The Fellow will make an integrated structural, petrologic, and geochronologic study of major structural discontinuities in the Grenville Province of eastern North America. Orogenic cores will be examined to decipher progressive development of ductile fabrics especially with reference to porphyroblast growth, the kinematic evolution of shear zones, and the development of fault zones at their deepest levels. Use will be made of isotopic analysis of Sa (samarium) and Nd (neodymium) for radiometric geochronology. The Fellow will spend his fellowship tenure at the University of Michigan.