Radiometric dating of rocksfossils

In case the significance of these results is ignored, a few sentences from the Gale “ …it is not widely appreciated, outside the ranks of those who work directly in geochronology or meteoritics that, judged by modern standards, the meteoritic lead-lead isochron is very poorly established.

However, it is even more surprising to learn that the lead isotope ratios chosen by Patterson Most meteorites have lead isotope ratios similar to those of present day common lead.The values they assumed were based on the lead isotope ratios observed for three meteorites.Since meteorites have not proved to be the ancient objects from the sky that one might imagine, it is surprising that they should be assumed to give the primordial lead composition on Earth.Up until 1972 these could be explained as being contaminated with radiogenic lead from uranium and thorium decay.In 1972, however, Gale showed unequivocally that there is by no means sufficient uranium and thorium to account for what could previously have been called radiogenic lead.

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