Abdel-Mohsen M. Morsi

Ostracode turnover and sea-level changes associated with the Paleocene-Eocene thermal maximum

The ostracode response to oceanographic changes during the Paleocene-Eocene thermal maximum (PETM, ca. 55 Ma) is largely unknown. The Gebel Duwi section (Egypt) provides a detailed ostracode record across the PETM in a middle neritic setting. Quantitative analysis of this record reveals two significant results. (1) The PETM is marked by a sharp faunal turnover, as indicated by abundance changes, local extinctions, and immigrations. This turnover punctuated a gradual basin-wide faunal transition. (2) During the ∼60 k.y. period prior to the PETM, relative sea level fell rapidly by ∼15 m. This sea-level fall was followed by an ∼20 m sea-level rise during the PETM. A possible eustatic control on these fluctuations suggests the presence of a cryosphere and variations in its size during this time of global warmth.

Reconstruction of a latest Paleocene shallow-marine eutrophic paleoenvironment at Sidi Nasseur (Central Tunisia) based on foraminifera, ostracoda, calcareous nannofossils and stable isotopes (d13C,d18O)

In order to unravel faunal and paleoenvironmental parameters in shallow marine settings prior to the Paleocene- Eocene thermal maximum, we investigated the Sidi Nasseur section (NAS) in Central Tunisia. This section exposes Paleocene to lower Eocene shales and marls of the El Haria Formation. The uppermost Paleocene part of the Sidi Nasseur section is marked by poor to moderately rich, but fairly diversified nannofossil associations, containing the typical latest Paleocene taxa of the top of NP9a. The ostracode record displays an almost continuous record in the uppermost Paleocene part of the section. Representatives of Aegyptiana, Paracosta, Reticulina and Reymenticosta make up the major part of the ostracode fauna. The benthic foraminiferal assemblage consists of numerous small calcareous benthic foraminifera, like Anomalinoides midwayensis and Lenticulina spp. and many large Frondicularia phosphatica, Pyramidulina spp. These, together with the non-calcareous agglutinated foraminifera and the rare planktic foraminifera, indicate an inner neritic to coastal environment with eutrophic conditions, regularly interrupted by oxygen deficiency. The dominance of non-calcareous benthic foraminifera between intervals with abundant calcareous benthic foraminifera suggests post-mortem dissolution. The foraminiferal d13C record (based upon Pyramidulina latejugata) of the latest Paleocene in the Sidi Nasseur area is very similar to these from coeval sediments at Gebel Duwi and Gebel Aweina in Egypt. Oxygen isotopic ratios indicate a marine setting with a water composition affected by evaporation. During the latest Paleocene, the highly productive shallow water environment evolved to shallower water depths with higher salinity and increasing dominance of A. midwayensis.

High-resolution ostracode records of the paleocene/eocene transition in the South Eastern Desert of Egypt — Taxonomy, biostratigraphy, paleoecology and paleobiogeography

Two high-resolution records (Gebel Duwi and Gebel Aweina, southern part of the Eastern Desert, Egypt) across the Paleocene/Eocene boundary were investigated for their ostracode contents. We particularly focused on the taxonomy, biostratigraphy, paleoecology and paleobiogeography of the ostracode assemblages and on the question whether there was a relationship between faunal and environmental changes associated with the Paleocene/Eocene thermal maximum (PETM). The two sections yielded a total of 29 different taxa, 19 in Duwi and 17 in Aweina, respectively. Four species,Cytherella aegyptopunctata, “Bairdia” malzi, Alocopocythere schmitzi andAegyptiana duwiensis are newly described. The ostracode fauna recorded in Aweina reflects outer neritic deposition, whereas the fauna at Duwi represents a middle neritic environment. Among the many taxa first appearing close to the Paleocene/Eocene boundary in Aweina and/or Duwi, onlyLeguminocythereis lokossaensis, Dahomeya alata anteroglabrata, Buntonia jordanica subjordanica, Nigeroloxoconcha aegyptiaca punctata andCytherella aegyptopunctata were not observed below the interval of the PETM in Egyptian sediments. During the latest Paleocene, some of these taxa migrated from West African basins, possibly through the Trans-Saharan Seaway. Just a few taxa disappeared during the PETM:Reticulina lamellata, Alocopocythere schmitzi andAegyptiana duwiensis. The Paleocene/Eocene boundary interval is also marked by enhanced aggradation and degradation inParacosta species, possibly resulting from lowered oxygen and/or enhanced food levels. These faunal and environmental shifts were controlled by a complex interplay between oceanographic, climatic, and sea-level changes.KurzfassungDie Ostrakoden zweier hochauflösender Profile (Gebel Duwi und Gebel Aweina, im südlichen Teil der Östlichen Wüste, Ägypten), die dem Bereich der Paleozän/Eozän-Grenze abdecken, wurden untersucht. Die Schwerpunkte waren die Taxonomie, Biostratigraphie, Palökologie und Paläobiogeographie der Ostrakodenvergesellschaftungen und die Frage, ob es einen Bezug zwischen Faunen- und Umweltveränderungen im Zusammenhang mit dem Paleozän/Eozän Thermalen Maximum (PETM) gab. Die zwei Profile enthielten insgesamt 29 unterschiedliche Taxa, bzw. 19 in Duwi und 17 in Aweina. Vier Arten werden neu beschrieben:Cytherella aegyptopunctata, „Bairdia“ malzi, Alocopocythere schmitzi undAegyptiana duwiensis. Die Ostrakoden-Fauna von Aweina zeigt Ablagerung auf dem äußeren Schelf an, während die Fauna von Duwi Sedimentation auf dem mittleren Schelf belegt. Unter den vielen Arten, die in Aweina und/oder Duwi nahe der Paleozän/Eozän-Grenze zum ersten Mal erschienen, wurden nurLeguminocythereis lokossaensis, Dahomeya alata anteroglabrata, Buntonia jordanica subjordanica, Nigeroloxoconcha aegyptiaca punctata undCytherella aegyptopunctata nicht unter dem PETM Bereich in Sedimenten Ägyptens beobachtet. Während des späten Paleozäns emigrierten einige dieser Taxa aus westafrikanischen Becken in die Tethys hinein, möglicherweise durch die transsaharische Meeresstraße. Nur wenige Taxa verschwanden gleichzeitig:Reticulina lamellata, Alocopocythere schmitzi undAegyptiana duwiensis. Der Bereich der Paleozän/Eozän-Grenze wird auch von erhöhter Aggradation und Degradation inParacosta Arten gekennzeichnet, was möglicherweise mit geringen Sauerstoff- und/oder erhöhten Nährstoffgehalten in Verbindung steht. Diese Fauna- und Umweltverschiebungen wurden von einem komplexen Zusammenspiel von ozeanographischen, klimatischen und Meeresspiegeländerungen verursacht.

Senonian ostracodes from east-central Sinai, Egypt; biostratigraphic and paleobiogeographic implications

Abstract Detailed study of the ostracod faunas from the Senonian succession in the area of east-central Sinai yielded 26 ostracode species and subspecies belonging to 18 genera and 10 families. Among these, two species, Ovocytheridea aegyptiaca and Neocythere? ventrolineata are newly described. Stratigraphic and paleobiogeographic distribution of the recorded species are outlined. Whereas most of the Lower Senonian species seem to be localized to Egypt and neighbouring areas in Israel, those from the Upper Senonian exhibit a wider geographic distribution throughout North Africa and the Middle East.

Plankton stratigraphy of the Early and Middle Miocene Kareem and Rudeis Formations in the central part of the Gulf of Suez, Egypt

The planktonic foraminifera and nannofossils of three wells in the Gulf of Suez penetrating the Early to Middle Miocene Upper Rudeis and Kareem Formations are attributed (from top to base) to the Middle Miocene Globorotalia peripheroronda Partial Range Zone (M6), the earliest Middle Miocene Praeorbulina sicana–Orbulina suturalis Interval Zone (M5), subdivided into the Praeorbulina glomerosa s. strict.–O. suturalis Interval Subzone (M5b) and the P. sicana–P. glomerosa s. str. Interval Subzone (M5a) and the Early Miocene Globigerinoides bisphericus Partial Range Subzone (M4b). The appearance of O. suturalis at the base of Subzone M5b represents the final stage of evolution of the Globigerinoides trilobus–Praeorbulina–Orbulina Lineage. In addition, the calcareous nannoplankton assemblages indicate the Sphenolithus heteromorphus Zone (NN5) and the Helicosphaera ampliaperta Zone (NN4). These biozones are well correlatable with those established by El-Heiny and Martini (1981, Geol Mediterr. Tome, VIII(2): 101–108) from the southwestern flank of the Gulf of Suez.

Late Cenomanian ostracode faunas from the area south of Ain Sukhna, western side of the Gulf of Suez, Egypt

Study of ostracode faunas from a Cenomanian exposure represented by the Galala Formation in the area south of the town Ain Sukhna on the western side of the Gulf of Suez has yielded 11 species belonging to 10 genera. The recorded species have been taxonomically described, discussed where required, and illustrated. The ostracode assemblage is characteristic for the late Cenomanian. It is composed of taxa of a typical marine shelf setting. The majority of the recorded species have a vastly extending geographic distribution in the areas along the southern shores of the Tethys, indicating the absence of significant geographic barriers along this stretch during the late Cenomanian.

Oculobairdoppilata gen. nov. (Ostracoda, Bairdiidae): a new genus from the Paleocene of Tunisia

A new marine ostracod genus, Oculobairdoppilata, belonging to the family Bairdiidae, is described from Paleocene deposits in Tunisia. Its main characteristic is the occurrence of an eye tubercle in the anterodorsal part of the valves. Internally, small denticles and corresponding sockets are present at the terminal parts of the dorsal edge of the right and left valves, respectively. It is the first bairdiid with an external eye structure to be described, although the existence of such a genus was predicted previously.