Phase relations and melting of nominally ‘dry’ residual eclogites with variable CaO/Na2O from 3 to 5 GPa and 1250 to 1500 °C; implications for refertilisation of upwelling heterogeneous mantle

Rosenthal, Anja; Yaxley, Gregory M.; Crichton, Wilson A.; Kovàcs, István; Spandler, Carl; Hermann, Jörg; Sándorné, Judit K.; Rose-Koga, Estelle; Pelleter, Anne-Aziliz

doi:10.1016/j.lithos.2018.05.025

Cited by 11 publications

(8 citation statements)

References 65 publications

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“…Alternatively, by the time peridotite begins to melt, pyroxenite G2 might melt to ~100% and at this stage, melt of pyroxenite reacts with peridotite to form a hybrid enriched peridotite lithology. Indeed, Rosenthal et al (2018) note that in upwelling heterogenous mantle domains, siliceous eclogitic melts will react with encapsulating mantle peridotite, effectively refertilising it and producing hybrid pyroxene-and garnet-rich rocks.…”

Section: Melting Mixed Peridotite-pyroxenite Lithologiesmentioning

confidence: 99%

Magmatism in the North Atlantic Igneous Province; mantle temperatures, rifting and geodynamics

Hole

Natland

2020

Earth-Science Reviews

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We have re-evaluated mantle potential temperature estimates for the North Atlantic Igneous Province (NAIP). Temperature estimates involving olivine addition to pillow-lava glasses are unreliable because host glasses formed along the liquid+olivine+plagioclase cotectic and not just the olivine liquidus. Additionally, magma chamber processes can generate picritic lavas containing only magnesian olivine, but picrites alone do not require high mantle temperatures. Furthermore, petrological models tend to overestimate TP in picrites containing appreciable accumulative olivine further confusing the issue. Selected aphyric lavas from West Greenland, which cannot have accumulated olivine, suggest maximum TP~1500°C. Petrological models for Icelandic glasses suggest a maximum TP~1450° C which is consistent with olivine-melt and olivine-spinel equilibration temperatures. However, melting of 'damp' peridotite beneath Iceland would reduce this estimate perhaps by 50°C. The NAIP mantle was lithologically and chemically heterogeneous and was made of a hybrid pyroxenite-peridotite lithology, the pyroxenite component being derived from recycling of subducted slabs. However, there is no necessity for the subducted slabs to have been recycled to the core-mantle boundary. Pyroxenite could have been derived from Caledonian-aged slabs that also hosted helium with high 3 He/ 4 He within the shallow mantle, which was inherited by Palaeocene or young melts. The pyroxenite component was more readily fusible than the peridotite component under the same P-T conditions, allowing variations in melt production rate throughout the province. Melting of lithologically variable mantle is consistent with observed radiogenic isotope variability in Icelandic basalts and related trace-element variations in throughout the NAIP. We propose that magmatism in the NAIP resulted from extensional tectonics above 'warm' mantle that had been internally heated beneath thick continental lithosphere prior to continental break up. Only in areas of extension did magmatism occur, thus explaining the apparently widespread initial phase of magmatic activity.

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Section: Melting Mixed Peridotite-pyroxenite Lithologiesmentioning

confidence: 99%

Magmatism in the North Atlantic Igneous Province; mantle temperatures, rifting and geodynamics

Hole

Natland

2020

Earth-Science Reviews

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“…In addition, Figure 4 shows that the D Coe Al and D Coe Ti from Wang and Takahashi (1999) and Rosenthal et al (2018) are exceedingly smaller than those constrained by us at similar P-T conditions. The abundances of these elements in both studies were quantified by the EMP technique so that their accuracies were limited.…”

Section: Coementioning

confidence: 66%

Experimental constraints on trace element partitioning between coesite and hydrous silicate melt at 5 GPa and 1500–1750°C

Yan

Liu

Sun

et al. 2021

Sci. China Earth Sci.

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Trace element partitioning between coesite and hydrous silicate melt has been investigated at 5 GPa and 1500−1750°C. High-P experiments successfully produced large coesite crystals in equilibrium with large silicate melt pools (plus kyanite and corundum crystals in some cases). Scanning electron microscopy and micro-Raman spectroscopy were employed to characterize the phases and the textures. Wavelength-dispersive electron microprobe analyses were performed to quantify conventional major elements, and laser ablation-inductively coupled plasma-mass spectrometry analyses were successfully conducted to quantify trace elements. Eventually, high-P partition coefficients were obtained for 33 elements. In general coesite is a very pure phase. With a few possible exceptions like Sc, Ti, and V, nearly all other trace elements are incompatible in coesite. Moreover, the partitioning behaviors of nearly all trace elements except some 4+ cations cannot be readily described by the lattice strain model, presumably implying a minor role for the cation size in the trace-element partitioning. Combining our experimental results with the results in the literature, some T and P effects on the element partitioning behavior have been observed: T seemingly has different effects on different trace elements, but P might negatively correlate with the partition coefficients in all cases. Due to its large modal fraction in some subducted materials such as the continental crustal material, coesite might play an important role in the distributions of some trace elements, Ti for example.

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“…The results of this study strongly support the hypothesis that hybrid mantle heterogeneities such as Px1 may contribute to refertilization of the Earth's mantle. Starting from a deep peridotite-dominated mantle enclosing eclogites or pyroxenites, mantle refertilization results from a complex series of processes (e.g., Spandler et al, 2008;Rosenthal et al, 2018). Mantle heterogeneities undergo dynamic and polybaric transformation mostly driven by multiple episodes of partial melting and interactions with the surrounding mantle.…”

Section: Composition Of Pyroxenite-derived Melts At 2 Gpa and Their Rmentioning

confidence: 99%

“…Their partial melts are expected to react with the surrounding peridotite either modifying the composition of the rising melts (Pilet et al, 2008;Mallik and Dasgupta, 2012 or creating new hybrid rocks, called secondary or stage 2 pyroxenites (e.g., Yaxley and Green, 1998;Sobolev et al, 2005Sobolev et al, , 2007Herzberg, 2006Herzberg, , 2011Lambart et al, 2012). Heterogeneous upwelling mantle is subject to continuous events of partial melting and melt-rock reactions that potentially replace the mafic components with a compositionally wide range of hybrid lithologies, including metasomatized peridotites and variably residual pyroxenites (e.g., Yaxley and Green, 1998;Spandler et al, 2008;Rosenthal et al, 2014Rosenthal et al, , 2018. Petrological studies on ultramafic massifs have interpreted some pyroxenites embedded in mantle peridotite as natural examples of secondary pyroxenites, originated through high-pressure melt-peridotite reactions (i.e., Garrido and Bodinier, 1999;Bodinier et al, 2008;Gysi et al, 2011;Marchesi et al, 2013;Borghini et al, 2013Borghini et al, , 2016Borghini et al, , 2019Montanini and Tribuzio, 2015).…”

Section: Introductionmentioning

confidence: 99%

Melting relations of anhydrous olivine-free pyroxenite Px1 at 2&#8201;GPa

Borghini¹,

Fumagalli²

2020

Eur. J. Mineral.

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Abstract. The reaction between melt derived by mafic heterogeneities and peridotites in an upwelling mantle may form hybrid olivine-free pyroxenites. In order to evaluate the impact of these lithologies on the chemistry of primitive magmas and their ability to give rise to new mantle heterogeneities, we experimentally investigate the melting relations at 2 GPa of the model olivine-free pyroxenite Px1 (XMg=0.81, SiO2=52.9 wt %, Al2O3 = 11.3 wt %, CaO = 7.6 wt %). The subsolidus assemblage consists of clinopyroxene, orthopyroxene, and garnet. At 2 GPa, the solidus of Px1 is located between 1250 and 1280 ∘C, at a temperature about 70 ∘C lower than the solidus of fertile lherzolite. At increasing melt fraction, the sequence of mineral phase disappearance is garnet–clinopyroxene–orthopyroxene. Across the solidus, partial melting of Px1 is controlled by reaction garnet + clinopyroxene = liquid + orthopyroxene, and above 1300 ∘C, once garnet is completely consumed, by reaction clinopyroxene + orthopyroxene = liquid. Orthopyroxene is the liquidus phase, and at 1480 ∘C olivine-free pyroxenite Px1 is completely molten indicating a melting interval of about 200 ∘C. Isobaric melt productivity is similar to garnet clinopyroxenites, and it is more than 3 times that of a fertile lherzolite at 1400 ∘C. Px1 partial melts cover a wide range of XMg (0.57–0.84), with SiO2, Al2O3 and Na2O decreasing and Cr2O3 increasing with the degree of melting. CaO content in partial melts increases as long as clinopyroxene is involved in melting reactions and decreases after its exhaustion. At 2 GPa and for melting degrees higher than 10 %, Px1 produces MgO-rich basaltic andesites matching the composition of eclogitic melts in terms of silica and alkali contents but with significantly higher XMg values. These melts differ from those derived from lherzolites at 2 GPa by higher SiO2 and lower CaO contents. Their high silica activity makes them very reactive with mantle peridotite producing hybrid orthopyroxene-rich lithologies and residual websterites. Melt–rock reactions likely prevent direct extraction of melts produced by olivine-free pyroxenites.

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Phase relations and melting of nominally ‘dry’ residual eclogites with variable CaO/Na2O from 3 to 5 GPa and 1250 to 1500 °C; implications for refertilisation of upwelling heterogeneous mantle

Cited by 11 publications

References 65 publications

Magmatism in the North Atlantic Igneous Province; mantle temperatures, rifting and geodynamics

Magmatism in the North Atlantic Igneous Province; mantle temperatures, rifting and geodynamics

Experimental constraints on trace element partitioning between coesite and hydrous silicate melt at 5 GPa and 1500–1750°C

Melting relations of anhydrous olivine-free pyroxenite Px1 at 2&#8201;GPa

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Phase relations and melting of nominally ‘dry’ residual eclogites with variable CaO/Na2O from 3 to 5 GPa and 1250 to 1500 °C; implications for refertilisation of upwelling heterogeneous mantle

Cited by 11 publications

References 65 publications

Magmatism in the North Atlantic Igneous Province; mantle temperatures, rifting and geodynamics

Magmatism in the North Atlantic Igneous Province; mantle temperatures, rifting and geodynamics

Experimental constraints on trace element partitioning between coesite and hydrous silicate melt at 5 GPa and 1500–1750°C

Melting relations of anhydrous olivine-free pyroxenite Px1 at 2&amp;#8201;GPa

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Phase relations and melting of nominally ‘dry’ residual eclogites with variable CaO/Na2O from 3 to 5 GPa and 1250 to 1500 °C; implications for refertilisation of upwelling heterogeneous mantle

Melting relations of anhydrous olivine-free pyroxenite Px1 at 2 GPa