Re-evaluation of Infiltration-driven Regional Metamorphism in Northern New England: NewTransport Models with Solid Solution and Cross-layer Equilibration of Fluid Composition

The spatial distribution of reactants and products of infiltration-driven decarbonation reactions can be a record of the geometry and amount of reactive fluid flow during regional metamorphism. In the past, these distributions have been interpreted assuming (1) minerals are fixed in composition and (2) single layers are chemically isolated. Because neither assumption is normally valid, new transport models were developed that specifically predict the spatial distribution of reactants and products of the well-studied biotite-forming reaction in marls from northern New England.The models consider (1) iso-thermal and isobaric (iso-P^T) flow, (2) horizontal flow in the direction of increasing T (up-T flow), and (3) vertical, upward flow in the direction of decreasing P andT (down-P^T flow). All models assume a medium composed of many thin layers that differ in the amounts and compositions of mineral solid solutions prior to reaction, that fluid flow is parallel to layering, and that fluid com