Giant 500 Km impact crater found in Antarctica

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ANDREA
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Giant 500 Km impact crater found in Antarctica

Post #1by ANDREA » 02.06.2006, 21:31

I wish to share this information, just received. :wink:
The crater is buried under a half mile ice, is about 300 miles wide, and could be the cause of big extinction due 250 million years ago.

CCNet 89/06 - 2 June 2006
(1) ANTARCTIC IMPACT CRATER LINKED TO ANCIENT DIE-OFF
MSNBC.com, 1 June 2006
http://www.msnbc.msn.com/id/13089686/
By Robert Roy Britt
Senior science writer, Space.com
Scientists say impact might have caused extinction 250 million years ago

An apparent crater as big as Ohio has been found in Antarctica. Scientists think it was carved by a space rock that caused the greatest mass extinction on Earth, 250 million years ago.

The crater, buried beneath a half-mile (1 kilometer) of ice and discovered by some serious airborne and satellite sleuthing, is more than twice as big as the one involved in the demise of the dinosaurs.

The crater's location, in the Wilkes Land region of East Antarctica, south of Australia, suggests it might have instigated the breakup of the so-called Gondwana supercontinent, which pushed Australia northward, the researchers said.

"This Wilkes Land impact is much bigger than the impact that killed the dinosaurs, and probably would have caused catastrophic damage at the time," said Ralph von Frese, a professor of geological sciences at Ohio State University.

The crater is about 300 miles (500 kilometers) wide. It was found by looking at differences in density that show up in gravity measurements taken with NASA's GRACE satellites. Researchers spotted a mass concentration, which they call a mascon - dense stuff that welled up from the mantle, likely in an impact.

"If I saw this same mascon signal on the moon, I'd expect to see a crater around it," Frese said. (The moon, with no atmosphere, retains a record of ancient impacts in the visible craters there.)

So Frese and colleagues overlaid data from airborne radar images that showed a 300-mile-wide subsurface, circular ridge. The mascon fit neatly inside the circle.

"And when we looked at the ice-probing airborne radar, there it was," he said Thursday.

The Permian-Triassic extinction, as it is known, wiped out most life on land and in the oceans. Researchers have long suspected a space rock might have been involved. Some scientists have blamed volcanic activity or other culprits.

The die-off set up conditions that eventually allowed dinosaurs to rule the planet.

The newfound crater is more than twice the size of the Chicxulub crater in the Yucatan peninsula, which marks the impact that may have ultimately killed the dinosaurs 65 million years ago. The Chicxulub space rock is thought to have been 6 miles (10 kilometers) wide, while the Wilkes Land meteor could have been up to 30 miles (50 kilometers) wide, the researchers said.

The work was financed by NASA and the National Science Foundation. The discovery, announced Thursday, was initially presented in a poster paper at the recent American Geophysical Union Joint Assembly meeting in Baltimore.

The researchers say further work is needed to confirm the finding. One way to do that would be to go there and collect rock from the crater to see if its structure matches what would be expected from such a colossal impact.

If confirmed, this could be a very important addition to our knowledge of Earth history.
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Post #2by Hunter Parasite » 02.06.2006, 21:42

let's just hope that doesnt happen again anytime soon. i'm not i the mood for a mass extinction.

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Post #3by Dollan » 02.06.2006, 22:06

This is a *very* interesting discovery. Not only because we may be looking at the initial cause of the Permian Mass, but also because we just *might* be looking at the cause of the opening of the Atlantic.

I think, though, that one major flaw with the interpretation of this event is when it is said other such impacts have been erased by the Earth's dynamic surface. For myself, I think that if this is indeed confirmed as a major impact, we're looking at the only such sized impact since the beginning of the Phanerozoic. there's no evidence to suggest other mass extinctions on the sheer level of the Permian Mass, and smaller imapct seem to fit the bill for the other major events (who would've thought that the KT could be considered small by any terrestrial comparison!).

Still, this is a fascinating bit of news.

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Post #4by ajtribick » 02.06.2006, 22:07

What's quite interesting about this is the way that both in this case and in the case of the Chicxulub impact, there seems to be a flood basalt dated to around the same time roughly on the opposite side of the planet (Siberian Traps for the Permian, Deccan Traps in India for the Cretaceous)

Permian map
End Cretaceous map

Not sure if this is just coincidence though...

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Post #5by selden » 02.06.2006, 22:12

While looking for some related information, I found a paper at http://www.pubmedcentral.nih.gov/articl ... rtid=33699
which mentions that there were large lava fields formed in Siberia at about the same time as those mass extinctions. Siberia is on almost exactly the opposite side of the planet from the Ross Sea. This is consistant with other hypotheses I've read which suggest that a major impact on one side of a planet will generate waves that will cause major tectonic activity when they converge on the opposite side of the planet. The Hellas Basin and Tharsis dome on Mars seem to be another example.
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Post #6by Dollan » 02.06.2006, 22:16

Not to mention Mercury's Caloris Basin and the chaotic terrain on the opposite side of the planet.

It's amazing that such an effect could be felt through such a relatively massive planet as Earth is.

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Post #7by ANDREA » 02.06.2006, 22:24

selden wrote:While looking for some related information, I found a paper at http://www.pubmedcentral.nih.gov/articl ... rtid=33699
which mentions that there were large lava fields formed in Siberia at about the same time as those mass extinctions. Siberia is on almost exactly the opposite side of the planet from the Ross Sea. This is consistant with other hypotheses I've read which suggest that a major impact on one side of a planet will generate waves that will cause major tectonic activity when they converge on the opposite side of the planet. The Hellas Basin and Tharsis dome on Mars seem to be another example.

Wow Selden, what an interesting article.
I supposed that such catastrophic effects could be visible only on moons, but now I've discovered that this happened on Mars and Earth too!
Well', I'm asking how did anything survive to this. :wink:
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Post #8by Hunter Parasite » 03.06.2006, 13:16

i survived it because im special :) anything that survived (if anything survived) they were probably simple worms and bacteria.

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Post #9by ANDREA » 03.06.2006, 13:30

Hunter Parasite wrote:i survived it because im special :) anything that survived (if anything survived) they were probably simple worms and bacteria.
If you are serious (and I hope so, this is not a "Purgatory" post :wink: ), I think you are mistaking: 250 million years are not enough to start again from bacteria up to the actual biological assesment. If you give a look to the article in the given link, they speak of
"...extinction of 85% or more of all species in the oceans, approximately 70% of land vertebrates, and significant extinctions of plants and insects"

so life started from a good point anyhow. 8)
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Post #10by Hunter Parasite » 03.06.2006, 13:36

gah, i always skip over things. well, at least we still had our fishies.

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Post #11by ANDREA » 03.06.2006, 13:44

BTW, just not to be misunderstood, what I showed here is only a paper on the matter, nothing has already been demonstrated beyond any doubt, so I'm sure that in the next future a lot of scientists will be in Antarctica to solve the doubt. :wink:
As I wrote at the bottom of my first post
    "If confirmed..."
and this has already to be done.
I hope that they will be able to give us a positive answer, but for the moment this is only a valuable hypothesis, no more. :?
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Post #12by Ynjevi » 03.06.2006, 19:04

The P/T mass extinction event wiped out almost every (but fortunately for us, not all!) mammal-like reptile aka synapsid which were the top land animals at that time. Synapsids managed to regain their status in the early Triassic until they were supplanted by dinosaurs.

If I remember correctly, about 95% of all species died at that time making it far more deadly than the K/T event. It was especially devastating to marine species, probably because the assembly of Pangaea caused sea levels to drop drying up all shallow seas.

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Post #13by Malenfant » 03.06.2006, 19:12

Sounds pretty interesting... I'm not sure how a 300km wide crater could kickstart plate tectonics though, I mean sure it'd melt a good way into the crust and probably the upper mantle, but would that necessarily split up continents? I don't think that's necessarily true at all.
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Post #14by ANDREA » 03.06.2006, 20:20

Malenfant wrote:Sounds pretty interesting... I'm not sure how a 300km wide crater could kickstart plate tectonics though, I mean sure it'd melt a good way into the crust and probably the upper mantle, but would that necessarily split up continents? I don't think that's necessarily true at all.

I correct you, sorry, its 300 miles, almost 500 km, so it's more believable, IMHO. :wink:
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Post #15by Malenfant » 03.06.2006, 21:22

ANDREA wrote:
Malenfant wrote:Sounds pretty interesting... I'm not sure how a 300km wide crater could kickstart plate tectonics though, I mean sure it'd melt a good way into the crust and probably the upper mantle, but would that necessarily split up continents? I don't think that's necessarily true at all.
I correct you, sorry, its 300 miles, almost 500 km, so it's more believable, IMHO. :wink:


Even if it's 500 km, I don't think that is believeable. It means that the depth of the crater is probably 50-100km deep - certainly enough to penetrate the crust, but there's still nothing to suggest that would be enough to initiate plate tectonics where nothing was happening before. Sure, you'd get enormous melting and shockwaves, but a 500km basin is still pretty tiny compared to the Earth as a whole.
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Post #16by bdm » 05.06.2006, 02:54

Malenfant wrote:
ANDREA wrote:
Malenfant wrote:Sounds pretty interesting... I'm not sure how a 300km wide crater could kickstart plate tectonics though, I mean sure it'd melt a good way into the crust and probably the upper mantle, but would that necessarily split up continents? I don't think that's necessarily true at all.
I correct you, sorry, its 300 miles, almost 500 km, so it's more believable, IMHO. :wink:

Even if it's 500 km, I don't think that is believeable. It means that the depth of the crater is probably 50-100km deep - certainly enough to penetrate the crust, but there's still nothing to suggest that would be enough to initiate plate tectonics where nothing was happening before. Sure, you'd get enormous melting and shockwaves, but a 500km basin is still pretty tiny compared to the Earth as a whole.

It may not have started a rift on its own, but a 500 km crater is a very large weak spot in the crust that can make the crust more susceptible to rifting at that point. If the crust is going to rift anywhere near that crater, the rift would have a much easier time passing through the shattered crust near the crater than to pass through the undisturbed rock farther away. Had the impact not occurred there, the rift would likely still exist, but probably in a different location.

It's a bit like a genetic susceptibility to a particular disease. The susceptibility does not cause the problem on its own, but merely increases the probability of the event (disease or crustal rifting) occurring.

As for the depth of the crater, a crater 100 km deep is going right through the crust to the mantle. Not many places on Earth have the crust more than 100 km deep.

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re

Post #17by John Van Vliet » 06.06.2006, 22:54

well to ,slightly, get off topic

I would realy love to see in the NEAR futcher ( spelling) ( as in 1 to 5 years) a 150 ft. peace of rock hit the arizonia desert again.
That just might get the world gov's off there asses .

but that is just my opinion !

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Re: re

Post #18by buggs_moran » 06.06.2006, 23:53

john Van Vliet wrote:well to ,slightly, get off topic

I would realy love to see in the NEAR futcher ( spelling) ( as in 1 to 5 years) a 150 ft. peace of rock hit the arizonia desert again.
That just might get the world gov's off there asses .

but that is just my opinion !


No offense John, but Arizona...far too close to family. How about somewhere more remote, LIKE Antarctica, just scary enough. Of course, 150 ft would make a bang and would only affect around a 5 or 10 mile radius. Thanks but no thanks. :)
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Re: re

Post #19by Malenfant » 06.06.2006, 23:53

john Van Vliet wrote:I would realy love to see in the NEAR futcher ( spelling) ( as in 1 to 5 years) a 150 ft. peace of rock hit the arizonia desert again.
That just might get the world gov's off there asses .

but that is just my opinion !


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http://angryflower.com/astero.gif
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re

Post #20by John Van Vliet » 07.06.2006, 16:57

Well i like the cartoon , i was thinking that there is one hole out there why not make it two . Antartica is nice and remote but the odds of an NEO
being in that odd of an orbit is well????



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