Preferential cataclastic grain size reduction of feldspar in deformation bands in poorly consolidated arkosic sands

▸ Degree of cataclasis in deformation bands correlates with shear strain. ▸ Weaker grains show more efficient grain size reduction than stronger minerals. ▸ Retention of Fe-hydroxide rich fluids indicated permeability reduction within the bands. ▸ Clay sized material is produced by mechanical processes. ▸ No chemical alteration or generation of clay minerals is observed.