Rare earth element partitioning between minerals from anhydrous spinel peridotite xenoliths

Stosch, H.-G.

doi:10.1016/0016-7037(82)90031-x

Cited by 157 publications

(56 citation statements)

References 46 publications

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“…The V-shaped REE patterns have often been observed for terrestrial olivine or dunites in al pine peridotites (Frey, 1969;Frey et al, 1971), ultramafics associated with ophiolites (Suen et al, 1979;Pallister and Knight, 1981), ocean floor peridotites (Frey, 1984), ultramafic inclusions (Tanaka and Aoki, 1981), and ultramafic xenolith (Kurat et al, 1980;Stosch, 1982). These authors presented possible interpretations for the V-shaped REE patterns and the interpretations are summa rized as follows; (a) sources with high LREE/ HREE ratios relative to chondritic pattern, (b) LREE enrichment by alteration and metasomatism, and (c) LREE enrichment in fluid inclusion in olivine or at the grain surface.…”

Section: Element Partitioning Between Olivine and Silicate Meltmentioning

confidence: 93%

Experimental study of major and trace element partitioning among olivine,metallic phase and silicate melt using chondrite as starting material:Implication for V-shaped REE patterns of the pallasite meteorites.

1998

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The partition coefficients of rare earth elements (REE) and Sr between olivine and silicate melt and those of Ga, In and TI between metallic phase and silicate melt were experimentally determined under atmospheric pressure using L6 chondrite (ALH-76009) as a starting material. Temperature and oxygen fugacity were finely controlled; temperature = 1320, 1370, 1420 and 1440°C and oxygen fugacity = 0.5, 1.0, 1.5 and 2.0 log units lower than the Fe-FeO boundary on the iron-oxygen phase diagram.Olivine formed at 1320°C shows REE partition patterns with horizontal or heavy-REE-enriched features, having partition coefficients from 0.02 to 0.08. Inclination of light-REE increases with increase of tem perature of olivine formation. Finally, at the temperature of 1440°C near the liquidus of the chondrite, olivine/liquid partitioning of REE displays a V-shaped feature with partition coefficients of 0.15-0.8 for La, 0.08-0.3 for Lu and 0.05-0.09 for Dy and Er. The V-shaped REE patterns are known to be characteristic of olivine in the main group pallasites, for which our REE results imply the formation at higher tempera tures near the liquidus of olivine. Our results of major element partitioning also support the idea that such pallasites were formed at a temperature near the liquidus. Experiments of this study show that compositions of olivine formed at 1440°C are Fa8-Fa13 comparable to those of the main group pallasites, while those formed at 1320°C are Fa15-Fa18.The REE concentrations in the ferrous olivine of two pallasites, Springwater (Fa18 ,o) and Eagle Station (Fa20.0), were determined here. It was found that their chondrite-normalized REE patterns also show V shaped features, as observed for the olivine of the main group pallasites, the Brenham (Fa12 .5) and Thiel Mts. (Fa13.0) pallasites. These results suggest that the olivines of Springwater and Eagle Station were also formed at temperatures near liquidus around 1450°C. The difference in major element compositions between the main group pallasites (Brenham and Thiel Mts.) and the other pallasites (Springwater and Eagle Station) may be due to differences in major element compositions of their sources, oxygen fugacity at their formation and/or the cooling history of the pallasites. In the last case, it is reasoned that at lower temperatures (e.g., ca. 1300°C), Fe and Ni in olivine of non-main group pallasites were reequilibrated with those in the metal phases, but V-shaped REE patterns were retained because the diffusibility of REE is lower than those of Fe and Ni. The main group pallasites are considered to be free from the lower temperature reequilibrium processes.

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Section: Element Partitioning Between Olivine and Silicate Meltmentioning

confidence: 93%

Experimental study of major and trace element partitioning among olivine,metallic phase and silicate melt using chondrite as starting material:Implication for V-shaped REE patterns of the pallasite meteorites.

1998

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“…Heavy REE ( . The model assumes equilibration in the spinel stability field, but spinel was neglected because of the very low partitioning of REE in this mineral [Stosch, 1982]. Melting proportions were adjusted to match the modal composition of residual peridotites proposed by Kostopoulos [1991, This [nodel is similar to the previous one, except that LREE-enriched melt with ocean island basalt (OIB) composition is continuously infiltrated at base of the column.…”

Section: Melting and Fluid-rock Reactions Without Fluid Transportmentioning

confidence: 99%

A plate model for the simulation of trace element fractionation during partial melting and magma transport in the Earth's upper mantle

Vernieres¹,

Godard²,

Bodinier³

1997

J. Geophys. Res.

183

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Abstract. We propose a new plate model for the simulation of trace element transfer during magmatic and metasomatic processes taking place in the Earth's upper mantle. As in previously published plate models, porous flow is accounted for by propagation of fluid batches through macrovolumes of mantle rocks. Being released from spatiotemporal constraints, the plate model allows much more freedom than the one-dimensional porous-flow models for the simulation of fluid-rock interactions. Hence this approach may account for a wide range of mantle processes, including melt extraction during compaction of molten peridotites, porous flow associated with chromatographic effects, or fluid-rock reactions occurring upon melt infiltration at the base of the conductive mantle. The applications presented in this study show several results consistent with published trace element data for mantle rocks and basaltic volcanism. In particular, the proposed models may provide simple explanations for (1) the ultrarare-earth-element-depleted composition of peridotites and interstitial melts residual after mid-ocean ridge basalt extraction, (2) the negative correlation between light rare earth element / heavy rare earth element (LREE/HREE) ratio and refractory character of peridotites, as observed in several suites of mantle rocks, and (3) the origin of ultra-LREE-enriched metasomatic fluids infiltrated in the lithospheric mantle.

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“…As found by other analyzers of ultrabasic rocks (e.g., Prinzhofer and Allègre, 1985), the chrome spinels resisted dissolution and left a small black residue in all cases. However, the chrome spinels have the lowest REE concentrations of minerals in ultramafic rocks (Stosch, 1982) and make up less than 1% of the peridotites. This residue is unlikely to have had any significant effect on the bulk-rock concentrations.…”

Section: Bulk-rock Analysesmentioning

confidence: 99%

Trace Element Geochemistry of Peridotites from the Izu-Bonin-Mariana Forearc, Leg 125

Parkinson¹,

Pearce²,

Thirlwall³

et al. 1992

Proceedings of the Ocean Drilling Program

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Trace element analyses (first-series transition elements, Ti, Rb, Sr, Zr, Y, Nb, and REE) were carried out on whole rocks and minerals from 10 peridotite samples from both Conical Seamount in the Mariana forearc and Torishima Forearc Seamount in the Izu-Bonin forearc using a combination of XRF, ID-MS, ICP-MS, and ion microprobe. The concentrations of incompatible trace elements are generally low, reflecting the highly residual nature of the peridotites and their low clinopyroxene content (<2%). Chondrite-normalized REE patterns show extreme U shapes with (La/Sm) n ratios in the range of 5.03-250.0 and (Sm/Yb) n ratios in the range of 0.05-0.25; several samples show possible small positive Eu anomalies. LREE enrichment is common to both seamounts, although the peridotites from Conical Seamount have higher (La/Ce) n ratios on extended chondrite-normalized plots, in which both REEs and other trace elements are organized according to their incompatibility with respect to a harzburgitic mantle. Comparison with abyssal peridotite patterns suggests that the LREEs, Rb, Nb, Sr, Sm, and Eu are all enriched in the Leg 125 peridotites, but Ti and the HREEs exhibit no obvious enrichment. The peridotites also give positive anomalies for Zr and Sr relative to their neighboring REEs. Covariation diagrams based on clinopyroxene data show that Ti and the HREEs plot on an extension of an abyssal peridotite trend to more residual compositions. However, the LREEs, Rb, Sr, Sm, and Eu are displaced off this trend toward higher values, suggesting that these elements were introduced during an enrichment event. The axis of dispersion on these plots further suggests that enrichment took place during or after melting and thus was not a characteristic of the lithosphere before subduction.Compared with boninites sampled from the Izu-Bonin-Mariana forearc, the peridotites are significantly more enriched in LREEs. Modeling of the melting process indicates that if they represent the most depleted residues of the melting events that generated forearc boninites they must have experienced subsolidus enrichment in these elements, as well as in Rb, Sr, Zr, Nb, Sm, and Eu. The lack of any correlation with the degree of serpentinization suggests that low-temperature fluids were not the prime cause of enrichment. The enrichment in the high-field-strength elements also suggests that at least some of this enrichment may have involved melts rather than aqueous fluids. Moreover, the presence of the hydrous minerals magnesio-hornblende and tremolite and the common resorption of orthopyroxene indicate that this high-temperature peridotite-fluid interaction may have taken place in a water-rich environment in the forearc following the melting event that produced the boninites. The peridotites from Leg 125 may therefore contain a record of an important flux of elements into the mantle wedge during the initial formation of forearc lithosphere. Ophiolitic peridotites with these characteristics have not yet been reported, perhaps because the precise equiva...

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Rare earth element partitioning between minerals from anhydrous spinel peridotite xenoliths

Cited by 157 publications

References 46 publications

Experimental study of major and trace element partitioning among olivine,metallic phase and silicate melt using chondrite as starting material:Implication for V-shaped REE patterns of the pallasite meteorites.

Experimental study of major and trace element partitioning among olivine,metallic phase and silicate melt using chondrite as starting material:Implication for V-shaped REE patterns of the pallasite meteorites.

A plate model for the simulation of trace element fractionation during partial melting and magma transport in the Earth's upper mantle

Trace Element Geochemistry of Peridotites from the Izu-Bonin-Mariana Forearc, Leg 125

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