Detailed field mapping reveals that continental rifting is strongly deforming the Gebel Qattamiya-Gebel
Um Reheiat area and the entire Cairo-Suez district, in north Eastern Desert of Egypt. Rift-related structures
are predominantly represented by E to WNW, NNW and NW oriented faults. The E to WNW oriented
faults are small and build up the Gebel Qattamiya en echelon fault belt, whereas the faults trending
NNWand NWestablish a pervasive horst and graben structural style involving some rhomb-shape horsts
as Gebel Qattamiya (GQRH), Gebel Um Reheiat (GURRH) and south Gebel Um Reheiat (SGURRH). Rock
units of the Eocene succession and Oligocene sediments are well exposed and highly controlled by riftrelated
structures. Rifting was developed through two rift-phases; initial and major ones. The initial
phase (a newly recognized phase in this contribution) has been occurred in Late Eocene (Priabonian),
while the main phase was prevailing during Late Oligocene-Early Miocene time and is characterized by
hydrothermal veins and basaltic eruptions. Continental transtension in the Cairo-Suez district, including
the study area, was probably synchronous with a major tectonic stage (Pyrenean-Atlasic movement) of
continental collision between AfricaneArabian and Eurasian plates in Late EoceneeOligocene time.
Field investigation suggests that the transfer of displacement (slip) from the Gulf of Suez proto-rift into
the EeW oriented faults ‘‘relays’’ is an important mechanism, which helps to explain the current
structural framework and tectonic evolution of the Cairo-Suez district. Reactivation of such faults with
right-lateral divergent wrenching with NEeSW oriented extension deformed the Cairo-Suez district with
several EeWoriented en echelon fault belts (e.g. Gebel Qattamiya fault belt in the study area). Thus the
Cairo-Suez district represents an accommodation or transfer zone in northeastern Egypt, intercepting the
‘‘far-field stresses’’ from the ArabianeNubian Shield, the Red Sea-Gulf of Suez rift and the Maghrebian
Shield. |
