A Cellular Automata Breccia Simulator (CABS) and its application to rounding in hydrothermal breccias

Dissolution processes are ubiquitous in surficial and hydrothermal environments. Solution breccias are formed when dissolution processes dominate and are widely observed in hydrothermal systems. Distinct fragment shapes develop during dissolution and can be used as diagnostic tools for characterizing the nature of the process.This paper presents a new simulator for hydrothermal breccias based on a 3D cellular automata model—thus called CABS (Cellular Automata Breccia Simulator)—that simulates various processes in virtual rocks, including dissolution, metosomatic exchange and precipitation. The code for this simulator is publicly available.The evolution of fragment shape complexity (boundary fractal dimension) during dissolution is evaluated using CABS. Results show that shape complexity increases for both surface-independent (kinetic regime) and dependant processes (diffusion-limited regime). In the case of a lognormal relationship between the probability of dissolution and the surface available for dissolution within the diffusion-limited regime, complexity remains constant and is accompanied by progressive rounding of the fragments. Increased porosity accelerates the rate of the process. The dissolution regime thus plays a crucial role in determining the relative importance of hydromorphic or clastic transport mechanism.