Structural evolution of the eastern shoulder of the Suez rift: Um Bogma area

Abstract

Detailed field study of Um Bogma area, eastern shoulder of the Suez rift, indicates its failure by rupture in response to NE-SW extension at the early (Oligo-Miocene to Early Miocene)stage of rift opening. Deformation during this stage was characterized by horst-graben and step faulting without block tilting. Further extension in the rift, at later stages, did not affect Um Bogma area but formed listric normal faults west of it. These listric rift-bounding faults led to the abandonment of Um Bogma area to become part of the rift shoulder unaffected by further extension or tilting. In this way, the earliest rift opening affected an area wider than the present-day width of the rift.