Nitrogen storage capacity of phengitic muscovite and K-cymrite under the conditions of hot subduction and ultra high pressure metamorphism

The origin and evolution of Earth's nitrogen

“…However, it is noteworthy that Sokol et al. (2023) [ 75 ] discovered the production of K-cymrite in the pelite system at pressure ≥6.3 GPa, and its bulk nitrogen content was 3.2–5.9 wt%, including 1.4–1.6 wt% NH 4 + , up to 0.5 wt% NH 3 and 4–6 wt% N 2 . Thus, K-cymrite may act as a hidden redox-insensitive nitrogen reservoir in the mantle, involved in the deep nitrogen cycle.…”

“… Mineral–fluid partition coefficients of nitrogen ( \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} $D_N^{{mineral}/fluid}$\end{document} ) as a function of pressure. The \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} $D_N^{{mineral}/fluid}$\end{document} for biotite, taken from reference [ 182 ], generally increase with increasing pressure, while the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} $D_N^{{mineral}/fluid}$\end{document} for phengite, taken from references [ 75 , 77 , 192 ], show a decrease with increasing pressure. Note that the large scattering of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} $D_N^{{mineral}/fluid}$\end{document} at a given pressure is caused by the variation in oxygen fugacity and the concentration of nitrogen in fluid [ 75 , 76 ].…”

“…The experiments were conducted at conditions that are relevant for the early Earth magma ocean, mantle melting, subduction zone processes and magmatic degassing within the shallow crust. In combination with high-precision in situ analyses using an electron microprobe [ 62 , 63 ], Fourier-transform infrared (FTIR) and Raman spectroscopy [ 64 , 65 ], secondary ion mass spectrometry (SIMS) [ 63 , 66–68 ], and NanoSIMS [ 64 , 69 ], these experiments reveal a significant redox dependence of nitrogen behavior and the transition of nitrogen from a highly volatile element to a lithophile or a siderophile element in geological materials; its solubility in mantle minerals and melts [ 67–74 ], its partitioning between minerals, fluids and silicate melts [ 61 , 75–77 ], and its partitioning and isotope fractionation between metallic and silicate melts in planetary magma oceans [ 78–83 ] all depend on redox conditions. These experimental results, when considered alongside observations of natural samples, provide preliminarily constraints on the accretion processes of Earth's nitrogen [ 78 , 81 , 84 ].…”