Large anorthosite bodies associated with high-grade regional metamorphism and anatectites are nearly restricted to orogens of Precambrian age. They may indicate different conditions for Precambrian tectonics or different circumstances of plate interactions, however to test various models for their formation an accurate temporal framework for the development of metamorphism, anatexis, melt accumulations and emplacement in orogens is required. This project will utilize the well studied Adirondack sector of the Grenville orogeny which contains classic anorthosite plutons to develop a detailed chronology of events. Results are expected to produce sufficient data to test models of anorthosite development, which will have applications in other Precambrian orogenic belts.