Young-earth creationism and radiometric dating

I received an email from a fellow named Adam recently and thought I'd address it here.

Adam asked me to look at an online article by Andrew Snelling, a young-Earth creationist titled The Failure of U-Th-Pb “Dating” at Koongarra, Australia.  It's actually pretty old by now, published in 1995 in the CEN (Creation Ex Nihilo) Technical Journal (now called the Journal of Creation).  This "journal" is put out by Creation Ministries International, a young-Earth creationist organization whose What We Believe page states things like:

- The account of origins presented in Genesis is a simple but factual presentation of actual events and therefore provides a reliable framework for scientific research into the question of the origin and history of life, mankind, the Earth and the universe.

- The great Flood of Genesis was an actual historic event, worldwide (global) in its extent and effect.

- By definition, no apparent, perceived or claimed evidence in any field, including history and chronology, can be valid if it contradicts the Scriptural record.

Given that last statement, by any definition of the word, these people do not do science. They do Biblical apologetics. Needless to say, the CEN Technical Journal is not a scientific peer-reviewed journal.

A number of years ago now, I was more heavily involved in attempting to refute young-earth creationist (YEC) arguments (the religiously-based set of beliefs that the Earth is 6,000 or so years old, evolution is false, and Noah's flood was a real event exactly as described in Genesis).  Here's an example.  At the time I thought it was important because of the widespread acceptance of these ideas (or some of these ideas) by a large portion of Americans and my belief in the importance of science literacy.

I've since mostly given up.  I still believe science is important and certainly think that YEC ideas are complete nonsense (and actually harmful in some ways).  The problem is that refuting these ideas gets you nowhere.  It takes time away from real work (I'm procrastinating right now as I write this) and you end up never convincing anyone.  YEC's don't believe the Earth is 6,000 years old because they've studied geology, they believe it because the Bible implies it (the age, of course, is nowhere directly stated, it's obtained through inference).  It's usually a waste of time to debate YEC's because their ideas, at their heart, are religious beliefs ultimately based on their views of scripture, and not science

 I'll also mention that Andrew Snelling, the author of the paper, appears to be a bit ethically-challenged, in my opinion, by having led two lives (at least in his past papers, I have no idea what he's up to today) - one as a mainstream geologist blithely publishing about billion-year-old rocks in Koongarrra without critical comment and the other as a young-earth creationist arguing in YEC publications and church lectures that the Earth is only 6000 years old according to those same rocks!  Here's an interesting article from The Skeptic.

Anyway, back to the paper...  From what I see (and I basically just skimmed it), Snelling essentially claimed in this paper that the Koongarra area of Australia, an economically-important uranium deposit, has been an open system with exchange of uranium (U) & lead (Pb) isotopes so that no meaningful U-Pb radiometric age can be determined from minerals there.

U-Pb dating works because different isotopes of uranium (atoms of the uranium come in different isotopes depending upon the number of neutrons in the nucleus of the atoms) will decay at constant rates to isotopes of lead.  For example, U-238 will decay to Pb-206 with a half-life of 4.47 billion years!  With sensitive instruments called mass-spectrometers, we can measure these isotopes and work out the ages of minerals contained in rocks.  The problem can come if the rocks act as open systems and allow exchange of U and Pb atoms into or out of the minerals which will monkey up your ages.  Geologists can usually tell, by careful examination of the regional geology and microscopic examination of the minerals, if this is a problem.

So Snelling claims in this paper that the Koongarra system was an open system.  He writes: "At the Koongarra uranium deposit, Australia, there is ample evidence of open system behavior, or repeated migration, of U and Pb..."  Then he argues that radiometric ages from this area are therefore unreliable.  The rest of the paper is detail supporting this.

This may well be true.  I know next to nothing about Koongarra and Snelling has studied it for years.  I can't really say if his conclusions are valid or not.  But, even if he is, so what?  Koongarra minerals are unreliable for radiometric dating because of open-system behavior.  Big deal.  This is not anything that would upset any ideas in geology (there are thousands of articles in the geologic literature about studies on the limitations on radiometric dating).

What's puzzling, however, is in Snelling's other life as a mainstream geologist (see The Skeptic article referenced above), he also wrote things like:

The oldest rocks in the Koongarra area, domes of granitoids and granitic gneiss, are of Archaean age [older than 2500 million years]. The Archaean rocks are mantled by Lower Proterozoic [younger than 2500 million years] metasediments: all were later buried deeply, heavily folded and, between 1870 and 1800 million years ago, were subjected to regional metamorphism at considerable temperatures and pressures.

Why would he say the ages are completely unreliable in a YEC publication and then speak of almost 2 billion-year-old rocks in a mainstream publication? The YEC publication even cites (Snelling, 1990) the mainstream publication in the References list without comment. It's bizzare. That's why I called him "ethically-challenged."

Anyway, let's take Snelling at his word (at least in the YEC journal paper) and agree that the Koonarra radiometric ages are not reliable because it was an open system.  That certainly doesn't support Snelling's grand conclusion at the end of the paper that:

Creationists should therefore not be intimidated by claims that U-Th-Pb radiometric “dating” has “proved” the presumed great antiquity of the earth, and the strata and fossils of the so-called geological column.

That's just nuts!  He cites one geologic deposit in Australia where groundwater alteration may have occurred making it difficult to get an accurate U-Pb radiometric age of mineralization and then extrapolates to tens of thousands of U-Pb radiometric ages from all over the Earth (and meteorites too) saying they have to be unreliable as well - and he's ignoring the K-Ar, Rb-Sr, Sm-Nd, etc. radiometric ages as well which all use different minerals and isotopes and techniques to derive ages.
 
There's no need for a detailed rebuttal of the paper (it doesn't even deserve a general rebuttal since it's an old paper in a creationist "journal" with no credibility to start with).  The basic premise of the paper is flawed - one example of where U-Pb radiometric dating may not be appropriate (arguably and not even a big deal) throws out centuries of geologic science.  Complete and utter nonsense.