Feedback among reaction, fracturing, and fluid Flow in mantle rock-fluid interactions

Abstract

Serpentinization and carbonation of mantle peridotite involve solid volume expansion, which can lead to clogging and suppression of further reaction. Therefore, fracturing induced by reaction has been proposed as a key mechanism enabling extensive reaction progress, but the underlying processes remain poorly understood.In this study, we conducted flow-through experiments using sintered MgO aggregate as an analog material. We simultaneously measured changes in solid volume, permeability, and axial stress associated with volume-expanding reactions.In high-porosity MgO samples, permeability initially decreased, followed by an increase in axial stress leading to yielding. After yielding, reaction continued while permeability remained sustained. In contrast, low-porosity samples showed minimal initial reaction progress, but once fracturing began, a cascading events-reaction, fracturing, and permeability enhancement-was observed.Our results demonstrate that even under isotropic stress conditions, local anisotropy can generate significant differential stress during reaction. This suggests that in natural peridotite bodies, substantial serpentinization or carbonation may occur following a long induction period, driven by such cascading processes.