Hannah Shabtian, Brown University, presents:
It's not just a phase: Experimental constraints on hydrous phyllosilicate rheology and dehydration-induced weakening
Exhumed subduction zones preserve evidence for the strong influence of hydrous phyllosilicates and their evolution on interface strength, yet the mechanical behavior of these minerals under subduction-zone conditions remains incompletely characterized. I present recent experimental constraints on the high-pressure, high-temperature rheology of talc and chlorite, two hydrous phyllosilicates commonly occurring in subduction zones, and explore the implications of their deformation for subduction interface strength, strain localization, and mechanical decoupling. I also discuss the rheology of talc during dehydration, where we observe pronounced weakening and distributed ductile deformation that cannot be readily explained by fluid-assisted deformation or the rheology of reaction products. Our results highlight that the evolving mechanical behavior of subduction interfaces ultimately reflects an interplay between the rheology of constituent minerals, phase distributions, and reaction processes.
