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Extraterrestrial impact kills megafauna?

  1. Oct 20, 2007 #1
    I'm still working on the last glacial transition. The other week I drafted this comment:

    Any questions?
     
  2. jcsd
  3. Sep 11, 2010 #2
    (necropost) Meanwhile it looks like the comet lost its sparkle.

     
  4. Jun 3, 2011 #3
    Another necropost (but the previous posts have not lost any significance).

    While the impact idea waned, several scholars pursue an extraterrestrial event of another kind, solar activity.

    Paul A. LaViolette (2011) Evidence for a Solar Flare Cause of the Pleistocene Mass Extinction, February 18, 2011. Radiocarbon, vol. 53, No. 2 (June 1, 2011): 303 - 323

    Abstract

    I also recommend reading http://sd.ddns.us/science/article/pii/S1040618211001480 of an author who is well known to some of us :wink:

    There are however other devellopments on which I will report later that give some substantiation to Richard Muller's favorite quote of Josh Billings:

     
    Last edited by a moderator: Apr 26, 2017
  5. Jun 3, 2011 #4
    Notice that Laviolette (2011) builds his case around a 14C carbon spike in the atmospheric CO2 around 12900 years ago that correlates with the onset of the Younger Dryas.

    Notice the dating problems mentioned in the OP:

    Finally notice also that Fiedel (2011) in the previous post recognises this dating problem and mentions for calibration purposes a new calibration table INTCAL09.

    Would a comparison of the calibration tables INTCAL04 and INTCAL09 shed some light on these issues?

    I wondered that too and the result was ...erm, remarkable. I think that is worth a seperate thread.

    Oh if anyone wants to have the cited papers for scrutiny, please pm me.
     
    Last edited: Jun 3, 2011
  6. Jun 4, 2011 #5
    After some consultation, it may be better to keep the narration in this thread, but I need to elaborate on carbon dating techniques and calibration to demostrate how and why things went wrong here with the extrateresstrial hypothesis, the 14C spike and the dating of the lower (older) Younger Dryas boundary.

    Now you could read the wiki about carbon dating which is excellent or take it to the detailed level with http://researchcommons.waikato.ac.nz/bitstream/10289/3622/1/Hogg%20Intcal09%20and% [Broken]. But let me elaborate about that in the next post.
     
    Last edited by a moderator: May 5, 2017
  7. Jun 4, 2011 #6
    Okay so a quick overview of carbon dating then, which is based on the amount of nuclear unstable carbon-14 with a half value time around 6000 years.

    Carbon-14 is produced due to interaction of cosmic rays in the atmosphere in which neutrons interact with 14Nitrogen atoms as follows:

    [URL]http://upload.wikimedia.org/math/5/2/f/52f20ea2f25b231f49d14690009d67a6.png[/URL]

    The 14C oxidizes and mingles with the atmospheric CO2 entering the carbon cycle. As the 14C decays again with time, the ratio of 14C to normal 12C decreases and this says something about the age of the mechanism. If the starting ratio was constant, dating would have been rather simple

    However since these processes are highly variable we do not know the initial 14C/12C ratio. So we would need to calibrate the dating with something that can both be carbon dated and dated otherwise.

    Far out the best calibration is done with things that due have some annual accumulation; tree rings, annually layered deposits in deep lakes (varves), speleothems and coral.

    Of these tree rings are the most accurate as the 14C changing processes are the simplest, the wood is made directly from atmospheric CO2 and can obviously be carbon dated directly. The problem however is that good treering assemblies go only back as far as about 12,500 years

    Annual lake varves can also be counted very accurately, the problem is that it does not contain a lot of carbon datable macro fossils.

    annual Speleothem- and Coral rings can also both be counted and carbon dated (carbonates), however there is also a problem here as the carbon is not directly coming from the atmosphere.

    That's where the biological fertilizer comes in contact with the rotating vanes of a machine that produces a high speed low pressure airflow.

    More later
     
    Last edited by a moderator: Apr 26, 2017
  8. Jun 4, 2011 #7
    I am reading and taking all this in - honest

    So thanks for posting.

    :smile:
     
  9. Jun 4, 2011 #8
    Thanks for the feedback. I appreciate that greatly. I'm just trying to illustrate where certain parts of earth science stands now and how important it is to try and think of everything that can affect the 'whodunit'-reconstruction.

    Anyway, to get back to the problems with coral or any marine carbon dating, it's the mixture of carbon sources. For air sources we dont mind a few weeks or even years between the formation of the 14C in the higher atmosphere and the time it got fixed by photosynthesis, entering the biologic part of the carbon cycle. But for the sea/ocean is different. Some carbon did indeed enter the water recently but it is mixed with dissolved carbonates that have been in the water for a long time, like dissolved limestone etc, and hence depleted from 14C, decreasing it's ratio. This is called the "basin effect".

    Now if you have overlapping calibration series of land and marine data, you can calibrate the basin effect (calibrate the calibration) and it is found in some instances that the basin effect is rather constant and amounts for a few hundred years carbon dating.

    But if you find a couple of instances where this is true, is it also always true?
     
  10. Jun 4, 2011 #9

    Dotini

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    Fascinating investigation of a good mystery, Andre. I've been interested in this for a long time, ever since I marveled at the saber-tooth tigers of the La Brea tar pit museum, so I appreciate your posts very much.

    If there was a super-CME which wiped out megafauna in the Americas, how might it be that the megafauna of Africa were spared?

    Respectfully,
    Steve
     
  11. Jun 4, 2011 #10

    Evo

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    Is there anything you would like me to ask Stuart?
     
    Last edited by a moderator: Apr 26, 2017
  12. Jun 4, 2011 #11
    Maybe advise him to take note of this thread. There is an issue coming up with his paper. Maybe, we could have a good discussion.
     
  13. Jun 4, 2011 #12
    Excellent question Steve, One could probably to electromagnetic cosmic influence to be redirected towards the poles like the aurora borealis and aurora australis, but I don't think there is a reason for such audacities.

    Anyway, to continue, as I said earlier

    So having some carbon dating calibration back ground now, it's maybe time for the wow.

    data sets: Intcal09, Intcal04.

    Been busted once for making my own graphs, but nobody else does it, so I take that risk:

    apkal3.jpg

    Ideally, both graphs should overlap with only tiny abbarations, but the difference in our time frame of interest is huge, notice that the calibration of ~10,900 14C years, the approximate boundary of the Younger Dryas, (yellow line) used to calibrate roughly to something like 12,870 calendar years BP with Intcal04, but it calibrates now, with Intcal09, to something like 12720 Calendar years.

    That is major and far fetching, but why is that so?
     
    Last edited: Jun 4, 2011
  14. Jun 4, 2011 #13
    Oh, before we concentrate on the why, remember that Laviolette (2011) mentions a radio carbon spike in this time frame:

    We see in the intcal data sets linked to in the previous post that there is also a column "Delta 14C permil". That looks like the ratio of radiocarbon. So we can plot that too for both Intcal tables:

    20zocch.jpg

    Sure enough Intcal04 shows a significant radiocarbon spike corresponding with the mentioned Caracio Basin varve record, but look what happened with Intcal09. It's gone, only a little spike remains, hardly outstanding against other local spikes, but some 250 years later.

    That is even more far fetching.
     
  15. Jun 5, 2011 #14
    So for the why question, we need to scrutinize the original publication Reimer et al 2009. (I see that I mutilated the earlier link in my previous post yesterday and it doesnt work, but nobody noticed :cry: What is that guys? Don't you care reading the science behind all this? )

    Anyway considering this discrepancy we just discovered, Reimer et al write:

    But the result of that decision is far fetching
     
  16. Jun 5, 2011 #15

    lisab

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    I'm a noob on this topic, but that 'basin effect'...I'm not getting a lot of info on that term. I tried looking up 'lake effect' but that's a meteorological term about snow formation.
     
  17. Jun 5, 2011 #16
    Right Lisa, good catch, my bad. Mea culpa. :redface: I meant to say 'reservoir effect', the same mentioned as 'reservoir age' in Reimer et al:

    So there is the whole problem, changes in the ocean flows, whcih were disrupting the expectation that the reservoir effect caused a more of less constant age different. But this assumption produced a spurious 14C spike that sent future researchers on a tangent in an attempt to explain that. Hence LaViolette 2011 loses it's principle cause, no more big radiocarbon spike at the onset of the Younger Dryas.

    Obviously we can also say something more about the timing of the mysterious onset of the Younger Dryas now next.
     
  18. Jun 6, 2011 #17
    Anyway, that decision in Reimer et al (2011) keeps bugging me:

    If a scientist 'could, in theory,' solve a problem, he will, I would think. Moveover it would be pretty important to know the reservoir age devellopment. So why not here?

    It gets more intruging if you look at the graphs of the original Hughen et al 2000 in science, particurly the line up with the Younger Dryas in the GISP2 icecore, also showing the -now- spurious 14C spike.

    http://www.ncdc.noaa.gov/paleo/pubs/hughen2000/fig4.jpg

    This has always looked like a pretty solid base to establish the onset of te Younger Dryas at 12,900 Cal years BP. But now these data between "12,552–12,944 cal BP' are essentially voided by that decision.
     
  19. Jun 6, 2011 #18
    I promissed issues wth Fiedel (2011):

    I observe that his analysis is accurate most of the time, except however.., and maybe I may quote the following:

    I dont understand the boldface (mine). The orginal dating of the periglacial oscilations is publiced in Brauer et al (2001) Lateglacial varve chronology and biostratigraphy of lakes Holzmaar and Meerfelder Maar, Germany Boreas 30 pp 83 - 88. There is no mentioning of any ice core in that publication, just the correlating of the varve stratigraphy without external calibrations and it finds for the Younger Dryas 11 590–12680 varve years BP in the Meerfelder maar and for the Holzmaar, 11600–12 606 varve years, independently of any other dating. The difference is discussed.

    ----

    Fiedel then mentions multiple research results, including the 14C spike problems, all suggesting that the onset of the Younger Dryas -in Europe- was around 12,700, but nevertheless he concludes:

    Unfortunately, with the deletion of exactly those Cariaco data in INTCAL09, much of the substantiation for that assessment has disappeared.
     
    Last edited by a moderator: Apr 26, 2017
  20. Jun 7, 2011 #19
    Anyway, the Cariaco problem keeps bugging me. This is what http://www.nature.com/ngeo/journal/v1/n4/full/ngeo128.html (Cited by Reimer et al 2009) propose:

    While Hughen et al (1998) found originally:

    But maybe we are looking at the wrong problem. As Fiedel (2011) sums up, there exist several annually counted geologic records for the whole younger dryas. European lake varve records and the GRIP ice core tend to count ~1050 years, whereas the GISP-II ice core and the Cariaco basin foraminifera varves counted ~1300 years. So maybe it is not a reservoir age problem but a year counting problem?
     
    Last edited by a moderator: May 5, 2017
  21. Jun 7, 2011 #20
    That counting problem could be supported by the work of the Polish Quartenary geologist Tomas Goslar in Goslar et al 1999, Variations of atmospheric 14C concentrations over the Allerod-Younger Dryas transition, Climate Dynamics (1999) 15 : 29Ð42

    It compares the carbon dating versus annual varve counting of the Swedish lake Madtjarn and the Polish lake Gosciaz
    (Sorry Borek, my keybord does not produce all those random outcrops on the letters) against marine counts of corals and sure enough the Cariaco basin.

    2uysxvt.png

    The caption:

    The area of interest is obviously the red oval where the spline function goes down steeply while the Cariaco crosses go almost horizontal. I guess that could have been the hypothetical result if the Cariaco varves count was too high.

    Notice also that Goslar et al place the older Younger Dryas boundary around 12650 Cal year BP.

    But the Cariaco chronology was selected for the INTCAL tables while the other were not. It's a choice I guess. But objective?
     
  22. Jul 22, 2011 #21
    I realize that the focus of the thread has shifted from the extraterrestrial event itself to it's alleged dating, giving an interest gap of some 200 years. I did not mention another interesting feature that also strongly supports the later date for the beginning of the Younger dryas and that is the gigantic eruption of the Laacher See maar type volcano which ejected many cubic km of material into the atmosphere, that eventually formed an uniformly aged widespread layer known as the Laacher See tephra, which can be used to calibrate dating, the tephrochronology

    The general consensus via multiple dating is that the eruption took place 12,900 years ago hence the article in wiki (erronously) reads:

    No..no..no wrong. Reason why you never can trust wikipedia. It's as good as whoever wrote it. Take any scientific publication mentioning both the onset of the Younger Dryas and the Laacher see and it will telll that the Laacher See erupted some ....200 years earlier. Again! 200 years. The most accurate report is from the lake layer (varves) counting in the Eifel for instance from Lucke and Brauer 2004 - see OP. But also http://www.wsl.ch/staff/felix.kaiser/PDFs/Kromer_etal.2004.pdf [Broken] on page 1205 (3) mention that under "absolute placement of the pinechronology..."

    Notice however that Kromer et al do not mention the exact date of the Laacher see eruption, while they adhere to the erronous 12.900 bp date for the onset of the Younger Dryas, comparing it with the Cariaco basin grey scale.

    So what was that exact date for the eruption? 11,063 +/- 12 carbon years dated from then living trees in situ buried by the volcanic ash, see this. So both the INTCAL04 and INTCAL09 would transfer that to some 12940 cal years BP, however THE Laacher see specialist, Felix Riede determines 12,920BP. Fine with me. What is 20 years in between friends.

    But we still have to apply that 200 years between the onset of the Younger Dryas and the eruption, which would bring us -via another completely independent way- to 12,720 years BP. Remember that Lucke and Brauer counted to ~12,680 with a one procent error. I guess we can live with that 40 years.

    However with that overlooked/ignored(?) 200 years problem, the discussion of Kromer et al 2004 gets a completely different dimension. I have to OCR that paper somehow for quotes.
     
    Last edited by a moderator: May 5, 2017
  23. Jul 22, 2011 #22
    Yes what else might be hidden in the Laacher see tephra? Haynes reports an elk. That's very interesting.
     
  24. Jul 22, 2011 #23
    It looks interesting, is it a mistake based on the way they took the measurements inaccurately from one time to the next? Or is a something to do with the differences in methods used to collect the data and how each method might be prone to a different result?

    I don't understand the thread in its entirety, I am just asking in hopes to understand it a little more. In any event, when you say these are isotope levels, is that synonymous with "radio carbon" levels?

    People have theories that cold periods might be due to lack of sun spot activity. Does isotope levels relate to that in any way, or is this something entirely different? Hope this not bothersome. You just have a really good understanding of this. (I have never heard the term Younger Dryads till today)
     
    Last edited: Jul 23, 2011
  25. Jul 23, 2011 #24
    That's a good question, earth science is akin to forensic science, all about causalities, but which caused what or was it the other way around or was it something else. Hence, the biggest problem is the inherent unavoidable affirming the consequent fallacy

    Obviously for causality dating is extremely important - what came first - and the many different ways of dating events are compared constantly, usually with satisfactory results. However, it's also possible that some erroneous results are assumed to be right and may propagate to other chronologies, which are calibrated/adapted to the wrong one. Maybe that caused the two camps for the start of the Younger Dryas, 12,900 cal BP versus 12,700 Cal BP.

    So the counters of the annual sedimentation layers of the Caracio basin counted 200 layers too many maybe? or maybe they corrolated it to other chronologies like the GISPII ice core, firmly assuming it to be right. Only they can tell and there could be other explanations as well.

    That graph shows the calibration tables to calibrate the calculated 14C age to real age, which is based on the remaining radioactive 14C isotopes in the sample. Maybe that this wiki is clear on that, but if not I'll try to explain more.

    It's all sort of related. Many isotope fractination processes, like water evaporation and condensation are temperature dependent, so if isotope ratios in precipitation, for instance 18O versus 16O, change with time, one could conclude that this is caused by temperature. However, here is the affirming the consequent fallacy again: (a causes b, we see b hence it was caused by a). But isotope ratios can also change due to other circumstances but that would go OT.


    No, on the contrary, it's fine. thanks for the feedback. Essentially it's my fault if it was all incomprehensable, and hence the thread would be useless then. My intention is merely to show the complexities and uncertainties in Earth science and how difficult it is to keep on the straight and narrow of the scientific truth.
     
    Last edited: Jul 23, 2011
  26. Jul 23, 2011 #25
    Anyway Baales et al 2002 give a most excellent exposition of the Laacher See volcanic event and their analysis of the Younger Dryas dating problem agrees roughly with mine. Obviously they were first. By combining different data and techniques they find that the eruption took place in the late spring of 12,916 Cal years BP and...


    The different annual countings between the Laacher See Tephra layer and the onset of the Younger Dryas averages 205, so that would get to a start for the Younger Dryas of 12,711 Cal years BP plus a certain eror margin of course.

    I wonder about the validity of using erroneous records to get to that average.
     
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