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Two studies along the west bank of the Gulf of Suez show that: (1) complex cross structures control the subcrop pattern and synorogenic facies; (2) brittle faulting in the preorogenic rocks gives way to more plastic behavior in overlying units; and (3) secondary normal faults sole within the cover but reflect underlying fault patterns.
Gebel Zeit is the eroded crest of a major horst block, exposing Precambrian through Recent rocks. Internal structures include gulf-parallel faults, normal cross faults, and complex keystone grabens. Internal faulting, in conjunction with erosion, controls the reservoir subcrop pattern and synorogenic facies, including location of porous reefs.
The Ras Issaran horst system exposes Miocene to Recent deformed sediments. Continuing movements on cross faults control synorogenic clastic facies and reef locations. Reversal of movement direction on cross faults is common. Even through thick cover, the internal breakup of the horst is discernable.
The role of secondary cover faulting has been neglected in the Gulf of Suez. At Gebel Zeit, brittle faulting in the rigid preorogenic rocks dampens out as less pronounced faulting and folding in the plastic Miocene cover. At Ras Issaran, faults in the brittle Plio-Pleistocene clastics apparently sole in underlying evaporites. While these faults are decoupled from the underlying primary structures, they mimic the concealed fault pattern and provide clues to later movements of these faults. More detailed investigation of the internal breakup of horsts and the role of secondary faulting in the Gulf is needed.
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