Soft Matter and Complex Systems Seminar

Coupled precipitation-dissolution processes are ubiquitous in hydrogeochemical systems which are out ofchemical equilibrium. However, as already remarked by Ortoleva et al. [1], the precipitation front will in generalmove with a velocity different from that of a dissolution front; thus the distance between them will increase intime. However, there are a number of systems where the both fronts appear to move with the same velocity. Oneexample might be the terra rossa formation process. According to some geological theories [2] this kaolinite-dominated soil grows when kaolinite precipitation produces hydrogen ions that dissolve the underlying calcite-dominated bedrock. In the case of terra rossa the velocities of the dissolution and precipitation front agree to within 1%, which does not seem accidental. We propose a simple model system, which attempts to mimic such a growth process and discuss possible mechanisms of the apparent reaction fronts synchronization. Then we study their further implications for the dynamics of the system.
[1] P. Ortoleva et al., Physica D: 19, 334 (1986).
[2] E. Merino and A. Banjerjee, J. Geol., 116, 62 (2008).

Coupled precipitation-dissolution processes are ubiquitous in hydrogeochemical systems which are out ofchemical equilibrium. However, as already remarked by Ortoleva et al. [1], the precipitation front will in generalmove with a velocity different from that of a dissolution front; thus the distance between them will increase intime. However, there are a number of systems where the both fronts appear to move with the same velocity. Oneexample might be the terra rossa formation process. According to some geological theories [2] this kaolinite-dominated soil grows when kaolinite precipitation produces hydrogen ions that dissolve the underlying calcite-dominated bedrock. In the case of terra rossa the velocities of the dissolution and precipitation front agree to within 1%, which does not seem accidental. We propose a simple model system, which attempts to mimic such a growth process and discuss possible mechanisms of the apparent reaction fronts synchronization. Then we study their further implications for the dynamics of the system.
[1] P. Ortoleva et al., Physica D: 19, 334 (1986).
[2] E. Merino and A. Banjerjee, J. Geol., 116, 62 (2008).