Solution behavior of reduced N–H–O volatiles in FeO–Na2O–SiO2–Al2O3 melt equilibrated with molten Fe alloy at high pressure and temperature

Кадик, А. А.; Litvin, Yu. A.; Колташев, В. В.; Kryukova, E. B.; Плотниченко, В. Г.; Tsekhonya, T. I.; Кононкова, Н. Н.

doi:10.1016/j.pepi.2012.10.013

Cited by 39 publications

(22 citation statements)

References 59 publications

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“…18), but is greater under reducing conditions. When conditions are more reducing than those defined by the IW buffer, the nitrogen solubility does, though, continue to increase with increasing hydrogen fugacity (decreasing oxygen fugacity) (Kadik et al 2011(Kadik et al , 2013(Kadik et al , 2015; see also Fig. 18) similar to that observed at ambient pressure in the absence of hydrogen (Fig.…”

Section: He Nesupporting

confidence: 51%

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Nitrogen in the Earth: abundance and transport

Mysen

2019

Prog Earth Planet Sci

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The terrestrial nitrogen budget, distribution, and evolution are governed by biological and geological recycling. The biological cycle provides the nitrogen input for the geological cycle, which, in turn, feeds some of the nitrogen into the Earth's interior. A portion of the nitrogen also is released back to the oceans and the atmosphere via N 2 degassing. Nitrogen in silicate minerals (clay minerals, mica, feldspar, garnet, wadsleyite, and bridgmanite) exists predominantly as NH 4 +. Nitrogen also is found in graphite and diamond where it occurs in elemental form. Nitrides are stable under extremely reducing conditions such as those that existed during early planetary formation processes and may still persist in the lower mantle. From experimentally determined nitrogen solubility in such materials, the silicate Earth is nitrogen undersaturated. The situation for the core is more uncertain, but reasonable Fe metal/silicate nitrogen partition coefficients (> 10) would yield nitrogen contents sufficient to account for the apparent nitrogen deficiency in the silicate Earth compared with other volatiles. Transport of nitrogen takes place in silicate melt (magma), water-rich fluids, and as a minor component in silicate minerals. In melts, the N solubility is greater for reduced nitrogen, whereas the opposite appears to be the case for N solubility in fluids. Reduced nitrogen species (NH 3 , NH 2 − , and NH 2 +) dominate in most environments of the modern Earth's interior except the upper~100 km of subduction zones where N 2 is the most important species. Nitrogen in magmatic liquids in the early Earth probably was dominated by NH 3 and NH 2 − , whereas in the modern Earth, the less reduced, NH 2 + functional group is more common. N 2 is common in magmatic liquids in subduction zones. Given the much lower solubility of N 2 in magmatic liquids compared with other nitrogen species, nitrogen dissolved as N 2 in subduction zone magmas is expected to be recycled and returned to the oceans and the atmosphere, whereas nitrogen in reduced form(s) likely would be transported to greater depths. This solubility difference, controlled primarily by variations in redox conditions, may be a factor resulting in increased nitrogen in the Earth's mantle and decreasing abundance in its oceans and atmosphere during the Earth's evolution. Such an abundance evolution has resulted in the decoupling of nitrogen distribution in the solid Earth and the hydrosphere and atmosphere.

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Section: He Nesupporting

confidence: 51%

“…The Mysen et al 2008). b Data at oxygen fugacity below that of the IW buffer (data from Kadik et al 2011Kadik et al , 2013Kadik et al , 2015 2000 2500 3000 3500…”

Section: He Nementioning

confidence: 99%

Nitrogen in the Earth: abundance and transport

Mysen

2019

Prog Earth Planet Sci

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“…However, considering that nitrogen solubility in reduced silicate melt ranges up to a few wt. % (Kadik et al, 2011(Kadik et al, , 2013Roskosz et al, 2013) and only a few hundred ppm nitrogen was present in our silicate melt, partial crystallisation during quench may not have caused exsolution of nitrogen. The observed systematic dependence of D N metal/silicate on oxygen fugacity ( Fig.…”

Section: Resultsmentioning

confidence: 84%

“…Figure 1 shows that regardless of pressure or temperature, D N metal/silicate increases with increasing oxygen fugacity, as calculated from the composition of the coexisting quenched metal and silicate (Table S-1). The trend in Figure 1 can be rationalised if one assumes that under these very reducing conditions below the iron-wüstite buffer, nitrogen is mostly dissolved as N 3-ion in the silicate melt (Kadik et al, 2011(Kadik et al, , 2013Li et al, 2015), while it dissolves as interstitial N atoms in the metal (Häglund et al, 1993 Figure 1. We noticed that the silicates recovered from the multi-anvil experiments performed at 5.0 to 7.0 GPa were not completely glassy, but contained fine-grained quench crystals.…”

Section: Resultsmentioning

confidence: 99%

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Nitrogen isotope fractionation during terrestrial core-mantle separation

Li¹,

Marty²,

Shcheka³

et al. 2016

Geochem. Persp. Let.

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doi: 10.7185/geochemlet.1614The origin and evolution of the terrestrial nitrogen remains largely unresolved. In order to understand the potential influence of core-mantle separation on terrestrial nitrogen evolution, experiments were performed at 1.5 to 7.0 GPa and 1600 to 1800 °C to study nitrogen isotope fractionation between coexisting liquid Fe-rich metal and silicate melt. The results show that the metal/silicate partition coefficient of nitrogen D N metal/silicate ranges from 1 to 150 and the nitrogen isotope fractionation d15 N metal-silicate is −3.5 ± 1.7 ‰. Calculations show that the bulk Earth is more depleted in d 15 N than the present-day mantle, and that the presentday mantle d 15 N of −5 ‰ could be derived from an enstatite chondrite composition via terrestrial core-mantle separation, with or without the addition of carbonaceous chondrites. These results strongly support the notion that enstatite chondrites may be a main component from which the Earth formed and a main source of the terrestrial nitrogen. Moreover, in the deep reduced mantle, the Fe-rich metal phase may store most of the nitrogen, and partial melting of the coexisting silicates may generate oceanic island basalts (OIBs) with slightly positive d15 N values.

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