Dating of sedimentary rocks
From a creationist perspective, the 1997–2005 RATE (Radioisotopes and the Age of The Earth) project successfully made progress in documenting some of the pitfalls in the radioisotope dating methods, and especially in demonstrating that radioisotope decay rates may not have always been constant at today’s measured rates (Vardiman, Snelling, and Chaffin 2000, 2005).Yet much research effort remains to be done to make further inroads into not only uncovering the flaws intrinsic to these long-age dating methods, but towards a thorough understanding of radioisotopes and their decay during the earth’s history within a biblical creationist framework.Various methods have been devised to determine this initial or common Pb, but all involve making unprovable assumptions.Zircon does incorporate initial Pb when it crystallizes. It cannot be proven that the Pb in apparently cogenetic U- or Th-free minerals is only initial Pb, and that it is identical to the initial Pb in the mineral being dated.However, even uncertainties of only 1% in the half-lives lead to very significant discrepancies in the derived radioisotope ages.The recognition of an urgent need to improve the situation is not new (for example, Min et al. It continues to be mentioned, at one time or another, by every group active in geo- or cosmochronology (Boehnke and Harrison 2014; Schmitz 2012).Nor can the measured Pb isotope ratios be used to somehow decide what proportions of them are the initial Pb without recourse to unprovable assumptions about the mineral or rock’s history or their interpreted U-Th-Pb ages within an assumed deep time history.
The uncertainties associated with direct half-life determinations are, in most cases, still at the 1% level, which is still significantly better than any radioisotope method for determining the ages of rock formations.Once radioactive decay of U and Th started after creation, daughter Pb isotopes were added inside the earth.Then catastrophic plate tectonics during the Flood stirred the mantle and via partial melting added new rocks to the crust.However, problems remain in the interpretation of the measured Pb isotopic ratios to transform them into ages.Among them is the presence of non-radiogenic Pb of unknown composition, often referred to as common or initial Pb.