Experimental Study of the Multicomponent Chemical Diffusion of Major Components (SiO2, Al2O3, Na2O, CaO, MgO, and FeO) and the $$\text{CO}_{3}^{2-}$$ Anion at Interaction between Basalt and Kimberlite Melts under a Moderate Pressure

The paper presents the first experimental results on the chemical interdiffusion of major components (SiO2, Al2O3, Na2O, CaO, MgO, and FeO) and the $$\text{CO}_{3}^{2-}$$ anion at interaction between basalt and kimberlite melts under moderate pressures. The research was carried out using a high gas pressure apparatus of original design at Ar or CO2 pressures of 100 MPa and a temperature of 1300°C, with the use of the method of diffusion pairs. It is established that the rate of the oncoming chemical diffusion of all major components of melts (SiO2, Al2O3, Na2O, CaO, and MgO) and $${\text{CO}}_{3}^{{2 - }}$$ anion is almost identical at the interaction of model basalt and kimberlite carbonate-containing melts and is approximately one order of magnitude higher than the diffusion rate of these components at the interaction of melts in the more polymerized andesite–basalt model system. The latter is explained by the significantly lower viscosity of the boundary melt (Montana boundary), which is formed during the interaction of model basalt and kimberlite melts. The equal diffusion rates of CaO and the $${\text{CO}}_{3}^{{2 - }}$$ anion indicate that the CaCO3 carbonate diffuses from kimberlite to basalt (both model and natural) melts by means of the diffusion of the end members. The pattern of the diffusion processes significantly changes when melt of natural magnesian basalt interacts with model kimberlite. Thereby calcite diffuses into magnesian basalt also by means of diffusion of the end members. The diffusion rates of all other components of the melts (SiO2, MgO, and FeO) significantly increase. A weak exponential concentration dependence of all diffusing components is determined, with this dependence close to D(i) = constant.