The Avalon composite terrane of the northern Appalachian orogen represent a college of tectonostratigraphic terranes that were amalgamated in the late Precambrian, accreted as a composite terrane to North America during the early-middle Paleozoic, and were subsequently dispersed variable distances relative to each other. Identification of the constituent terrane elements within the composite terrane has been controversial, their tectonothermal evolution is uncertain, and the nature and timing of amalgamation, accretion and dispersal are poorly constrained. This project will address these issue through a comprehensive structural and 40Ar/39Ar geochronological study of a representative portion of the Avalon composite terrane in southwestern New Brunswick where recent studies have shown an important late Precambrain terrane boundary may exist. Results of a reconnaissance 40Ar//39Ar isotopic survey indicate that a significant contribution can be made in the proposed study area. The project couples detailed structural mapping kinematic analysis and petrological studies with a program of 40Ar/39Ar mineral dating designed to resolve the region's tectonothermal evolution. The study will substantially improve knowledge of the nature, timing and kinematics of tectonothermal events recorded in the Avalon composite terrane and, thereby, will greatly facilitate the identification and correlation of constituent late Precambrian terranes.
