Start Sm nd dating method

Sm nd dating method

All members of this group have similar chemical properties and...

The initial or primordial ratio of must be determined from other dating methods.

At some time in the past there was a melting event causing the fractionation of Rb into the melt which then forms crustal material.

As time goes by that Rb decays to Sr and the radiogenic Sr is enriched in the crust but depleted in the mantle.

This value is based on the weighted average of four direct counting determinations in the period 1961–1970 and the recalibration in the 1970s of Sm-Nd model ages of two meteorites by forcing them (essentially by circular reasoning) to agree with their Pb-Pb isochron and model ages.