Facies analysis, cyclicity and biostratigraphy of the Upper Cretaceous Sudr Formation, Wadi El Dakhl, West Gulf of Suez, Egypt: implications for sea-level changes and tectonics.

The Upper Cretaceous Sudr Formation at Wadi El Dakhl, West Gulf of Suez (Northeast Egypt) has been described to analyze the facies and their cycles in conjunction with the influence of sea level and tectonics. The Sudr Formation (~ 130 m thick) is composed mainly of chalk and chalky limestone, with intercalations of argillaceous limestone and marl. It could be divided into two members; the Markha of the early–middle Campanian age and Abu Zenima of the late Campanian–Maastrichtian age. Biostratigraphically, nine planktonic foraminiferal zones have been recorded which encompass the studied section. Petrographic studies of the Sudr Formation led to identify five facies types; four carbonate facies and one marl facies. These facies have been deposited in the environmental conditions of an inner, middle, outer shelf, and open marine basinal setting. Two types of cyclicity have been identified: shallowing-upward and deepening-upward cycles which indicate a change in oscillation in the relative sea level. The comparison of the studied sea-level curve with the global curves of Haq et al. (Science 365:1156–1167, 1987) and Haq (Glob Planet Change 113:44–58, 2014) refer to general correspondence between them in addition to the clear effect of the tectonic events that influenced the obtained sea-level curve of the present study. Three pronounced tectonic events that impacted the deposition of the studied Sudr Formation were recorded. These tectonics were operated during the late Santonian, middle Campanian, and late Maastrichtian time interval. These tectonics are most probably related to the collision of African/Arabian and Eurasia Plates. [ABSTRACT FROM AUTHOR]