Abstract
By enhancing mass transfer and energy release, the cycle of volatiles and melt is a major component of subduction. Investigating this fluid cycle is therefore critical to understand the past and current activity of subduction zones. Fluids can significantly affect rock electrical conductivity and elastic parameters that are measured using electromagnetic and seismic methods, respectively. This letter emphasizes how these geophysical methods complement each other to provide information about the storage of fluids in subduction systems. By compiling electromagnetic and seismic results from various subduction zones, a possible correlation between electrical conductivity and seismic wave attenuation anomalies in the mantle wedge is observed, consistent with fluid accumulation. A possible relationship between geophysical properties and the slab age is also suggested, whereas no significant trend is observed between electrical conductivity or seismic wave attenuation and estimates of water flux in the mantle wedge. These field-based relationships require further constrains, emphasizing the need for new measurements in the laboratory.
Highlights
By enhancing mass transfer and energy release, the cycle of volatiles and melt is a major component of subduction
By enhancing mass transfer and energy release, the cycle of fluids in subduction zones is a critical component of slab recycling and continental building processes
A better understanding of the role of melt and volatiles in subduction zones is key to improving our knowledge of the geodynamic processes at work
Summary
The dynamics and time-evolution of subduction are driven by mechanical and chemical processes that influence buoyancy forces, slab motion, contrasting thermal fields, phase equilibria, and volatile transport. Most electrical images of the subduction zones present two anomalies unnecessarily connected along or above the slab: a backarc conductor and a near-trench conductor (Table 1) These conductive areas are usually interpreted as zones of fluid accumulation, in agreement with petrological modeling (e.g., Schmidt and Poli 1998). It is interesting to note that these possible fluid sinks are not vertically aligned with the arc volcanoes at the surface (e.g., Worzewski et al 2011), though they may be rela ted to the volcanic plumbing system In case these conductive reservoirs contribute to the volcanic activity, the shift in their location may be due to mantle flow and buoyancy processes in the mantle wedge, as suggested by some numerical experiments (e.g., Gerya and Yuen 2003). The detection of these reservoirs using electromagnetic measurements highlights the fact that electrical studies can be a powerful tool to investigate volcanic plumbing systems in subduction
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