Medhat M. M. Mandur

Implications of calcareous nannoplankton biostratigraphy and biochronology of the Middle–Late Miocene of the Nile Delta, Egypt

The Middle–Late Miocene subsurface successions from the Southeastern Mediterranean coast were studied based on the calcareous nannoplankton. The study was established on three boreholes selected from the offshore Nile Delta region, which are Port Fouad M-5, Baltim-1, and NDOB-1. The boreholes were chosen from different petroleum concessions within the North Delta basin. The standard nannoplankton biozonation of Mediterranean areas was used in this study. The studied rock successions cover the Sidi Salim and Qawasim formations, which are widely recognized targets for gas exploration. The study of the calcareous nannoplankton in the studied successions revealed eight biozones, and they are from base to top: Sphenolithus heteromorphus (NN5), Discoaster exilis (NN6), Discoaster kugleri (NN7), Catinaster coalitus (NN8), Discoaster hamatus (NN9), Discoaster calcaris (NN10), Discoaster quinqueramus (NN11), and Amaurolitus tricorniculatus (NN12). The Langhian/Serravalian, the Serravalian/Tortonian, and the Tortonian/Messinian boundaries were defined and discussed. The biochronological dates of the identified nannoplankton biozones were used to calculate the sedimentation rates of the studied rock successions. The calculations revealed two cycles of successive changes of sedimentation rates, which are attributed to regressions phases in Sidi Salim and Qawasim formations.

Integrated planktonic stratigraphy and paleoenvironments of the Lower-Middle Miocene successions in the central and southern parts of the Gulf of Suez, Egypt

Lower to Middle Miocene successions in three offshore wells named GS 160-2, QQ-89, and Ras Elush-2 located in the central and southern parts of the Gulf of Suez were examined for their planktonic foraminifera, calcareous nannofossil assemblages, and paleoenvironments. These successions are subdivided from older to younger into Aquitanian Nukhul, Burdigalian-Langhian Rudeis, Langhian Kareem, and Serravallian Belayim formations. The identified foraminifera includes 54 benthic species belonging to 25 genera and 47 planktonic species belonging to 11 genera, in addition to 64 calcareous nannofossil species belonging to 21 genera. The stratigraphic distribution of these assemblages suggests classifying the studied successions into seven planktonic foraminiferal and six calcareous nannoplankton biozones. The planktonic foraminiferal and calcareous nannoplankton biozones are integrated. Different environments ranging from shallow inner to outer shelf are recognized. This is based on quantitative analyses of foraminifera including benthic biofacies, planktonic/benthonic ratio, and diversity. Syn-rift tectonics played an important role in configuration of the Miocene depositional history in the Gulf of Suez region.

Calcareous nannofossil biostratigraphy and paleoecology of the Maastrichtian in the western coast of the Gulf of Suez, Egypt

Calcareous nannofossil content of the Maastrichtian succession at the western coast of the Gulf of Suez in Egypt has been studied. This study aims to contribute in the understanding of high-resolution biostratigraphy and paleoecologic interpretations. Five biozones (Reinhardtites levis, Arkhangelskiella cymbiformis, Lithraphidites quadratus, Micula murus, and Micula prinsii) were distinguished. According to the paleoecologic parameters (cool-water, warm-water, productivity, preservation, and the ratio of Micula decussata/Watznaueria barnesae), the studied succession is subdivided into five ecozones. The environment of each ecozone is deduced; M. Prinsii, M. murus, and L. quadratus ecozones are characterized by a cooler climate, but R. levis and A. cymbiformis ecozones are characterized by a warmer climate.