NUMERICAL MODELING OF FLUID PRESSURE GRADIENTS IN ANISOTROPIC ROCKS UNDERGOING HETEROGENEOUS DEFORMATION

The migration of crustal melts is considered to play a critical role in the rheological evolution of migmatite terranes. Movement of melt through the system is controlled by the thermal and mechanical properties of the melt and the host rocks, the rate of melt generation, the volume increase associated with specific melting reactions, and the orientation of regional and local stress and strain fields. Three-dimensional numerical modeling was undertaken to investigate the distribution of fluids in a melt-bearing system during heterogeneous deformation. Melt and other fluids have been shown to migrate down strain-induced pressure gradients into dilatant sites such as boudin necks, tension gashes and shear zones. At the grain scale, these zones of local extension serve as melt sinks and may become interconnected over time. Similar processes may govern the pervasive flow of melt through the crust and thereby affect the distribution of relatively weak melt-bearing zones on a variety of scales.