Skip to Main content Skip to Navigation
Journal articles

Nitrogen diffusion in silicate melts under reducing conditions

Abstract : The behavior of nitrogen during magmatic degassing and the potential kinetic fractionation between N and other volatile species (H, C, O, noble gases) are poorly known due to the paucity of N diffusion data in silicate melts. To better constrain N mobility during magmatic processes, we investigated N diffusion in silicate melts under reducing conditions. We developed uniaxial diffusion experiments at 1 atm, 1425 °C, and under nominally anhydrous reducing conditions (f O2 ≤ IW-5.1, where IW is oxygen fugacity, f O 2 , reported in log units relative to the iron-wüstite buffer), in which N was chemically dissolved in silicate melts as nitride (N 3-). Although several experimental designs were tested (platinum, amorphous graphite, and compacted graphite crucibles), only N diffusion experiments at IW-8 in compacted graphite crucibles for simplified basaltic andesite melts were successful. Measured N diffusivity (D N) is on the order of 5.3 ± 1.5 × 10-12 m 2 s-1 , two orders of magnitude lower than N chemical diffusion in soda-lime silicate melts (Frischat et al. 1978). This difference suggests that nitride diffusivity increases with an increasing degree of melt depolymerization. The dependence of N 3diffusion on melt composition is greater than that of Ar. Furthermore, N 3diffusion in basalticandesitic melts is significantly slower than that of Ar in similarly polymerized andesitic-tholeiitic melts at magmatic temperatures (1400-1450 °C; Nowak et al. 2004). This implies that N/Ar ratios can be fractionated during reducing magmatic processes, such as during early Earth's magma ocean stages.
Document type :
Journal articles
Complete list of metadata

https://hal.archives-ouvertes.fr/hal-03306221
Contributor : Evelyn Füri <>
Submitted on : Thursday, July 29, 2021 - 8:47:38 AM
Last modification on : Saturday, August 21, 2021 - 3:07:25 AM

File

2021 Boulliung et al AmMineral...
Publisher files allowed on an open archive

Identifiers

Collections

Citation

Julien Boulliung, Célia Dalou, Laurent Tissandier, Evelyn Füri, Yves Marrocchi. Nitrogen diffusion in silicate melts under reducing conditions. American Mineralogist, Mineralogical Society of America, 2021, 106 (4), pp.662 - 666. ⟨10.2138/am-2021-7799ccbyncnd⟩. ⟨hal-03306221⟩

Share

Metrics

Record views

22

Files downloads

46