ESR dating of barite in sulphide deposits formed by the sea-floor hydrothermal activities

Toyoda, Shin; Fujiwara, Taisei; Uchida, Ai; Ishibashi, Jun Ichiro; Nakai, S.; Takamasa, Asako

doi:10.1093/rpd/ncu136

Cited by 8 publications

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“…As discussed by Toyoda et al (2014), microscopic observation revealed that sulfide minerals with various size and various occurrence fill the spaces among barite crystals, suggesting repeated stages of mineralization, which starts with sulfate precipitation and followed by sulfide precipitation. Thus the samples would consist of minerals in various ages.…”

Section: Resultsmentioning

confidence: 86%

“…Assuming that Ra is populated only in barite as confirmed by Okumura et al (2010), the internal and external dose rates of alpha, beta and gamma rays given to the barite minerals were calculated (Toyoda et al 2014). The alpha effectiveness of 0.043 was adopted (Toyoda et al 2012).…”

Section: Methodsmentioning

confidence: 99%

“…It is the most important feature of hydrothermal barite in the aspect of dose rate estimation that the only source of the radiation is internal radium (Okumura et al 2010;Toyoda et al 2014). The dose rate was calculated from the concentrations of radium and its daughter nuclei as the following.…”

Section: The Dose Rate Conversion Factors and The Decay Corrections Fmentioning

confidence: 99%

“…The newest dose rate conversion factors, which are to be multiplied to the concentrations of U, Th, K to obtain dose rate, were reported by Guérin et al (2011) for U and Th in radioactive equilibrium and for K together with the contributions of each nucleus in the decay chains. Toyoda et al (2014) obtained the dose rate conversion factors from their table for 226 Ra only in the case of radioactive equilibrium. By summing up the energy contributions of the nuclei in the chains listed in Guérin et al (2011), the dose rate conversion factors for 226 Ra and 228 Ra were calculated so that the dose rate can be obtained in the case of radioactive disequilibrium as shown in Table 29.2.…”

Section: The Dose Rate Conversion Factors and The Decay Corrections Fmentioning

confidence: 99%

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ESR Dating of Barite in Sea-Floor Hydrothermal Sulfide Deposits in the Okinawa Trough

Fujiwara

Toyoda

Uchida

et al. 2014

Subseafloor Biosphere Linked to Hydrothermal Systems

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ESR (electron spin resonance) ages were determined for barite crystals extracted from hydrothermal sulfide deposits taken at Daiyon-Yonaguni Knoll field, Hatoma Knoll field, Iheya North Knoll field, Hakurei Site of Izena Hole field, Yoron Hole field of the Okinawa Trough. The ages range from 4.1 to 16,000 years, being consistent with detection of 228 Ra in younger samples and radioactive equilibrium/disequilibrium between radium and daughter nuclei. The variation of the ages within each sample is mostly within the statistical error range. The relative order of the ages is consistent with the result of 226 Pb method, but the determining absolute ages is still an issue. The order of ages of the 5 hydrothermal fields would be arranged, from young to old as follows; Yoron Hole field, Daiyon-Yonaguni Knoll field, Hatoma Knoll field, being nearly equal to Iheya North Knoll field. KeywordsBarite Dating Electron spin resonance Hydrothermal activities IntroductionThere have been many scientific efforts devoted for studies on active sea-floor hydrothermal fields found in Okinawa Trough (Ishibashi et al. Chap. 23). The evolution of these hydrothermal fields is one of the important issues. Dating methods have been employed for hydrothermal sulfide deposits, such as the U-Th disequilibrium method (e.g. You and Bickle 1998) applicable for the age range more than several thousand years, and 226 Pb and 228 Th method (e.g. Noguchi et al. 2011) for the range less than 150 years. The age range of several hundred years is essential to estimate the life time of hydrothermal activities. However, dating methods for the age range are lacking. Okumura et al. (2010) made the first practical application of ESR dating technique to a sample of seafloor hydrothermal barite to obtain ages of 300 and 3,620 years, while Kasuya et al. (1991) first pointed out that barite can be used for ESR dating. Toyoda et al. (2011) determined the optimum ESR condition while Sato et al. (2011) confirmed that the signal is thermally stable enough for an age range of several thousand years.Seafloor massive sulfide deposits are composed of sulfide minerals such as pyrite, sphalerite, chalcopyrite and galena, and also include sulfate minerals such as anhydrite and barite. The sulfate minerals precipitate by mixing of hydrothermal fluid and seawater, while the sulfide minerals precipitate from the hydrothermal fluid mainly by cooling (Hannington et al. 1995). It is generally considered that a combination and/or switch of these two modes of hydrothermal precipitation lead to growth of sulfide structures such as a chimney and mound and that of large hydrothermal T. Fujiwara S. Toyoda (*) A. Uchida Okayama University of Science, Okayama, Japan e-mail: toyoda@dap.ous.ac.jp deposits (e.g. Tivey 2007). Takamasa et al. (2013) determined ESR ages for barite in sulfide deposits in the South Mariana Trough hydrothermal field, and concluded that the ages are consistent with U-Th ages. In this study, the ages of various hydrothermal sulfides in the Okinawa Trough a...

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Section: Resultsmentioning

confidence: 86%

Section: Methodsmentioning

confidence: 99%

Section: The Dose Rate Conversion Factors and The Decay Corrections Fmentioning

confidence: 99%

Section: The Dose Rate Conversion Factors and The Decay Corrections Fmentioning

confidence: 99%

See 2 more Smart Citations

ESR Dating of Barite in Sea-Floor Hydrothermal Sulfide Deposits in the Okinawa Trough

Fujiwara

Toyoda

Uchida

et al. 2014

Subseafloor Biosphere Linked to Hydrothermal Systems

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“…They showed that the ESR ages are roughly consistent with the U-Th ages. While Toyoda et al (2014) discussed several detailed technical issues such as the dose rate conversion factors, the sample edge effect for gamma ray dose, and the correction for the decay of 226 Ra, Fujiwara et al (2015) made the first practical systematic dating work with ESR on barite of sea-floor hydrothermal sulfide deposits taken at Okinawa Trough on total of 18 samples (60 subsamples) with new formulas which take the radioactive disequilibrium of Ra daughter nuclei into account. The obtained ages range 4 to 16000 years, showing that the ESR method has a wide application age range.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2016

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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 228 Ra 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 228 Ra content is not obtained. The method to estimate the contribution from 228 Ra series has to be developed in future for those in which 228 Ra is not detected. The age limit of ESR dating of barite would be 5000 to 6000 years due to the decay of 226 Ra, which is also found by simulation of the accumulated dose.

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Immediate Change of Radiation Doses from Hydrothermal Deposits

Toyoda

Sato

Uchida

et al. 2014

Subseafloor Biosphere Linked to Hydrothermal Systems

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The radiation from the sulfide deposits taken at Okinawa Trough was measured on-board by a NaI gamma ray spectrometer immediately after the retrieval of the sample onto the research vessel. Gamma ray peaks were identified as those from daughter nuclei of 226 Ra and 228 Ra. The slight change with time of the radiation dose from those deposits is probably due to the geometric arrangement in measurements. As results, no change in radiation dose was observed in the time range up to 90 h after retrieval of the samples from the submarine vehicle.

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ESR dating of barite in sulphide deposits formed by the sea-floor hydrothermal activities

Cited by 8 publications

References 8 publications

ESR Dating of Barite in Sea-Floor Hydrothermal Sulfide Deposits in the Okinawa Trough

ESR Dating of Barite in Sea-Floor Hydrothermal Sulfide Deposits in the Okinawa Trough

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

Immediate Change of Radiation Doses from Hydrothermal Deposits

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