BIG BANG IN ANTARCTICA -- KILLER CRATER FOUND UNDER ICE

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.

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.

Recent studies by Chattergee (sp?) in India point to the existence of the Shiva Crater and the edge of the Deccan Traps, about 200 by 400 miles and the same age (65 my) as the Yucatan (dinosaur) crater.

From: Astrobio.net;

At the time of the K−T extinction, India was an island located over the Reunion hotspot. Hotspots are fixed points where hot material from the mantle rises to the Earth's surface. This underground welling flooded portions of India with a vast amount of lava. Today, these cooled lava fields are called the Deccan Traps.

The slow outpouring of Deccan lava probably began a few million years before the K−T extinction. Then about 65 million years ago, the trickle became a torrent.
--------------------------------------------------
They don't buy the idea of a "Shiva Crater" but seem to associate an acceleration of activity in the Deccan Traps to the the Chicxulub event. It may be that a large impactor might effect volcanism at distant locations. The Antarctica impactor may have caused increased volcanism at the P-Tr boundary in the location of the Siberian Traps. Where was the Hawaiian Hotspot 250mya?

:')

Evidence Of Meteor Impact
Found Off Australian Coast
by Donald Savage
May 13, 2004
Most scientists agree a meteor impact, called Chicxulub, in Mexico's Yucatan Peninsula, accompanied the extinction of the dinosaurs 65 million years ago. But until now, the time of the Great Dying 250 million years ago, when 90 percent of marine and 80 percent of land life perished, lacked evidence and a location for a similar impact event. Becker and her team found extensive evidence of a 125-mile-wide crater, called Bedout, off the northwestern coast of Australia... During recent research in Antarctica, Becker and her team found meteoric fragments in a thin claystone "breccia" layer, pointing to an end-Permian event. The breccia contains the impact debris that resettled in a layer of sediment at end-Permian time. They also found "shocked quartz" in this area and in Australia... Quartz can be fractured by extreme volcanic activity, but only in one direction. Shocked quartz is fractured in several directions and is therefore believed to be a good tracer for the impact of a meteor... The Bedout impact crater is also associated in time with extreme volcanism and the break-up of Pangea. "We think that mass extinctions may be defined by catastrophes like impact and volcanism occurring synchronously in time," Becker said. "This is what happened 65 million years ago at Chicxulub but was largely dismissed by scientists as merely a coincidence. With the discovery of Bedout, I don't think we can call such catastrophes occurring together a coincidence anymore," she added.

Popular Science for March 2004 (p 56) had a Dawn Stover piece on the Permian-Triassic extinction. There's a table showing four possibilities and a summary of points for each, and also writes that "it's possible that more than theory is correct." A huge impact on water would send a shockwave throughout the oceans and seas, with the potential of releasing the methane in gas hydrates and the poisonous hydrogen sulfide gas that displaces oxygen in the depths. She ignores that likelier possibility and writes instead that an impact could trigger volcanic eruptions, "which in turn could have kicked off deadly acid rain showers." My guess is, Dawn Stover went to Penn State and studied volcanology for a while. ;')

The Suspect The Theory The Evidence The Proponents The Holes

Asteroid impact A space rock strikes in the tropics, spews debris into the air and triggers lethal climate change Scientists found 250 million year old rocks from Antarctica and China said to contain meteorite fragments Researchers at the University of Rochester, Harvard, and UC Santa Barbara Scientists have yet to find the ultimate smoking gun, a crater

Sudden methane explosion A massive cloud of methane gas abruptly bursts from the ocean, cataclysmic flooding and fires ensue Great Dying fossils show a sudden sharp rise in carbon-12 isotopes, best explained by a methane belch Chemical engineer Gregory Ryskin at Northwestern University The explosion requires an improbable 10,000 gigatons of methane

Slow methane leak Volcanoes of frozen deposits leak methane over thousands of years, depleting oxygen The burrowing reptile Lystrosaurus, adapted for low-oxygen conditions, thrived during this period Researchers at the University of Oregon, the South African Museum, and the University of Washington The leak could not deplete enought oxygen to cause global death, critics say

Hydrogen sulfide stink bomb Lethal levels of hydrogen sulfide, emitted by anaerobic bacteria, are expelled from the ocean into the air Proponents are searching for signs of sulfur bacteria in Japanese sediments dated to the extinction Scientists at Penn State, the University of Colorado, and the University of Tokyo There's no proof that the upper layers of ancient oceans were devoid of oxygen

Newest to oldest, as if in strata, in order to observe the evolution. ;')

Meteor May Have Started Dinosaur Era
by Kenneth Chang
May 17, 2002
In the layer of rock corresponding to the extinction, the scientists found elevated amounts of the rare element iridium. A precious metal belonging to the platinum group of elements, iridium is more abundant in meteorites than in rocks on Earth. A similar spike of iridium in 65 million-year-old rocks gave rise in the 1970's to the theory that a meteor caused the demise of the dinosaurs... The levels are only about one-tenth as high as those found at the later extinction. That could mean that the meteor was smaller or contained less iridium... In the same rock layer, Dr. Olsen and his colleagues found a high concentration of fern spores -- considered an indicator of a major disruption in the environment. Because spores carried by the wind can travel long distances, ferns are often the first plants to return to a devastated landscape. The scientists found more evidence of rapid extinction in a database of 10,000 muddy footprints turned to rock in former lake basins from Virginia to Nova Scotia... Because the sediment piles up quickly in lake basins, the researchers were able to assign a date to each footprint, based on the layer of rock where it was found. They determined that the mix of animals walking across what is now the East Coast of North America changed suddenly about 200 million years ago. The tracks of several major reptile groups continue almost up to the layer of rock marking the end of the Triassic geologic period 202 million years ago, then vanish in younger layers from the Jurassic period... Last year, researchers led by Dr. Ward reported that the types of carbon in rock changed abruptly at this time, indicating a sudden dying off of plants over less than 50,000 years. The footprint research reinforces the hypothesis that the extinction was sudden.
Asteroid 'destroyed life 250m years ago'
by Dr David Whitehouse
BBC News Online
Friday, 23 February, 2001, 10:56 GMT
Earth's biggest mass extinction 251 million years ago was triggered by a collision with a comet or asteroid, US scientists say. They have reached this conclusion by looking at atoms from a star trapped inside molecular cages of carbon. The impact occurred when all the Earth's land was joined together into a supercontinent called Pangea... Researchers have no idea where on the planet's surface the space object came down, but they have identified traces of it. In rock layers laid down at the time, there is a much higher concentration of complex carbon molecules called fullerenes that have different types, or isotopes, of helium and argon trapped inside them... The researchers believe these particular fullerenes are extraterrestrial because the gases trapped inside have an unusual ratio of isotopes that indicate they were made in the atmosphere of a star that exploded before our Sun was born... The telltale fullerenes were extracted from sites in Japan, China and Hungary, where the sedimentary layer at the boundary between the Permian and Triassic periods had been exposed... The research was made difficult because there are few 251-million-year-old rocks left on Earth. Most rocks of that age have been recycled through the planet's tectonic processes.
Physics News Update
by Phillip F. Schewe and Ben Stein
December 14, 1992
An asteroid impact may have caused the mass extinction that occurred at the boundary between the Permian and Triassic periods 250 million years ago, said Michael Rampino (212-998-8995) of NYU at the AGU meeting. He asserted that he has found evidence---in the form of gravity anomalies and certain rock deposits---for such an impact in the South Atlantic, in an area where, many scientists believe, South America, Africa, and other land masses fit together in the primordial supercontinent called Gondwanaland. Rampino claims that the gradual breakup of Gondwanaland into present-day continents may have been initiated by the catastrophic impact. Another scientist at the meeting, Verne Oberbeck of NASA/Ames (415-604-5496) also believes an impact may have sundered Gondwanaland and that, in general, impacts should be given more credit for shaping earlier Earth geology. In particular, he believes that the small rock sediments called tillites, usually thought to result from the grinding and plowing action of glaciers, may in part be debris from impacts. Consequently, Oberbeck suggested, there might have been fewer glacial periods than is usually believed. Rampino went so far as to say that all tillites are of impact origin. Unlike the theory that describes the KT (Cretaceous-Tertiary) catastrophe 65 million years ago (when the dinosaurs became extinct) in terms of an asteroid impact, the notion that the PT catastrophe was caused by an impact or that tillites result from impacts is anything but a majority opinion; indeed, many scientists at the meeting were skeptical about Rampino's and Oberbeck's ideas. Thomas Crowley of the Applied Research Corp. (409-846-1403), a paleo-climatologist, said that his reaction to the proposed impact origin of tillites was one of "considerable disbelief, bordering on incredulity." For one thing, he said, tillite deposits are too extensive over time and physical extent to have been caused by an impact.

New Extinction Clues Point to Deep Impact
by Paul Recer
May 10, 2001
New evidence shows that an extinction event in which more than half of all Earth species died 200 million years ago happened quickly, possibly as a result of an impact from outer space. The extinction, at the boundary of the Triassic and Jurassic periods of geologic history, is similar in its suddenness to two extinction events that have been linked to space rocks' impacts on the Earth. Researchers analyzing deposits from a rock formation on a remote beach front in Canada found evidence of a sharp shift in organic carbon levels at precisely the point in time that the Triassic-Jurassic extinction occurred. This is the first time scientists have found a clear carbon signature for what is called the TJ event, said Peter D. Ward, a researcher at the University of Washington... Similar evidence has been found for the Cretaceous-Tertiary extinction event 65 million years ago that killed off the dinosaurs, and for the much earlier Permian extinction 250 million years ago that killed 90 percent of all species... If the researchers find evidence that a space rock impact caused the TJ extinction, it will mean that three of the five major extinctions in the 4.5-billion-year history of the Earth are linked to the impact of asteroids or comets... Ward said that no impact crater on Earth has been shown to have a proven link to the TJ extinction event, although the Manicougan Crater in Quebec is considered a candidate. That crater was caused by a space impact, but it has been dated at 214 million years, well before the TJ event.

" Young Earth Theory "does not compute" -- not even for creationists (those who understand science, that is...)"

How do you deal with the fact that science is founded on induction and the fallacy of asserting the consequent? How do you deal with the weaknesses of empiricism? How do you deal with the fact that universal laws can never be justified by the appeal to particulars?

Science is worshipped today as THE oracle of truth and knowledge, but that's only because people are poorly taught in the philosophy of science and are therefore ignorant of the limits of science. Real scientists, knowing their limits, are humble. Science is fine for showing us how to manipulate the physical world and how to behave in the lab. But outside of that it can't give us truth. By its very nature it can't give us truth. It can only give us inductive conclusions which can never be called truth or knowledge and must forever remain theory, here today and replaced tomorrow.

Scientists who understand the game will never talk about truth and knowledge, they will only talk about theory and hypothesis.

I know what your reply will be. You will want to list out all the successes of science because you believe that pragmatism defines truth. However, pragmatism will not solve the fundamental limts of science.

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The Suspect	The Theory	The Evidence	The Proponents	The Holes
Asteroid impact	A space rock strikes in the tropics, spews debris into the air and triggers lethal climate change	Scientists found 250 million year old rocks from Antarctica and China said to contain meteorite fragments	Researchers at the University of Rochester, Harvard, and UC Santa Barbara	Scientists have yet to find the ultimate smoking gun, a crater
Sudden methane explosion	A massive cloud of methane gas abruptly bursts from the ocean, cataclysmic flooding and fires ensue	Great Dying fossils show a sudden sharp rise in carbon-12 isotopes, best explained by a methane belch	Chemical engineer Gregory Ryskin at Northwestern University	The explosion requires an improbable 10,000 gigatons of methane
Slow methane leak	Volcanoes of frozen deposits leak methane over thousands of years, depleting oxygen	The burrowing reptile Lystrosaurus, adapted for low-oxygen conditions, thrived during this period	Researchers at the University of Oregon, the South African Museum, and the University of Washington	The leak could not deplete enought oxygen to cause global death, critics say
Hydrogen sulfide stink bomb	Lethal levels of hydrogen sulfide, emitted by anaerobic bacteria, are expelled from the ocean into the air	Proponents are searching for signs of sulfur bacteria in Japanese sediments dated to the extinction	Scientists at Penn State, the University of Colorado, and the University of Tokyo	There's no proof that the upper layers of ancient oceans were devoid of oxygen