Thermal and mechanical processes during deformation of the middle crust affect the style of tectonic interactions observed at the earth s surface, however not elough is known about the middle crust to allow predictive models. This project will use the extensively exposed middle crustal rocks of the southwest United States to study the mutual interaction of plutonism, deformation and metamorphism at middle crustal levels to attempt to determine its control on the strength and behavior of the continental lithosphere during orogeny. Work will focus on testing the idea that the middle crust is heterogeneous but crudely rheologically layered and that various depths have characteristic Ptt loops. Results will help clarify middle crustal deformation dynamics for the Proterozoic of the Southwest, which should provide elements of general model for middle crustal deformation.
