One of the creationist claims for a young Earth is that Helium is found in Zircons, which are dated to be over 100,000 years old. They say no Helium should be left because it would have diffused out of the rock or fossil. In a rock containing Uranium, wouldn't Helium continue to be produced even to this day? Why is this not an argument against the presence of Helium indicating a young Earth? The arguments I read concern themselves with the diffusion of Helium, not its continued production.
$\begingroup$
$\endgroup$
Add a comment
|
1 Answer
$\begingroup$
$\endgroup$
Any mineral grain that contained original atoms of U-238 (the most common natural Uranium isotope) will accumulate 8 Helium atoms for each atom of Uranium before that individual atom reaches stability as Lead in particular Pb-206. The first decay in the long chain from U-238 to Pb-206, U-238 to Thorium (Th-234) has a half-life of 4,468,000,000 years, that's about as long as we think the world has been around, that transition produces 1 Helium atom per Uranium atom involved. There is a constant production of Helium inside Zircons. As Uranium is the only element in the decay chain that will be incorporated into Zircon as it forms this means that we can count the Helium or the daughter isotopes (which is the more usual approach) in order to work out the age of formation so any Helium diffusion would make no difference whatsoever.