Sameh S. Tahoun

Palynomorph biostratigraphy of the Cretaceous (Hauterivian–lower Cenomanian) of the South Sallum Well, North Western Desert, Egypt

A palynological analysis has been carried out on the lower–middle Cretaceous rock units encountered in the subsurface section of the South Sallum well, north Western Desert of Egypt. Eighty-three ditch cutting samples have been analyzed palynologically and produced 71 species belonging to 49 genera, which allow recognizing ten informal sporomorph zones restricted to northern Western Desert ranging from early Cenomanian to Hauterivian. The erected palynozones are not only applicable to the western part of the Western Desert, but valid to the north Western Desert as well. They are correlated with well-documented zonations established for the same interval from other localities in the north Western Desert of Egypt and outside in north Africa.

Leiosphaeridia and Pterospermella acritarch genera as shallowing phase indicators in the early Jurassic, North Sinai, Egypt

The first attempt in Egypt to throw the light on the importance of Leiosphaeridia and Pterospermella acritarch genera has been done in the present study. Five ditch-cutting samples collected from the Mashabba Formation in North Sinai have been palynologically investigated. This study demonstrates the stratigraphic importance of these genera in the Jurassic sediments and increases their value in future sequence stratigraphical and paleoenvironmental/paleoecological interpretations. Both genera in the subsurface Early Jurassic interval of the Mashabba Formation indicate shallow water conditions. A good relationship between the recovery of these genera and the coarsening of the clastics has been recognized. Moreover, high counts of these acritarchs genera correlate with the increasing of sand content and vice versa. Hence, the abundance of Leiosphaeridia and Pterospermella can be an indication of the regressive events and associated low/fall sea levels in the Early Jurassic of Egypt.

A review of the angiosperm pollen genus Cretacaeiporites Herngreen, with one new species from the Upper Cretaceous of Egypt

An emended diagnosis of the angiosperm pollen genus Cretacaeiporites is proposed to encompass all attributed species. A comprehensive review of all Cretacaeiporites species is also given with the description of C. aegyptiaca sp. nov. from the subsurface mid-Cretaceous (Bahariya Formation) of northwest Egypt. A new combination, C. krutzschi (Boltenhagen) comb. nov., is also proposed. The review includes the original diagnosis of each taxon, holotype line illustrations and remarks on how to differentiate them from each other, in addition to a compilation of their known stratigraphical range and occurrences based on an exhaustive survey of their previous records.

A Cretaceous sporomorph palynozonation and the palaeobiogeography of northern Egypt

ABSTRACT The multiple biozonal nomenclatures given for the same time segment at different locations in northern Egypt are problematic, as such multiplicity is highly confusing and considerably limits the correlative value of these nomenclatures within the Egyptian territory, in the Elaterates phytogeoprovince and in the Tethyan Realm. Thirty-one wells are selected and used in this work to establish a standard and unified, semi-formal, generalised Egyptian sporomorph palynozonation scheme for northern Egypt. Marker taxa are carefully picked and tracked from the different previously established palynostratigraphies, and they are methodically re-used in the present unified framework on a regular basis, where their first down-hole appearance [last appearance datum (LAD)] palynoevents are utilised to erect a regional palynostratigraphical scheme. Ten sporomorph interval zones (IZ) and two subzones are reconstructed, established and palynologically specified from all of the studied wells. The authors surveyed the palynofloral assemblages characterising different areas of the world in order to derive meaningful palaeobiogeographical implications. Connecting these databases furnishes a comprehensive palynostratigraphical framework for inter-continental correlations with the Egyptian assemblages. In addition, such correlations confirm the dating acquired from the recovered palynological markers and assemblages presented in the current review. Comparisons of coeval assemblages confirm that the extensions and boundary limits of the palaeoprovinces of the recorded sporomorphs exhibited a gradual change and that their areal extent evolved with time. Due to the wide geographical occurrences of the recorded marker taxa during the pre-Albian stages of North and West Africa, western Atlantic and east South America, the proposed sporomorph zones can be confidently applied in these areas. During the Albian–Cenomanian such correlations can be applied only between North and West Africa and east South America.

A Cretaceous dinoflagellate cyst palynozonation of northern Egypt

ABSTRACT The multiplicity of dinoflagellate cyst biozones in Cretaceous rocks limits their correlation applications, and the variations in the scientific bases of such zonations complicates age determinations and limits the validity of reliable inter-basinal correlations. The present work provides a useful summary of the dinoflagellate cyst occurrence data in Egypt and a proposed working Egyptian biozonation scheme for the area. The most diagnostic dinoflagellate cyst bioevents, in a definite time interval which occurs widely in most of the studied Egyptian, North African and Tethyan sections, are selected to be marker taxa for the erected zones. The eastern Canadian and northern European data consistently show much higher range tops for the dinoflagellate cysts at those high latitudes. The comparison and correlation of the contemporaneous dinoflagellate cyst range tops from Egypt and geographically neighbouring North African areas are vital for selecting widely distributed marker taxa and testing their validity and applicability to intercontinental correlations in the Tethyan Realm. Based on 29 wells located across Northern Egypt, this work provides a potentially useful scheme that unifies the different previously established dinoflagellate cyst palynozonation frameworks for Cretaceous rocks. The index palyno-events represented by the last occurrence datums (LODs) of the marker dinoflagellate cyst taxa are carefully picked from palynostratigraphies established earlier and methodically, consistently used to create a new regional palynostratigraphical scheme for all of the northern Egyptian territory. Ten dinoflagellate cyst interval zones were identified and described; these are, in descending stratigraphic order from youngest to oldest, Dinogymnium acuminatum (Maastrichtian–Campanian), Odontochitina operculata (Santonian–Coniacian), Cyclonephelium vannophorum (Turonian), Dinopterygium cladoides (late–middle Cenomanian), Coronifera oceanica (middle–early Cenomanian), Oligosphaeridium complex (late–middle Albian), Subtilisphaera perlucida (early Albian), Cribroperidinium orthoceras or C. edwardsii (Aptian–late Barremian), Muderongia simplex or Pesudoceratium anaphrissum (Barremian–late Hauterivian) and Systematophora silybum (Hauterivian–Berriasian).