Cenomanian rocks in the Sinai Peninsula, Northeast Egypt: Facies analysis and sequence stratigraphy

Abstract

Five stratigraphic sections of the Cenomanian rocks exposed in the Sinai Peninsula are described and interpreted on the basis of field observations and facies analysis in order to reconstruct their depositional environments and sequence stratigraphic framework. Based on their lithologic characteristics, the Cenomanian successions consist of mixed siliciclastic–carbonate rocks. The Cenomanian successions are dominated by carbonate production in the northern and eastern parts of the study area. Siliciclastic supply increases southward. Detailed petrographic investigations made it possible to recognize several clastic and carbonate facies types. The facies recognized and their related palaeoenvironments document a lateral transition between inner- and mid ramp settings. The inner-ramp setting occurs in the south and west central Sinai where the peritidal flat, lagoonal, high-energy shoals facies dominate. The mid-ramp setting is assumed to have developed in the north and east central Sinai where intertidal and low-energy subtidal facies interfingers with a few storm-influenced deposits occur. The main factors controlling ramp deposition were eustatic sea-level fluctuations combined with environmental influences such as autochthonous carbonate productivity and siliciclastic supply. In terms of sequence stratigraphy, the Cenomanian successions in Sinai exhibit two superimposed depositional sequences, each of which shows retrogradational (transgressive systems tract) and aggradational to prograditional (highstand systems tract) packages of facies. The retrograditional facies display a predominance of subtidal carbonate facies, whereas the prograditional and aggradational facies show an increase of peritidal carbonates and siliciclastic deposits.