Reaction-driven cracking during mineral hydration, carbonation and oxidation

In this paper we present recent and ongoing results of research on crystallization pressure and the reaction-driven cracking process that can result when hydration, carbonation, and/or oxidation reactions produce large changes in volume, viscosity is high (low temperature) and reaction rates are fast (large chemical potential, catalysts present, etc). Our focus is on natural processes involving reaction of olivine – the primary mineral constituent in the Earth’s upper mantle – with surface waters, and on analogue experiments intended to maximize reaction rates at low temperature (up to ~ 300°C) in a laboratory setting. We show that crystallization pressures can reach 100’s of MPa, enough to fracture rocks in the upper crust. Studies of natural and laboratory systems show that reaction-driven cracking produces fracture spacing down to 10’s or 100’s of microns, less than the diffusion distance on time scales of years, sufficient to produce 100% alteration of mantle rocks.