Awkward but promising: Compromise paper from Andronikov & Van Hoesel


The presence of a possible meteoritic component in the same sediments suggests that an ET event occurred at approximately the same time. However, whether the presence of the meteoritic component is due to a local meteorite impact/airburst or to a much stronger event remains unclear. Anyway, it is quite possible that some short and dramatic event took place just before the onset of the Younger Dryas climate oscillation, but, as was emphasized by Haynes et al. (2010), an understanding of what happened at c. 12.9– 12.8 ka BP requires further research.

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  • Casual visitor

    Quotes from Peeters (paper suggested above by agimarc):

    1. “Using the obtained density variation for grain size, instead of the linear decrease suggested by
    Bonadonna and Philips (2003), the tephra dispersal modelling reveals that less tephra is being deposited
    in the more proximal areas and more tephra is being deposited in distal areas. This difference between
    modelled fallout using both density – grain size relationships, increases with increasing plume height,
    erupted mass and increasing maximum wind speed. Especially in highly explosive eruptions, there
    appears to be a significant increase in tephra being deposited further away from the vent, than what is
    predicted from the model using the density variation suggested by Bonadonna and Philips (2003). This
    suggests that models being used for hazard assessment for large eruptions should definitely incorporate
    a more detailed density – grain size relationship than what has been used so far. ”

    This implies that the LSE has an atypical distribution of tephra by grain size, so that the models had to be adjusted to incorporate it.
    This by size distribution fits the impact hypothesis.

    2. The ejected magma volume did not only dwarf the erupted volume of the more than 300 scoria cones scattered
    throughout the Eifel region, it was also larger than more recent Plinian eruptions like the AD79 Vesuvius
    eruption, the 1980 Mount St Helens eruption and even the 1991 eruption of Pinatubo. …
    The influence of external water during the beginning and ending phases of the LS eruption was very important.

    This means that the LSE is by far the largest event in the area that is filled with volcanoes. This is an oddity. It is not an oddity if it was an impact, but otherwise…

    3.The Western Eifel volcanic field (WEVF) extends over 600 km2 and is made of approximately 240 volcanoes
    which are aligned in a NW-SE direction. … Even though the EEFV is only made up of 100
    volcanoes, it contains four highly differentiated phonolitic volcanic complexes: Rieden, Wehr,
    Dümpelmaar and Laacher See… the fields originate from two different sources in the mantle.
    There are 340 volcanoes in the complex, but only four explosive ones, of which the LS is by far the greatest.

    4. Oppenheimer (2011) acknowledges that the volcanism of the Eifel is
    related to the collision between the African and Eurasian plates and adds to it that the fact that
    volcanism is concentrated in bursts could possibly be linked to the loading and unloading of the
    European continent by ice sheets. … The oldest well-documented phase is that of the Rieden volcanic complex
    (ca. 380 – 430 ka) during which 5 km3 DRE phonolitic magma erupted. The second phase is characterized
    by the construction of the southeastern subfield of the EEVF approximately 190 – 215 ka ago. …
    The first Wehr eruption was dated at 215 ± 4 ka
    (40Ar/39Ar dating; Van den Bogaard, 1989) and most scoria cones in the subfield are formed within
    20,000 years after this first eruption. The third phase (ca. 100 – 150 ka) consists of two minor phonolite
    eruptions: the second eruption of Wehr volcano, around 151 ± 11 ka, and the 116 ± 16 ka eruption of
    the Dümpelmaar (both 40Ar/39Ar dating; Van den Bogaard, 1989). Both eruptions formed a phonolitic
    volcano. The fourth and last phase is characterized by one large scale eruption, namely the 12,900 ± 560
    a (40Ar/39Ar dating; Van den Bogaard, 1995) eruption of the Laacher See volcano. …Even before the LSE, the present Laacher See (LS) area had a relative negative topography to its
    surroundings and supposedly already contained a shallow lake. (p15-16)
    Details of the mentioned 4 explosions point that they are very rare.

    5.A unique feature that attracted volcanologists to study the LSE and its deposits is that the magma
    chamber of the Laacher See Volcano was almost completely emptied during the eruption (Schmincke,
    2004). In most cases only a limited fraction of the melt in a magma chamber is erupted whereas the bulk
    leftover magma remains in the magma chamber or is withdrawn to deeper levels. Due to the seepage of
    water into the magma chamber during the ending phase, new batches of magma which would
    otherwise not have erupted were thrown out as a result of pulsating phreatomagmatic explosions.
    The almost complete emptying of the magma chamber made it possible to model the pre-eruptive magma
    chamber of LS before it erupted. The material stored at the top of the magma chamber, which erupted
    first, is now preserved as the lowermost deposits whereas the topmost deposits represent the bottom
    of the magma chamber. Wörner and Schmincke (1984a) stated that the magma chamber was zoned from highly evolved, volatile-rich and crystal-poor phonolite at the top towards slightly more mafic, crystal-rich phonolite at the bottom.

    Another oddity: complete empyting of the magma chamber. An oddity for a volcano, but not so for the impact scenario. This is exactly what would be expected from an impact. The uppermost part was volatile rich because the impactor would have contributed the volatiles, and crystal poor for the same reason, while the bottom part was denser and erupted after the water from the lake rushed in into the opened cavity to initiate the later phase of the eruption.

    6.Wörner and Schmincke (1984b) argue that a third differentiation stage was responsible for the
    discrepancies of oxides between the calculated and observed magma compositions at the top layer of
    the magma chamber. Because an unrealistically high volume of the lower part of the zoned magma
    chamber would need to crystallize in order to achieve the extreme trace element enrichment towards
    the top layer of the magma chamber, or magma mixing would require an extremely fractionated liquid
    as one end-member, liquid-state differentiation or liquid-state thermogravitation diffusion (LSTD) could
    have caused the extreme enrichment….(p19)

    The RRE enrichment in the upper part of the magma chamber (as expected from the alternative impact scenario) is extremely difficult and even found unrealistic to explain from the volcanologist’s point of view. Over and over again they had to invoke the word ‘extremely’, ‘extreme’ to cope with the observed facts.

    These uniquenesses by the power of the occam razor point to the alternative explanation that naturally explains them by standard theory of impacts.

    7. Wörner (1982) predicted that the magma chamber of LS was set in shallow crustal
    levels around 3 to 6 km depth.(p20)
    All that overlying rocks were supposed to have been blasted away by the explosion, but produced no shards of irregular shape. Only an impact can do such a thing. Remember the eruption of he Eyjafjallajökull (or whatever is it’s name), the Iceland volcano from few years ago. It made a lot of ash that was irregular in shape. No such ash in the LS tephra is an extreme oddity.

  • Casual visitor


    It was not the LS eruption that put the dust into orbit, but the main impact a decade later that was much more powerful. Devastating enough to separate epochs, and equally rare. But the peaks of Pt indicate that there was a smaller impact a decade earlier, certainly from the encounter with the same object, as in the SL9 scenario. One orbit earlier.

    The LS event was a precursor event if it is an impact site, and as a minor impact it only put dust into the stratosphere, which is why it might not show in the ice cores. not in large quantity anyway.

  • Jonny McAneney

    If the Laacher See impact was minor, and only injected dust into the stratosphere, the fact that platinum from the impact reached Greenland should also imply that Laacher See dust would also reach Greenland, since one would have mixing of material at the impact site.

    The ice core platinum concentrations may well be extraterrestrial in nature, but the issue is whether they are coeval with Laacher See, and currently I see no concrete evidence to support that. I wish you luck though in the publishing of your data in peer review.

  • Casual visitor

    It is true that if Pt from the impact site ended in the ice cores, then the LS dust must have done that too, at least a small amount of it. But, how do you know that the small amount of dust which did end up in the ice cores, did not come from the LS ? Petaev checked the relative abundances, which means that even a tiny amount of dust was sufficient for his task.

    I feel that discussion has come to an end, presumably due to the exhaustion of participants. (Or perhaps because I raised too many questions at once. Sorry.)

    For the end, I will ask just one simple question: is the presented data sufficient to raise a reasonable suspicion that LS is an impact site ?

    If yes, they must be coeval, if not, the coeval minor impact site is elsewhere and the LSE is at some other time, in which case dating records need recalibration.

    I would not do recalibrating just because the LS tephra was not yet found in the ice cores. If somebody finds it at some other time layer, then it would be a good reason but until then I am not convinced either that the stated dates are erroneous by centuries. A missing parameter is not a proof of its non-existence, only a reason for perhaps further research.

  • Hermann Burchard

    Jonny speaks “Without Laacher See tephra in the ice core, you cannot positively prove that the platinum anomaly in GISP2 occurs contemporaneously with Laacher See.”

    & doublespeaks:

    “I agree with you that one cannot expect to find tephra in the ice cores from ANY volcanic eruption.”

    Also, you do not understand impact volcanism: “Many pyroclasts found in other volcanoes have aerodynamic shapes due to being ejected from the eruption in a partially melted state.”

    See my earlier post on flawed Ivanov-Melosh (2003) paper

  • Howdy all –

    Another paper with an extended discussion of volcanic activity in the Eifel volcanic field. CV summarized a bit of it in an earlier comment. Cheers –

  • Howdy CV –

    From the following, it appears that the LS tephras were rather run of the mill Plinian tephras with normal inclusions / vesicles. Cheers –

  • Casual visitor

    Hello agimarc,

    You are looking for a proof that is either impossible, or extremely difficult to be obtained. The aerogel which was used on Stardust was specifically designed to collect samples in vacuum of space and was kept in special conditions on the spacecraft. I’ve seen that material. It looks like a sponge made of glass. Very ugly and dangerous stuff.

    Do you really believe that it would be possible after 13 ka to extract a bubble of gas from tephra that was exposed to weathering for all the time since and convince a skeptic like you into anything about it ?

    As for the papers on LS, I don’t think that any one of them has considered impact volcanism as an option and then evaluated the arguments.

    Check the point six from my list: they found enrichment in RREs unrealistic and impossible to explain. The RREs are common in space and are the tell-tale signs of impact, especially when coupled with excess of PGEs.

    Why are the solids not a good enough proof to you ?

  • Jonny McAneney


    defintion of doublespeak: “Doublespeak is language that deliberately obscures, disguises, distorts, or reverses the meaning of words.”

    I have not done so. I have pointed out two scientific facts:

    1) The only true way to prove a link between a volcanic event in one chronology to a volcanic event in another chronology is through finding and identification of tephra from that volcano in both chronologies.

    2)Not all volcanic eruptions deposit tephra in Greenland Ice cores.

    This is not doublespeak, and I have not deliberately obscured, disguised or distorted these facts. Indeed, I did explain why it is that not all volcanoes deposit tephra onto the Greenland ice cap. If they did, tephrochronologists would have a far easier time with the bounty of data.

    I can see how you may have thought it was double speak, where on one hand I say that the only way to prove a connection is to find ice core tephra, and on the other seemingly saying it may not be found. That though is not obscuring the issue, it is simply stating the facts. Laacher See tephra may never be found in the ice cores.

    Regarding your assertion of (and I presume you mean me here) my lack of understanding of impact volcanism. I will freely admit that I am not an expert in either regular or impact volcanism. However, I am confused by this last statement in that you seem to be implying that aerodynamic pyroclasts are a signature of impact volcanism only. or at least that is my inference? Would this inference be correct, and if so, are you denying that aerodynamic pyroclasts, such as so called Pele’s tears, are not observed in regular volcanism observed in modern volcanoes that are not impact induced? So if these aerodynamic pyroclasts occur in regular and impact volcanism, how can one possibly use them to support an argument for one mechanism over the other?

  • Jonny McAneney

    Casual Visitor,

    Yes , I think we have indeed come to an end of our discussion on the matter, and to continue would risk just treading over the same ground as we go around over circles. I will answer your question though. I am not currently convinced that the evidence to date is conclusive that Laacher see is an impact site. To put this clear, I am not adverse to the idea of it being an impact site, merely that at the moment I am not convinced that it is. That doesnt mean I wont be convinced (or even lean more that direction) in the future with stronger evidence.

    I have enjoyed our tete-a-tete though, and appreciate your efforts to present your argument.

  • Hermann Burchard

    A note of no import: Laach is archaic (OHG) for lake, and is preserved only for Abbey Laach (Maria Laach) founded 1092, a tourist Mecca for the early pre-gothic architecture. (See here.)

    Laacher See being a pleonasm (“Laker Lake”), my preference would be to use “Laach,” but the Eifel folk must have their say.

  • Casual visitor


    I’ll answer the question regarding the pyroclasts.
    There is overly too much of them in this case, which means that there was too much energy in the system. This is unusual for a volcano, but can be explained if an impactor provided the extra energy.

    That is not a definitive proof, but just one more of the many tell-tale signs of impact. Between the two competing explanations, the pure volcanic event case has often more difficulties in explaining the various markers, and in the case of the enrichment with RREs even entirely fails to do so.

  • Howdy CV –

    What I was thinking of was excavation of layered tephras (remember there were multiple blasts) rather closer in to the vent where they are thick and more importantly buried and protected from the elements by all later layers.

    If cometary (Centaur) in nature, you should see an increase in heavy water similar what was observed in Hale-Bopp or 67P or about 3x natural concentrations on earth. Difficult to do? Absolutely, especially given welded tuffs are soft and relatively porous.

    I think we are at an impasse. Wanted to thank you for forcefully arguing another possible event / mechanism – another tool for the kit. I’m not where you are yet, but look forward to additional info as it arises. I don’t think we are at the end of this particular journey. More like the beginning.

    No expertise on volcanism. Simply another hobbyist. Cheers –

  • Casual visitor

    One correction of myself: ‘RRE’ should be ‘REE’ – rare earth elements. They are present in the lower tephra layer, which means in the upper part of the lava chamber. Thus they did not came up from another impact site and their presence in detected extreme quantity is ‘unrealistic’. Thus, them alone are a strong signature of impact.
    Chemically, there are also PGEs (Pt group elements).

    Physically, there is a large excess of energy, showing as the force of explosion. This is also a very strong proof, with multiple markers.

    On macro scale, the pattern of tephra distribution is an additional proof, especially in the plume direction (NE).

    One more proof, not yet mentioned, is the striking symmetry of the crater and a somewhat elliptical shape.

    As far as I know nobody ever tried to use heavy water as an impact marker. However, He3 has been used for that purpose successfully on the Tunguska site, but that was a recent event. I think that if one wants solid proof, the solids are sturdier.

  • Paul_Repstock

    Just so that readers do not misunderstand; I never suggested that the impact crater penetrated to the molten outer core or even deep into the mantle. What I referred to was the Impact Energy or shock-wave. Given Chixulub’s estimated potential energy of approximatly 1.30 x 10 (8th) Megatons of TNT or 10 Billion tons, the earth absorbed this huge amount of energy. My theory was that the energy was released on the other side of the globe.