Talk:Permian–Triassic extinction event/Archive 1

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Archive 1

Archive 2

Archive 3

inconsistency, dead clades

"Dead clades walking" which became extinct in the Triassic include: bryozoa; Orthocerida; the Goniatitida and Prolecanitida orders of ammonites; procolophonids (the last of the Permian anapsid reptiles).

But the article on bryozoa says they're still around. If I knew more I'd fix it, but there is an error in here somewhere. ErikHaugen 19:53, 15 March 2007 (UTC)

Thanks for catching this; bryozoa certainly still exist, so I changed it to "many". Also found another error, which listed inarticulate brachiopods as "completely extinct". Reports of their deaths are greatly exaggerated (likewise for inarticulates). Cheers Geologyguy 20:06, 15 March 2007 (UTC)

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)

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

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)

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)

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)

Gamma Burst - not likely

A gamma burst occurs for c:a 5 seconds to 10 minutes. If hitting a planet, it would succeed to destroy exactly 50% of the ozone layer, and wreaking havoc on exactly 50% of a planet. At most. The number of species to become extinct would be less than 50%, considering that some species should have a distribution that is exposed to gamma rays only partially. Unless of course the gamma burst happen to hit the planet on the side where an overwhelming number of all the species of the planet happen to live. Said: Rursus ☺ ★ 19:49, 3 June 2007 (UTC)

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...

Yeah, why not. But such a statement is very very hard to prove for reasons mentioned in the article: an impact crater in an ocean would pretty soon be submerged into the mantle because of subduction. Said: Rursus ☺ ★ 19:51, 3 June 2007 (UTC)

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)

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.

—Preceding unsigned comment 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)

Even if there is a crater, where is the collateral evidence that this extinction was sudden? I agree with quercus robur (who posted above) regarding better evidence for three waves of extinction over 100,000 years. The fossil records do not show any sudden disaster like they did for the K-T extinctionTrilobitealive 04:19, 21 December 2006 (UTC)

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)

How would a drought cause the extinction of so many sea creatures?Obbop 04:42, 26 November 2006 (UTC)

There is another possible cause of the P-T climate change that is gaining traction and should be mentioned. The P-T boundary roughly coincides with the galactic cosmic ray (GCR) flux minimum of the last billion years due to our solar system's relative location in our galaxy, i.e. between the spiral arm pattern, and there is now enough evidence for GCR being a major factor in low level cloud formation for the CERN "CLOUD" (Cosmics Leaving OUtdoor Droplets) experiment to have been funded and proceeding. In short, the deepest ice ages have coincided with a large GCR flux, thought to cause increases in low clouds, and the hottest periods have coincided with few galactic cosmic rays, and therefore relatively few low clouds to reflect sunlight away.

http://www.blackwell-synergy.com/doi/full/10.1111/j.1468-4004.2007.48118.x?cookieSet=1 (note especially Fig 8:"Four switches from warm "hothouse" to cold "icehouse" conditions during the Phanerozoic are shown") http://en.wikipedia.org/wiki/Henrik_Svensmark http://cloud.web.cern.ch/cloud/documents_cloud/cloud_memo.pdf

I've done very little wikipedia editing in the past, I believe this is incendiary enough to warrant mention in Talk: before composing an addition to the actual "P-T extinction event" entry Ggoodknight 17:01, 8 June 2007 (UTC)

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)

P-Tr is the better one, the Triassic symbol is not in Unicode, but it should look like:

. Said: Rursus ☺ ★ 20:14, 3 June 2007 (UTC)

Actually, no, the symbol for Triassic is a large capital T with a small capital (not lower case) R attached to the stem. Like this:

Cheers Geologyguy 22:02, 3 June 2007 (UTC)

Edriostege

This seems to be a species like a brachiopod but cant find any info on it, anyone know of it? Enlil Ninlil 02:42, 1 January 2007 (UTC)

Methane hydrate gasification theory

Does anybody know more about this? The "P-Tr extinction" article's account currently seems to be almost entirely based on the BBC's "Horizon" programme. Since about 1990 "Horizon" has been dumbed down and is now very prone to sensationalism and misleading over-simplification, and the "P-Tr extinction" article's account (current version) seems to suffer from these faults.Philcha 14:51, 14 January 2007 (UTC)

Antarctic impact event

This part of the article needs to be streamlined. A large chunk of it is irrelevant to the P-Tr extinction because it's about stages in the break-up of Pangaea, which happened in the Jurassic. The rest reads like a press release and needs to be condensed into a summary of the evidence and debate.Philcha 15:05, 14 January 2007 (UTC)

That part could be largely removed. The idea of a gigantic crater in Wilkes Land is not based on any solid evidence, and the timing is more or less guesswork. Unnecessary sensationalism based on a press release. An impact event as a possible culprit should not dismissed, however.--JyriL ^talk 19:12, 16 January 2007 (UTC)

Very much agree - since the possible crater has its own page at Wilkes Land crater, and especially because of the really wide bracket on its timing, I think it should not get so much play here. If there is any info on this page that is not on the Wilkes Land crater page, it could be added there, and a one-line statement about the possible role of that possible crater could remain on this page. Cheers Geologyguy 19:28, 16 January 2007 (UTC)

"A combination" (of causes)

At present this section just throws everything in for the sake of it, including the supernova (no evidence for this) and Antartic impact (needs clarification, see previous discussion topic). OTOH a reference to Arens and West's (2006) "press / pulse" model (see Extinction event) would be useful - Pangaea caused long-term stress, a sequence of catastrophes finished the job.Philcha 15:05, 14 January 2007 (UTC)

I agree with Philcha that the current status of the section is very bad, it seems almost like a bad joke. The previous versions seem to be better quality, a revert to some earlier version (e.g. 12 months before) would make the section more clear etc. IJ 62.77.83.227 19:27, 10 April 2007 (UTC).

Don't you dare revert to a year ago! I rewrote a lot of the article in Jan 2007 - what died and what survived, consequences, causal theories (someone added "A combination" later). I know of other improvements that are needed, and I'll probably remove "A combination" when I implement these. It will be redundant anyway, because there's a fairly plausible causal chain already: Siberian Traps -> global warming -> methane hydrate emissions -> more global warming -> anoxic oceans -> H2S emissions. Philcha 00:51, 20 April 2007 (UTC)

More victims needed

Does anyone know of additional taxa which became extinct? Especially land plants (the fungal spike suggests land plants suffered badly, although the survival of the herbivorous procolophontids suggests there were enough left to eat) and land invertebrates (a tough one, since they don't fossilise well).Philcha 17:12, 16 January 2007 (UTC)

I've seen hints that land plants suffered the lowest % extinction, e.g. [2]. And hints that land plants had a brief boom after the start of the extinction of marine and terrestrial animals. Can anyone point to evidence about these points? I've also seen several statements that the P-Tr extinction was the only one which had a noticeable effect on insects. Can anyone point to evidence?Philcha 10:54, 17 January 2007 (UTC)

Impact section rewritten

Considering all the negative comments above about the impact section, I've taken the brave step of completely rewriting and shortening it, while adding a lot of references to refereed papers (now makes referencing in the rest of the article look very sparse - if anyone can help, please do). I have left out all the details of the Wilkes Land and Bedout structures because these can be found on the own pages, and the evidence is so speculatively that it only rates passing mention. The Wilkes Land article has recently changed to clearly point out its speculative nature; the Bedout article does need serious work, which I might tackle shortly. Zamphuor 15:40, 27 January 2007 (UTC)

Well, to my eye this is great, and the length, content, and emphasis in the Impact section are now both appropriate, excellently referenced, and encyclopedic. Thanks very much! Cheers Geologyguy 15:50, 27 January 2007 (UTC)

This page is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page.