Parameterizations of calcic clinopyroxene—Melt trace element partition coefficients

Bédard, Jean H.

doi:10.1002/2013gc005112

Cited by 125 publications

(52 citation statements)

References 63 publications

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Section: Resultsmentioning

confidence: 99%

“…Liquid REE concentrations were calculated using the clinopyroxene/basalt partition coefficients [ Hauri et al ., ; Bédard , ]. The average phenocryst Al iv contents for the phenocrysts of Figure were used to determine clinopyroxene‐basalt partition coefficients from the equations in Bédard []. For both sets of partition coefficients, the LREE matched the whole‐rock and glass values [ Beier et al ., ; Nichols et al ., ], but the calculated liquids had slightly lower HREE concentrations than the whole‐rocks.…”

Section: Resultsmentioning

confidence: 99%

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Exploring the mineralogical heterogeneities of the Louisville Seamount Trail

Dorais

2015

Geochem Geophys Geosyst

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Diopside phenocrysts of the Louisville Seamount Trail show an increase in Ti, Al, and Na with decreasing Mg/(Mg + Fe) as is typical for clinopyroxene in alkalic basalts. Chondrite‐normalized REE patterns of calculated liquids from LA‐ICPMS analyses are comparable to whole‐rock and glass values. Exceptions are clinopyroxene crystals from the Rigil Seamount, the second oldest seamount drilled at the northern end of the chain. Some crystals from this site are strongly zoned with distinct compositional boundaries between cores and mantles. The cores have high Mg/(Mg + Fe) and low Al and Ti concentrations compared to the mantles and phenocrysts. Major element, clinopyroxene discrimination diagrams indicate that the clinopyroxene mantles and phenocrysts crystallized from alkalic basalts. In contrast, the Mg‐rich cores have tholeiitic affinities. The REE abundances of the cores are similar to that of clinopyroxene from transitional tholeiites of the Kerguelen Archipelago. Calculated liquid La/Yb values for the cores have ratios that are similar to transitional tholeiites in Hawaii, whereas the mantles have higher La/Yb values similar to Hawaiian alkalic basalts. The major and trace element compositions of clinopyroxene cores from the Rigil seamount suggest that a transitional tholeiitic magma was present, but no evidence for Hawaiian shield‐type tholeiites was found. Plagioclase crystals from the Rigil seamount have 86Sr/86Sr from 0.70306 to 0.70363, within the range of FOZO. The transitional tholeiitic signature of the Mg‐rich clinopyroxene cores probably did not have a distinct source compared to other Louisville magmas, but more likely indicates a higher degree of partial melting (2–5%) of that FOZO source.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Exploring the mineralogical heterogeneities of the Louisville Seamount Trail

Dorais

2015

Geochem Geophys Geosyst

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“…On one hand, we calculated H 2 O/Ce ratios based on the estimated magma water content (Table ) and the Ce content measured for the bulk rock [ Zeng et al , ]. On the other hand, we calculated the H 2 O/Ce ratio of the melt equilibrium with several specific cpx phenocrysts in the samples FYS10 and FYS07, based on the H 2 O and Ce concentrations in cpx phenocrysts and their partition coefficients (the partition coefficient for Ce is the average value of the results calculated from Equations 298, 302, 314 and 248 in Bédard (). The H 2 O partition coefficient is from Equation 10 in O'Leary et al []).…”

Section: Discussionmentioning

confidence: 99%

“…2 and 3, D Ce and D H2O are the partition coefficient of Ce and H 2 O between cpx and basaltic melts, which are calculated based on equation (10) in O'Leary et al . [] and equation (298), (302), (314), and (248) in Bédard []. 4, H 2 O/Ce ratio is calculated by ( C H2O cpx/ D H2O )/( C Ce / D Ce ).…”

Section: Discussionmentioning

confidence: 99%

Recycled oceanic crust and marine sediment in the source of alkali basalts in Shandong, eastern China: Evidence from magma water content and oxygen isotopes

et al. 2015

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The magma water contents and cpx δ18O values in alkali basalts from the Fuyanyshan (FYS) volcano in Shandong, eastern China, were investigated by an inverse calculation based on the water content of clinopyroxene (cpx) phenocrysts, the ivAlcpx‐dependent water partitioning coefficient Dwaternormalcnormalpnormalxtrue/melt, and secondary ion mass spectrometer, respectively. The calculated water content (H2O wt.) of magma ranges from 0.58% to 3.89%. It positively correlates with heavy rare earth element concentrations and bulk rock 87Sr/86Sr ratios, and it negatively correlates with Nb/U ratios. However, it is not correlated with bulk Mg# (Mg# = 100 × Mg / (Mg + Fe)) and (La/Yb)n (n represents primitive mantle normalization). Combined with the rather homogenous distribution of water content within cpx grains, these correlations indicate that the water variations among different samples represent the original magma signature, rather than results of a shallow process, such as degassing and diffusion. The δ18O of cpx phenocrysts varies from 3.6‰ to 6.3‰ (±0.5‰, 2SD), which may be best explained by the involvement of components from the lower and upper oceanic crust with marine sediments within the mantle source. The H2O/Ce ratios of the calculated melts range from 113 to 696 and form a positive trend with bulk rock 87Sr/86Sr, which cannot be explained by the recycled Sulu eclogite or by the metasomatized lithospheric mantle. Our modeling calculation shows that the decoupling of εHf and εNd could be caused by the involvement of marine sediments. Combing the high Ba/Th ratios, positive Sr spikes, and low Ce/Pb ratios for the Fuyanshan basalts, we suggest that the hydrous nature of the FYS basalts was derived from the hydrous mantle transition zone with ancient sediments.

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“…The range of REE compositions for melts calculated to be in equilibrium with the clinopyroxenes of the plagioclase‐bearing ultramafic rocks, using clinopyroxene/liquid partition coefficients from Bédard [], is shown in Figure . Using clinopyroxene/liquid partition coefficients from Lee et al .…”

Section: Petrology and Composition Of The Plagioclase‐bearing Ultramamentioning

confidence: 99%

Effect of melt/mantle interactions on MORB chemistry at the easternmost Southwest Indian Ridge (61°–67°E)

Paquet

Cannat

Brunelli

et al. 2016

Geochem Geophys Geosyst

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The easternmost part of the Southwest Indian Ridge (61°–67°E) is an end‐member of the global ridge system in terms of very low magma supply. As such, it is a good laboratory to investigate the effect of melt/mantle interactions on the composition of erupted basalts: for a given volume of erupted basaltic melt, the volume of reacted mantle is potentially greater than at more magmatically robust ridges. We analyzed major, trace element and isotopic compositions in three groups of rocks: plagioclase‐bearing ultramafic and gabbroic rocks dredged in nearly amagmatic spreading corridors; basalts from the sparse volcanic cover of these corridors (“ultramafic seafloor basalts”); and basalts dredged from the intervening, more volcanically active domains (“volcanic seafloor basalts”). Ultramafic seafloor basalts have significantly lower CaO and Al2O3 contents at a given MgO than most volcanic seafloor basalts. We propose that both types of basalts are derived from similar parental melts, but that the ultramafic seafloor basalts are more affected by reactions between these parent melts and the mantle rocks in the lithosphere below the ridge. We infer that these reactions occur in the walls of conduits that allow the aggregated melts extracted from the melting mantle to rise through the axial lithosphere and to the eruption sites. The principal effect of these reactions is to enrich the asthenospheric melts in MgO through olivine dissolution. This effect is not expected to be as noticeable, but could still play a role in basalt petrogenesis at more magmatic regions of the global slow‐spreading MOR system.

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Parameterizations of calcic clinopyroxene—Melt trace element partition coefficients

Cited by 125 publications

References 63 publications

Exploring the mineralogical heterogeneities of the Louisville Seamount Trail

Exploring the mineralogical heterogeneities of the Louisville Seamount Trail

Recycled oceanic crust and marine sediment in the source of alkali basalts in Shandong, eastern China: Evidence from magma water content and oxygen isotopes

Effect of melt/mantle interactions on MORB chemistry at the easternmost Southwest Indian Ridge (61°–67°E)

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