Role of fault interactions in controlling synrift sediment dispersal patterns: Miocene, Abu Alaqa Group, Suez Rift, Sinai, Egypt

Although fault growth is an important control on drainage development in mo dern rifts, such links are difficult to establish in ancient basins. To und erstand how the growth and interaction of normal fault segments controls st ratigraphic patterns, we investigate the response of a coarse-grained delta system to evolution of a fault array in a Miocene half-graben basin, Suez rift. The early Miocene Alaqa delta complex comprises a vertically stacked set of footwall-sourced Gilbert deltas located in the immediate hangingwall of the rift border fault, adjacent to a major intrabasinal relay zone. Sed imentological and stratigraphic studies, in combination with structural ana lysis of the basin-bounding fault system, permit reconstruction of the arch itecture, dispersal patterns and evolution of proximal Gilbert delta system s in relation to the growth and interaction of normal fault segments. Struc tural geometries demonstrate that fault-related folds developed along the b asin margin above upward and laterally propagating normal faults during the early stages of extension. Palaeocurrent data indicate that the delta comp lex formed a point-sourced depositional system developed at the intersectio n of two normal fault segments. Gilbert deltas prograded transverse into th e basin and laterally parallel to faults. Development of the transverse del ta complex is proposed to be a function of its location adjacent to an evol ving zone of fault overlap, together with focusing of dispersal between adj acent fault segments growing towards each other. Growth strata onlap and co nverge onto the monoclinal fold limbs indicating that these structures form ed evolving structural topography. During fold growth, Gilbert deltas progr aded across the deforming fold surface, became progressively rotated and in corporated into fold limbs. Spatial variability of facies architecture is l inked to along-strike variation in the style of fault/fold growth, and in p articular variation in rates of crestal uplift and fold limb rotation. Our results clearly show that the growth and linkage of fault segments during f ault array evolution has a fundamental control on patterns of sediment disp ersal in rift basins.