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Science 2 January 2004:
Vol. 303. no. 5654, pp. 70 - 72
DOI: 10.1126/science.1090266
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Reports

Osmium Isotope Heterogeneity in the Constituent Phases of Mid-Ocean Ridge Basalts

Abdelmouhcine Gannoun,1* Kevin W. Burton,1 Louise E. Thomas,1 Ian J. Parkinson,1 Peter van Calsteren,1 Pierre Schiano2

Radiogenic isotope variations in mid-ocean ridge basalts (MORB) are commonly attributed to compositional variations in Earth's upper mantle. For the rheniumosmium isotope system, constituent MORB phases are shown to possess exceptionally high Re/Os (parent/daughter) ratios, consequently radiogenic 187Os is produced from the decay of 187Re over short periods of time. Thus, in the absence of precise age constraints, Os isotope variations cannot be unambiguously attributed to their source, although Re–Os isotope data for constituent minerals can yield crystallization ages, details of equilibration, and initial Os isotope values that relate directly to the mantle source.

1 Department of Earth Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK.
2 Laboratoire Magmas et Volcans, Université Blaise-Pascal, 5 Rue Kessler, 63038 Clermont-Ferrand, France.

* To whom correspondence should be addressed. E-mail: a.gannoun{at}open.ac.uk

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Asthenospheric signature in fertile spinel lherzolites from the Viliga Volcanic Field in NE Russia.
T. Ntaflos, C. Tschegg, M. Coltorti, V. V. Akinin, and J. Kosler (2008)
Geological Society, London, Special Publications 293, 57-81
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