Helium isotopes on the Pacific-Antarctic ridge 52.5°–41.5°SReportar como inadecuado

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1 IPGP - Institut de Physique du Globe de Paris 2 LDO - Domaines Océaniques 3 GM - Unité de recherche Géosciences Marines Ifremer

Abstract : The first isotopic data and concentrations of helium are reported for the Pacific-Antarctic ridge between 52.5°S and 41.5°S. The 4He-3He ratio is extremely homogeneous over more than 1200 km, with a mean ratio of 99,275 R-Ra = 7.29 and a standard deviation of 2719 0.19, which is the lowest dispersion observed for the global mid oceanic ridge system. Moreover, the Menard T.F. is a frontier between two mantles with slightly different helium isotopic ratios 96,595 ± 1520 and 100,347 ± 2330. No difference in the helium concentration between the two ridge segments defined by the Menard T.F. can be observed, as well as no significant difference in the U and Th contents suggesting that the difference in helium isotopic ratio is old >500 My and may represent a slight difference in degassing or-and trace element depletion history

Keywords : helium isotopes mantle geochemistry Pacific-Antarctic ridge

Autor: A. Moreira Manuel - Laure Dosso - Hélène Ondréas -

Fuente: https://hal.archives-ouvertes.fr/


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