The Permian mass extinction

[Brady Yoon]

Do astronomers have any leads to what caused the Permian-Triassic mass extinction?

[Essan]

There's always new theories coming up, but the main one involves a combination of the Siberian Traps basalt eruption, coupled with a later release of methane hydrate.

http://www.bbc.co.uk/science/horizon...arthdied.shtml

Just to confuse matters, there may have been a large meteorite impact around the same time:

http://www.cnn.com/2003/TECH/science...ica.meteor.ap/

Interestingly, if there was a meteorite impact in the S Hemisphere, it may have been roughly opposite to the Siberian Traps, just as the Chicxulub impact was on the opposite side of the world to the Deccan Traps - suggesting that impacts and basalt eruptions may be linked.

There's still a lot of dispute on the exact timing of these events.

[milli360]

There's always new theories coming up, but the main one involves a combination of the Siberian Traps basalt eruption, coupled with a later release of methane hydrate.

http://www.bbc.co.uk/science/horizon...arthdied.shtml

Cool stuff, Essan. I see you are an administrator over at the UK Weather World board. Looks like an interesting place.

That article at that link misspells one of the names, it's Vincent Courtillot, not Courtillon. Courtillot is a leading proponent of the volcanic aspect of the cause of extinctions--in the early nineties, Scientific American ran a point-counterpoint of impacts vs volcanoes, with Walter Alvarez writing the impact article, and Courtillot writing the volcano article. At the time, I think Courtillot was French Minister of Education, Research and Technology.

Just to confuse matters, there may have been a large meteorite impact around the same time:

http://www.cnn.com/2003/TECH/science...ica.meteor.ap/

Interestingly, if there was a meteorite impact in the S Hemisphere, it may have been roughly opposite to the Siberian Traps, just as the Chicxulub impact was on the opposite side of the world to the Deccan Traps - suggesting that impacts and basalt eruptions may be linked.

There's still a lot of dispute on the exact timing of these events.

I had an opportunity to talk to Dr. Courtillot at an AGU meeting once, and I pointed out the poster presentation next to mine--by Michael Rampino, one of the originators of the antipodal impact theory. Courtillot was surprised that Rampino's papers had gotten published, he thought they'd been completely debunked.

[Tom Mazanec]

Don't huge impact craters often have "chaotic terrain" antipodally located?
Hmmmm...

[milli360]

Don't huge impact craters often have "chaotic terrain" antipodally located?
Hmmmm...

I think there's one prominent example, Caloris on Mercury. It's appeared in a geology textbooks over the past twenty or thirty years--probably what inspired some of the ideas. I remember when it first occurred to me, my geophysics professor snapped his fingers and opened up Tarbuck and Lutgens, I think, and showed me that picture of Mercury.

[Essan]

Essan[/b]. I see you are an administrator over at the UK Weather World board. Looks like an interesting place.

Thanks


Problem with the antipodal impact theory is that where we have clear evidence of an impact: Chicxulub, and a basalt eruption: Deccan Traps, the latter appear to have started 10s of thousands of years before the impact....

However the fact that impacts, basalt eruptions and mass extinctions seem to go hand in hand suggests there may be some link. And, of course, we can't be 100% certain our dating processes are correct.

[dgruss23]

essan: Problem with the antipodal impact theory is that where we have clear evidence of an impact: Chicxulub, and a basalt eruption: Deccan Traps, the latter appear to have started 10s of thousands of years before the impact....

But isn't the uncertainty in the age estimates quite a bit larger than a few 10's of thosands of years?

[milli360]

dgruss23:

essan: Problem with the antipodal impact theory is that where we have clear evidence of an impact: Chicxulub, and a basalt eruption: Deccan Traps, the latter appear to have started 10s of thousands of years before the impact....

But isn't the uncertainty in the age estimates quite a bit larger than a few 10's of thosands of years?

Like your quote scheme. Can you search on that then?

Some dates are established relatively, rather than absolutely. For instance, the iridium layer or shocked quartz layer is usually assumed to have been laid down immediately after the impact. If it's on top of the volcanics, what else can you conclude?

PS: Ah, that works perfectly. It's easy to do, too.