Mass transfer in the diagenesis of sediments is accomplished by the movement of solutions, and by diffusion. In a recent paper, Garrels et al. (1949) showed that the rate of transport by diffusion is independent of the permeability, but dependent upon an “effective directional porosity.” Values of this parameter for several different rocks were determined by diffusion measurements. In view of the analogy which exists between diffusion and electrical conduction this result could have been predicted from electrical data, and the “effective directional porosity” is more easily determinable by electrical measurements.
In a rock composed of nonconductive minerals, diffusion and electrical conduction will occur only in the pore space, and along sinuous paths. Hence, in such a case, the effective diffusion constant and electrical conductivity will be given by
These deductions are confirmed by experiment and several tables of data for various rocks are presented.