the Earth's mantle shoots straight up through the Earth's crust. The timing suggests that these volcanoes are related to asteroid impacts, Abbott and Isley report in Earth and Planetary Science Letters (vol 205, p 53).

Unreliable dates

Not everyone agrees. "I am not enthusiastic about the idea that impacts systematically control Earth's activity," says Boris Ivanov from the Institute of Geospheres Dynamics in Moscow. He has used computer models to investigate the effect of meteorites on the Earth's crust, and says he does not believe impacts are capable of having a significant effect on the planet's geological processes.

And geochemist Christian Koeberl from Vienna University argues that the dates Abbott used are not reliable. "The impacts and volcanoes can only be correlated to within tens of millions of years," he says. "This doesn't really prove anything."

But elsewhere, there is growing support for the idea that Earth's volcanism may be closely entwined with meteorite impacts.

Massive surge

Adrian Jones and David Price from University College London say Abbott's work backs up their recent computer simulations. These models suggest meteorites bigger than about 10 kilometres across could sometimes punch right through the Earth's crust, causing huge volcanic eruptions (Earth and Planetary Science Letters, vol 202, p 551).

"A large impact has the ability to cause instant melting where it hits, creating its own impact plume in the mantle and resulting in a massive surge of lava spilling out," Jones explains.

Until now Abbott and Isley were not sure how impacts might trigger volcanic eruptions, but the UCL model suggests a mechanism. It would also explain why we do not see as many meteorite craters as we might expect, as the surges of molten rock would obliterate them.

Double whammy

Jones speculates that many of the impact craters Abbott analysed could have been created by mere fragments of bigger asteroids that hit elsewhere at the same time and broke through the crust, ultimately leaving no trace.

For example, the 10 kilometre-wide asteroid that hit Chicxulub in Mexico 65 million years ago is widely blamed for wiping out the dinosaurs. But it could have been a piece from a much bigger rock that hit India, triggering the surge of volcanic activity known as the Deccan Traps.

"Many areas that exhibit extensive volcanism from the past, such as the Deccan Traps and the Siberian Traps, may in fact be sites of gigantic meteorite impacts," says Jones. Perhaps the dinosaurs would have survived a meteorite impact alone, but the double whammy of a meteorite and volcanoes pushed them to extinction.

Kate Ravilious


TOPICS: News/Current Events
KEYWORDS: archaeology; catastrophism; earths; ggg; godsgravesglyphs; history; impacts; meteorite; volcanism
I nominate the 1628BC explosion of Santorini (Exodus) as a candidate for a meteorite impact.
1 posted on 12/13/2002 8:36:39 AM PST by blam
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To: RightWhale
Ping.
2 posted on 12/13/2002 8:37:37 AM PST by blam
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To: blam
'Could say something about the Hawaiian hot spot, which does not apprear tectonically driven. Interesting....
3 posted on 12/13/2002 8:44:20 AM PST by onedoug
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To: blam
You know, Al Gore invented meteorites. ;)
4 posted on 12/13/2002 8:45:27 AM PST by freedumb2003
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To: blam
Dallas Abbott from Columbia University and her colleague Ann Isley from the State University of New York studied the timing of these 38 impacts and found that they correlate strongly with eruptions of "mantle-plume" volcanoes during the same period.

Considering, for example, that Hawaii and Iceland are hot-spot (or mantle-plume) volcanic zones, they erupt almost continually, so of course you'll be able to get a correlation with such features. And the impact at the end of the Cretateous down in Yucatan did not create a plume, and that was a biggie. Dittoes for the impact at the southern end of the Chesapeake - I don't see a Mt. Norfolk erupting down there.

It would be more impressive if the researchers were able to correlate major impacts with outbreaks of flood basalts. Now THOSE are truly nasty...

5 posted on 12/13/2002 8:53:01 AM PST by dirtboy
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To: blam
For example, the 10 kilometre-wide asteroid that hit Chicxulub in Mexico 65 million years ago is widely blamed for wiping out the dinosaurs. But it could have been a piece from a much bigger rock that hit India, triggering the surge of volcanic activity known as the Deccan Traps.

The Yellowstone hot spot created the Columbia flood basalts. There does not have to be correlation with an impact to get these events. Plus, 65 million years ago, India was very close to the Reunion hot spot, an extremely active one. They need more evidence and less inference.

6 posted on 12/13/2002 8:55:28 AM PST by dirtboy
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To: freedumb2003
You know, Al Gore invented meteorites. ;)

This new theory perplexes me; why would Al Gore invent meteorites which could possibly do so much damage to one of his other creations, Earth?

7 posted on 12/13/2002 9:03:45 AM PST by ALASKA
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To: onedoug
'Could say something about the Hawaiian hot spot, which does not apprear tectonically driven. Interesting....

Backtrack the Hawaiian hotspot on the earth's crust to where the impact might have been. Remember hotspots remain stationary in reference to the earth's crust while the plates move over them.

8 posted on 12/13/2002 9:14:23 AM PST by Mike Darancette
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To: Mike Darancette
hotspots remain stationary in reference to the earth's crust

crust s/b core my bad!!!

9 posted on 12/13/2002 9:18:22 AM PST by Mike Darancette
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To: dirtboy
And the impact at the end of the Cretateous down in Yucatan did not create a plume,...

EXTRATERRESTRIAL INFLUENCES ON MANTLE PLUME ACTIVITY

Earth and Planetary Science Letters
Volume 205, Issues 1-2, 30 December 2002, Pages 53-62
by Dallas H. Abbott and Ann E. Isley

Abstract

We use time series analysis to compare the impact histories of the Earth and Moon with the record of mantle plume activity. We use events with errors in their ages of 150 Ma. The terrestrial and lunar impact records, when smoothed at a 45-Ma interval, correlate at a 97% confidence level. This high confidence level suggests that we have an adequate sampling of most of the major impact events on the Earth. We then test the idea that existing mantle plumes may be strengthened by impacts. When smoothed at a 45-Ma interval, strong plumes correlate with the terrestrial impact record at better than a 99% confidence level. No time lag is discernible between the data sets, which is expected given their present error level. When the time series are smoothed at a 30-Ma interval, there are 10 major peaks in impact activity. Nine out of ten of these peaks have a counterpart in either or both of the strong mantle plume or the mantle plume time series. As a result, the strong mantle plume and the impact time series correlate at the 97% confidence level. The mantle plume and the impact time series correlate at the 90% confidence level. Finally, the Deccan plume showed greatly increased activity immediately after the Chixculub impact. The results of our analysis suggest that large meteorite and cometary impacts may well increase the amount of volcanism from already active mantle plumes.

Also, I thought that Iceland was an area where the sea floor was spreading.

10 posted on 12/13/2002 9:27:26 AM PST by Mike Darancette
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To: Mike Darancette
"And the impact at the end of the Cretateous down in Yucatan did not create a plume,..."

I read that the Chicxulub meteorite came in at a 35 degree angle, may be that's why it didn't 'punch' through.

11 posted on 12/13/2002 9:37:05 AM PST by blam
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To: blam
I read that the Chicxulub meteorite came in at a 35 degree angle, may be that's why it didn't 'punch' through.

Exactly so, even a smaller object hitting at higher angle would be more likely to punch through. Also an object hitting mid-ocean (where the crust is thin) would be more apt to create a plume.

12 posted on 12/13/2002 9:41:11 AM PST by Mike Darancette
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To: Mike Darancette
Re the Emperor Seamount chain, which abruptly trends more westerly about midway toward the Aleutians, where its earlier remnants are finally subducted, to be reassimilated back into the mantle.

What a world, eh?

13 posted on 12/13/2002 10:37:00 AM PST by onedoug
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To: blam
I nominate the 1628BC explosion of Santorini (Exodus) as a candidate for a meteorite impact.

Doesn't fit the profile. From Pellegrino's Unearthing Atlantis, it had a long history as a volcanic hotspot before and since the Iron Age biggie that devastated Minoan Crete 70 miles over the water. The Thera (where did you get Exodus?) excavations seem to show pipes for geothermal hot and cold running water.

14 posted on 12/13/2002 10:42:33 AM PST by VadeRetro
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To: blam
Not to mention that a big earthquake apparently devastated the city on Thera, leading to its near-total abandonment well before the explosion.
15 posted on 12/13/2002 10:44:57 AM PST by VadeRetro
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Comment #16 Removed by Moderator

To: blam
One of the worst candidates you could find. For one, it's not big enough (the article is talking about truly gigantic flood-basalt type eruptions....comparitavely, Santorini was small and localized.)

Also, Santorini is on a plate boundary, and its existence can be easily ascribed to normal tectonic volcanism.
17 posted on 12/13/2002 11:42:04 AM PST by John H K
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To: Ookie Wonderslug
I am crazy or can yall visualize this too?

You're crazy, but I don't see what that has to do with this ;^)

The Deccan traps were not at the antipodes from the Chicxulub impact site. The shock waves from Chicxulub would not meet at that point. A paired asteroid impact could explain both features.

A more interesting question (and possible proof of the theory) is where is the contra coup scars from the Deccan and or Siberian traps? If either one was a scar from a BIG impact, there should be "disturbed" features 180° from it. Anyone know what was opposite India 65 mya? Or Siberia 230 mya? Does either exhibit shattered rock, or have they been subducted in the meanwhile?

The other obvious question is where are the other impact debris, surely all the splatter couldn't have reached escape velocity, could it?

Also, I highly recommended this book: T.rex and the crater of doom by Walter Alvarez, Princton University Press, ISBN 0-691-01630-5. Not only is it a very well told tale of the discovery of the Chicxulub impact site, it is a superb geology text. It packs a tremendous geology education in an accessible, easy to digest and understand form.

18 posted on 12/13/2002 12:06:54 PM PST by null and void
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To: blam
Two things. Would punching a hole in the crust actually produce a volcano? It's not as if the interior of the earth is just waiting for this in order to break through.

The other thing is the Martian volcanos, which correlate with a basin on the other side of the planet and look like a large asteroid plowed right through the planet and punched almost through in the earea of the volcanos, which are grouped in a relatively small area.

19 posted on 12/13/2002 12:28:00 PM PST by RightWhale
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To: VadeRetro
"it had a long history as a volcanic hotspot before and since the Iron Age biggie that devastated Minoan Crete 70 miles over the water. "

Yup, that's my argument against an impact also. It's in an already previously active area.

20 posted on 12/13/2002 3:27:14 PM PST by blam
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To: Ookie Wonderslug
"It would create a shockwave/pressure wave that would travel all the way across the planet that would concentrate on the other side. I am crazy or can yall visualize this too?"

It's the first time I have ever heard this or even considered it. I like the simpler idea of the 'punch through.'

21 posted on 12/13/2002 3:31:39 PM PST by blam
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To: blam
Yes. Imagine you are standing at the exact opposite side of the globe from a major impact.

The shock wave radiates out in all directions from the blast at the speed of sound in rock.

You get a sharp bump straight up when the shockwave traveling the shorter path straight through the core reaches you first.

About the time that settled down the surface wave reaches you. From all sides. At once. Concentrated. Focused. Nearly as intense as the impact itself.

The pressure wave jets you and acres of liqufied bedrock towards the heavens...

22 posted on 12/13/2002 3:44:14 PM PST by null and void
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To: VadeRetro
"The Thera (where did you get Exodus?) "

Santorini could have provided all the fireworks, famines and etc. for the Exodus.
The Santinori plume would need to be 30 miles high to be visible in the Nile Valley. The recent Pinatubo volcano was 26 miles high.
The destroyed walls of Jerico are just above the Santorini ash layer and dated appropriately by charred wheat. (The Egyptian Kings List would have to be wrong)

It's just a idea, I absolutely do not want to get into another Lost Tribes discussion!!

23 posted on 12/13/2002 3:44:28 PM PST by blam
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To: blam
Oh, yeah! I'm familiar with the (speculative) Exodus/Atlantis identifications of Thera. Your syntax threw me.
24 posted on 12/13/2002 3:47:26 PM PST by VadeRetro
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To: VadeRetro
"Oh, yeah! I'm familiar with the (speculative) Exodus/Atlantis identifications of Thera. Your syntax threw me."

I did some studying on Thera/Santorini/Akatori and have drifted away from it as a possibility for Atlantis, I favor South America presently. BTW, in the 1300's a Jewish guy named Joseph Nazi owned the whole island.

25 posted on 12/13/2002 4:31:20 PM PST by blam
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To: blam
My take that the origin of the Atlantis legend will never be rock-solid, but if Thera and Crete weren't Atlantis then nothing was.
26 posted on 12/13/2002 6:40:52 PM PST by VadeRetro
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To: VadeRetro
My take is ... etc.
27 posted on 12/13/2002 6:42:30 PM PST by VadeRetro
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To: null and void
Neato imagery there.
28 posted on 12/13/2002 6:53:48 PM PST by txhurl
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To: blam
Earth's volcanism linked to lava.
29 posted on 12/13/2002 7:02:36 PM PST by Consort
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To: Jimer
"Earth's volcanism linked to lava."

Do you have a Lava flag? (grin)

30 posted on 12/13/2002 7:05:16 PM PST by blam
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To: txflake
~.~ thank you...
31 posted on 12/13/2002 10:06:13 PM PST by null and void
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Not a ping, just a GGG update.
Please FREEPMAIL me if you want on, off, or alter the "Gods, Graves, Glyphs" PING list --
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32 posted on 01/10/2005 11:24:18 AM PST by SunkenCiv (the US population in the year 2100 will exceed a billion, perhaps even three billion.)
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33 posted on 04/14/2006 1:51:49 PM PDT by SunkenCiv (https://secure.freerepublic.com/donate/)
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Catastrophism

34 posted on 04/14/2006 1:58:29 PM PDT by SunkenCiv (https://secure.freerepublic.com/donate/)
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· join list or digest · view topics · view or post blog · bookmark · post a topic ·

 
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35 posted on 03/10/2008 12:22:53 PM PDT by SunkenCiv (https://secure.freerepublic.com/donate/______________________Profile updated Saturday, March 1, 2008)
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