The Solution Kinetics of Calcite

The solution alteration of a limestone depends on the rate at which water entering the rock becomes saturated. This rate is governed by the rate of transport of solute away from the solid-liquid interface, where the solution is always saturated. For laminar flow in a straight circular capillary of radius a, the solution will be 90 per cent saturated after penetrating a distance 0.572v̄a²/D, where v̄ is the average flow velocity of the fluid and D is the diffusion constant of the solute in the solution. Under normal conditions below the water table, v̄ and a are sufficiently small that the water in a limestone is always saturated with respect to calcium carbonate. Solution alteration can therefore take place only where the water first enters the rock or where the solubility changes.