Calcareous Nannoplankton From The Turonian-Maastrichtian Sequence East Of El Qusaima, Ne Sinai, Egypt
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On terms of calcareous nannoplankton, the Turonian-Maastrichtian sequence in the studied area is subdivided into a number of nannoplankton zones. The recorded biozones represent the Turonian, Coniacian, Campanian and Maastrichtian, while the Santonian is missing due to structural activity and/or to stratigraphic hiatus in the investigated succession. The Turonian/Coniacian boundary is defined by the first occurrence of Marthasterites furcatus, and the Campanian/Maastrichtian boundary can be placed at the extinction level of Eiffellithus eximius. Warm water conditions are suggested for the Turonian, Coniacian and Campanian periods, as indicated by the increased values of the Micula staurophora/Watznaueria barnesae ratio. There is some nannofossil evidences to suggest that the temperature was already declining in the uppermost Campanian and has continued throughout the Maastrichtian. Coccolith diversity was high during the Coniacian and the Campanian and decreased rapidly to few species in the Maastrichtian.