Variable water input controls evolution of the Lesser Antilles volcanic arc.

Area of Science:

• Geochemistry
• Geophysics
• Petrology

Background:

• Oceanic lithosphere transports water into the mantle via subduction.
• Subducted water influences magma generation, seismicity, and continental crust formation.
• Tracing deep fluid sources in subduction zones is complex.

Purpose of the Study:

• Investigate the source of subducted water in the Lesser Antilles volcanic arc.
• Determine the role of hydration in arc evolution and associated hazards.
• Link subducted plate structure and hydration to seismic and volcanic activity.

Main Methods:

• Analysis of boron trace element and isotopic fingerprints in melt inclusions.
• Multi-disciplinary approach combining geochemical and geophysical data.
• Study of Atlantic subduction zones as a key example of non-uniform hydration.

Main Results:

• Serpentine (hydrated mantle) is the dominant source of subducted water in the central Lesser Antilles arc.
• Fracture zones subducted over the past 10 million years are the likely host for this serpentine.
• Current dehydration of fracture zones correlates with high seismicity and low shear velocities.
• Past dehydration events align with increased volcanic productivity and thicker arc crust.

Conclusions:

• Subducted plate structure and hydration directly control arc evolution.
• The deep water cycle, particularly from hydrated mantle, plays a critical role in arc magmatism and seismicity.
• Understanding subduction zone hydration is key to assessing volcanic and seismic hazards.