ESR dating of barite taking into account the contribution from extinct ²²⁸Ra to the equivalent doses.

The conventional ESR ages of two barite samples, in which ²²⁸Ra was not detected, were 973 and 357 years. After correction for the possible contribution of extinct ²²⁸Ra and its daughters, the age differences were only about 2 years. This indicates that the contribution of ²²⁸Ra is negligible in practice unless the initial ²²⁸Ra/²²⁶Ra ratio in particularly high. However, it is still necessary to investigate further if the fluid ratio may vary spatially or temporally.