How Gondwanaland got Australia to move out of the neighbourhood without being obvious

[sff_corgi_lj]

Gacked from electroweak, co-creator of A Miracle of Science:

From Space.com, BBC Science/Nature News, the Sydney Morning Herald and The Age

Big news from the American Geophysical Union Joint Assembly held in Baltimore this past May 23-26: A team of Ohio University, NASA, Russian and Korean scientists led by Prof. Ralph von Frese from OSU, who had been looking at differences in density that show up in gravity measurements taken with NASA's GRACE satellites noticed, beneath Antarctica's icy surface, a 321-kilometre-wide plug of mantle material — a mass concentration, or "mascon" in geological parlance — that had risen up into the Earth's crust. Cross-referencing against radar imagery, the team found a corresponding 500-kilometre-diameter circular ridge, also still buried beneath 1.6km of ice, which seemed to confirm their suspicions.

The mascon is located in Wilkes Land, East Antarctica; its coast faces Australia, which claims the area as far as the Antarctic Treaty allows such claims.

'...[the impact] could have begun the break-up of Gondwana supercontinent by creating the tectonic rift that pushed Australia northward," the team's leader Ralph von Frese said in a statement. "The rift cuts directly through the crater, so the impact may have helped the rift to form."

The size of the meteor itself has been compared to the city of Sydney; the resulting impact ridge to the size of Tasmania.

The impact is now thought to have started the Permian-Triassic extinction, which wiped out most life on land and in the oceans. Immediate effects would have included shock waves, firestorms, earthquakes, tsunami and vapourised materials contaminating the atmosphere. Secondary side effects from the damage, which punched completely through the earth's crust, would have been supervolcanism perpetuating the environmental changes for centuries.

False-colour radar image of the mascon, ridge and comparison to the Chicxulub crater of Yucatan
Interactive Flash animation of the breakup of Pangaea/Gondwanaland
GIF animation of breakup of Pangaea/Gondwanaland (wow, lookit India fly!)

Any errors in summation are mine, due to the fact that I'm still getting dressed, ack!

Comments

[barsukthom.livejournal.com]

Well, gosh!
The Lovecraftian implications are staggering!

[sff-corgi.livejournal.com]

I have enough nightmares, thanks. ;)

[crwilley.livejournal.com]

I could get lost surfing that site...but wow, how cool.

[sff-corgi.livejournal.com]

Hee, which site? There's something like a dozen links up there!

[crwilley.livejournal.com]

Space.com.

[sff-corgi.livejournal.com]

Oh, yeah; I was flirting with being FarTooLate by playing 'follow the links'. ^_^

[wombat1138.livejournal.com]

Whooooaaa. Dude.

Holy Second Impact, Batman!

[sff-corgi.livejournal.com]

[reads page] Eeeenteresting. One of these days I'll have to watch that series.

Got a good link for explaining the 'angel' references?

[wombat1138.livejournal.com]

Spoilers ahoy!

Mind you, some aspects of Eva are just deeply inexplicable. Perhaps not quite as much as the Utena movie, but Eva's last few episodes and movies inhabit the same sort of Utenesque territory where the only relevance of the literal level is to convey the underlying metaphor. Or at least I think that's how it worked; it's been a while since I've watched anything from either series.

(Utena's director also did a lot of work on Sailor Moon iirc, the invocation whereof has just put me in the mood for another viewing of the Utena AMV set to Dweezil Zappa's cover of Britney Spears' "Hit Me Baby".)

Yay! A post about Australia!

[ashavah]

Ooooh, thank you. Very interesting.

*waves yay Australia flag*

Also: you've heard of the Sydney Morning Herald. I think I love you. (The SMH is my favourite newspaper.)

Yours,

JK

Re: Yay! A post about Australia!

[sff-corgi.livejournal.com]

I didn't hear of it, necessarily - electroweak scared it up. :) But you've never heard me rant about Luna Park, I guess.

(What, you haven't noticed my new nightowl icon?)

Re: Yay! A post about Australia!

[ashavah]

Hee. No, I haven't heard you rant. But I have noticed the icon.

And I don't care if you hadn't heard of the SMH before, you've heard of it now. So it counts. ;-P (No, I'm not stubborn at all.)

Re: Yay! A post about Australia!

[cerrberus.livejournal.com]

The Big Smoke's got one of the most beautiful urban settings in the world.
But...I rather preferred Adelaide.
Hooroo.

[panamdea.livejournal.com]

Huh. I wish I could find an actual paper about this rather than summaries and the abstract. I can't tell from what they're suggesting it started the P-T event or just contributed to it. The extinction started sometime before the actual boundary and the break up really happened after, so I'd love to know how accurate the dates on this crater are. Regardless, I find myself reluctant to trust these things until I've at least seen the paper. Funny that Science and Nature didn't seem to mention it in their news sections in the last couple of months - they normally mention stuff that's big in the editorial news pick bits.

The big thing with the P-T is that none of the explanations thus far explain all of the trends we see in the rock record. Most of them are covered by a combination of potential triggers (climate change due to supercontinent formation and the impact that had on ocean circulation patterns, also possible alteration in mass balances due to change in drift dynamics, likely massive volcanism also linking to climate change etc). So if this is what actually triggered those triggers, it's a pretty cool finding. It's still a pretty cool finding, but less big if it's just a contributing factor etc. I can't remember if anybody's suggested anything like the iridium anomaly at the K-T around the P-T before, though I think with the other crater there were some argon isotopes or something as well as impact breccia, but I seem to remember it was fairly local.

On an ironic note, a guy who was really condescending at me at a conference a couple of years ago has just had a book published about the P-T extinction and the debate over it, so I imagine he's not best amused by the timing! It's apparently a good book, I was planning to get hold of a copy at some point as it's a really interesting area.

Thanks for posting this! I've not read the BBC news science section for a while, which is quite unusual for me actually. That and the tennis page are the only bits I read on a regular basis!

Sorry, I have to have a geology 101 TA moment here.... I'm sorry! 200Mya when Pangea started to break up was the end of the Triassic, not the P-T. Pangea had just formed at the P-T. Also, Pangea was the supercontinent that broke up - Gondwanaland was just a piece that broke off, the rest was Laurasia. So technically it's the break up of Pangea or the separation of Gondwanaland and Laurasia.

[sff-corgi.livejournal.com]

I have to have a geology 101 TA moment...

Just one?!? ;)

Problem w/ this crater appears to be the 1.6Km of hard ice. Now, if Bush keeps going the way he's going, all they'll have to do realsoonnow is just sweep some slush off.... [/rimshot]

Pangea was the supercontinent that broke up - Gondwanaland was just a piece that broke off...

:nodnod: But it was the Gondwanaland part of Pangea. Hey, what caused India to go scooting around that fast? Or is it just because it's relatively smaller than the other bits and got to be all by itself in the middle of nowhere for so long?

[panamdea.livejournal.com]

Just noticed I'd not replied to this....

It's a good question, and honestly (and possibly embarassingly), I actually don't know. I've had a look at my notes and things and I don't think it's something I've ever covered. It's one of those really obvious questions I've never thought to ask.

I would hazard a guess that there's something about the geometry of the plate boundaries around it which has caused the plate movement to be so rapid. However, what that is, I don't know, as if you look at a map of plate boundaries there's nothing obviously special about the Australian-Indian plate in that respect.

This is going to annoy me for a while and I'm going to have to go and find out....!

I actually heard the guy who presented the data talking about this on science Friday the other week and I wasn't really satisfied by what he had to say either. Though he did say they had planst to do a low level fly over to do more accurate gravity anomaly readings and might look at the "rubble" that glaciers from the area drop to see if it contains any non-terrestrial material. Other than that I've not been able to find much info. My adviser says I can borrow is copy of the PT book that's been recently published, but of course, it doesn't cover this.

[sff-corgi.livejournal.com]

Now, there's always the possibility it's just a PoV thing - it looks, in the animation, relatively fast because of the space around it and the other plates moving away from it simultaneously. They deal with this in deep space astronomy all the time, eh.

But I'd love to know what you find out. I started digging plate tectonics not long after my dinosaur phase, but I think it might be as much for the same reason that I pour over Professor Tolkein's maps, matching up features, as any left-brain reason. ^_^

[panamdea.livejournal.com]

No, it really did move that fast - it's insanley rapid actually. Since the collision with Asia (~50Mya in the Eocene, I believe), India is moving north about 5cm/yr, but before the collision, it was moving about 15cm/yr. That's way faster than any other tectonic plate has ever moved.

I love maps so very much. There's something totally cool about seeing the world spread out in front of you! Palaeomaps are even more fun. There's something fabulous about watching the world change. The father of one of the professor's in my department was a mover and a shaker in the plate tectonics revolution - it's weird to think that such a huge shift in our world view is so recent, relatively speaking.

Every kid goes through a dinosaur phase and a playing in the dirt phase. Some of us just don't grow out of those phases. They call us palaeontologists... ;)