Atomic structure and physical properties of peridotite glasses at 1 bar

Earth’s mantle, whose bulk composition is broadly peridotitic, likely experienced periods of extensive melting in its early history that formed magma oceans and led to differentiation formation an atmosphere. However, the physical behaviour poorly understood, as high liquidus temperatures rapid quench rates required preserve peridotite liquids glasses have so far limited their investigation. In order better characterize atomic structure estimate properties such glasses, we examined Raman spectra quenched melts, equilibrated at 1900 °C ± 50 ambient pressure under different oxygen fugacities ( f O 2 ), from 1.9 log units below 6.0 above Iron-Wüstite buffer. Fitting with Gaussian components assigned molecular entities (Q-species) permits extraction mean state polymerisation glass. We find proportions Q 1 (0.36–0.32), (0.50–0.43), 3 (0.16–0.23) vary Fe 3+ /Fe TOT (Fe = 2+ + where increasing produces increase expense near-constant . To account for offset between Raman-derived NBO/T (2.06–2.27) those determined by assuming exists entirely a network modifier former (2.10–2.44), ∼2/3 ferric iron ∼90% ferrous must behave modifiers. employ deep neural model, trained predict alkali alkaline-earth aluminosilicate melts properties, observe how small variations peridotite-like affect viscosity. For Fe-free model yields viscosity ∼ −1.75 Pa s 2000 °C, similar experimental determinations iron-bearing melts. The predicts changes melt yield lower than 0.1 s, barely affecting Rayleigh number. Therefore, typical oceans, least bar, oxidation are unlikely ocean fluid dynamics.