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U-series dating of speleothems is also addressed, to allow for expanded discussion of the issues involved in obtaining and interpreting U-series dates of fossil coral reefs.The chapter also overviews how U-series dating in sea-level applications is carried out, including the basic theory behind the method, field techniques, assessment of sample integrity, data reporting, and relevant considerations for data interpretation.Of the four isotopes of lead, two are formed from the uranium isotopes and one is formed from the thorium isotope; only lead-204 is not known to have any long-lived radioactive progenitor.Primordial lead is thought to have been formed by stellar nuclear reactions, released to space by supernovae explosions, and incorporated within the dust cloud that constituted the primordial solar system; the troilite (iron sulfide) phase of iron meteorites contains lead that approximates the primordial composition.To me it has been a real eye opener to see all the processes that are taking place and their potential influence on radiometric dating.Radiometric dating is largely done on rock that has formed from solidified lava.The Earth can be assumed to be a very large sample containing lead evolving from primordial lead by radiogenic increments.

This belief in long ages for the earth and the existence of life is derived largely from radiometric dating.Consequently the ages obtained are minimum ages (terminus ante quem) which are frequently much younger than the real ages of the underlying artworks.Moreover, a much more serious but rarely considered source of error contradicts the assumption of a closed system., method of establishing the time of origin of a rock by means of the amount of common lead it contains; common lead is any lead from a rock or mineral that contains a large amount of lead and a small amount of the radioactive progenitors of lead— isotope thorium-232.The important characteristic of common lead is that it contains no significant proportion of radiogenic lead accumulated since the time that the mineral or rock phase was formed.

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