Petrologic and Stable Isotopic Study of the Release, Transport, and Deposition of CO2 During Regional Metamorphism

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9706638 Ague Tectonometamorphic processes during orogenic pulses can influence the CO2 budgets of the atmosphere and hydrosphere, and produce global climatic change. Processes include: (1) release of CO2 by metamorphic decarbonation and (2) sequestering of CO2 by rapid underthrusting and burial of carbonate-rich terranes. The PIs will investigate processes of decarbonation attending prograde infiltration of metamorphic and magmatic fluids and carbonate deposition in carbonate-bearing veins. Field area is the Orange-Milford belt in Connecticut. The nature, degree and length scales of mass transfer of H2O, CO2 and chemical elements and O, C, H and S isotopes will be determined by mapping chemical and isotopic fronts across lithologic contacts and evaluating net transfer and mass balance. PIs will investigate: (1) oxygen isotope zonations in in porphyroblasts, (2) porphyroblast growth reatlive to isotopic fron propagation, (3) isotpoic systemmatic of mineral in clusions in porphyroblasts, (4) cross-cutting relatios betweenn vien sets and prophyroblasts, (5) timing of mass transfer relative to folding and cleavage development, and (6) sedimentary/diagentic/low-grade effects in order to distinguish them from higher-grade phenomena. Geochemical modeling of fluid-rock interactions as a function of P, T and wallrock type will constrain the processes and efficiency of carbonation/decarbonation.