Multicomponent diffusion in silicate melts: SiO2–TiO2–Al2O3–MgO–CaO–Na2O–K2O System

Geological Notes Diffusion of Water in Silicate Melts

The transport of water in silicate melts is examined from a theoretical point of view, taking into account the presence of both H20 and OH species. It was assumed that only H20 molecules may diffuse and that a constitutive relationship between the number density nH 0 of H20 molecules and the total water content (n:E) exists such that nH,o = g(n:E) . This is related to dissociation or to chemica...

Diffusion of H, C, and O Components in Silicate Melts

Viscosity models for silicate melts

Rheology of silicates (melts or super cooled as glasses) is one of the most important fields to mankind, as geological activity largely influences life. In this paper, unifying empirical models for the Non-Newtonian shear viscosity and the extensional viscosity are proposed. The models have only one parameter, the zero shear viscosity (the Newtonian plateau), and are valid for a vide range of c...

Molecular H2O as carrier for oxygen diffusion in hydrous silicate melts

Dissolved water is known to dramatically enhance oxygen diffusion in silicate melts, glasses and minerals. A quantitative theory has been developed to explain this phenomenon by transport via molecular H2O diffusion [Y. Zhang, E.M. Stolper, G.J. Wasserburg, Diffusion of a multi-species component and its role in the diffusion of water and oxygen in silicates, Earth Planet. Sci. Lett., 103 (1991)...

Effects of structural relaxation on cationic tracer diffusion in silicate melts

Dingwell, D.B., 1990. Effects of structural relaxation on cationic tracer diffusion in silicate melts. Chem. Geol., 82: 209-216. The glass transition in silicate melts is a curve in time-temperature space marking the transition of the melt structure from an unrelaxed, disequilibrium glass to a relaxed, equilibrium liquid. Tracer diffusivity data obtained in glasses vs. liquids cannot be compare...