Lithostratigraphy and biostratigraphy of the Cenomanian–Santonian strata of Sinai, Egypt

Abstract

The Cenomanian–Santonian successions of Sinai mainly consist of inner-shelf siliciclastics and carbonates. Five formations (Halal, Raha, Abu Qada, Wata, Matulla) have been recognized and a multibiostratigraphic framework has been constructed. The biostratigraphic assignments of the formations are mainly based on calcareous nannofossils. Their semiquantitative distribution within nine sections is presented, enabling us to identify the biozones CC10–CC16 in some cases. Ammonites are abundant in the uppermost Lower Turonian Mammites nodosoides Zone only. Planktic foraminifera of the Coniacian–Santonian Dicarinella concavata and D. asymetrica zones have been found. In addition to these groups, ostracods are used to differentiate between the stages supplemented by data in the literature on benthic foraminifera and rudists. Some modifications of previous lithostratigraphic schemes are proposed for the sections studied: from the ammonite data, a hiatus is proposed between the Halal/Raha and Abu Qada formations (Cenomanian/Turonian boundary); the Abu Qada Formation is considered to range from the M. nodosoides Zone to the lowermost Upper Turonian; and the base of the Matulla Formation is uppermost Turonian (CC13). A combined lithostratigraphic and biostratigraphic correlation of ten sections along a N-S transect allows the differentiation of eleven stratigraphic units. Units 1–8 within the Cenomanian–Turonian Halal, Raha, Abu Qada and Wata formations are considered to be synchronous. In contrast, ‘Syrian Arc’ tectonics most probably led to diachronous deposition of units 9–11 within the Coniacian–Santonian Matulla Formation.