Subduction zones affect the physical and chemical evolution of Earth by recycling material back into the mantle and facilitating fluid and mass flux between the surface and interior. Some of the most devastating hazards on Earth, such as the transient release of accumulated stress and pressure during earthquakes and volcanic eruptions, are strongly influenced by the availability, quantity, and composition of these subduction inputs. Therefore, understanding how subduction zone dynamics affect our planet and society requires detailed studies of the mass cycle architecture, from the initial inputs, material processing and segregation, and the final outputs. Particularly important is connecting the geological and geochemical observations of exhumed terranes and arc outputs with geophysical imaging of active systems and geodynamic modeling across all spatial and time scales for a holistic understanding of mass cycling. This session welcomes geologic, geochemical, geodynamic, geophysical, experimental, and interdisciplinary contributions that place constraints on subduction zone processes.