2D MODELING OF MELT PERCOLATION IN THE MANTLE - THE ROLE OF A MELT DEPENDENT MUSH VISCOSITY

2D-melt percolation models in the partially molten mantle are presente d. Previous work has shown that melt solitary waves develop in respons e to the non-linear dependence of mush permeability to melt concentrat ion. The present study focuses on the wave evolution when the mush vis cosity abruptly drops, around a critical concentration f(c). 2D-waves develop with a diameter, that shortens as the melt concentration incre ment for viscosity drop narrows. They are initiated inside 1D-maturing horizontal waves at melt concentration of about 4Xf(c). Both 1D- and 2D-waves collect all the melt whose concentration exceeds f(c). These features may help to explain the distribution and organization of some melt impregnations observed in mantle outcrops.