The upper Cretaceous interval of the Khoman Formation in the Tamera well, Siwa area, Western Desert of Egypt was studied for the first time on the basis of calcareous nannofossils. Twenty-one nannofossil species were ...The upper Cretaceous interval of the Khoman Formation in the Tamera well, Siwa area, Western Desert of Egypt was studied for the first time on the basis of calcareous nannofossils. Twenty-one nannofossil species were identified from this interval. The study interval includes the Micula murus Zone, which is precisely dated as Late Maastrichtian age. The Micula murus Zone includes besides the marker species: Micula decussata, Watznaueria barnesae, Arkhangelsktella cymbiformis and relatively rare occurrences of Eiffellithus turrisieffellii, Cribrosphaerella ehrenbergii, Thoracosphaera operculata and Braarudosphaera bigelowii. The latest Maastrichtian Micula prinsi Zone is missing, and an unconformity surface is detected in this well. The high abundance of Micula decussata is indicative of very low surface productivity and high-stress environmental conditions. Several nannofossil species are recognized as cool water indicators such as Micula decussata, and Arkhangelsktella cymbiformis.展开更多
文摘The upper Cretaceous interval of the Khoman Formation in the Tamera well, Siwa area, Western Desert of Egypt was studied for the first time on the basis of calcareous nannofossils. Twenty-one nannofossil species were identified from this interval. The study interval includes the Micula murus Zone, which is precisely dated as Late Maastrichtian age. The Micula murus Zone includes besides the marker species: Micula decussata, Watznaueria barnesae, Arkhangelsktella cymbiformis and relatively rare occurrences of Eiffellithus turrisieffellii, Cribrosphaerella ehrenbergii, Thoracosphaera operculata and Braarudosphaera bigelowii. The latest Maastrichtian Micula prinsi Zone is missing, and an unconformity surface is detected in this well. The high abundance of Micula decussata is indicative of very low surface productivity and high-stress environmental conditions. Several nannofossil species are recognized as cool water indicators such as Micula decussata, and Arkhangelsktella cymbiformis.
