Cenomanian–Turonian transition in a shallow water sequence of the Sinai, Egypt

Abstract

Environmental and depositional changes across the Late Cenomanian oceanic anoxic event (OAE2) in the Sinai, Egypt, are examined based on biostratigraphy, mineralogy, d13 C values and phosphorus analyses. Comparison with the Pueblo, Colorado, stratotype section reveals the Whadi El Ghaib section as stratigraphically complete across the late Cenomanian-early Turonian. Foraminifera are dominated by high-stress planktic and benthic assemblages characterized by low diversity, lowoxygen and low-salinity tolerant species, which mark shallow-water oceanic dysoxic conditions during OAE2. Oyster biostromes suggest deposition occurred in less than 50 m depths in low-oxygen, brackish, and nutrient-rich waters. Their demise prior to the peak d 13 C excursion is likely due to a rising sea-level. Characteristic OAE2 anoxic conditions reached this coastal region only at the end of the d 13 C plateau in deeper waters near the end of the Cenomanian. Increased phosphorus accumulations before and after the d 13 C excursion suggest higher oxic conditions and increased detrital input. Bulk-rock and clay mineralogy indicate humid climate conditions, increased continental runoff and a rising sea up to the first d 13 C peak. Above this interval, a dryer and seasonally well-contrasted climate with intermittently dry conditions prevailed. These results reveal the globally synchronous d 13 C shift, but delayed effects of OAE2 dependent on water depth.

Biostratigraphic Revision of Middle-Cretaceous Biostratigraphy Succession in South Zagros Basin

“…In order to conduct a biostratigraphic study of Mid-Cretaceous strata in the south Zagros region, four stratigraphic sections of the Sarvak Formation were selected, which are named: Nour Since the biofacies of both studied sections are mainly comprised of benthic and pelagic foraminifers, the identification of Mid-Cretaceous foraminifers was provided [13][14][15][16][17][18][19][20][21][22][23][24]. The vertical distribution of identified formainifers and other microfossils led us to established biozones.…”

Realistic Paleobathymetry of the Cenomanian–Turonian (94 Ma) Boundary Global Ocean

“…This exactly spells out the difference between the two bathymetry dataset and highlights the importance of reconstructing the shelf-slope-wedge. This has special significance especially for the C-T time, as for decades the paleoclimate community has argued for extensive shallow epicontinental seas [36,[62][63][64][65][66][67][68][69][70][71][72][73][74][75][76] for example, to explain oceanic anoxic events. The OES C-T Ocean compared to Modern Ocean, has 4.75% more area (ocean area) less than 1000 m deep (maximum extent of combined euphotic and disphotic zone depth).…”

A reconstruction of the palaeoecology and environmental dynamics of the Bahariya Formation of Egypt

“…The ammonites Neolobites vibrayeanus (d 'Orbigny, 1841) and Baculites sp (Lamarck, 1799a) are also known from Bahariya (Stromer, 1936;Kassab & Obaidalla, 2001;Wiese & Schulze, 2005;Abdel-Gawad et al 2006;Gertsch et al 2010;El-Sabbagh et al 2011).…”