Reactivation and Fault Activity Mapping of the Late Cretaceous Sequence in Abu Roash Area, North Western Desert, Egypt

By

Sh. M. Sakran¹

(1) Cairo University, Cairo, Egypt

 The detailed structural analyses of fault zone characteristics and other reactivation criteria in the Late Cretaceous sequence of Abu Roash area unraveled the reactivation history of this geologically important sector. The NE-SW trending major faults acted as a southern marginal fault zone to the Natrun Basin in the north during Late Cretaceous sedimentation. Changes in distribution and nature of deformation products within the zones of these faults suggest syn-sedimentary Late Cretaceous movement was dip slip and normal. A later most probably Santonian phase of dextral transpression is also indicated. Syn-sedimentary fault deformation of the hangingwall sediments increases towards the major NE-SW trending faults. The fault zone characteristics of these minor faults revealed both distributed and localized shearing. Thrust movement overprinted the older hangingwall minor synthetic extensional faults. The common NW-SE, N-S, and ENE-WSW faults have no evidence of syn-sedimentary pre- Santonian movement and are interpreted as the echo of Late Santonian dextral transpression and the associated basin inversion.