Evidence from hafnium isotopes for ancient sub-oceanic mantle beneath the Rio Grande rift
Article Abstract:
The hafnium (Hf) and neodymium isotope compositions for 25 lavas from the Rio Grande rift in the southwestern United States were determined. These samples were derived from the upwelling asthenosphere and represent the entire range of Sr, Nd and Pb isotope compositions that have been identified for the mantle in this particular rift. The results showed that the rift samples have Nd and Hf isotope ratios that are significantly less than the ocean-island Nd-Hf array. These results suggest that the sample are derived from the ancient asthenospheric mantle that melted at shallow levels beneath the oceans.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1993
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Two mantle-plume components in Hawaiian picrites inferred from correlated Os-Pb isotopes
Article Abstract:
The osmium and lead isotopic compositions which form linear, negative arrays in the picritic Hawaiian lavas indicate the mixing of two mantle-plume components. The two mantle components have similar bulk compositions and are isotopically distinct. The plumes have their origin in the deep mantle. The Hawaiian picrites have contributions from primitive mantle. None of the models used in the study give a complete picture of the composition of the lavas.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1996
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Evidence from Re-Os isotopes for plume-lithosphere mixing in Karoo flood basalt genesis
Article Abstract:
The relative abundance of isotopes of osmium in the flood basalt of Karoo indicates that this material is a mixture of sub-continental lithospheric mantle and sub-lithospheric material from a mantle plume. This finding reconciles geochemical data on the possible regions of magma source with physical models of magma plumes.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1992
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