Diapiric ascent of magmas through power law crust and mantle

There has never been a convincing explanation of the way in which diapirs of molten granite can effectively rise through mantle and crust. It is argued here that this is mainly because the country rocks have previously been assumed to be Newtonian, and it is shown that granitoid diapirs rising through thermally graded power law crust may indeed rise to shallow crustal levels while still molten. It is shown that when the wall rock behaves as a power law fluid, the diapir's ascent rate increases, without a similar increase in the rate of heat loss. In this way, diapirs rising at 10 to 10²m/yr can ascend into the middle or upper crust before solidification. Strain rate softening rather than thermal softening is the mechanism that allows diapirism to occur at such rates. -from Authors