Geophysical Journal | 2011 volume 33 2

Threshold of percolation and permeability of partially molten

© Aryasova O.V.

Permeability of partially molten bimineral aggregate with differing grain sizes and grain forms is numerically modeled. It is assumed that melt appears only at edges of contacting grains of different compositions. Every grain is supposed to consist of a number of identical square (2D case) or cubic (3D case) elements. Belonging of an element to one of the compositions is defined randomly. In this case it is assumed that the elements with the same composition, which share a side combine to form a grain without internal boundaries. Therefore the grains of each of "minerals" may have a complicated form and different sizes. It is demonstrated that formation of an infinite cluster of melt inclusions requires melting at the edges of more than about 15% of grains. The latter value may be adopted as a permeability threshold. Therefore, if the modal content of the first consumed mineral phase is too low to overcome the connectivity threshold, an infinitesimal melting is not accompanied by melt segregation.

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