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| Detailed Reference Information |
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Chazot, G., Menzies, M.A. and Harte, B. (1996). Determination of partition coefficients between apatite, clinopyroxene, amphibole, and melt in natural spinel lherzolites from Yemen: Implications for wet melting of the lithospheric mantle. Geochimica et Cosmochimica Acta 60(3): 423-437. doi: 10.1016/0016-7037(95)00412-2. |
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Plio-Quaternary basaltic volcanic fields along the south coast of Yemen contain mantle xenoliths of anhydrous and metasomatized amphibole-(+/- apatite) bearing spinel Iherzolites. Partial melting of clinopyroxene and/or amphibole in a closed system produced silicate glass from which new clinopyroxene, olivine, and spinel have crystallized. Partition coefficients between mineral phases in the matrix and particularly those (apatite, clinopyroxene, amphibole) formed during the metasomatic event, and between glass and the new clinopyroxene crystallized from it have been calculated by analyzing trace element composition with an ion microprobe. Partition coefficients between apatite and clinopyroxene or amphibole are large (e.g., much greater than 1)for the REEs, Ba, Sr, Y, and Hf and confirm that apatite, when present in the mantle, is an important repository for these elements. On the other hand, partitioning between amphibole and clinopyroxene is very close to unity for most of the analyzed trace elements, except for Ba, Nb, Zr, and Hf. Trace element ratios such as Zr/Nb, Ba/Zr, or Ba/Nb can thus be used in basaltic rocks to assess the presence of amphibole in their mantle sources. Partition coefficients between clinopyroxene and melt are within the range of published values for most of the analyzed elements, with some low values for Zr (e.g., 0.030-0.353) and near unity for the HREE. Using partition coefficients between amphibole and clinopyroxene and D-cpx/melt from the literature, we calculate the partitioning of trace elements between amphibole and a basaltic melt. The D-amp/melt Obtained are lower than most of the published values, but are in good agreement with recent values measured in experiments at 1.5 GPa and 1100 degrees C. The partition coefficient for Nb between amphibole and melt is always low (<0.20), which indicates that residual amphibole during partial melting in hydrated mantle (amphibole-bearing peridotite) cannot account for Nb depletion in are magmas. |
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Sample Description |
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Analytical Techniques |
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Keywords
trace-elements, high-pressure, crystallization, series, sr, metasomatism, xenoliths, basalts, liquid, rocks |
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Publisher
Elsevier Science
P.O. Box 211
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The Netherlands
(+31) 20 485 3757
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