THE CENOMANIAN/TURONIAN OCEANIC ANOXIC EVENT IN THE RAZZAK #7 OIL WELL, NORTH WESTERN DESERT, EGYPT: PALYNOFACIES AND ISOTOPE ANALYSES

The Western Desert of Egypt is one of the world's major Jurassic and Cretaceous hydrocarbon provinces. Twenty-two carbonate samples from the “E”, “F”, and “G” members of the Abu Roash Formation in the Razzak #7 oil well were analyzed to determine hydrocarbon source rock potential as well as environment of deposition. The recovered dinoflagellate cysts are mainly long ranging but support a late Cenomanian to Santonian age for these units. Palynofacies analysis (kerogen quality and quantity) indicates oil and wet gas prone material, and implies reducing shallow marine paleoenvironmental conditions. The high total organic carbon (TOC) values, usually greater that 5.0 wt%, confirm the inferred reducing conditions. Detailed carbon and oxygen stable isotopic and organic carbon analyses indicate that the δ¹³C_org profile fluctuation across the Abu Roash “E”, “F”, and “G” members corresponds well with changes in TOC abundances. A positive δ¹³C_org excursion (-23.81 ‰ vs. VPDB) believed to mark the oceanic anoxic event 2 (OAE2) of the Cenomanian/Turonian boundary was identified within the organic-rich shaly limestone in the basal part of the Abu Roash "F" Member. This excursion also coincides with the peak TOC measurement (24.61 wt%) in the samples.