Consider some molten rock in which isotopes and elements are distributed in a reasonably homogeneous manner.
Therefore, the Y-intercept of the isochron line gives the initial global ratio of could be subtracted out of each sample, and it would then be possible to derive a simple age (by the equation introduced in the first section of this document) for each sample.
Unfortunately, one must wade through some hefty math in order to understand the procedures used to fit isochron lines to data.
General comments on "dating assumptions" All radiometric dating methods require, in order to produce accurate ages, certain initial conditions and lack of contamination over time.
Each such age would match the result given by the isochron.
Gain or loss of In order to make the figures easy to read (and quick to draw), the examples in this paper include few data points.