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钐-钕(Sm-Nd)同位素研究可用来评价地壳生长的历史,有时可给出反映壳幔分异时间的“地壳形成”年龄。然而,如果一个样品是不同时期来源于地幔的物质的混合物,那么Sm-Nd同位素分馏系列可能只提供该样品中的物质存留于大陆壳内的平均时间估计值。在这些情况下,Sm-Nd同位素不给出地壳形成年龄的直接信息。这些年龄只有在得到了其他地质和地质年代信息的支持后才可解释为壳幔分离的时间。错误的解释会导致对地壳发育得出错误的结论。
Sama-neodymium (Sm-Nd) isotope studies can be used to evaluate the history of crustal growth and sometimes provide “crustal” ages that reflect crust-mantle divergence times. However, the Sm-Nd isotopic fractionation series may only provide an estimate of the mean time for the material in the sample to remain in the continental crust if one sample is a mixture of materials from the mantle at different times. In these cases, Sm-Nd isotopes do not give direct information on the age at which the crust is formed. These ages can only be explained by the time of crust-mantle separation only with the support of other geological and geochronological information. Wrong interpretation leads to wrong conclusions about crustal development.