9303791 Davidson Twenty years of high precision bulk geochemical analyses, while broadening our overall understanding as to the role of contributing components, has failed to provide a complete model for magma genesis at convergent margins. Until magma chamber processes can be identified, understood and quantified, grand unifying hypotheses will continue to be the subject of circular debate. We propose a different approach. Chaos Crags in the Lassen Volcanic National Park has long been recognized as the classic result of magma mingling (Heiken and Eichelberger, 1980). By sampling at the length scales of interaction (mm-cm; rather than hand samples) we aim to achieve a quantitative understanding of the mingling process, its effects on bulk chemistry, and its overall importance to the sustained evolution of the southernmost volcanic edifice of the Cascade Range.
