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BIG BANG IN ANTARCTICA -- KILLER CRATER FOUND UNDER ICE
Ohio State University ^ | 01 June 2006 | Staff (press release)

Posted on 06/01/2006 2:26:58 PM PDT by PatrickHenry

Ancient mega-catastrophe paved way for the dinosaurs, spawned Australian continent.

Planetary scientists have found evidence of a meteor impact much larger and earlier than the one that killed the dinosaurs -- an impact that they believe caused the biggest mass extinction in Earth's history.

The 300-mile-wide crater lies hidden more than a mile beneath the East Antarctic Ice Sheet. And the gravity measurements that reveal its existence suggest that it could date back about 250 million years -- the time of the Permian-Triassic extinction, when almost all animal life on Earth died out.

Its size and location -- in the Wilkes Land region of East Antarctica, south of Australia -- also suggest that it could have begun the breakup of the Gondwana supercontinent by creating the tectonic rift that pushed Australia northward.

Scientists believe that the Permian-Triassic extinction paved the way for the dinosaurs to rise to prominence. The Wilkes Land 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 meteor is thought to have been 6 miles wide, while the Wilkes Land meteor could have been up to 30 miles wide -- four or five times wider.

"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.

He and Laramie Potts, a postdoctoral researcher in geological sciences, led the team that discovered the crater. They collaborated with other Ohio State and NASA scientists, as well as international partners from Russia and Korea. They reported their preliminary results in a recent poster session at the American Geophysical Union Joint Assembly meeting in Baltimore.

The scientists used gravity fluctuations measured by NASA's GRACE satellites to peer beneath Antarctica's icy surface, and found a 200-mile-wide plug of mantle material -- a mass concentration, or "mascon" in geological parlance -- that had risen up into the Earth's crust.

Mascons are the planetary equivalent of a bump on the head. They form where large objects slam into a planet's surface. Upon impact, the denser mantle layer bounces up into the overlying crust, which holds it in place beneath the crater.

When the scientists overlaid their gravity image with airborne radar images of the ground beneath the ice, they found the mascon perfectly centered inside a circular ridge some 300 miles wide -- a crater easily large enough to hold the state of Ohio.

Taken alone, the ridge structure wouldn't prove anything. But to von Frese, the addition of the mascon means "impact." Years of studying similar impacts on the moon have honed his ability to find them.

"If I saw this same mascon signal on the moon, I'd expect to see a crater around it," he said. "And when we looked at the ice-probing airborne radar, there it was."

"There are at least 20 impact craters this size or larger on the moon, so it is not surprising to find one here," he continued. "The active geology of the Earth likely scrubbed its surface clean of many more."

He and Potts admitted that such signals are open to interpretation. Even with radar and gravity measurements, scientists are only just beginning to understand what's happening inside the planet. Still, von Frese said that the circumstances of the radar and mascon signals support their interpretation.

"We compared two completely different data sets taken under different conditions, and they matched up," he said.

To estimate when the impact took place, the scientists took a clue from the fact that the mascon is still visible.

"On the moon, you can look at craters, and the mascons are still there," von Frese said. "But on Earth, it's unusual to find mascons, because the planet is geologically active. The interior eventually recovers and the mascon goes away." He cited the very large and much older Vredefort crater in South Africa that must have once had a mascon, but no evidence of it can be seen now.

"Based on what we know about the geologic history of the region, this Wilkes Land mascon formed recently by geologic standards -- probably about 250 million years ago," he said. "In another half a billion years, the Wilkes Land mascon will probably disappear, too."

Approximately 100 million years ago, Australia split from the ancient Gondwana supercontinent and began drifting north, pushed away by the expansion of a rift valley into the eastern Indian Ocean. The rift cuts directly through the crater, so the impact may have helped the rift to form, von Frese said.

But the more immediate effects of the impact would have devastated life on Earth.

"All the environmental changes that would have resulted from the impact would have created a highly caustic environment that was really hard to endure. So it makes sense that a lot of life went extinct at that time," he said.

He and Potts would like to go to Antarctica to confirm the finding. The best evidence would come from the rocks within the crater. Since the cost of drilling through more than a mile of ice to reach these rocks directly is prohibitive, they want to hunt for them at the base of the ice along the coast where the ice streams are pushing scoured rock into the sea. Airborne gravity and magnetic surveys would also be very useful for testing their interpretation of the satellite data, they said.

NSF and NASA funded this work. Collaborators included Stuart Wells and Orlando Hernandez, graduate students in geological sciences at Ohio State; Luis Gaya-Piqué and Hyung Rae Kim, both of NASA's Goddard Space Flight Center; Alexander Golynsky of the All-Russia Research Institute for Geology and Mineral Resources of the World Ocean; and Jeong Woo Kim and Jong Sun Hwang, both of Sejong University in Korea.


TOPICS: Culture/Society; Philosophy
KEYWORDS: antarctic; antarctica; bolide; canopy; catastrophism; chicxulub; creation; crevolist; deccantraps; evolution; extinction; godsgravesglyphs; greatdying; impact; impactcraters; lakevostok; massextinction; meteor; meteorimpact; ohsomysteriouso; permian; ptextinction; russia; stalactites; stalagmites; thegreatdying; velaincident; velikovsky
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Everybody be nice.
1 posted on 06/01/2006 2:27:00 PM PDT by PatrickHenry
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To: VadeRetro; Junior; longshadow; RadioAstronomer; Doctor Stochastic; js1138; Shryke; RightWhale; ...
Evolution Ping

The List-O-Links
A conservative, pro-evolution science list, now with over 370 names.
See the list's explanation, then FReepmail to be added or dropped.
To assist beginners: But it's "just a theory", Evo-Troll's Toolkit,
and How to argue against a scientific theory.

2 posted on 06/01/2006 2:28:10 PM PDT by PatrickHenry (Unresponsive to trolls, lunatics, fanatics, retards, scolds, & incurable ignoramuses.)
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To: PatrickHenry

This is huge news if it pans out.


3 posted on 06/01/2006 2:28:38 PM PDT by Altair333 (Red Rover, Red Rover, Send Mexico Right Over)
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To: PatrickHenry

300-mile-wide crater

That's a big 'un. Wow.


4 posted on 06/01/2006 2:29:08 PM PDT by NormsRevenge (Semper Fi - "The Road to Peace in the Middle East runs thru Damascus.")
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To: PatrickHenry
Lunar Mascons:
5 posted on 06/01/2006 2:31:09 PM PDT by BenLurkin
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To: PatrickHenry

Is the P-T event associated with an irridium layer?


6 posted on 06/01/2006 2:31:09 PM PDT by DBrow
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To: PatrickHenry; blam; SunkenCiv

I had wondered if the super-continent break-up might have been related to a monsterous impact.


7 posted on 06/01/2006 2:32:20 PM PDT by WoofDog123
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Comment #8 Removed by Moderator

To: BenLurkin
Near Lake Vostok?


9 posted on 06/01/2006 2:32:30 PM PDT by BenLurkin
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To: PatrickHenry
The Chicxulub meteor is thought to have been 6 miles wide, while the Wilkes Land meteor could have been up to 30 miles wide -- four or five times wider.

30 miles wide. Kinda explains why 95% of life died out.

10 posted on 06/01/2006 2:33:02 PM PDT by Centurion2000 (The social contract is breaking down.)
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To: PatrickHenry
while the Wilkes Land meteor could have been up to 30 miles wide

That's gonna leave a mark....

11 posted on 06/01/2006 2:33:11 PM PDT by The_Victor (If all I want is a warm feeling, I should just wet my pants.)
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To: PatrickHenry

bump


12 posted on 06/01/2006 2:33:16 PM PDT by lesser_satan (EKTHELTHIOR!!!)
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To: Altair333

Their research, backup data, and logic looks pretty good.

It makes sense that an earlier collision (but smaller than the original earth -> moon collision) happened to kill the Premian species.

It is Bush's fault that the crater lies on a rift line.


13 posted on 06/01/2006 2:33:17 PM PDT by Robert A Cook PE (I can only donate monthly, but Hillary's ABBCNNBCBS continue to lie every day!)
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To: PatrickHenry

I'm sure women and minority dinosaurs were hardest hit.


14 posted on 06/01/2006 2:33:31 PM PDT by Lekker 1 (("Stocks have reached what looks like a permanently high plateau" - I. Fisher, Yale Econ Prof, 1929))
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To: PatrickHenry

My crater is bigger than your crater.


15 posted on 06/01/2006 2:33:45 PM PDT by angkor
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To: Molly Pitcher

300 mile wide crater...wow.


16 posted on 06/01/2006 2:34:16 PM PDT by Dog
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To: Altair333

This doesn't surprise me in the least. I have a feeling before it's all over we'll find all kinds of things buried under a mile of ice.....things that will answer a lot of questions.


17 posted on 06/01/2006 2:35:08 PM PDT by Diego1618
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To: angkor
Ok.

now, knowing that the Antarctic land mass has moved a long ways since the breakup of the original continental masses, why did the mass they found underneath stay with the surface rock?
18 posted on 06/01/2006 2:35:21 PM PDT by Robert A Cook PE (I can only donate monthly, but Hillary's ABBCNNBCBS continue to lie every day!)
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To: PatrickHenry
Planetary scientists have found evidence of a meteor impact much larger and earlier than the one that killed the dinosaurs -- an impact that they believe caused the biggest mass extinction in Earth's history.

And it was caused by Karl Rove!

19 posted on 06/01/2006 2:35:33 PM PDT by JRios1968 (In memoriam...)
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To: Centurion2000

that must have had an exponentially greater climate impact than the C-T (alvarez) impact.


20 posted on 06/01/2006 2:37:18 PM PDT by WoofDog123
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