DIRECTION OF FLUID-FLOW DURING CONTACT-METAMORPHISM AROUND THE BURSTALL GRANITE, AUSTRALIA

Marbles adjacent to the Burstall granite, Mary Kathleen, Australia, record up-temperature fluid flow during contact metamorphism. These fluids were water-rich and probably partially derived from devolatilization reactions. By contrast, Fe-rich skarns closer to the granite were formed by fluids emanating from the granite flowing down temperature. The rocks in the Burstall granite aureole record the operation of two contrasting fluid-flow regimes during contact metamorphism that is predicted by numerical models of fluid flow around cooling plutons, but which has rarely been documented around mesozonal plutons.