Partial melting in the core of orogens likely controls the rheology of the crust subsequent to crustal thickening. Geophysical observations suggest that the deep crust under active orogens, such as southern Tibet, is decoupled from the lithospheric mantle and the rigid upper crust. This deep crust probably has a low viscosity and is able to flow. This project is aimed at providing an observational database to these conceptual geodynamic models by study of migmatites associated with the Shuswap metamorphic core complex in the Canadian Cordillera. The work will determine the P-T time paths of the metamorphic rocks, locate partial melting on this path and determine pressure of emplacement. Textural and petrologic analysis will constrain the conditions of partial melting and will determine flow of the partially mullen crust from shape preferred orientations of minerals. Results will be useful in testing and refining models of orogenic collapse and extension. ***
