Irma Appora

California Institute of Technology

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Edward M. Stolper

California Institute of Technology

Catherine Deniel

Laboratoire Magmas et Volcans

John M. Eiler

California Institute of Technology

Philippe Vidal

Identités et Différenciation de l'Environnement des Espaces et des Sociétés

Bernard Marty

Centre de Recherches Pétrographiques et Géochimiques

Alan Matthews

Hebrew University of Jerusalem

Jean‐Alix Barrat

Centre National de la Recherche Scientifique

Pierre Vellutini

Marien Ngouabi University

Cooperative Institutions

Centre National de la Recherche Scientifique

California Institute of Technology

Planetary Science Institute

Hebrew University of Jerusalem

University of Chicago

Institut de Recherche pour le Développement

Université de Bretagne Occidentale

Institut Universitaire de France

Geological Society of America

Arizona State University

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He, Ar, Sr, Nd and Pb isotopes in volcanic rocks from Afar: Evidence for a primitive mantle component and constraints on magmatic sources.

GEOCHEMICAL JOURNAL (1993)

Bernard Marty Irma Appora Jean‐Alix Barrat Catherine Deniel Pierre Vellutini

He, Ar, Sr, Nd and Pb isotopic ratios have been determined for a set of submarine basaltic glasses from the Gulf of Tadjoura and subaerial lavas from Afar, Republic of Djibuti. Rare gases were recovered by vacuum crushing and analysed with a new analytical system. Helium isotopic ratios up to 15 Ra show the occurrence of a "high 3He" hot spot beneath Afar and indicate the occurrence of a plume originating from a gas-rich, presumably deep, region of the mantle. He-Ar isotope systematics indicate a mixing between three geochemical end-members: the plume component, enriched in 3He, a radiogenic, possibly crustal, component, and the atmosphere. Low 40Ar/36Ar ratios are interpreted as the result of selective atmospheric contamination of Afar magmas, but the process of contamination is unclear. In a He-Sr-Nd-Pb space, Afar data are plotted in a field similar to basic lavas emitted in Iceland (Djibuti territory) and in the Reykjanes Ridge (Gulf of Tadjoura) and differ by their He isotopic ratios from lavas emitted in EM (e.g., Gough and Tristan da Cunha) and HIMU (e.g., Saint Helena and Tubuaii) hot spots analysed so far.

Mantle plume

Radiogenic nuclide

Subaerial

10.2343/geochemj.27.219

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Citations (65)

Experimental determination of oxygen isotope fractionations between CO2 vapor and soda-melilite melt

Geochimica et Cosmochimica Acta (2003)

Irma Appora John M. Eiler Alan Matthews Edward M. Stolper

Melilite

Anorthite

Melt inclusions

10.1016/s0016-7037(02)01090-6

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Citations (43)