Re-equilibration processes in grain-internal domains: The interrelation of mineral reactions and deformation during metamorphism (TP14)

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Stranded reactions in grain interiors are used to study the parameters controlling re-equilibration processes in metamorphic rocks. We focus on mineral host/inclusion arrangements, which were affected by re-equilibration under changing ambient conditions (P, T, X, stress) to variable degree. Using available sample material from Austroalpine basement units in the Eastern Alps, we intend to compare inclusion-domains that behaved as essentially closed systems with those which were open for material exchange with the matrix. Special focus will be placed on the interrelation of mineral reactions, chemical mass transport and deformation. Constraining the influence of structural heterogeneities such as microfractures, (sub)grain boundaries and phase boundaries on material rheology, microstructure development and mineral reactions is supposed to yield new information on the behaviour of complex reactive systems under tectonic load. The intended research relies on the characterization of microstructures, textures and mineral compositions with an emphasis on high resolution analytical techniques (electron microprobe analysis, scanning electron microscopy, electron backscatter diffraction, cathodoluminescence, dual focused ion beam technique). These methods will be applied to host/inclusion boundaries, host internal reaction fronts and potential passageways for material transport in strained and unstrained host domains. State of the art material characterization will provide the basis for thermodynamic modelling of phase equilibria, diffusion modelling and mechanical modelling in order to identify and quantify the controlling parameters during metamorphism and their interplay.