Two diagrams from the paper
The molecular dynamic model of water in a phyllosilicate mineral interlayer in equilibrium with bulk water i.e., free fluid phase (top) is used for depicting the pressure-temperature-domain with water-intercalated crystalline interfaces during slab subduction. The range of this domain is determined by the water intercalation/deintercalation transition line for the mica interlayer under a water activity of 0.6 (bottom). The D80 thermal model for the central Honshu subduction zone is adopted (Syracuse et al., 2010). Credit: Chen et al. [2023], Figures 1b and 10
Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
Source: Journal of Geophysical Research: Solid Earth

What is a plausible alternative mechanism to the percolation flow of a water bearing fluid released out of a subducting slab? Chen et al. [2023] explore the possibility of stacking the released water in the effective 2D fluidic phase within intercalated crystalline interfaces of phyllosilicate minerals like graphite, mica, or brucite. Using molecular dynamic simulations, they demonstrate a possible conduit of water flow through an effective quasi-2D fluidic phase.

The authors find that, indeed, the water intercalation under pressure-temperature-conditions of subducting slabs is thermodynamically driven in the considered three kinds of crystalline interfaces: graphite, brucite, and muscovite mica interlayers. The indispensable condition for this water intercalation into the crystalline interface is that the crystalline surface and water should not be well connected by hydrogen bonds. The most important issue is that H2O intercalation into the crystalline interface might facilitate aseismic slip, which may transmit easily earthquake-triggering stress changes making the dehydration embrittlement hypothesis less necessary.

Citation: Chen, M., Zhu, R., Zhu, J., & He, H. (2023). Percolation of low-dimensional water at crystalline interfaces mediates fluid migration in subducting slabs. Journal of Geophysical Research: Solid Earth, 128, e2023JB027124. https://doi.org/10.1029/2023JB027124

—Nikolai Bagdassarov, Associate Editor, JGR: Solid Earth

Text © 2023. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.