Facies Relationships, Structural Timing, and Foraminiferal Biostratigraphy of Morgan Hinge Zone, Gulf of Suez, Egypt

John L. Smale, Robert C. Thunell, Michael H. Garbee, Dana Q. Coffield, Stephen K. Perry

Detailed facies mapping and foraminiferal biostratigraphic correlation of surface exposures within the Morgan hinge zone, west bank, Gulf of Suez, provides synrift time lines that constrain deformational history. In addition, biostratigraphic and depositional events in the Suez rift bear similarities to those of the Mediterranean Sea, but within a more restricted environment. The Morgan hinge zone comprises a structurally complex cross-strike accommodation feature cutting northeast-southwest across the north-northwest-south-southeast Suez rift and separating domains of northeast-dipping tilt blocks in the north from southwest-dipping blocks in the south. Rocks affected by this zone crop out at the north end of the Esh el Mellaha tilt block. Detailed regional mapping corre ated by planktonic biostratigraphy shows that marginal sedimentation during the early Miocene consisted of carbonate buildups broken by cross-cutting channels carrying clastics from the western rift margin, across the Esh el Mellaha tilt block, into wide fan-delta systems, and finally into rapidly tilting and subsiding, marl-dominated subbasins. During middle and late Miocene evaporite deposition, marginal algal carbonates and lagoonal or sabkha anhydrites graded laterally to halite in the deeper parts of the rift. Associated clastic concentrations are generally limited to the margins. Individual vertical sections within the hinge zone show both regional and local regressive and transgressive cycles controlled by the interaction of regional vertical movements and eustatic sea level varia ions with the hinge zone's complexly faulted and eroded tilt blocks. These regional events tie the stratigraphy and evolution of the Suez rift to the Mediterranean, clearly placing the Suez-Red Sea rift in a wider context.

AAPG Search and Discovery Article #91043©1986 AAPG Annual Convention, Atlanta, Georgia, June 15-18, 1986.