RESUMEN
This paper
describes a model representing the process of partial melting of deforming
mantle rock, and the associated melt migration due to differential buoyancy. The
model is a double free-boundary problem of degenerate type, and is typical of
such slow, reactive two-phase flows. Prescription of boundaryconditions
is problematical, but in some sense the model picks its own; a realistic
asymptotic solution involving rather novel boundary layer behaviour
is presented, for the case of two fixed boundaries, and it is then shown how
the free boundaries can be determined a posteriors. The implications for geophysical
behaviour are discussed.