Particle shape evolution in natural carbonate granular wear material

A fundamental yet still unresolved puzzle provided by cataclasis is whether particle size reduction mostly progresses through time by the same fragmentation mechanism or not. Available field, laboratory and numerical modelling results on the evolution of cataclastic rocks are still controversial. The evidence that cataclastic rocks exert a primary control on the frictional strength, stability, seismic velocity and permeability properties of fault zones encourages further research on cataclasis. Here, we report data on particle shape from natural cataclastic rocks in poorly layered carbonates in the Apulian foreland of the Southern Apennines of Italy. Particle shape analyses show that particle angularity decreases with increasing size and, for a given size class, it decreases with increasing fractal dimension of the particle size distribution. These results offer support to the temporally and spatially variable nature of rock comminution.