Helium isotopes on the Pacific-Antarctic ridge (52.5°–41.5°S)

Type Article
Date 2008-05
Language English
Author(s) Moreira M1, Dosso Laure2, Ondreas Helene3
Affiliation(s) 1 : Univ Paris Diderot, Inst Phys Globe, Equipe Geochim & Cosmochim, F-75005 Paris, France.
2 : IFREMER, CNRS, UMR6538, F-29280 Plouzane, France.
3 : CNRS, UMR7154, F-75005 Paris, France.
Source Geophysical Research Letters (0094-8276) (American Geophysical Union), 2008-05 , Vol. 35 , N. 10 , P. NIL_49-NIL_54
DOI 10.1029/2008GL033286
WOS© Times Cited 18
Keyword(s) Pacific Antarctic ridge, mantle geochemistry, helium isotopes
Abstract The first isotopic data and concentrations of helium are reported for the Pacific-Antarctic ridge between 52.5 degrees S and 41.5 degrees S. The He-4/He-3 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.
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