Replacement processes in the earth's crust

Abstract

Afundamental question in metamorphism is: What is the mechanism that converts one mineral assemblage into another in response to a change in the physical and/or chemical environment? The fact that aqueous fluids must be involved in such large-scale re-equilibration has been demonstrated by petrological, mineralogical, micro-structural and isotopic data. Fluid-mineral reactions take place by dissolution-precipitation processes, but converting one rock into another requires pervasive transport of reactive fluid through the entire rock. The generation of reaction-induced porosity and the spatial and temporal coupling of dissolution and precipitation can account for fluid and element transport through rocks and the replacement of one mineral assemblage by another.