The MORB-like isotopic character and extreme diversity of trace element compositions within ALeutian magnesian andesites suggest that these rocks are key to the understanding of magma generation processes in the Aleutian arc. While magnesian andesites are rare in the central and eastern Aleutians, they are volumetrically important in the western arc where subduction rates are low. Magnesian andesites are of interest because they include compositions that (apparently) range from melts of nearly pure "mantle wedge" to melts of nearly pure subducting slab. This project is to determine the composition of the mantle wedge and quantify the contributions of subducting slab and mantle wedge components to more common magmatic rocks of the central and eastern arc. Determinations of mineral and whole-rock major element, trace element, and isotope (Sr, Nd, Pb) compositions will be sufficient to characterize magnesian andesites within the familiar framework of "normal" Aleutian magmatic rocks.
