Smith Lecture: Are Long-lived Stratovolcanos Low-pass Filters for Magma Transport or is There a Highway from Hell?
Arc stratovolcanoes localize magmatic activity for 10s to 100s kyr, leading to self-cannibalization and the emergence of polybaric subvolcanic magma storage regions. Partial melts accumulate within mush zones and sills at various levels in the crust. Dense primitive mantle-derived magmas that ascend from mantle source regions encounter those density barriers on their way to the surface, leading to stalling and an evolution to more buoyant magmas through fractionation, mixing, and assimilation. This model suggests that long-lived arc stratovolcanoes act as low-pass filters for primitive magmas from the mantle, where the frequency of magma addition from the mantle is converted in the crust to a slower integrated ascent rate as magmas stall, evolve and accumulate.This view stands in contrast to models that suggest rapid ascent from the magma source regions, with limited magma residence in the crust. I will explore these different views and discuss a potential coexistence of these end-members.