Biostratigraphy and Facies Analysis of the Eocene Rocks between Hammam Faraun and Wadi Tayiba, West Central Sinai, Egypt

Abstract

The Eocene successions exposed in the area between HammamFaraun and Wadi Tayiba in western Sinai have been studied in terms of foraminiferal distribution to figure out the biostratigraphicdistribution and facies setting of these successions. Two sections were measured. One at Gebel HammamFaraun, and the other to the south at WadiThal-WadiTayiba area. The Eocene succession of HammamFaraun (WaseiyitFm) is different from the rest of the area as it consists of mass gravity flow facies that represents a syntectonic deposition in a basin margin environment. This succession is rich in Nummulites which has been investigated thoroughly to identify them and determine the age of the succession. Three species has been identified. These species are Nummulites burdigalensis (Harpe De La, 1926), Nummulites alpinus Schaub, 1951 and Ruetimeyrina murchisoni (Rütimeyer, 1850) n.gen.(Boukhary et. al., in press). These species assign the Waseiyit Formation of HammamFaraun to Lower Eocene Ypresian age. WaseiyitForamation grades laterally to the lower part of the Thebes Formation. Wadi Thal-Wadi Tayiba Eocene succession extends in age to the upper Eocene. Five rock units were recognized. From Base to top, they are Thebes, Darat, Khaboba, Tanka and Tayiba Formations. Starting from the top of the Thebes Formation, these units were studied sratigraphically with the aid of planktonic Foraminifera. Seven planktic zones were established that range from Middle to upper Eocene. These zones are Acarininabullbrooki Zone, Globigerinathekamexicana Zone, Morozovelloideslehneri Zone, Globigerinathekaeuganea Zone, Acarinina (Truncorotaloides) rohri Zone, Turborotalia cerroazulensis cocoaensis Zone, and Globigerinatheka index tropicalis Zone. Benthic foraminifera, on the other hand, have been used to configure paleoecology and sedimentation history of the Middle-Upper Eocene units. The results show that the succession deposited in arelatively deep shelf environment in early Middle Eocene and normal shelf in Middle Eocene that has been affected temporarily by an upwelling event during thelater part of Morozovelloideslehneri Zone and Globigerinathekaeuganea Zone. The commence of Late Eocene may have witnessed a drop in sea level that may have been overprinted later by a tectonic uplift.