<abstract xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">Electron Spin Resonance (ESR) dating of marine barite in chimneys deposited from hydrothermal vents was attempted to determine the time since hydrothermal activity occurred. In this study, we used Barite (BaSO4) precipitated in icroenvironments in the chimneys deposited from the hydrothermal vents at the Archaean site in South Mariana spreading centre (12°56.4'N, 143°37.9'E) and at Hakurei site in the Izena caldron (27°15'N, 127°04'E) for ESR measurements. ESR spectrum of marine barite is characterized by an electron-type centre with g values of 2.0034, 2.0022 and 1.9995 attributed to SO3-. The signal intensity increased with gamma ray dose. The dose rates of hydrothermal chimneys from the Archaean site and from the Hakurei site were calculated using a model that assumed a grain size and that incorporation of radionuclides after 226Ra in U series into the chimney, and assuming the efficiency of the defect formation by alpha particles to be the same as that for OSL. The ESR ages were estimated to be 470 years old for barite from the Archaean site and 5670 years old for one from the Hakurei site, although there is a considerable difference between the present ESR ages and the 210Pb/226Ra disequilibrium ages previously reported.</abstract>

Electron Spin Resonance (ESR) dating of marine barite in chimneys deposited from hydrothermal vents was attempted to determine the time since hydrothermal activity occurred. In this study, we used Barite (BaSO4) precipitated in icroenvironments in the chimneys deposited from the hydrothermal vents at the Archaean site in South Mariana spreading centre (12°56.4'N, 143°37.9'E) and at Hakurei site in the Izena caldron (27°15'N, 127°04'E) for ESR measurements. ESR spectrum of marine barite is characterized by an electron-type centre with g values of 2.0034, 2.0022 and 1.9995 attributed to SO3-. The signal intensity increased with gamma ray dose. The dose rates of hydrothermal chimneys from the Archaean site and from the Hakurei site were calculated using a model that assumed a grain size and that incorporation of radionuclides after 226Ra in U series into the chimney, and assuming the efficiency of the defect formation by alpha particles to be the same as that for OSL. The ESR ages were estimated to be 470 years old for barite from the Archaean site and 5670 years old for one from the Hakurei site, although there is a considerable difference between the present ESR ages and the 210Pb/226Ra disequilibrium ages previously reported.

ESR Dating of Marine Barite in Chimneys Deposited from Hydrothermal Vents

Department of Applied Physics, Okayama University of Science, 1-1 Ridai-cho, Kita-ku, Okayama 700-0005, Japan

Department of Earth and Planetary Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan

Earthquake Research Institute, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan

Geochronometria

{"article-title":"ESR Dating of Marine Barite in Chimneys Deposited from Hydrothermal Vents"}

Electron Spin Resonance (ESR) dating of marine barite in chimneys deposited from hydrothermal vents was attempted to determine the time since hydrothermal...

ESR Dating of Marine Barite in Chimneys Deposited from Hydrothermal Vents

Publié en ligne: 05 janv. 2011

Pages: 57 - 61

DOI: https://doi.org/10.2478/v10003-010-0019-z

Mots clés
marine barite, ESR, dating, hydrothermal chimney

This content is open access.

ESR Dating of Marine Barite in Chimneys Deposited from Hydrothermal Vents

Publié en ligne: 05 janv. 2011

Pages: 57 - 61

DOI: https://doi.org/10.2478/v10003-010-0019-z

Mots clésmarine barite, ESR, dating, hydrothermal chimney

This content is open access.

Mots clés
marine barite, ESR, dating, hydrothermal chimney