Talk:Permian–Triassic extinction event/Archive 1

message: "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)
replies: text: 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)
thread_title:  inconsistency, dead clades 

message: 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)
replies: text: 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)

text: 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)
replies: text:  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)
thread_title:  Question! 

message: 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)
thread_title:  Miscellaneous 

message: 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)
thread_title: Gamma Burst - not likely

message: 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)
thread_title: Ocean overturn

message: 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)
replies: text: 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)
replies: text: 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)

text: —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)
replies: text: 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)
thread_title: New Crater in Antarctica

message: *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)
thread_title:  Causes 

message: 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)
replies: text: 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)
replies: text: 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)
thread_title: P-T vs P-Tr

message: 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)
thread_title: Edriostege

message: 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)
thread_title: Methane hydrate gasification theory

message: 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)
replies: text: 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)
replies: text: 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)
thread_title: Antarctic impact event

message: 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)
replies: text: 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)
thread_title: "A combination" (of causes)

message: 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)
thread_title: More victims needed

message: 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)
replies: text: 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)
thread_title: Impact section rewritten