Normal fault growth, displacement localisation and the evolution of normal fault populations: the Hammam Faraun fault block, Suez rift, Egypt

Abstract

Fault segment linkage, migration of the locus of fault activity, and displacement localisation were important processes controlling the late Oligocene–Recent evolution of the normal fault population of the Hammam Faraun fault block, Suez rift. Initial fault activity was distributed across the fault block on fault segments that had attained their final length within 1–2 My of rifting. These initial segments then either grew by increasing displacement and linked to form longer segmented fault zones or died, during a rift initiation phase that lasted 6–8 My. Following this rift initiation phase, displacement became localised onto >25-km-long border fault zones bounding the fault block and many of the early high-displacement intra-block fault zones died. Following displacement localisation onto the major faults bounding the fault block, the locus of maximum displacement continued to migrate, with post-Middle Miocene displacement focused on the western margin of the fault block. This migration of fault activity between major crustal-scale normal faults can be viewed in terms of strain localisation at the rift scale. The results from this study question conventional fault growth models based on final displacement distributions, and highlight the sequential nature of faulting on major normal faults bounding domino-style tilted fault blocks.