FORAMINIFERAL BIOSTRATIGRAPHY AND PALEOENVIRONMENTS OF THE LOWER PALEOGENE SUCCESSION IN CENTRAL AND SOUTH SINAI, EGYPT

The Qalit Nakhl and Gebel Samra successions of the lower Paleogene were deposited on the southern branch of the unstable shelf in Sinai, Egypt. Foraminiferal assemblages were studied from a total of 118 samples collected from Q. Nakhl (55 samples) and G. Samra (63 samples). In both sections, planktic foraminifera dominate all the studied samples making 54 to 95% of the assemblages. Well-preserved planktic species allowed identification of fifteen biostratigraphic zones and subzones (Pα-E4). These range from Danian to Ypresian, with evidence of a Maastrichtian- Paleocene unconformity at Q. Nakhl section. Relatively low sedimentation rates (3.7 to 39.5 mm/kyr) characterize the Early Paleogene interval of this study. Nevertheless, the rate of sediment accumulation at the Q. Nakhl section is slower than that of the G. Samra, particularly during Pα to P5 biozones, which may indicate reduced sediment supply due to rapid relative sea-level increase to the North. Similar to the adjacent areas (e.g., Markha section), a major decrease in the proportion of planktic foraminifera at the Danian/Selandian boundary suggests a significant environmental disturbance related to globally recognized sea-level change. This event is also associated with sporadic disappearance of deep marine benthic taxa. In general, benthic foraminiferal assemblages of the Q. Nakhl section is less diverse than that of the G. Samra. Furthermore, the Early Paleogene benthic assemblage of the former is dominated by infaunal morphotypes, which may indicate oxygen depleted seafloor. Conversely, benthic foraminiferal assemblages of the G. Samra suggest well-oxygenated bottom waters of middle to upper bathyal environments.