Nitrogen-Isotopic Studies of High-Temperature Fluid-Rock Interactions

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9405625 Bebout The proposed research will extend existing research to test the utility of the N-isotopic system as a tracer of high temperature fluid-rock interactions, both in metamorphic and magmatic systems. The project will (1) constrain sources of fractionation in the N isotopic system (through melting, devolatilization, etc.; primarily among N2, NH3, and NH4+), (2) identify N-isotopic signatures characteristic of various magmatic, metamorphic, and meteoric fluid sources, and (3) improve techniques for the more routine extraction of N from silicate materials for isotopic analysis. The first two goals will be achieved through study of N isotopic systematics for three field areas: the Skiddaw Granite and Aureole, England, the Birch Creek Granite and Aureole, California; and the Peninsula Ranges Batholith, California. The third goal will involve continuation of experimentation with high-temperature combustion and fusion techniques, further lowering of analytical blanks, and improvement of techniques for mass spectrometry of extremely small N2 samples.