Volatile-consuming reactions fracture rocks and self-accelerate fluid flow in the lithosphere

Masaoki Uno, Kodai Koyanagawa, Hisamu Kasahara, Atsushi Okamoto, Noriyoshi Tsuchiya

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


Hydration and carbonation reactions within the Earth cause an increase in solid volume by up to several tens of vol%, which can induce stress and rock fracture. Observations of naturally hydrated and carbonated peridotite suggest that permeability and fluid flow are enhanced by reaction-induced fracturing. However, permeability enhancement during solid-volume-increasing reactions has not been achieved in the laboratory, and the mechanisms of reaction-accelerated fluid flow remain largely unknown. Here, we present experimental evidence of significant permeability enhancement by volume-increasing reactions under confining pressure. The hydromechanical behavior of hydration of sintered periclase [MgO + H2O fi Mg(OH)2] depends mainly on the initial pore-fluid connectivity. Permeability increased by three orders of magnitude for low-connectivity samples, whereas it decreased by two orders of magnitude for high-connectivity samples. Permeability enhancement was caused by hierarchical fracturing of the reacting materials, whereas a decrease was associated with homogeneous pore clogging by the reaction products. These behaviors suggest that the fluid flow rate, relative to reaction rate, is the main control on hydromechanical evolution during volume-increasing reactions. We suggest that an extremely high reaction rate and low pore-fluid connectivity lead to local stress perturbations and are essential for reaction-induced fracturing and accelerated fluid flow during hydration/carbonation.

Original languageEnglish
Article numbere2110776118
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number3
Publication statusPublished - 2022 Jan 18


  • Carbonation
  • Reaction-enhanced permeability
  • Reaction-induced fracturing
  • Serpentinization
  • Volume-increasing reactions


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