Magdy S. Mahmoud

Palynology (pollen, spores and dinoflagellates) and cretaceous stratigraphy of the Dakhla Oasis, central Egypt

Abstract A re-assessment of the Cretaceous succession in the Dakhla area, central Egypt, is presented on the basis of new palynological evidence from the Six Hills and Maghrabi Formations. Miospore ages for the Six Hills Formation range from Early Neocomian to late Barremian-Early Aptian(?). The upper Six Hills (to lower Abu Ballas?) interval is the only unit that yielded marine dinoflagellates in addition to terrestrially derived miospores. Marine influence was thus effective below the base of the marine Abu Ballas Formation, which is here regarded as Early Aptian in age. The overlying Sabaya Formation could range down into the Aptian. Miospore assemblages from the Maghrabi Formation in the Dakhla area contain the new species Retimonocolpites variplicatus , tricolpates and tricolporates, but no triporates, which favours an Albian to Early Cenomanian age. Maghrabi assemblages in the Kharga area include triporates, which is broadly consistent with a Late Cenomanian to Turonian age. The formation may thus be diachronous, becoming younger from west to east. It is concluded that an eastward shift of the depocentre took place from the Dakhla area in Early Cretaceous time to the Kharga area in Albian to Late Cretaceous time.

Early Cretaceous palynology of three boreholes from northern Western Desert (Egypt)

Abstract A palynological study has been carried out on Early Cretaceous ditch rock samples from three boreholes drilled in the northern Western Desert of Egypt. The palynomorph content was qualitatively and quantitatively analysed with emphasis on dinoflagellate cysts and sporomorphs. The first provided the ages, necessary for correlation of the boreholes. Two successive sporomorph palynofloras and three successive dinoflagellate cyst palynofloras could be recognized in the Lower Cretaceous of the Western Desert. Furthermore, depositional environments were deduced resulting in identification of different paleoenvironmental regions in the northern Western Desert. The palynological compositional development is compared with contemporaneous successions from Europe, Atlantic, North Africa, Egypt and other parts of the Tethyan Realm.

Barremian Angiosperm Pollen and Associated Palynomorphs from the Dakhla Oasis Area, Egypt

Pollen grains characteristic of the local pre-tricolpate, pre-Aptian phase of angiosperm evolution have been recovered from the upper part of the Six Hills Formation in the Dakhla Oasis area, Egypt. Highest abundance (up to 16.5 per cent) and diversity of angiosperm pollen is attained in samples from the Tineida 2 borehole, which also display a remarkable variety of different aperture types for a palynoflora of late Barremian age. Monosulcate, columellate tectates such as Retimonocolpites are most important, but a single trichotomosulcate grain as well as monoporate and inaperturate types that have not been reported from many coeval palynofloras, are also present. The following new taxa are described using same-grain SEM/LM techniques: Tucanopollis annulatus Schrank, sp. nov., Retimonocolpites pennyi Schrank and Mahmoud, sp. nov. and Retiacolpites columellatus Schrank, gen. et sp. nov. Phytogeographic links are closest with palynofloras previously described from the late Barremian of West Africa (Gabon, Congo), that is within the Northern Gondwana or Dicheiropollis etruscus/Afropollis Province.

Jurassic-Cretaceous (Bathonian to Cenomanian) palynology and stratigraphy of the West Tiba-1 borehole, northern Western Desert, Egypt

Abstract Land-derived pollen and spores and marine dinoflagellate cysts were extracted from the Jurassic and Cretaceous sediments of the West Tiba-1 borehole, northern Western Desert, Egypt, On the basis of the recovered palynomorphs, of known stratigraphical significance, the following stages were assessed: Bathonian-Oxfordian (Middle-Late Jurassic) and Hauterivian, Aptian-Early Albian, Late Albian-Early Cenomanian, Early Cenomanian and Late Cenomanian (Early-Middle Cretaceous). No palynomorphs diagnostic for the Berriasian, Valanginian and Barremian stages (Early Cretaceous) were depicted. Based on the nature and composition of the identified palynomorph content, five informal palynomorph assemblage zones were recognised. These are: the Gonyaulacysta jurassica-Korystocysta kettonensis Assemblage Zone (PI, Bathonian-Oxfordian), Ephedripites-Aequitriradites verrucosus Assemblage Zone (PII, Hauterivian), Afropollis jardinus-Duplexisporites generalis-Tricolpites Assemblage Zone (PIIl, Aptian-Early Albian), Nyssapollenites-Elaterosporites Assemblage Zone (PIV, Late Albian-Early Cenomanian) and Assemblage Zone PV (Early-Late Cenomanian). The latter zone was differentiated into two subzones, namely the Classopollis brasiliensis-Elaterosporites klaszii Assemblage Subzone (PVa, Early Cenomanian) and Afropollis kahramanensis -Triporates Assemblage Subzone (PVb, Late Cenomanian). The time stratigraphy of the studied interval was revised. The occurrences and types of the dinoflagellate cysts, extracted from the studied succession, reflect a general shallow (shelf) marine pal˦oenvironment.

Palynology and palaeoenvironment of the Quseir Formation (Campanian) from central Egypt

Abstract The palynofloras of the basal part of the Quseir Formation in the Bulaq area, central Egypt, are overwhelmingly of terrestrial origin. They are dominated by angiosperms (mainly Foveotricolpites and Arecipites). Pteridophytic spores are abundant, amongest which the Deltoidospora/Cyathidites association and Gabonisporis vigourouxii are the most frequent. Aquatic plants (e.g. Ariadnaesporites spores) and freshwater algae (e.g. Ovoidites and Pediastrum) occur in appreciable amounts. The association is indicative of a fluvio-lacustrine environment characterized by widespread moist and aquatic habitats under a warm-humid (tropical) palaeoclimate. An angiosperm-based dating as Campanian (most probably Early Campanian) is suggested. Proteacidites sp. 3 Lawal and Moullade and Syncolporites schrankii Awad are the most significant angiosperms, which are not known to range before the Campanian in the “Senonian Palmae Province” areas. The Bulaq assemblages bear a close relationship with the Palmae palynofloras of North Africa, but differ significantly from those of West Africa.

Carbonaceous bodies of debatable organic provenance in the Banded Iron formation of the Wadi Kareim area, Eastern Desert, Egypt

Abstract The role of micro-organisms in the precipitation of the Precambrian Banded Iron Formation is discussed. The discovery of life in the Archaean rocks is described ( cf . Gruner 1925), noting that the sedimentary record documents more than 3000 Ma of Archaean and Proterozoic time. Stromatolites, microfossils and geochemical markers provide fragmentary but critically important evidence for early evolution (Knoll 1990). Precambrian microfossils (mainly microflora) have recently been extracted and described from the clastic sediments of the Hammamat Group. In the present work we introduce the first identified microfossils occurring in chert bands in the Banded Iron Formation (BIF) of the Wadi Kareim area, Eastern Desert, Egypt. Replacement and reaction textures between the postulated organic remains and both iron oxide and silica are described and an explanation offered.

Palynostratigraphy and palaeoenvironmental significance of the Cretaceous palynomorphs in the Qattara Rim-1X well, North Western Desert, Egypt

Palynological and palynofacies analyses were carried out on some Cretaceous samples from the Qattara Rim-1X borehole, north Western Desert, Egypt. The recorded palynoflora enabled the recognition of two informal miospore biozones arranged from oldest to youngest as Elaterosporites klaszii-Afropollis jardinus Assemblage Zone (mid Albian) and Elaterocolpites castelainii–Afropollis kahramanensis Assemblage Zone (late Albian–mid Cenomanian). A poorly fossiliferous but however, datable interval (late Cenomanian–Turonian to ?Campanian–Maastrichtian) representing the uppermost part of the studied section was also recorded. The palynofacies and visual thermal maturation analyses indicate a mature terrestrially derived organic matter (kerogen III) dominates the sediments of the Kharita and Bahariya formations and thus these two formations comprise potential mature gas source rocks. The sediments of the Abu Roash Formation are mostly dominated by mature amorphous organic matter (kerogen II) and the formation is regarded as a potential mature oil source rock in the well. The palynomorphs and palynofacies analyses suggest deposition of the clastics of the Kharita and Bahariya formations (middle Albian and upper Albian–middle Cenomanian) in a marginal marine setting under dysoxic–anoxic conditions. By contrast, the mixed clastic-carbonate sediments of the Abu Roash Formation (upper Cenomanian–Turonian) and the carbonates of the Khoman Formation (?Campanian–Maastrichtian) were mainly deposited in an inner shallow marine setting under prevailing suboxic–anoxic conditions as a result of the late Cenomanian and the Campanian marine transgressions. This environmental change from marginal to open (inner shelf) basins reflects the vertical change in the type of the organic matter and its corresponding hydrocarbon-prone types. A regional warm and semi-arid climate but with a local humid condition developed near/at the site of the well is thought to have prevailed.

Foraminiferal Pennsylvanian marble from Gebel El Hisinat Area, Eastern Desert, Egypt

Abstract The graphitic foraminiferal marble of Gebel El Hisinat Area is interbedded within folded eugeosynclinal metasediments and metavolcanics which were considered before as Pre-Cambrian. The whole succession attains a grade of metamorphism up to the highest temperature subfacies of the greenschist facies. The marble band contains rare arenaceous Pennsylvanian foraminifera comprising Endothyra media, Endothyra cl. and Mooreinella biserialis . Accordingly the original basin of sedimentation has been subjected to orogenic movement in the Hercynian period.

On the occurrence of some Paleocene palynomorphs from the Dakhla and Esna formations, Kharga Oasis area, Egypt

Abstract Paleocene palynomorphs are hardly extracted from the uppermost Dakhla Formation succession and the lowest Esna Formation rocks in two surface sections, northeast Kharga Oasis, Egypt. The identified palynomorphs are mainly dominated by small-sized angiosperm pollen. Foraminiferal test linings are abundant. Smooth land-derived spores and marine dinoflagellate cysts are rare, the latter are always distorted and not easy to identify. Gymnosperm pollen are never observed. Due to poor and less diverse palynomorphs, the dating of the studied section is controlled by previous foraminiferal studies. However, such palynofloral assemblage confirms the already known open marine depositional environment.