Foraminiferal Biostratigraphy, Graphic Correlation, and Depositional History of the Early Miocene, Gemsa Plain, Gulf of Suez, Egypt

John L. Smale, Robert C. Thunell, S. Schamel

Exposures of the early Miocene successions in the Gebel Gharamul and Gebel el Zeit regions, along with subsurface Gemsa Plain well logs, have been graphically correlated using Shaw's method. Three important regional events have been recognized. From oldest to youngest they include the following: (1) The Early Clysmic event, which is marked by strong onlap and truncation (Nukhul Formation), (2) The Mid-Clysmic or Mid-Rudeis event, which is associated with the G. subquadrata datum (LAD) and is characterized by structural truncation and downlap. Marginal outcrops of the Gemsa subbasin show internal disconformities marked by the presence of igneous boulder conglomerates, siliciclastic pulses, and synsedimentary slumps. A possible fan delta proximal to Gebel el Zeit was initia ed at this time. Other fan deltas from both Wadi Dara and Wadi Dib continued to be active primary conduits for clastic distribution from the rift shoulders. Basinward, structural highs were formed and eroded, and continuous sedimentation occurred in structurally low areas. (3) The Kareem/Belayim event, which is characterized by an increase in sedimentation rate. Overall, the early synrift sedimentation patterns can provide limits on the timing of fault-block movements. Increased biostratigraphic resolution allows for better correlation of lateral facies changes across the half-graben and results in an improved stratigraphy over that presently used.

AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.