Normal fault growth, displacement localisation and the evolution of normal fault populations: the Hammam Faraun fault block, Suez rift, Egypt Rob L. Gawthorpe a, * , Christopher A.-L. Jackson a , Mike J. Young a , Ian R. Sharp b , Adel R. Moustafa c , Christopher W. Leppard a a Basin and Stratigraphic Studies Group, Department of Earth Sciences, University of Manchester, Manchester M13 9PL, UK b Norsk Hydro Research Centre, Sandsliveien 90, Bergen, Norway c Department of Geology, Ain Shams University, Cairo 11566, Egypt Received 2 September 2001; accepted 25 June 2002 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. q 2002 Elsevier Science Ltd. All rights reserved. Keywords: Normal fault population; Fault growth; Displacement localisation; Suez rift 1. Introduction The evolution and linkage of fault segments to form continuous, basin-bounding normal fault zones is recog- nised as a first-order control on the size and shape of sedimentary basins in extensional settings (e.g. Anders and Schlische, 1994; Gawthorpe et al., 1994). The evolution of normal fault zones is therefore recorded in the stratigraphy of rift basins (e.g. Prosser, 1993; Morley, 1999; Contreras et al., 2000; Gawthorpe and Leeder, 2000; Meyer et al., 2002) and in the geomorphology of their hinterlands (e.g. Leeder et al., 1991; Leeder and Jackson, 1993; Eliet and Gawthorpe, 1995; Goldsworthy and Jackson, 2000). Conventional models of fault growth suggest that faults grow by systematic increases in maximum displacement and length, and that faults within a fault population become linked with time (e.g. Walsh and Watterson, 1988; Cart- wright et al., 1995; Dawers and Anders, 1995; Cowie, 1998; Ackermann et al., 2001; Mansfield and Cartwright, 2001). However, the detailed temporal evolution of individual faults and fault populations is still poorly constrained and these aspects of fault growth can only be addressed where information from stratigraphy or landscape allows sequen- tial reconstruction of displacements and lengths of fault zones (Gawthorpe and Leeder, 2000). Recent studies of ancient fault systems, utilising syn-rift stratigraphy, have begun to provide insights into fault growth histories, but are generally confined to single fault zones. Some of these studies support conventional models of fault growth, where propagation and linkage are important in fault evolution (e.g. Contreras et al., 2000; Dawers and Underhill, 2000). In contrast, others suggest alternative growth models, in which fault lengths are nearly 0191-8141/03/$ - see front matter q 2002 Elsevier Science Ltd. All rights reserved. PII: S0191-8141(02)00088-3 Journal of Structural Geology 25 (2003) 883–895 www.elsevier.com/locate/jstrugeo * Corresponding author. E-mail address: rob.gawthorpe@man.ac.uk (R.L. Gawthorpe).