NUMERICAL SIMULATION OF FLUID FLOW WITH ENHANCED PERMEABILITY RELATED TO CALC-SILICATE MINERAL REACTIONS AROUND PLUTONS
Results show that after magma intrusion, overall fluid flow is away from the intrusion as the hydrostatic head in the inner aureole becomes elevated with temperature increase. In all cases, fluid composition in inner aureole evolves rapidly toward high XCO2fluid as metamorphic reactions begin before water is exsolved out of the pluton. Only after tremolite and diopside-forming reactions come to completion and local fluid pressure drops, infiltration of H2O from the pluton becomes significant and can drive production of minerals such as wollastonite and vesuvianite. In the case of homogeneous permeability structure, fluid flux and composition are dispersed, while in layered permeability, highest fluid flux is confined to high permeability layers and fluid composition remains discrete. When permeability increase is related to reaction progress, the highest fluid flux is confined to inner aureole. The reaction-enhanced permeability model is in agreement with field and geochemical observations that suggest confinement of reactive fluid flow largely to inner calc-silicate contact aureoles.