CONCEPTUAL MODELS OF ARC MAGMATISM: LOOKING TO THE FUTURE (Invited Presentation)

Decades of study on volcanic arcs have provided insight into the overarching processes that control magmatism, and how these processes manifest at individual volcanoes. These studies have lead to an understanding of the first order processes of melt generation in the mantle and the crustal evolution of specific magma compositions erupted at volcanoes. However, an intermediate scale of research question at arcs remain largely unresolved. For example, the cause of ubiquitous and dramatic intra-arc variations in volcanic flux and composition. Investigating such arc-scale issues requires greater quantitative comparison of geophysical and geochemical data, linked through sets of common intensive variables. In this study, we use the common variable of heat, and estimate the heat budget associated with the compositions of Quaternary volcanism in the Cascades Arc and compare this to the heat required to produce the observed geophysical properties of the crust. These calculations suggest the along-strike volcanic variability in the Quaternary Cascades Arc is primarily related to variations in the flux of basalt into the crust, rather than variations in their crustal storage history. Given this observation, we can then explore the relative roles of mantle wedge volatile content, temperature, and flow field in producing the along-strike variations in mantle basalt flux, and other intriguing relationships that highlight the connectivity of the magmatic system from mantle to volcano.