Magma ascent by porous flow

Abstract

Using a generalized form of Darcy's law that includes matrix deformation, solitary wave solutions called magmons, consisting of localized regions of high porosity that ascend through the porous matrix, are extended to two spatial dimensions, and their impact on igneous processes is discussed. It is suggested that magmons are unlikely to be important in regions of broad upswelling where compaction processes are unimportant. Liquid supplied from below to a stable partially molten region of the athenosphere, as occurs beneath ocean volcanic centers or in subcontinental mantle, is expected to ascend in magmons. The waveform of a magmon ascends faster than the liquid within the magmon, taking in new liquid from above as old liquid is lost from below, and it is suggested that magmons can mobilize small degrees of partial melt and deliver it to the surface.