干旱区生态环境知识资源中心

Two strike-slip movements in the NW-SE direction were recorded in the Duwi area northwest of Quseir (Egypt). Three origins of outcrop-scale normal faults were inferred. Rock fragmentation, gouge, deformation bands, and slip surface formation are the successive steps in nucleation of the neoformed normal faults. Four generations of splay fractures were recorded; they are iterative. Parallel, sub-parallel, and horsetail splay fractures are common, en echelon fractures less common, and wing fractures rare. Four stages of book-shelf structure formation were recorded. Wide variation in lithology and rheology of rocks resulted in formation of several oversteps, flat and ramp, and bends along the fault planes. Displacement along outcrop-scale faults ranges from few centimeters to tens of meters. Great displacement is restricted to the main faults that mark the basement-sediment contact and pre-rift-syn-rift sediment contact. Due to strain localization, displacement partitioned along small faults. Mode I (extension) and Mode III (shear) fractures characterize the fault damage zones. There is an ambiguous relationship between the amount of fault displacement and damage zone width.