Abstract

Subjecting a water-rock system to load can enhance the rock solubility by (1) increasing normal pressure at the dissolving surface and (2) raising the elastic energy of the rock. For pressure-solution surfaces such as grain contacts, solution seams, and stylolites, the pressure term in the chemical potential equation is orders of magnitude larger than the strain-energy term. Thus, the contribution of the strain energy to the overall solubility of the system is very small, and it is most often ignored. We show that the elastic strain energy at a pressure-solution interface can have a profound effect on the manner in which it evolves. The mechanism we propose is the following: inducing a discontinuity in elastic strain energy across a pressure-solution interface (e.g., by changing its curvature) can cause one side to become slightly more soluble than the other. Part of the material that is dissolved may diffuse the short distance across the fluid layer and raise the saturation in the vicinity of the less-soluble surface. If the fluid layer was already close to saturation, the dissolution at the less-soluble surface may be severely slowed down or even halted. Therefore, although the strain-energy difference across the interface has a negligible effect on the total amount of material that is dissolved there, it may cause only one side to dissolve. In this way, the formation of stylolites can be facilitated by heterogeneities in the elastic strain-energy difference along a pressure-solution interface.

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