The goal of the proposed research is to elucidate the origin of high-Mg tonalitic magmas hosted in juvenile crust in margin-related magmatic arcs. Understanding processes leading to the formation of juvenile tonalite is a first- order problem relevant to the magmatic construction of crust within orogenic belts. The proposed study will involve collection of mineral chemical and whole-rock and isotopic geochemical data for the Cretaceous Mount Stuart Batholith of the Washington Cascades. The project should clarify the variable roles of high-level magmatic processes (e.g., fractionation, assimilation) so as to better constrain the variable impact of deeper level processes operative during melt formation and initial ascent.
