The interface-scale mechanism of reaction-induced fracturing during serpentinization

Peridotite serpentinization has first-order effects on geochemical and petrophysical processes in the lithosphere. This process induces intensive fracturing, generating fluid pathways to facilitate the hydration of vast amounts of originally impermeable rocks, but the mechanism linking interfacial reaction processes with fracture propagation has not been understood. By combining microstructural characteristics of olivine lizardite-serpentinization with fundamental aspects of interface-coupled dissolution-precipitation and crack growth theory, we propose a microstructurally consistent, self-propagating fracturing mechanism. Fracturing is driven by stress generated from the growth and transformation of a metastable amorphous proto-serpentine phase, where stress is localized within surface perturbations (etch pits and coalesced etch pits) that originate from the anisotropic dissolution of olivine. Water migration into fractures reiterates the process, resulting in hierarchical olivine grain segmentation. Our results indicate that the advancement of serpentinization at the grain scale is independent of solid-state diffusion and does not rely on external forces.