Multicomponent diffusion in the system potassium oxide-sodium oxide-calcium oxide-iron oxide-magnesium oxide-titanium dioxide-phosphorus pentoxide-aluminum oxide-silicon dioxide

Previous studies have successfully determined the multicomponent diffusion matrix [D] for melts analogous to real silicate magmas containing up to five components. This study presents the diffusion coefficients for a more complicated and geologically relevant nine-component basaltic melt at 1400°C and 1GPa. In general, the diffusion experiments exhibited the appearance of simple binary profiles with minimal diffusive coupling, as only eleven of the total fifty-six off-diagonal eigenvector components contained non-zero values. FeO and CaO, and to a lesser degree Na2O and K2O appeared to diffuse more readily against their concentration gradients, while the direction of uphill diffusion for FeO and CaO were always the same, yet opposite in direction to Na2O and K2O. The measured eigenvalues ranged from 7.10 x 10-11 m2.sec-1 corresponding to Al2O3 up to 4.91 x 10-10 m2.sec-1 corresponding to Na2O.