Year: 2026
Type: article
Abstract: Neon isotopes are key tracers of Earth’s volatile origin, yet their signatures in volcanic glasses may be modified by kinetic fractionation during magmatic degassing. Recent experiments have revealed vesicle-scale variations in 20Ne/22Ne, highlighting the need for quantitative constraints on the mass dependence of neon diffusion in silicate melts. Here, we use classical molecular dynamics simulations and a pseudo-isotope approach to determine the mass dependence exponent β for neon diffusion in a MORB melt over temperatures of 1473–1873 K and pressures of 0 to 10 kbar. We find a robust linear relationship between log D and log m, with β ≈ 0.24–0.29 at low pressure, significantly lower than the gas kinetic prediction of 0.5, and decreasing approximately linearly with pressure. These results indicate that diffusion-driven fractionation is limited at the melt scale but can generate measurable, transient isotopic enrichments in vesicles under strongly non-equilibrium degassing conditions. Our findings provide a physically grounded framework for interpreting neon isotope signatures in MORB glasses and assessing the preservation of mantle-derived volatile signals.
Source: Geochemical Perspectives Letters
Authors: J. Nteme, M. Moreira
Language: English
Subfield: Geochemistry and Petrology
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W7211910943