Modeling of formation of intraplate partial melting zones

This study suggests the mathematical model of dynamics of partial melting in lithosphere causing formation of magmatic systems. The intraplate magmatic systems can be formed at achievement of required thermodynamic conditions, which can be developed due to the following mechanisms: contact heating; decompression melting at mantle matter penetration into lithosphere; and heating by filtering mantle melts and fluids in the weakened lithosphere zones above the asthenospheric structure related to a hotspot. The most efficient mechanism from the point of time and heating degree is the latter one. It is heating of lithosphere matter by mantle melts and fluids, which is especially important for development of melting sites in these systems. At formation of intraplate magmatic systems the fluid is filtered in a porous medium, porous matrix melts partially, and finally a granulated medium is formed there. To decrease the processes of heat and mass transfer in this system, the equations of dynamics of multiphase multivelocity media are derived in this study. In contrast to the Darcy-type models used in previous studies, the suggested two-velocity hydrodynamics theory describing fluid motions in a porous medium with complex reology is the thermodynamically consistent one and allows the description of nonstationary nonlinear processes. The governing equations of the model describe both the process of filtration through the deformed porous matrix and hydrodynamics of heterophase granulated medium without pressure equilibrium in phases. The work was supported by the grants 08-05-00467, 09-05-00602, 09-05-01084 from the Russian Foundation for Basic Research.