Shallow-generated damage within non-planar strike-slip fault zones: role of sedimentary rocks in slip accommodation, SW Holy Cross Mountains, Poland

Abstract

We investigated exhumed damage zones of dextral strike-slip faults dissecting the south-western part of the Mesozoic cover of the Late Palaeozoic Holy Cross Mountains Fold Belt. Structural observations allow to examine the top 1–2 km of the fault zones that deformed asymmetrically with the most intense damage controlled by the non-planar geometry of the faults. The deformational style of fault zones and the roughness of slip surfaces on subsidiary faults within deflections of fault traces in the restraining and releasing bends were facilitated by rock fabric and porosity. High porous sandstones enhanced genesis of cataclastic shear bands within the damage zone and the smooth slip surfaces. Low porous limestones enhanced the formation of dilatant structures infilled with calcite within damage zones and rough slip surfaces. The complex structural pattern of damage zones records multiple episodes of slip and shows evidence of continuous seismic–aseismic modes of fault slip behaviour.