Mechanics of cataclastic ‘deformation band’ faulting in high-porosity sandstone, Provence

Abstract

We examine the factors controlling fault array growth in high-porosity sandstone. Cataclastic ‘deformation band’ faults with displacements ranging from 1 mm to 400 mm have much lower displacement-to-length ratios in relation to faults in other lithologies. An analysis of material properties controlling fault growth suggests that this is due to a relatively high frictional strength on the cataclastic fault. An example of a late fault with a relatively large displacement gradient terminates against a thick cataclastic deformation band of the earlier set. This is interpreted as reflecting a general increase in bulk cohesion of the material during development of cataclastic deformation bands.