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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."
Xu and Yang, 1993 and Yang et al. 1995 have reported Iridium spikes and Stishovite microspherules in non-marine P/T sediments in Australia and Antarctica. There's no Permian oceanic crust left since all of it has been subducted, and the Iridium and Stishovite levels are an order of magnitude smaller than C/T sediments, but it is still evidence of some type of major impact.
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This article from the BBC was a little more in-depth.
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6 miles = 9.66 kilometers
http://en.wikipedia.org/wiki/Chicxulub_Crater
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The fact that these disasters don't "kill the earth" is widely understood. Bacteria for instance can endure almost anything, and for the earth to be fysically destroyed, you would need a *very* big boulder. The problem is that more complex life does not take nearly as much abuse. So as long as you don't care about billions of people dying, if not extinction of the human race, then you can keep sleeping in total comfort. But for me that complex, self-aware life would have to start again would not be a comforting thought. This *did* bring a very complex eco-system to a grinding halt, and I don't think the human race would be able to survive such a disaster.
"...for the earth to be fysically destroyed, you would need a *very* big boulder."
Even bigger than you think. Current theory (speculation/whatever) says that the Earth-Moon system was created a few billion years ago when something the size of Mars smacked into the (pre) Earth. And it still wasn't destroyed - just changed a bit.
Of course, if that happened now even the bacteria would be *severely* upset about it.
Spelling Nazi alert: You mean "physically".
The actual interesting part would be that if the composition were the same, a spherical object six times as wide would have 216 times as much mass.
In other words, if it hit at anywhere close to the same speed, this one was A LOT more destructive.
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.
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.
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If we're going to be pedantic, something is a meteorite only if it strikes the earth. A meteor is merely an object from space (man-made satellites usually excluded) that enters the Earth's atmosphere, and may or may not become a meteorite--most meteors are too small and completely burn up/disintegrate before hitting land.
I'm sorry, I can't find "non-sequiter" in my dictionary. Perhaps you meant "non sequitur"?
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.