Talk:Permian-Triassic extinction event

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An assessment of this article took place along with other articles about Natural disasters during the week starting 20 February 2006.

Contents 1 Question! 2 Miscellaneous 3 See Also 4 Supernova evidence 5 Ocean overturn 6 The Bedout crater 7 New Crater in Antarctica 8 Causes 9 I don't get it 10 P-T vs P-Tr

[edit] Question!

Just a question from a physicist: suppose there was an impact event at this time. Now, given the incompressibility of fluids, how likely would an impact event be to directly trigger massive volcanism? In this case, it seems very plausible to me that the Siberian Traps eruption was directly triggered by a massive impact event somewhere else on earth. Any takers?

I had the same thought. I would expect the Siberian Traps to be exactly opposite from Wilkes Land crater at the time of the impact or geologically shortly thereafter. Is this indeed the case? It's hard to tell from plate tectonic animations. Paradaxiom 05:19, 3 June 2006 (UTC)

As a side note, the time range of creation for the Deccan Traps lie between 60 and 68 Ma, which neatly brackets the Cretaceous-Paleogene extinction (and Chicxulub, as well). I'm certain work has been done looking into this; i'll look into specifics later. SReynhout 12:00, 10 July 2006 (UTC)

There has been some serious thought put to this question, but the consensus seems to be that it is more likely that large impact which punchers the lithosphere and causing volcanism but rapid decompression of the mantle. Of cause the later volcanics have a habit of destroying the original crater. There is a very good article about this at Impact-induced decompression melting--Cludum mann 11:07, 15 August 2006 (UTC)

I'd like to add a comment on the so-called Wilkes Land crater. The discoverers—lunar geologists—claim that the area hides a circular mascon (mass concentration) and therefore it is a crater. On Moon, they are often associated with ancient impact craters. However, on Earth, impact craters have negative gravity anomalies. The claimed mascon happens to be the only proof they have. Ouch. No geologist take the suggested crater seriously. That should be mentioned in the article.--JyriL ^talk 19:28, 15 August 2006 (UTC)

[edit] Miscellaneous

I've just been watching a fascinating documentary about the permian extinction on TV, according to this fossil evidence recently (1999) discovered in Greenland shows that the extinction took place over some 100,000 years, and happened in 3 distinct phases- the Siberian traps caused global warming of some 5 degrees which accounted for much extinction on land- this also caused the seas to warm, in turn killing much marine life, and at the same time releasing vast quantities of methane from the seabed (and presumably from the huge amounts of rotting matter from all the dead sea life), which in turn warmed the global temp. by another 5 degrees, causing a second mass land extinction. This theory was put together by a guy from Leeds university in England, and apparently has the most credibility at the present time (tho i'm only a lay pwerson and am just basing this on the program I've just seen) quercus robur

Well, go ahead and clean up the above and insert it into the article! :) --Dante Alighieri 23:31 Dec 5, 2002 (UTC)

urg- bit tired at the moment- one for the 'to do' list- as you say, needs quite a bit of cleaning up to look presentable... I'm better at punk rock and one hit wonders minutiea when in this sort of frame of mind ;-), quercus robur

The show you watched seems to be on target (be careful about using the tele as source material in general though - programs often give the impression that crakpot ideas are well-accepted theories). --mav

This was BBC 2's 'Horizon' program (in the UK), which is a fairly respectable source, been going donkeys years, puts much current scientific thinking into laymans terms a dork like me can understand... This particular program was very well presented and gave attention to several other theories, plus reasons why they were less likely than this new theory... Cheers quercus robur

Great article! Just one quibble: the article states that "85% of all marine species and 70% of all terrestrial species went extinct." I don't see how this adds up to the claim, in Extinction event, that 95% of all species died during the Permian event. Could someone explain?

The 85% and 70% figures come from "U/Pb Zircon Geochronology and Tempo of the End-Permian Mass Extinction" by Bowring et. al. in Science (v. 280, pp. 1039-1045), published in 1998. This seems more credible than the 95% figure. --tad

Oh, and one more thing: the article states that "release of debris and carbon dioxide into the atmosphere reduces the productivity of life and causes both global warming and ozone depletion." If I'm not mistaken, release of ash/debris (similarly with volcanic eruptions) actually leads to global cooling. -- CYD

The bebris cause short to medium term cooling but the CO2 causes warming in the longer term. --mav

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I went to the BBC2 Horizons archive and tried to distill what I understood about methand hydrate gasification, and entered it. Sharpen it up! but add more references and external links to what you find, please! Wetman 06:04, 25 Nov 2003 (UTC)

[edit] See Also

A well-intentioned editor has crosslinked, via "See Also" sections, 3 articles among the 6 event-articles that extinction event links. Most of these are redundant to identical links within the running text (the preferred location for links; see Wikipedia:Manual of Style#See also and Related topics within). The remaining two either are redundant to the extinction event links elsewhere in the respective articles these (redunadant) links appear in, or deserve an explanation (within the running text) of their connection. --Jerzy(t) 17:20, 2004 May 7 (UTC)

[edit] Supernova evidence

While some sedimentary rock samples contain what may be records of short-term ozone destruction (large amounts of NOx gases and C14), this theory has little other evidence either for or against it.

How can those rocks contain C-14? It must have decayed a long time ago. Is there some method to determine how much C-14 was in the rock - maybe N-14 atoms if they stay where they were produced? 193.171.121.30 04:57, 21 Feb 2005 (UTC)

Yeah that is strange. All the carbon would be gone and you wouldn't imagine you could really test for nitrogen isotopes cause the atmosphere is swimming in it. There is a big C-13 excursion at that time, but that is usually interpreted as merely resulting from the disruption to the biosphere. Dragons flight 05:39, Feb 21, 2005 (UTC)

Agreed and removed sentence from article. Some sed. rock samples and what may be - weasel phrases. If someone has a reference to back it up, they can re-insert. -Vsmith 05:54, 21 Feb 2005 (UTC)

On a side note, ozone destruction shouldn't significantly reduce C-14 creation because the ozone layer has not much influence on the cosmic radiation. 193.171.121.30 11:46, 23 Feb 2005 (UTC)

No, the huge pulse of radiation and cosmic rays from the supernova itself would be expected to create an enormous overabundance of C-14 and nitrous oxides. The NOx subsequently depletes the ozone layer. That's the theory anyway. But as far as I am aware there is little evidence of it every having occured. Dragons flight 01:23, Feb 24, 2005 (UTC)

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• A supernova couldnt of caused the mass extinction because a supernove would of wiped out 100% of life on earth, which means that this article wouldnt exist.

--Sonic 17:14, 5 June 2006 (UTC)

As the article says, they mean a supernova of a nearby star, not the sun itself. thx1138 11:11, 6 June 2006 (UTC)

[edit] Ocean overturn

Like Lake Nyos and Lake Kivu, the ocean is filled with methane. A catastrophic event such as an meteor impact in the Pacific could raise ocean temperatures enough to release enough methane into the air to suffocate all life. Lake Kivu does this about every thousand years or so, it is possible in the oceans...

[edit] The Bedout crater

I removed this text, because the link seems to be dead and the substituted information and cited sources seem more informative and current.: "One group examining Bedout drill cores has pointed to certain unusual geologic features as evidence for an impact origin of this site (see [1]). However, this remains disputed with other experts favoring large scale volcanism as responsible for the Bedout structure." I added material on the Bedout structure, as I had missed the importance of the passive link before, and I've read this several times. Please vet my changes. --Wetman 16:07, 27 May 2005 (UTC)

Obviously, we will also want to add some mention of all the scientists that think Becker et al.'s work is full of holes. I may try to do this in few days, if no one gets to it first. Dragons flight 18:19, May 27, 2005 (UTC)

That would restore the full picture. Thanks. --Wetman 21:01, 27 May 2005 (UTC)

[edit] New Crater in Antarctica

It looks like this crater might explain a lot - could someone with more knowledge than I put this into perspective and add to the article? Thanks! http://researchnews.osu.edu/archive/erthboom.htm

Also: http://www.space.com/scienceastronomy/060601_big_crater.html --Xrblsnggt

Also: http://www.physorg.com/news68455520.html Serpentus 04:47, 3 June 2006 (UTC)

Just to throw a little cold water on this party, I'd like to point out that the researchers apparently have no evidence that it is a crater except that it is large, roundish, and associated with a mantle anomaly (each of which could equally well be associated with a mantle plume). And what's more they have no evidence at all that it is associated with the P-T extinction except that it is between 100 and 500 Myr old and the biggest thing going right now. If they drill into it and find melt and impact brecia from ~250 Myr ago, then I'll be impressed. Till then it is mostly just an interesting curiousity. Dragons flight 05:02, 3 June 2006 (UTC)

Yeah, everyone seems to grab the hype and ignore the simple total lack of evidence. There is precious little evidence for the structure actually being an impact site and no evidence to associate it with the PT boundary - except the possible age somewhere between mid Cambrian and mid Cretaceous. May be it is the guilty party, but for now we need lots of ice water on the super-hype. Vsmith 22:21, 5 June 2006 (UTC)

I agree. Additionally, I can't see how this new metiorite theory explains how marine life was affected so much more adversely than terrestrial life.

—The preceding unsigned comment was added by 202.47.114.34 (talk • contribs) 06:30, 8 June 2006.

The evidence for the crater seems to be gravity and ice-radar based; I don't know what the country rock is in that part of Antarctica (I'll get on to it as soon as my exams are over), but I would expect a magnetic high for a plug of mantle material. It appears that von Frese and his team don't have magnetic data yet (although they want it) Also, I've read a couple of times sentences that imply that the coastline cuts the crater, and that that is the spot that Australia would have been connected to Antarctica (e.g. "The rift cuts directly through the crater, so the impact may have helped the rift to form, von Frese said." http://researchnews.osu.edu/archive/erthboom.htm). If this is so, I'd expect much more evidence for the crater (possibly even ridge?) in South Australia (once again, I'll get onto geology of SA once my exams are over). -- Archean sax 03:30, 9 June 2006 (UTC)

[edit] Causes

• The mass extinction was so bad that I dont think that a meterite could be big enough to cause the mass extinction
• I think that the extinction was caused by a severe drought

--Sonic 17:11, 5 June 2006 (UTC)

[edit] I don't get it

How could global warming have caused this event when we all know that global warming is only caused by SUVs?

[edit] P-T vs P-Tr

P-T is, quite possibly, in more common usage as the recent edit summary says, but it is certainly NOT unambiguous: "T" is the geological symbol for Tertiary; a T with a capital R attached to the stem is the symbol for Triassic. Out of context (which here, it is not) "P-T" would be incorrect and confusing. Geologyguy 16:26, 22 September 2006 (UTC)