The assumption has been that the parent (U) and daughter (lead, Pb) remain locked in the tight crystal lattices of zircon, so that mineralogists can accurately measure ratios of the elements resulting from radioactive decay.That assumption has been called into question by a new paper just published in .First, the impact: Our findings have important implications for the use of zircon as a geochronometer, and highlight the importance of deformation on trace element redistribution in minerals and engineering materials.
I further revised my essay on November 24, 2005 to reply to Humphreys (2005a) and again on July 25, 2006 in response to Humphreys (2006).
Humphreys (2008b) even admits that his critics not only include secular scientists, but a diverse group of young- and old-Earth creationists, including members of the American Scientific Affiliation (ASA).
In particular, Humphreys (2008a) criticizes the religious diversity of ASA and briefly responds to criticism of his helium diffusion study from Isaac (2007, 2008a, 2008b). Loechelt applied multi-domain diffusion models to Dr Humphreys' and R. Gentry's data, which raise many new arguments that further undermine Dr. Loechelt (2008a; 2008b), which are at the old-Earth creationist Reasons to Believe website, are brief and less technical summaries of Loechelt (2008c).
For example, the reliable use of the mineral zircon (Zr Si O4) as a U-Th-Pb geochronometer and trace element monitor requires minimal radiogenic isotope and trace element mobility.
Here, using atom probe tomography, we document the effects of crystal–plastic deformation on atomic-scale elemental distributions in zircon revealing sub-micrometre-scale mechanisms of trace element mobility.