Atomistic insight into lithospheric conductivity revealed by phonon–electron excitations in hydrous iron-bearing silicates

Abstract Amphiboles are essential components of the continental crust and subduction zones showing anomalous anisotropic conductivity. Rock properties depend on physical their constituent minerals, which in turn crystal phonon electron density states. Here, to address atomic-scale mechanism peculiar rock conductivity, we applied situ temperature-dependent Raman spectroscopy, sensitive both states, Fe 2+ -rich amphiboles. The observed resonance scattering at elevated temperatures, combination with density-functional-theory modelling, reveals a direction-dependent formation mobile polarons associated coupled FeO 6 phonons transitions. Hence, temperature-activated electron-phonon excitations hydrous iron-bearing chain layered silicates atomistic source lithospheric Furthermore, reversible delocalization H + occurs similar temperatures even reducing atmosphere. occurrence either type charge carriers does not require initial mixed-valence state iron or high oxygen fugacity system.