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Antarctic Blast Made Australia, Room For Dinosaurs
Agent Provocateur writes "Posted on the Science Daily site is a story from Ohio State University about a massive Antarctic blast that may have contributed to the Permian-Triassic extinction." From the article: "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 is what always gets me about those Hollywood disaster movies. The BBC calls this The Day the Earth Nearly Died. And yet, as we can see, it didn't. Somehow, The Day After Tomorrow seems kind of pathetic in comparison.
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"...the Wilkes Land meteor could have been up to 30 miles wide..."
Wow, I knew some dinosaurs were big, but I didn't realize they were that big!
They are guessing that it was in the last 250 million years because they can still detect a mass concentration. I wonder if it is possible to drill to the bottom of an ice cap and then drill into the underlying crust. Doing that may make it possible to accurately date the impact.
Ice drills in my experience melt a hollow cylinder of ice and then extract the core. Presumably they would have to do this down to the surface and send a traditional drill down.
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That's just what God wants you to think.
How did the dinosaurs get here? It is my theory that they rode in on that meteor, bringing with them the advanced technologies that our government is still unearthing today (Al Gore "invented" the internet by digging it up from an ancient dinosaurian city). Also, "rawr" I'm a dinosaur.
Mr. President, shouldn't you be working on a plan to get us out of Iraq, rather than posting on slashdot?
Opinions on the Twiddler2 hand-held keyboard?
I'd tend to assume that any impact that size would be extremely unlikely to genreate the right conditions for the formation of life. We're talking about the kind of kinetic energy here that can boil oceans on impact, which would tend to foul up any chances of life emerging.
The conditions we currently think led to abiogenesis (the pre-evolutionary formation of life) weren't cataclysmic, they were merely improbably chemical reactions that might have arisen on the primordial earth - just a matter of something with a low probability having a few hundred million years to occur by chance in, in an environment with no pre-existing competeing lifeforms and plenty of potential habitat.
Now mind you, any major change in the ecology will open up new niches for creatures to evolve into, so in that sense an impact "creates new life", but that is exactly what the article is talking about. The mass die off precipitated by such an impact let the dinosaurs get started. The cretaceous die off got rid of the dinosaurs in turn, and let mammals take the top spot.
Erotic is when you use a feather. Exotic is when you use the whole chicken.
But the situation is much murkier with the Permian extinctions. Last I'd heard, we have yet to find clear evidence of an impact in the form of iridium, a dust layer or shocked quartz. So that sheds some doubt on the idea of an impact. Even if this is an impact crater, we don't know for certain that it dates to the time of the end-Permian mass extinctions: obviously, if it didn't occur at the same time as those extinctions, it couldn't have caused them. Given that the researchers are using radar and gravitometry, how do they know how old it is? You need to either do radiometric dating or look at the fossils to tell how old the underlying and overlying rocks are.
There is also some evidence that the Permian extinctions may have been drawn out, with several bouts of extinction occurring over the course of a million years or so, again that doesn't fit with an meteorite/comet impact. Anyhow, it might have been an impact, and it might not have been. It's still a mystery and probably will be for quite a while.
You know Clippy, that sort of non-sequiter was why we kicked you out of the Office help system. Don't make us do it again...
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Well, I see that we've found Adam. Crap, now the world's going to end in the dumbest imaginable way and we're all going to melt.
So the answer is "lots of existing species of animals", many of which would have been amphibians, reptiles, crossopterygians. Dinosaurs have more sophisticated circulatory systems than ordinary reptiles, so if the atmospheric oxygen percentage went down (for instance) as a result of vegetation changes, they might be at a selective advantage.
Pining for the fjords
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.
Thank you for for adding that! Saved us all the trouble of pulling out slide rules to work out that ugly divison problem ourselves!
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The cretaceous die off got rid of the dinosaurs in turn, and let mammals take the top spot.
It wasn't quite like that. The die-off simply got rid of most large animals (probably the ones that couldn't burrow or hide in some way to avoid several hours of intense heat after the impact). Some small dinosaurs carried on fine - today we call them birds! Also, for some periods in wasn't mammals that took the top spot - large birds have often been the major predators. Things are far, far more interesting that suggested by this statement.
6 miles = 9.66 kilometers
http://en.wikipedia.org/wiki/Chicxulub_Crater
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I am jut a bit lost here, how do they use gravimetric data to say with the certainty the article seems to suggest that this is an impact crater?
As far as I know from my the few classes I have had on gravimetric data without the help of other data you are usually pretty lost. It would be very difficult to say how deep, what size and what weight anamoly the gravimetric anomily has and even more make out it's shape.
Furthermore with these gravimetric data taken from a satelite and not from the surface you get even more "meaned data" (less precise) being further away from the anamoly I can figure, of course they probably have a huge data set and also extremely precise instrumentation at the satelite in space, maybe that makes up for the distance in some ways, but for now I remain very sceptical.
Another thing that makes me wonder is why they don't talk about doing seismic or seismologic checks to confirm their theory. I actually thought that there was a few seismic stations places in this region, if this anamoly is as huge as the article suggests then I would think it should be pretty clearly visible in the seismic data.
Anyhow gravimetrics is certainly not my area of expertise. I would if someone out there is able to show me where I go wrong if that is the case, then I'd be grateful.
Drilling through ice is a difficult process with lot's of problems.
One of the problems is that the ice is not lying still during the time that you are drilling, the ice creeps. That is once of the reasons why all the major drillings through ice are done on the top of the ice sheets where the movements are the least there.
The problem with Ice creep is pretty big, it is for example not possible for scientist to come back to the hole's they drilled before, like you do with holes in the earth, the holes shut pretty fast, depending on the speed of the ice crawl.
So I geuss it would be possible to drill the hole, but you would have to be pretty fast to get down there after you drilled the hole and get up some material of the underlying rock.
You would get very little material up and I think that present some problems also, how would you know if the rock sample you get up is alien to the enviroment from where it came when you don't have the rock in the vicinity of the sample to compare with and look for patterns etc. on.
What about for small values of 30 or for large values of 6?
Impersonating Tycho from Penny Arcade since before there was a PA.
Slashdoters are technical sorts so I don't think it's too pendantic to note that a meteor is a flash of light caused by a meteorite.
Comparing the widths of the meteorites is a lot less interesting than realizing that the mass ratio is about 125:1. Actually I suspect that the mass was estimated first from the size of the crater and then the diameter calculated, converted from metric to American, and the word "diameter" changed to the more easily understood "width".
Nate
The article posted above seems to be based on this from Ohio State University, which is better illustrated, etc.
If you want to "experiment" with results of various impacts, Arizona State has an online calculator.
If you want your life to be different, live it differently.
A couple of years ago an entirely different impact crater was discovered in Australia, with preliminary dating indicating that it happened at about the same time as this one. It, too, is huge -- not as monstrous as this here Antarctica sockdollager, but apparently about as apocalyptic as the one that reputedly KO'd the dinosaurs. Considering the history of our Solar System, I don't think that a multiple-impact armaggedon is at all out of the question. Hell, maybe we'll find even more impact craters, and have to come to the conclusion that it was some kind of supersized rain of fire that reset the planetary ecology switch.
And then, of course, we shouldn't forget about the largest volcanic eruption in the history of the planet that sparked up at just about the same time, too. An area roughly the size of Scandinavia simply melted into a mass of sulfurous, poisonous, volcanic goo for a couple of million years before settling down. I'm not terribly firm on my Permian Era geography, but I'd be willing to bet that the Siberian Traps event was pretty close to the opposite side of the planet at the time of the impacts.
My theory is trilobites grew large brains and built Hummers, which caused greenhouse gasses that killed a bunch of stuff, including themselves.
Table-ized A.I.
The Mariner 10 mission to Mercury revealed a key data item that Earthly geophysicists need to pay more attention to.
This is the Caloris Basin and, on the opposite side of Mercury, some very strange topography that is usually called "weird terrain".
The explanation is the the shock waves from the impact that created Caloris converged on the opposite side of Mercury and tore the landscape to pieces.
Well, Mercury is small and internally much cooler than Earth, so Mercury has a thick crust while the Earth's crust floats on magma.
A giant meteor impact like the one in what is now Antarctica should have the same sort of effect on Earth that happened on Mercury -- except when the Earth's crust gets shattered by converging shock waves, the magma can pour out. Thus the "Siberian Traps", which formed at about the same time as the Permian Extinction. All we need to solidify that speculation is to study the positions of the continents at that time (not where they have drifted to, today).
More evidence for this sort of Double Disaster comes from the Chixulub impact, which, when it happened, it is known that India was on the opposite side of the world, and the "Deccan Traps" were formed at the same time as the K-T boundary.
For one more example that I'm aware of, but which happened much longer ago than even the Permian extinction, is the Vredefort (sp?) Ring in South Africa, among the biggest known impact craters on Earth, and the Columbia Plateau magma outpourings of Oregon/Idaho/Washington, also among the biggest on Earth, and, I think, about the same age.... Life on Earth was only bacterial then, and it is difficult to know how little of it suvived that Double-Edged Disaster.