Characterizing Melt Flow in the Anatectic Zone

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Brown 0003531Melting of rocks in Earth's crust is an important process during mountain building (orogeny). It can account for the large volume of granite in upper levels of mountain belts, such as are exposed in the geologically active Himalayan mountain belt and in the eroded Appalachian and Variscan orogenic belts, and it is responsible for the chemical differentiation of the continental crust. In addition, the presence of melt and melt movement, in particular the extraction of melt from deep crustal sources and emplacement of melt in shallower crust, influence the rheology of the crust and can greatly affect the style of deformation associated with mountain building. This project aims to constrain the nature of the movement of melt generated by the fusion of rocks in the continental crust. To do this, a number of techniques, some well established and some novel, will be used to constrain the geometry of melt distribution in rocks that once hosted melt. New techniques include quantitative image analysis of melt-related structures in rocks, high-resolution computed X-ray tomography, and scanning electron microscope cathodoluminescence. Constraints thus obtained on the spatial distribution of melt will allow an assessment of the possible melt flow and deformation mechanisms associated with melt movement. This, in turn, will serve to constrain the possible rates of melt accumulation in large volumes, and the rates of melt-attended deformation, providing insight into the physical and chemical evolution of active mountain belts.