Imaging the Time-Dependent Evolution of Rock Strength: Chemo-Mechanical Coupling During Subcritical Crack Growth, Pressure Solution, and Healing in Calcite
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Harry Lisabeth
Lawrence Brekeley National Lab
- Date & Time
- Location
- Hybrid - in person at moffet and online via Microsoft Teams
- Host
- Rock Mechanics Lab
- Summary
The strength of rocks evolves continuously through a complex interplay between stress, microstructure, and chemical reactivity. Fluid-mediated processes play a central role in this evolution by coupling chemical reactions to the growth of damage, the redistribution of stress, and the recovery of mechanical integrity. Subcritical crack growth, pressure solution, and healing are often studied independently, yet each reflects a common underlying phenomenon: the ability of chemical reactions at confined interfaces to modify the microstructures through which rocks store, transmit, and relax stress over time.
In this talk, I present a series of experimental studies designed to directly observe chemo-mechanical coupling in calcite across multiple length scales. Isotopic tracer techniques are used to quantify in situ reaction rates during active pressure solution, providing direct constraints on stress-driven dissolution and mass transfer. Time-resolved synchrotron nano-tomography reveals the evolving geometry of grain contacts, crack networks, and reactive interfaces during deformation. Complementary X-ray microdiffraction and infrared imaging are employed to map residual stress fields, lattice strain, and fluid-assisted processes associated with crack healing and strength recovery.
Together, these measurements provide a direct view of the coupled evolution of reaction kinetics, interface structure, and stress during damage accumulation and healing. The results reveal how fluid-mediated reactions drive the nucleation and propagation of cracks, reorganize grain-contact networks through pressure solution, and promote the sealing and strengthening of fractures through healing. More broadly, these observations suggest that rock strength is not a static material property but an emergent, time-dependent consequence of chemo-mechanical feedbacks operating across scales. By directly observing these processes in situ, we establish new constraints on the mechanisms that govern the long-term rheological evolution of rocks in the Earth’s crust.