FLOW LAWS IN POLYMINERALIC AGGREGATES DEFORMED BY A COMBINATION OF DIFFUSION CREEP AND DISLOCATION CREEP

Microstructures in naturally deformed rocks in the upper crust demonst rate that creep strain in nature may be accommodated by a combination of dislocation creep, diffusion/dissolution processes and microcrackin g. A theoretical approach towards deriving an aggregate flow law is pr esented, where the strain in the constituent phases is assumed to occu r by simultaneous operation of diffusive mass transfer and crystal pla stic mechanisms (dislocation creep). Both uniform stress and uniform s train rate situations are considered.