Slab to back-arc to arc: fluid and melt pathways through the mantle wedge beneath the Lesser Antilles
- 1Department of Earth Science and Engineering, Imperial College London, London, United Kingdom (stephen.hicks@ucl.ac.uk)
- 2Department of Earth Science, University College London, United Kingdom
- 3School of Environmental Sciences, University of East Anglia
- 4School of Ocean and Earth Science, University of Southampton, Southampton, United Kingdom
- 5Woods Hole Oceanographic Institution, Falmouth, United States
- 6Geophysics Institute, Karlsruhe Institute of Technology, Karlsruhe, Germany
- 7Department of Earth and Environmental Sciences, Michigan State University, East Lansing, United States
- 8Seismic Research Centre, The University of the West Indies, St. Augustine, Trinidad and Tobago
- 9Department of Earth Sciences, Durham University, Durham, United Kingdom
- 10Instituto Dom Luiz, Universidade de Lisboa, Lisbon, Portugal
- 11Natural History Museum, London, United Kingdom
- 12Department of Earth Sciences, University of Oxford, Oxford, United Kingdom
- 13School of Earth and Environmental Sciences, Cardiff University, Cardiff, United Kingdom
Volatiles expelled from subducted plates promote melting of the overlying warm mantle, feeding arc volcanism. However, debates continue over the factors controlling melt generation and transport and how these determine the placement of volcanoes. To broaden our synoptic view of these fundamental mantle wedge processes, we image seismic attenuation beneath the Lesser Antilles arc, an end-member system that slowly subducts old, tectonised lithosphere. Punctuated anomalies with high ratios of bulk-to-shear attenuation (Qκ-1/Qµ-1 > 0.6) and VP/VS (>1.83) lie 40 km above the slab, representing expelled fluids that are retained in a cold boundary layer, transporting fluids towards the back-arc. The strongest attenuation (1000/QS~20), characterising melt in warm mantle, lies beneath the back-arc, revealing how back-arc mantle feeds arc volcanoes. Melt ponds under the upper plate and percolates toward the arc along structures from earlier back-arc spreading, demonstrating how slab dehydration, upper plate properties, past tectonics, and resulting melt pathways collectively condition volcanism.
How to cite: Hicks, S., Bie, L., Rychert, C., Harmon, N., Goes, S., Rietbrock, A., Wei, S., Collier, J., Henstock, T., Lynch, L., Prytulak, J., Macpherson, C., Schlaphorst, D., Wilkinson, J., Blundy, J., Cooper, G., Davy, R., and Kendall, J.-M.: Slab to back-arc to arc: fluid and melt pathways through the mantle wedge beneath the Lesser Antilles, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-11540, https://doi.org/10.5194/egusphere-egu23-11540, 2023.
