Transport and the cause for precipitation are by no means always independent processes, but a division is attempted here for clarity. 3.1. transport mechanisms 3.1.1.
Diffusion is a geologically very important transport mechanism.
The second basic transport mechanism is fluid flow. When a fluid flows, it takes with it its solute. In the first case, Darcian or advective flow, fluid flows down a gradient in hydraulic head, through interconnected pathways. With localised or channellised flow, the fluid by-passes most of the rock volume, whereas with pervasive flow, the fluid comes in close contact with most of the rock. In the second case, fluid is contained as a unit in a fracture and both fracture and fluid move at the same time and the same rate.