Application of a New Mathematical Model for Fluid-Rock Interaction to Contact and Regional Metamorphism

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A new mathematical model for fluid-rock interaction has been developed that overcomes the problematic assumptions in calculations of fluid-rock ratios. The new model permits determination of time-integrated fluxes (units of volume fluid per area rock) and direction of flow from petrologic, geochemical, and/or isotopic data on rock samples. If duration of flow and fluid pressure gradients can be estimated, Darcy velocities, and in situ permeabilities may be computed. Proposed research will further develop the model and apply it to several significant problems in contact and regional metamorphism. Results will provide the first systematic determination of fluxes, flow directions, and rock permeabilities in a wide range of metamorphic environments. Specific projects include: (1) the amount, geometry, and geologic controls of fluid flow on the scale of an entire regional metamorphic terrane (Waits River Formation, eastern Vermont); (b) the amounts and direction of fluid flow in a ductile shear zone and their relation to metasomatism (shear zones at Scourie, northwest Scotland); (c) the amount, geologic controls, and chemical effects of fluid flow at the top of a major granitic batholith (roof pendants in the Sierra Nevada); (d) the role of fluid flow in anatexis (Onawa contact aureole, central Maine); (e) the amount and petrologic effect of fluid flow during very low-grade regional metamorphism (Liassic black shales, central Swiss Alps); and (f) the role of fluid flow in regional metasomatism (Vassalboro Formation, south-central Maine).