Anhydrous melting of peridotite at 0?15 Kb pressure and the genesis of tholeiitic basalts

Jaques, A. L.; Green, David H.

doi:10.1007/bf00381447

Cited by 960 publications

(374 citation statements)

References 73 publications

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“…Third, the mantle melts polybarically, so the constant pressure restriction of most phase diagrams does not hold. These theoretical considerations have been conclusively verified by recent experimental studies that show a wide range of melt compositions in equilibrium with lherzolite for a single bulk composition and a single pressure [e.g., Jaques and Green, 1980;Fujii and Scarfe, 1985;Takahashi and Kushiro, 1983;. It is nonetheless tempting to draw a pseudo-ternary diagram and use it in a classical manner to discuss mantle melting.…”

Section: Phase Diagramsmentioning

confidence: 76%

“…The chemical considerations are that some elements, such as Na20, strongly prefer the melt to the solid mantle, and hence their concentrations in mantle melts are roughly inversely proportional to the extent of melting [Jaques and Green, 1980;Dick et al, 1984]. Other elements, such as FeO, are sensitive to the pressure of melting, with higher pressures leading to higher FeO contents in the melt [Langmuir and Hanson, 1980].…”

Section: A Working Modelmentioning

confidence: 99%

“…Some experiments suggest that substantial melt is generated over a small temperature interval near the solidus [see Figure 2 in Jaques and Green, 1980]. Knowledge of the melting relationships near the solidus is quite limited because there are few experimental data between 0 and 15% melting.…”

Section: B Mantle Liquidusmentioning

confidence: 99%

“…Knowledge of the melting relationships near the solidus is quite limited because there are few experimental data between 0 and 15% melting. During progressive melting of peridotite, it appears that clinopyroxene disappears as a residual phase after about 20% melting [e.g., Jaques and Green, 1980;Hess, this volume]. The subcalcic clinopyroxenes that exist at higher pressure might last to considerably higher melt fractions, however.…”

Section: B Mantle Liquidusmentioning

confidence: 99%

“…In practice, technical difficulties limit the experimentalist to working only at moderate pressures and with large melt fractions in the charge. Existing data provide quite complete information on moderate extents of melting [e.g., Jaques and Green, 1980;Stolper, 1980;Fujii and Scarfe, 1985;Takahashi and Kushiro, 1983;Takahashi, 1986]. But there are virtually no data for the relatively small extents of melting that may be so important for understanding melting processes beneath the ridge.…”

Section: Experimental Constraints On the Compositional Variations Caumentioning

confidence: 99%

See 4 more Smart Citations

Petrological Systematics of Mid-Ocean Ridge Basalts: Constraints on Melt Generation Beneath Ocean Ridges

Langmuir

Klein

Plank

2013

Geophysical Monograph Series

664

390

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Mid-ocean ridge basalts (MORB) are a consequence of pressure-release melting beneath ocean ridges, and contain much information concerning melt formation, melt migration and heterogeneity within the upper mantle. MORB major element chemical systematics can be divided into global and local aspects, once they have been corrected for low pressure fractionation and interlaboratory biases. Regional average compositions for ridges unaffected by hot spots ("normal" ridges) can be used to define the global correlations among normalized Na20, FeO, TiO2 and Si02 contents, CaO/Al203 ratios, axial depth and crustal thickness. Back-arc basins show similar correlations, but are offset to lower FeO and TiO2 contents. Some hot spots, such as the Azores and Galapagos, disrupt the systematics of nearby ridges and have the opposite relationships between FeO, Na 20 and depth over distances of 1000 km.Local variations in basalt chemistry from slow-and fast-spreading ridges are distinct from one another. On slow-spreading ridges, correlations among the elements cross the global vector of variability at a high angle. On the fast-spreading East Pacific Rise (EPR), correlations among the elements are distinct from both global and slow-spreading compositional vectors, and involve two components of variation. Spreading rate does not control the global correlations, but influences the standard deviations of axial depth, crustal thickness, and MgO contents of basalts.Global correlations are not found in very incompatible trace elements, even for samples far from hot spots. Moderately compatible trace elements for normal ridges, however, correlate with the major elements. Trace element systematics are significantly different for the EPR and the mid-Atlantic Ridge (MAR). Normal portions of the MAR are very depleted in REE, with little variability; hot spots cause large long wavelength variations in REE abundances. Normal EPR basalts are significantly more enriched than MAR basalts from normal ridges, and still more enriched basalts can erupt sporadically along the entire length of the EPR. This leads to very different histograms of distribution for the data sets as a whole, and a very different distribution of chemistry along strike for the two ridges. Despite these differences, the mean Ce/Sm ratios from the two ridges are identical.Existing methods for calculating the major element compositions of mantle melts [Klein and Langmuir, 1987;McKenzie and Bickle, 1988;Niu and Batiza, 1991] are critically examined. New quantitative methods for mantle melting and high pressure fractionation are developed to evaluate the chemical consequences of melting and fractionation processes and mantle heterogeneity. The new methods rely on new equations for partition coefficients for the major elements between mantle minerals and melts. The melting calculations can be used to investigate the chemical compositions produced by small extents of melting or high pressures of melting that cannot yet be determined experimentally. Application of the new models to the ...

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Section: Phase Diagramsmentioning

confidence: 76%

Section: A Working Modelmentioning

confidence: 99%

Section: B Mantle Liquidusmentioning

confidence: 99%

Section: B Mantle Liquidusmentioning

confidence: 99%

Section: Experimental Constraints On the Compositional Variations Caumentioning

confidence: 99%

See 3 more Smart Citations

Petrological Systematics of Mid-Ocean Ridge Basalts: Constraints on Melt Generation Beneath Ocean Ridges

Langmuir

Klein

Plank

2013

Geophysical Monograph Series

664

390

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What processes control the chemical compositions of arc front stratovolcanoes?

Turner

Langmuir

2015

Geochem Geophys Geosyst

102

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Arc front stratovolcanoes have global chemical systematics that constrain processes at convergent margins. Positive correlations exist for arc averages among ''fluid mobile,'' ''high field strength,'' and ''large ion lithophile'' elements. 143 Nd/ 144 Nd and 87 Sr/ 86 Sr from rear-arc lavas lacking subduction signature align with the oceanic ''mantle array,'' and correlate with arc front 143 Nd/ 144 Nd. Most chemical parameters (but not isotopes) also correlate well with crustal thickness and slightly less well with the slab thermal parameter, but not with the depth of the slab nor model slab surface temperatures. Successful models of arc volcanism should account for these global regularities. Two distinct models can quantitatively account for the observationsdifferent extents of melting of the mantle wedge caused by variations in wedge thermal structure, or varying contributions from the subducting slab owing to variations in the slab thermal structure. Both successful model scenarios require a significant flux of melted ocean crust to the mantle source of all volcanic arcs. The wedge melting model has constant contributions from ocean crust, sediment, and mantle wedge to lavas globally, while the slab model varies slab contributions with slab temperature. The wedge melting model fit improves by incorporating convergence rate and slab dip, which should affect the wedge thermal structure; the slab model is not supported by a similar analysis. The wedge model also more easily accommodates the isotope data. The two models predict different primary H 2 O contents, with large variations in H 2 O for the wedge model, and relatively constant H 2 O for the slab model. An evaluation of the effects of varying sediment compositions on arc lavas will benefit from considering the very different consequences of the two models.

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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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Anhydrous melting of peridotite at 0?15 Kb pressure and the genesis of tholeiitic basalts

Cited by 960 publications

References 73 publications

Petrological Systematics of Mid-Ocean Ridge Basalts: Constraints on Melt Generation Beneath Ocean Ridges

Petrological Systematics of Mid-Ocean Ridge Basalts: Constraints on Melt Generation Beneath Ocean Ridges

What processes control the chemical compositions of arc front stratovolcanoes?

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

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