Nitrogen solubility in molten metal and silicate at high pressure and temperature

Roskosz, Mathieu; Bouhifd, Mohamed Ali; Jephcoat, A. P.; Marty, Bernard; Mysen, Bjørn O.

doi:10.1016/j.gca.2013.07.007

Cited by 117 publications

(131 citation statements)

References 62 publications

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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: 83%

“…15 N values down to −25 ‰ and −40 ‰ observed in a few mantle diamonds are interpreted to be relicts of primordial nitrogen and are used to argue for an enstatite chondrite origin of Earth's nitrogen (Javoy, 1997;Palot et al, 2012;Cartigny and Marty, 2013 A significant fraction of nitrogen may have been segregated into the core during core-mantle separation (Roskosz et al, 2013). However, so far the potential influence of core-mantle separation on Earth's mantle nitrogen isotope evolution has never been investigated.…”

Section: Introductionmentioning

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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Section: Resultsmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Nitrogen isotope fractionation during terrestrial core-mantle separation

Li¹,

Marty²,

Shcheka³

et al. 2016

Geochem. Persp. Let.

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“…The organics can derive in part from the dense ISM before stellar birth, but also can be created inside the gas-rich disk. Based on models and observations, disk chemistry and transport can imprint variable C/N ratios (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12) in ices comparable to those of comets and primitive meteorites. During the stages of planetesimal formation when bodies grow to large sizes (greater than tens of kilometers), impact processing and thermal metamorphism can lead to greater disparity in the C/N content of preplanetary material (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Both C and N are moderately to highly soluble in molten Fe-rich alloy (8,9,39) and comparatively insoluble in silicate (40)(41)(42). Thus, much of the Earth's initial C and N inventories likely segregated to its metallic core or were released to the atmosphere.…”

Section: C/n-forming Terrestrial Worldsmentioning

confidence: 99%

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Tracing the ingredients for a habitable earth from interstellar space through planet formation

Bergin

Blake

Ciesla

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

165

175

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We use the C/N ratio as a monitor of the delivery of key ingredients of life to nascent terrestrial worlds. Total elemental C and N contents, and their ratio, are examined for the interstellar medium, comets, chondritic meteorites, and terrestrial planets; we include an updated estimate for the bulk silicate Earth (C/N = 49.0 ± 9.3). Using a kinetic model of disk chemistry, and the sublimation/condensation temperatures of primitive molecules, we suggest that organic ices and macromolecular (refractory or carbonaceous dust) organic material are the likely initial C and N carriers. Chemical reactions in the disk can produce nebular C/N ratios of ∼1-12, comparable to those of comets and the low end estimated for planetesimals. An increase of the C/N ratio is traced between volatile-rich pristine bodies and larger volatile-depleted objects subjected to thermal/accretional metamorphism. The C/N ratios of the dominant materials accreted to terrestrial planets should therefore be higher than those seen in carbonaceous chondrites or comets. During planetary formation, we explore scenarios leading to further volatile loss and associated C/N variations owing to core formation and atmospheric escape. Key processes include relative enrichment of nitrogen in the atmosphere and preferential sequestration of carbon by the core. The high C/N bulk silicate Earth ratio therefore is best satisfied by accretion of thermally processed objects followed by large-scale atmospheric loss. These two effects must be more profound if volatile sequestration in the core is effective. The stochastic nature of these processes hints that the surface/atmospheric abundances of biosphereessential materials will likely be variable.terrestrial worlds | elements | interstellar medium | comets | meteorites T he development of a habitable world and a stable biosphere requires the delivery of biogenic elements of which carbon and nitrogen are crucial. Carbon is the backbone for the chemistry of life and, in the form of CO 2 , combines with water to provide the greenhouse needed for a habitable Earth. Nitrogen is a key component of DNA, RNA, and proteins, while also present as the dominant constituent of our atmosphere. The processes that supply these crucial ingredients remain poorly understood. In interstellar space, C and N are abundant, but inherently volatile and so chiefly remain in the gas. Thus, the terrestrial planets, which accrete primarily from rocks and ices, are fed from C-and N-depleted materials and are carbon and nitrogen poor compared with the nebular disk from which they descend (1, 2). The carbon and nitrogen depletion of rocky bodies is a general phenomenon, observable not just in our solar system, but also in the polluted atmospheres of white dwarf stars, which trace the composition of disrupted planetesimals (3, 4). This volatile poor state of terrestrial planets is partially imparted from the starting materials. However, further differential loss of C and N can occur due to parent body processes such as thermal metamorphism, core s...

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Stability and compressibility of a new iron‐nitride β‐Fe₇N₃ to core pressures

Minobe

Nakajima

Hirose

et al. 2015

Geophysical Research Letters

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We have examined the phase relations in the iron‐rich portion of the Fe‐N binary system up to 150 GPa and 2720 K in a laser‐heated diamond anvil cell. Synchrotron X‐ray diffraction measurements revealed the formation of a new phase (β‐Fe7N3) above 41 GPa and ~1000 K. The β phase is structurally identical or very close to Fe7C3 and the most iron‐rich Fe‐N intermediate compound at its stability field. We also measured the volume of β‐Fe7N3 to 132 GPa and found its elastic property very similar to that of Fe7C3. Recently, it has been proposed that the density and sound velocities, in particular, shear wave velocity, in the Earth's inner core are reconciled with Fe7C3, but such properties could be explained by β‐Fe7N3 equally well. It is therefore possible that the inner core consists of Fe7(C,N)3, which is found as diamond inclusions and likely stable under inner core conditions.

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Nitrogen solubility in molten metal and silicate at high pressure and temperature

Cited by 117 publications

References 62 publications

Nitrogen isotope fractionation during terrestrial core-mantle separation

Nitrogen isotope fractionation during terrestrial core-mantle separation

Tracing the ingredients for a habitable earth from interstellar space through planet formation

Stability and compressibility of a new iron‐nitride β‐Fe₇N₃ to core pressures

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Nitrogen solubility in molten metal and silicate at high pressure and temperature

Cited by 117 publications

References 62 publications

Nitrogen isotope fractionation during terrestrial core-mantle separation

Nitrogen isotope fractionation during terrestrial core-mantle separation

Tracing the ingredients for a habitable earth from interstellar space through planet formation

Stability and compressibility of a new iron‐nitride β‐Fe7N3 to core pressures

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Stability and compressibility of a new iron‐nitride β‐Fe₇N₃ to core pressures