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Titolo:
Hf isotope geochemistry of the Galapagos Islands
Autore:
Blichert-Toft, J; White, WM;
Indirizzi:
Ecole Normale Super Lyon, Lab Sci Terre, F-69364 Lyon 7, France Ecole Normale Super Lyon Lyon France 7 Sci Terre, F-69364 Lyon 7, France Cornell Univ, Dept Geol Sci, Ithaca, NY 14853 USA Cornell Univ Ithaca NY USA 14853 niv, Dept Geol Sci, Ithaca, NY 14853 USA Univ Bretagne Occidentale, IUEM, F-29280 Plouzane, France Univ Bretagne Occidentale Plouzane France F-29280 29280 Plouzane, France
Titolo Testata:
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
, volume: 2, anno: 2001,
pagine: NIL_1 - NIL_23
SICI:
1525-2027(20010928)2:<NIL_1:HIGOTG>2.0.ZU;2-J
Fonte:
ISI
Lingua:
ENG
Soggetto:
COLLECTOR ICP-MS; MANTLE PLUMES; OCEANIC BASALTS; DEPLETED MANTLE; PB; EVOLUTION; HELIUM; SR; ND; ARCHIPELAGO;
Keywords:
hafnium isotope ratios; Galapagos Islands; oceanic island basalts; isotope evolution of the mantle; mantle plumes;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
43
Recensione:
Indirizzi per estratti:
Indirizzo: Blichert-Toft, J Ecole Normale Super Lyon, Lab Sci Terre, F-69364 Lyon 7, France Ecole Normale Super Lyon Lyon France 7 4 Lyon 7, France
Citazione:
J. Blichert-Toft e W.M. White, "Hf isotope geochemistry of the Galapagos Islands", GEOCH GEO G, 2, 2001, pp. NIL_1-NIL_23

Abstract

[1] We report Hf-176/Hf-177 ratios determined by multicollector inductively coupled plasma mass spectrometry on 49 basalts from the Galapagos Islands. The epsilon (Hf) values range from about +8, a value typical of many oceanic island basalts, to about +15, a value typical of mid-ocean ridge basalt. The epsilon (Hf) shows the expected correlation with epsilon (Nd) and inverse correlations with Sr and Pb isotope ratios. The range of values and correlations observed is consistent with Galapagos mantle plume-asthenospheremixing inferred from previous geochemical studies. While oceanic island basalt isotopic arrays suggest that multicomponent mixing is common in the sources of such basalts, the Galapagos is unusual in that depleted upper mantle appears to be a principal component. Thermal and dynamic interaction between the Galapagos mantle plume and the lithosphere and shallow asthenosphere is the most likely cause of mixing and of the geographic pattern of geochemical variation. The Galapagos Hf-Nd-Sr-Pb isotopic array diverges towardthe "plume" end, indicating the plume is heterogeneous. This heterogeneityis geographic, with distinct northern, central, and southern components. The central component and, to a lesser degree, the northern component are compositionally similar to the "common component" of plumes (variously calledPHEM, FOZO, and "C"), while the southern component is unique with relatively high epsilon (Hf) and Pb-206/Pb-204 compared Sr-87/Sr-86 and \epsilon (Nd).

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Documento generato il 05/04/20 alle ore 13:07:34