Granites are found at shallow to deep levels of exposure throughout the Earth's crust whereas migmatites are found usually at middle to deep levels. It has been postulated that migmatites are the site of granite melt generation and that subsequent magma separation from host rocks and buoyant ascent results in the familiar cross-cutting plutons of shallow crustal levels. It is proposed to test alternative models for the origin of migmatites and granites. Preliminary work suggests there is a spatial transition from migmatites to granites in southern Connecticut and that both rock types are contemporaneous. Integrated studies of field, structural, petrological, and geochemical characteristics will be conducted to determine 1) the relative age of rock units; 2) the thermal history of the region; and 3) the degree of chemical consanguinity of spatially related rock types. Techniques to be used include electron microprobe and inductively coupled plasma analysis. The relative importance of tectonic thickening vs. magmatic advection in heating the region will be determined. The role of crustal reworking in granite formation will be assessed.
