This proposal is a request for continued funding to carry out an ongoing research program on the genesis of comagmatic igneous rock associations. The primary aim of this research is to clarify the petrogenesis of igneous suites and to examine modifications of mantle-derived magmas with the continental crust environment. An auxiliary goal is to determine the character of the magma source regions and the temporal nature of the magma production events in order to advance our understanding of intraplate magmatism in a geodynamic context. The localities of study are alkaline complexes in New England, southern Quebec, and Zimbabwe. These are generally small, epizonal bodies composed of successive intrusions of varying composition. The methodology uses petrographic, major and trace element, and stable and radiogenic isotopic relationships with close temporal control to formulate specific petrogenetic models. Recent research efforts have yielded valuable information on the nature and details of the general open- system evolution of these magmatic complexes and on the nature of the sources and the timing of magmatism. Continued research should be highly rewarding not only for the specific localities and provinces under study but also for analogs elsewhere.
