Jim Mason made no reference to the Concordia line and I could not find any reference to the Concordia line on any articles on the CMI website, even though it is well known (e.g. Jim raised the issue of Helium concentrations in Zircon.This is interesting, but it was not discussed at the meeting and I do not know how Justin would respond.
He was invited to our meeting as a guest speaker solely for his expertise on radioactive dating. He often goes on field trials dating rocks in various regions of the Australian outback.
He has equipment at the University of Adelaide and does the dating analysis himself.
Uniformitarians assume magmas crystallized slowly over millions of years under conditions of thermodynamic equilibrium.
However, the biblical scenario suggests magmas crystallized quickly, and anticipates non-equilibrium conditions, and this would affect the way lead would have been incorporated in the zircon crystals.
Geologists now recognize that granites formed very rapidly, which is consistent with the biblical scenario.
As I pointed out in the article, when the isotopic abundances are being measured very near time zero and the half-life of the radioactive parent is very long, then even a small amount of radiogenic daughter being present at time zero will result in a large erroneous ‘age’ calculation.
However, sedimentary rocks can be age dated if a volcanic ash horizon or a diabase sill or dyke can be found within the sequence.
For example, if you find a dinosaur bone in a sedimentary sequence and you find an ash layer 10 meter above the bone and another ash layer 20 meters below it, you can determine the age of the two ash layers.
The other point that Justin made was that the dating for Uranium/Lead can be derived from 3 sources: U238 decay, U235 decay and the lead isotope ratio.