Abstract

The subduction water cycle is a key process for understanding the long-term evolution of surface water, arc volcanism, continental growth, mantle hydration and convection. Much of our current understanding of volatile recycling comes from studies in the Pacific and Indian Oceans where fast-spread oceanic lithosphere is subducted. In this talk I will present results from project VoiLA– a NERC -funded large grant that ran between 2015 and 2021 and targeted the Lesser Antilles subduction system in the slow-spread Atlantic. The project combined active source seismology, passive seismology, geochemistry and numerical modelling to investigate hydration of the incoming plate and dehydration below the arc and fore-arc. With an emphasis on active source seismology I will show that the incoming plate in the Atlantic case is much wetter and more laterally variable than Pacific/Indian Ocean examples. The results, when mapped onto the slab, show a clear correlation with the overlying mantle wedge properties obtained from passive-source seismology and arc geochemistry. Our work offers the potential to improve global volatile budget estimates back through geological time.

The talk will contain material from the following papers:

Braszus, B., et al., (2021). “Subduction history of the Caribbean from upper-mantle seismic imaging and plate reconstruction.” Nature Commun

Allen, R. W. et al., (2022). “The Role of Crustal Accretion Variations in Determining Slab Hydration at an Atlantic Subduction Zone.” JGR

Cooper, G. F. et al., (2020). “Variable water input controls evolution of the Lesser Antilles volcanic arc.” Nature

Davy, R. G. et al., (2020). “Wide-Angle Seismic Imaging of Two Modes of Crustal Accretion in Mature Atlantic Ocean Crust.” JGR

Hicks, S. P. et al., (2023). “Slab to back-arc to arc: Fluid and melt pathways through the mantle wedge beneath the Lesser Antilles.” Science Advances