The proposed research will focus on the mineralogic, and structural features preserved in gabbros and basalts of the Kap Edvard Holm, Nordre Aputiteq and Patulajivit complexes in order to characterize processes of elemental mass transfer related to hydrothermal metasomatism, stoping and assimilation during rifting in the North Atlantic. To achieve these goals we will address the following questions: 1) What are the cumulative effects of multiple intrusions on hydrothermal metasomatism and the evolution of porosity and permeability in gabbroic plutons and basaltic rocks? 2) How does hydrothermal metasomatism of host rocks affect subsequent mass transfer from host rocks to magma during stoping and assimilation? Completion of the research outlined in this proposal will provide a framework for understanding the geochemical and structural evolution of gabbro-hosted magma-hydrothermal systems during crustal rifting.