Normal Fault Population Evolution and Stratigraphic Response: An Example from the Hammam Faraun Fault Block, Suez Rift, Egypt

By

Rob Gawthorpe¹, Ian Sharp², Adel R Moustafa³, Chris Jackson¹, Chris Leppard¹, Mike Young¹

(1) University of Manchester, Manchester, United Kingdom (2) Norsk Hydro ASA, Bergen, Norway (3) Ain Shams University, Cairo, Egypt

 The evolution and linkage of fault segments to form continuous, basin-bounding normal fault zones is recognised as a first-order control on the size, shape and stratigraphy of sedimentary basins within areas of continental extension. We present results of an integrated structural and sedimentological study of the late Oligocene-Recent evolution of the Hammam Faraun fault block, Suez rift that allows the temporal evolution of fault populations to be investigated. Initial fault activity was distributed across the fault block on short (1-4 km long), low displacement (<1 km) segments, with most faults attaining their maximum length soon after the onset of rifting. Over the first 6-8 Myr of rifting, these initial segments either linked to form longer, segmented fault zones, or became inactive and died. Following this rift initiation phase, displacement became progressively localised onto >25 km long border fault zones bounding the fault block and many of the early intra-block fault zones became inactive. The locus of fault activity continued to migrate following linkage, with post Middle Miocene displacement focused on the western margin of the fault block. The dynamics of fault population evolution illustrated here are comparable to those suggested by analogue and numerical modelling studies and have important implications for the tectono-stratigraphic evolution of rifts and for understanding complex and often subtle syn-rift plays and structural compartmentalization of major fault blocks.