A fundamental question for pre-Cambrian tectonics is the timing and amounts of extraction of crustal material from the mantle and its addition to the crust. However, it has been difficult to distinguish new additions from recycled older crustal material. This project will employ isotopic technique to establish Nd-model ages and fix the time since the parental material of the rocks separated from the earth's mantle. Coupled with U-Pb ages, these data will allow the estimation of new materials to the Northeastern Appalachians during late proterozoic time (1300-1000 Ma).
