Stratigraphic studies on some Upper Cretaceous successions in Sinai, Egypt

Abstract

Three Upper Cretaceous stratigraphic sections have been measured and studied in detail covering the lateral variation in facies from south to morth Sinai; Gebel Ekma (Southern Sinai), East Themed area (Central Sinai), and Gebel Yelleg (Northern Sinai). Eight lithostratigraphic units are recognised ranging in age from late Albian to the Maastrichtian and representing the southern and the northern facies. The southern facies includes Raha Formation (early-late Cenomanian), Abu Qada Formation (late Cenomanian-early middle Turonian), Buttum Formation (early-early middle Turonian), Wata Formation (early-late Turonian), and Themed Formation (Coniacian-Santonian). The Sudr Chalk (Campanian-Maastrichtian) represents the Upper Senonian sequence in both facies. Biostratigraphically, seven ammonite zones have been recognised from the studied sections; Neolobites vibrayeanus Total Range Zone, Vascoceras cauvini-Pseudoaspidoceras pseudonodosoides-Rubroceras alatum Assemblage Zone, Choffaticeras quaasi-Choffaticeras securiforme Total Range Zone, Choffaticeras segne-Vasoceras hartti Total Range Zone, Choffaticeras sinaiticum-Thomasites rollandi Total Range Zone, Coilopoceras requienianum Total Range Zone, and Metatissotia ewaldi Total Range Zone. Twenty zones of bivalves, gastropods, and echinoids are constructed from the studied sections. Moreover, two larger foraminiferal zones: Orbitolina conica Total Range zone and Praealviolina cretacea Total Range Zone are recorded from the Cenomanian of Gebel Yelleg. The Albian/Cenomanian, Cenomanian/Turonian, Turonian/Coniacian, Coniacian/Santonian, Santonian/Campanian, and Campanian/Maastrichtian boundaries are discussed.