ESR dating of sea-floor hydrothermal barite: contribution of ²²⁸Ra to the accumulated dose

Electron spin resonance (ESR) dating of barite has been recently developed and is now practically applied to barite extracted from sea-floor hydrothermal deposits. The evolution of the accumulated dose to barite is simulated for an actual sample of barite in sea-floor hydrothermal sulfide deposit to find that the contribution of radioactive nuclei of ²²⁸Ra series can be important for the samples younger than 300 years old. Currently, any date over 50 years should be considered a maximum value when the ²²⁸Ra content is not obtained. The method to estimate the contribution from ²²⁸Ra series has to be developed in future for those in which ²²⁸Ra is not detected. The age limit of ESR dating of barite would be 5000 to 6000 years due to the decay of ²²⁶Ra, which is also found by simulation of the accumulated dose.