ABSTRACT
Chronometryhas been successfully applied to geochemical systems [1]. For instance, under the assumption that actinides are incorporated into zircons while the lead isotopes are not, the Pb concentration can be used to determine the age of azircon crystal, sensitive to time scales on the order of the age of the earth. In mixed-lanthanide minerals, an enhanced concentration of 143Nd relative to the other Nd Isotopes can be attributed to the αdecay of primordial 1×1011-year 147Sm over geological time scales.
