ESR (electron spin resonance) dating method has beenapplied to calcite, aragonite, hydroxyapatite, quartz andgypsum. Recently it was shown that this method is alsopractically applicable to barite, especially those in sea-floorhydrothermal sulfide deposits (Takamasa et al., 2013).ESR, 226Ra-210Pb, and 228Ra-228Th ages were determined forbarite crystals extracted from hydrothermal sulfide depositstaken at hydrothermal fields at the Okinawa Trough. The agesrange 4.1 to 16000 years where the ages obtained by the threemethods coincide in some of the samples while the 228Ra-228Thages are the youngest and ESR ages, the oldest and the 226Ra- 210Pb ages in between in the other samples. The samples withyounger ESR ages show younger 226Ra-210Pb ages and thosewith older ESR ages show older 226Ra-210Pb ages with nodetection of 228Ra. The inconsistency of the ages between thesemethods would be explained by the mixture of the baritecrystals with younger and older ages, formed by severalhydrothermal activities. The order of ages of the 5hydrothermal fields would be arranged, from young to old asfollows; Yoron Hole field, Daiyon-Yonaguni Knoll field,Hatoma Knoll field, being nearly equal to Iheya North Knollfield．Goldschmidt201
