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.

The stunning improvements in the performance of mass spectrometers during the past four or so decades, starting with the landmark paper by Wasserburg et al.

However, from a biblical perspective the earth was created by God on Day 1 of the Creation Week before the sun and the rest of the solar system were created on Day 4, all only about 6000 or so years ago.

Yet the earth would still have had an initial (created) Pb isotopic endowment.

U decay in those rocks added daughter Pb isotopes to the common or initial Pb isotopes in them, inherited from the rock’s sources.

So the Pb isotope ratios measured in these rocks today must be interpreted before their U-Pb ages can be calculated.

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).

The decay of Pb, respectively, forms the basis for one of the oldest methods of geochronology (Dickin 2005; Faure and Mensing 2005).

While the earliest studies focused on uraninite (an uncommon mineral in igneous rocks), there has been intensive and continuous effort over the past five decades in U-Pb dating of more-commonly occurring trace minerals.

Zircon (Zr Si O) in particular has been the focus of thousands of geochronological studies, because of its ubiquity in felsic igneous rocks and its claimed extreme resistance to isotopic resetting (Begemann et al. However, accurate radioisotopic age determinations require that the decay constants or half-lives of the respective parent radionuclides be accurately known and constant in time.