DIFFERENTIAL DEFORMATION AND METAMORPHISM IN ULTRAMAFIC BODIES OF THE BLUE RIDGE MOUNTAINS, NC

A series of ultramafic bodies exposed in the Blue Ridge Mountains of North Carolina, Georgia, and Virginia reflect varying degrees of metamorphism and high-pressure ductile deformation. While abundant geochemical data exist for these mafic and ultramafic bodies, only a few have been carefully studied with regards to structural context and microstructural relationships. A series of faculty-mentored undergraduate mapping projects seeks to characterize these variations and determine the tectonic context in which they formed.

While the late stages of ultramafic block emplacement involve disruption of material in a melange-style deformational setting, these units must have behaved differently at depth and may record in their microstructure the deformational conditions of the earlier stages. Detailed study and mapping of internal structure and microstructure of these bodies will provide valuable data on the earliest stages of continental collision and ophiolite emplacement. Preliminary recrystallized grainsize studies reflect paleostress differences of at least 7 MPa. The degree of retrograde metamorphism appears to increase toward the northeast, though this can also vary between bodies in the same vicinity.