Quantitative analysis and scaling of sheared granitic magmas

We present a quantitative treatment of the macroscopic behaviour of a shear ed granitic magma using Plot's theory [Biot, 1941] and a shear-dilatancy se nsitive material model for the solids. The calculations are relevant to a m agma in the solidosity range 0.55-0.7. The resulting excess pore pressure d istribution is a function of the position and the time. Results are present ed in graphical form. A scaling emerges that enables the results to be pres ented in nondimensional form. A sensitivity study is carried out of the par ameters describing the rheology of the solid matrix (including permeability features). The model enables the estimate of pressure and flow rates, thus opening a way of understanding the features in the granite crystal mush th at are caused by upflowing magma. At high strain rates (10(-10) s(-1)) flow rates due to shear far exceed melt movement due to buoyancy effects.