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Article Dans Une Revue Geochimica et Cosmochimica Acta Année : 2004

source enrichment processes reponsible for isotopic anomalies in oceanic island basalt

Dan Mckenzie*
  • Fonction : Auteur
Andreas Stracke
  • Fonction : Auteur
Francis Albarède
Karl Grönvold
  • Fonction : Auteur
R. Keith O'Nions
  • Fonction : Auteur

Résumé

A new method has been developed to separate the compositional variations in ocean island basalts into those that result from variations in source composition and from the melting process itself. The approach depends on correlations between isotope ratios, which can only come from source inhomogeneities, and elemental concentrations. Analysis of three data sets shows that the inhomogeneities beneath Theistareykir, in NE Iceland, Kilauea and Pitcairn can be produced by subduction of oceanic islands and volcanic ridges. The thicknesses of the lithosphere on which such islands were constructed and potential temperatures of the plumes that produced them can be estimated from the geochemical observations. Model ages are harder to determine, though simple assumptions give about 400 Ma for the Theistareykir source and 1.2 Ga for Kilauea. The model may also provide a physical explanation for the commonly used isotopic classification of ocean island basalts, with the isotopic composition changing from HIMU through EMII to EMI as the melt fraction increases. These results have been obtained from a small number of data sets obtained from ocean island basalts erupted in small areas during short time intervals. More such observations are needed to discover whether geochemical observations from other islands are consistent with the same model.

Domaines

Géochimie

Dates et versions

hal-00102033 , version 1 (28-09-2006)

Identifiants

Citer

Dan Mckenzie*, Andreas Stracke, Janne Blichert-Toft, Francis Albarède, Karl Grönvold, et al.. source enrichment processes reponsible for isotopic anomalies in oceanic island basalt. Geochimica et Cosmochimica Acta, 2004, 68, pp.2699-2724. ⟨10.1016/j.gca.2003.10.029⟩. ⟨hal-00102033⟩
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