A funny mistake by ICR and example of poor scholarship

Acts and Facts Magazine | The Institute for Creation ResearchIn this article (which is fast becoming a legend) Russ Humphreys claims that a 'cryogenic earth' is needed to retain He in zircon. Unfortunately, Humphreys mis-transcribed (this seems to be a problem of his: re Magnetic field discussion) the relevant temperatures cited in the article by Reiners et al. (2002). Reiners et al. cite a diffusion temperature of +190 C which Humphreys reports as -190 C ( a difference of nearly 400 C!). Then Humphreys claims that such a cryogenic earth would not be habitable. This is typical creationist scholarship and one of the many reasons why they do not publish in the mainstream literature.CheersJoe Meert

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Originally posted by Percipient:
I just want to make sure I understand the chain of logic plus a couple additional aspects of the Humphreys article.

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Humphreys says that geologists believe that helium within the earth should have long since diffused into the atmosphere, that the leakage rate into space is slow, and that therefore there should be a higher percentage of helium in the atmosphere than we actually find.

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Is that actually true?

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JM: Yes, and it goes a bit beyond that. They actually argue that helium cannot escape the atmosphere so there must be VAST amounts of helium in the atmosphere on an old earth.

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Humphreys goes on to say that geologists did not expect to find high levels of helium with zircons.

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Is that true?

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JM: That's false. Geologists are returning to U-He dating (one of the 'original' dating methods) because of it's ability to date young events. The closure temperature of helium to zircon is ~200 C (the article in question states ~190 C). At temperatures above ~190 C, helium begins to diffuse out of the lattice structure. Basically, if a rock resides at less that 7-10 kilometers depth (depending on local thermal conditions), zircons remain closed to helium diffusion.

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Lastly, about the mistake you were writing about, Reimans published a paper in Tectonophysics this year where they measured the rate of He diffusion in zircon recovered from within the earth and found that the amount of helium was consistent with geochronology if the temperature of the zircons did not exceed 374^oF (sorry, I still can't think in Centigrade). But Humphreys thought he saw a minus sign and thought it was -310^oF, which is impossible at great depths, of course, so he went off crowing about it before anyone reviewed his article.

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Do I have it right?

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If I've got all this right, the error must be so painfully obvious, why has ICR left the article up?

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--Percy

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Well, I've e-mailed ICR and have not yet gotten a response. This type of error seems to be something to watch for in Humphreys articles. Recall that he reversed the archeomagnetic graph in McElhinny's book and added a zero line. Here, he claims that the -190 C closure temperature is supported by the Tectonophysics article when it is +190 C. I'll let you know if ICR responds.CheersJoe Meert

Humphreys has responded to my 'feedback' e-mail. To be fair, we are both guilty of misunderstanding each other. I have placed a link to his response and my response to his claim at
More Faulty Creation Science from The Insitutute for Creation ResearchIn essence, he claims that it was not a transcription error on his part. That's fair enough, but given the context and the magnitudes of the numbers it was a realistic, if hasty, conclusion to reach regarding his study. The second point is that for some reason, Humphreys is asserting that zircons will reach steady-state ages based on their effective radius (so far as I can tell from what he supplied). Anyway, let me know if clarification is needed on any points.Cheersjoe Meert

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I don't get this. How does Humphreys know the amount of He there should be in a zircon? I think his point is that it should have diffused out of the crystal over long periods of time but there is still some there. Has he actually calculated some He balance? Wouldn't the actual rate of diffusion depend on a number of factors other than simple grain size? Doesn't the amount of He also have something to do with the U-composition of the zircon after it passed through closure?

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JM: It's all really weird. I am working out some calculations that I can show you this weekend when I am in town if you want. basically, his diffusion ideas can also easily be interpreted to signify that all radiometric ages we calculate are minima! That is hardly something ye-people would desire.CheersJoe Meert

[QUOTE] Any thoughts on the units of Humphreys' "closure interval", Joe? Am I missing something?[/B][/QUOTE]JM: D/a^2 has units of 1/s (diffusivity is length^2/time) so everything is kosher with his units. The problem, as I see it, with Humphreys attempt to separate diffusion from closure temperature. Closure temperature is a function of diffusion and is defined as the temperature at which diffusion becomes negligible for the mineral. There is then some trickery in his math to come up with this tci thing. Look at it this way. Let's look, in a very simple way at how one would calculate an age in Humphreys world versus ours. Assume that retention is 100% at the closure temperature (but only for a short time). After that diffusion rate out equals production rate in (his tci concept). So, let's say that element A decays to element B with a characteristic half life of 1000 years. For simplicity, let's say that 100,000 A's were in the mineral at Tc. Decay then proceeds as follows (in the normal apostate decay world).1st half life 50,000 parents and 50,000 daughters left and the age is 1000 years
2nd half life 25,000 parents and 75,000 daughters left and the age is 2000 years
3rd half life 12,500 parents and 87,500 daughters left and the age is 3000 years
etc....Now let's do this with Humphreys definition of 'closure'
1st half life (everything is 'normal') 50,000 parents and 50,000 daughters: Conventional interpretation of the age is 1000 years2nd half life (now the crystal 'opens' so that flux of daughter in = flux of daughter out) 25,000 parents and 50,000 daughters (the 25,000 daughter products formed diffused out)3rd half life 12,500 parents and 50,000 daughters (the 12,500 daughters formed diffused out)Our geochronologist does not know this and 'dates' the rock after two half lives and is unaware of Humphreys 1st law of diffusion. The age he/she gets is based upon the assumption that the system was closed to both parents and daughters. Therefore, the geochronologist assumes that at closure the mineral contained 75,000 parents (simply the sum of parents and daughters in the rock). The geochronologist figures that only 1 1/3 half lives have passed (this is an algebraic solution but useful to a first approximation) and therefore the rock is determined to be 1333 years old (it is actually 2000 years old)After the 3rd half life, the math is done again assuming that there were originally 62,500 parents in the rock. This time the age is 2.2 half lives and the geochronologist reports an age of 2200 years on a 3000 year old rock.Thus, the more time that the rocks obey Humphreys law, the younger the rocks appear relative to their 'true' age. Therefore, all our age determinations are too young!Unfortunately, he did not supply the relevant equations by which to check where this tci came from. I suspect trickery, but can't prove it without the paper.CheersJoe Meert

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Originally posted by Percipient:
I unfortunately can't give this the time it deserves this morning, but if He concentration within the zircon is a function of many factors including temperature history, geometry and size, diffusivity, ambient He concentration in material surrounding zircon, etc. and so forth, isn't this just another case of Creationists focusing on a process with sufficient complexity as to defy simply analysis, thereby making possible labyrinthine technical discussions where everyone gets lost at one time or another.

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If the earth is young and most geology the result of a world-wide flood then the evidence would be everywhere, particularly in the easily accessible geologic layers. That the evidence isn't there is why Creationists tend to focus on obscure arguments like the diffusion of He from zircon buried at depth.

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At some point someone here will sufficiently understand the issues that it can be presented in a manner understandable by us all. In the meantime, I hope we conduct ourselves in the manner of objective investigation rather than as rabid evolutionists more intent on showing up Humphreys than understanding the issues.

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--Percy

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JM: very astute observations Percy and quite accurate. Part of the problem with providing detailed criticism of these creationist stories is that they do not publish them in scientific journals. Instead, we have to try and understand what they are trying to say from things like Impact articles wirtten for the 'layperson'. I cannot provide detailed analysis of Humphreys article except to say that the tci concept appears to be a bit of smoke and mirrors to produce the desired result. I can also say that losing daughter product at the same rate it is formed would result in underestimates of the real age of the mineral in question. The whole point of trying to calculate closure temperatures is to help figure out the point at which daughter loss (via diffusion) is negligible in the mineral lattice. Humphreys is arguing (without basis, I believe) that non-negligible daughter loss occurs all the time. Unfortunately, he did not include that explanation in his reply to me. All that said, your original point stands on its own.CheersJoe Meert

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Closure temperature has nothing to do with balancing rates; it is rather the temperature at the time given by the crystal's apparent age. The descriptions of closure temperature as being a point of negligible diffusion (Meert), or as a point of balancing diffusion with production (Humphreys), are simply wrong. It is true to say that diffusion drops off very rapidly below closure temperature (it is an exponential function, after all).

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JM: Well, of course I want to argue a bit on this point. Negligible diffusion does not mean NO diffusion. Diffusion can still take place at and below the closure temperature, but it such diffusion will not significantly affect the age of the zircons so much as to make them only 1000's of years old. What Humphreys wants is for the zircons to reflect a very young age for the earth, closure temperature does not help him in this regard.CheersJoe Meert

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Originally posted by TrueCreation:
--Welcome back Joe Meert! I was beginning to worry that we lost a valuable participant here at evcforum. How was the vacation?

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--[Edit] - I'm still interested in your thoughts on my discrepancy illustrated in my e-mails from 11-2 & 11-4, if possible that would be fantastic.

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--[Edit 2] - Also, this is pretty simple I would guess but on Pg. 135 of Geodynamics - Second Edition (2002) they multiply 2 x 10⁸ km² by 65 mW m^-2 and get 1.30 x 10¹³ W. But I get the same quantity though with a power of 10. I have the feeling I will feel stupid later but I would like the correction on this point.

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JM: Did you convert km^2 to m^2 and convert mW to W?CheersJoe Meert