Impact of Structural Inheritance on Rift Geometry: Qattara Fault, The Main Bounding Fault of Abu Gharadig Basin, Northern Western Desert of Egypt

Abstract The Abu Gharadig Basin is a 300 km long Mesozoic rift basin in the northern Western Desert of Egypt. This basin's E‐W orientation differs from that of the other Mesozoic basins in the region. Despite being impacted by two Mesozoic rifting phases, the Abu Gharadig basin is oriented oblique to their extension directions. This study aims to account for the unique E‐W orientation of the Abu Gharadig Basin through detailed structural mapping of its main bounding fault (the Qattara Fault) by using seismic and borehole data. Our mapping indicates that the Qattara Fault is made up of six linked, differently oriented segments, some of which are parallel to the Jurassic or Cretaceous rifts whereas other segments show the effect of a pre‐existing E‐W structural fabric in northern Egypt. This pre‐existing structural fabric was reactivated and controlled the basin's orientation due to its low obliquity to the two Mesozoic rifting directions. The low obliquity in oblique rifts indicates the control of pre‐rift fabrics on the entire rift orientation in comparison with orthogonal rifts, which form perpendicular to the extension direction. Additionally, we found that the throw‐distance profiles of reactivated fault segments are different from those of newly formed segments and the throw‐distance profile of the entire linked (Qattara) fault is comparable to that of a single fault with maximum throw in the middle and minimum throws at the tips. The temporal variations of the Qattara Fault throw‐distance profiles show continued decrease in length and throw due to abandonment of rift extension.