Salah Y. El Beialy

Lower and Middle Miocene biostratigraphy, Gulf of Suez, Egypt based on dinoflagellate cysts and calcareous nannofossils

This is the first detailed stratigraphic correlation of Lower and Middle Miocene deposits in the Gulf of Suez, Egypt using dinoflagellate cysts. The correlation is based on 273 ditch-cutting samples from five onshore boreholes located along the southwestern margin of the Gulf of Suez. The interval studied is represented by the Nukhul, Rudeis and Kareem formations of the Gharandal Group, and the lower part of the Belayim Formation of the Ras Malaab Group. These Miocene deposits unconformably overlie the Lower or lower Middle Eocene. The dinoflagellate cyst record is more diverse than previously reported and many taxa are documented for the first time in Egypt. Five biozones are established and tied to a chronostratigraphic framework by calibration to calcareous nannofossils (NN biozones) obtained from the same set of samples: (1) Lingulodinium machaerophorum Assemblage Biozone (GOSl), Aquitanian through mid-Burdigalian; (2) Exochosphaeridium insigne Taxon-range Biozone (GOS2), lower through mid-Burdigalian; (3) Apteodinium spiridoides Interval Biozone (GOS3), mid-Burdigalian through lower Langhian; (4) Cleistosphaeridium placacanthum Interval Biozone (GOS4), upper Burdigalian, Langhian, and lower Serravallian?); and (5) Polysphaeridium zoharyi Assemblage Biozone (GOS5), upper Langhian and Serravallian? Comparison with other Miocene biozonations from the Mediterranean, Central Paratethys, North Atlantic region, and eastern USA indicate that the highest occurrences of Apteodinium spiridoides, Cordosphaeridium cantharellus, Distatodinium paradoxum, Exochosphaeridium insigne and Cleistosphaeridium placacanthum, and the lowest occurrences of Exochosphaeridium insigne and Sumatradinium soucouyantiae are important datums, whereas the lowest occurrences of Hystrichosphaeropsis obscura, Labyrinthodinium truncatum, and Operculodinium? borgerholtense provide useful supporting age control.

Dinoflagellates from the Miocene Rudeis and Kareem formations borehole GS-78-1, Gulf of Suez, Egypt

The Miocene Rudeis and the Kareem formations encountered in the Neogene part of the GS-78-1 borehole, Gulf of Suez produced diverse assemblages of dinoflagellate cysts, spores and pollen. The Early Miocene (Burdigalian) age assigned to the Rudeis Formation and the Early-?Middle Miocene (Langhian–Serravallian) age postulated for the Kareem formation is based on the presence of dinoflagellate cysts. These offer a good basis for biostratigraphic correlation of the Miocene deposits in the Gulf of Suez with those in the Nile Delta and Sinai in Egypt, and also with those present in key sections from the Mediterranean, the Canadian offshore sequences, Northwest Europe and from the North Atlantic. The terrestrial palynoflora (spores and pollen) affords no really precise, independent testimonyas to the age of the samples, apart from being generallyindicative of a Neogene age, in accord with the established gross age of the sediments, derived mainlyfrom planktonic forams, calcareous nannoplankton and dinoflagellate cysts. The Rudeis Formation was deposited in a relativelydeep water environment, based on the abundance fluctuations in miospores and dinoflagellates. However, the miospores recovered from the Rudeis Formation give an equivocal signal with respect to depositional environment. Such observed incursions of terrestrial elements in the Rudeis Formation could indicate that theymight have been carried about within the basin of deposition bythe waters of the Mediterranean Sea, or that theywere displaced into a deep water setting. The overlying Kareem Formation was identified as an outer continental shelf deposit to upper bathyal (distal) environment because it contains a higher percentage of marine dinoflagellate cysts in most investigated samples, except in its uppermost part which shows the lowest percentage of marine forms. These include Spiniferites ramosus, S. pseudofurcatus, Operculodinium centrocarpum, Polysphaeridium zoharyi, Systematophora placacantha and Lingulodinium machaerophorum. The consistent presence of P. zoharyi in the Kareem Formation indicates that the Gulf of Suez was at times in the tropical to subtropical belt during the Early-?Middle Miocene age. 2002 Elsevier Science Ltd. All rights reserved.

Early cretaceous palynomorphs from Gabal Musaba Salama area, Southwestern Sinai, Egypt

Abstract Palynological study of the kaolin-bearing Malha Formation of southwestern Sinai yielded a rich, well preserved palynomorph assemblage advocating a Neocomian age. The palynofloras are recovered only from 14 black shale samples associated with the kaolinitic beds. They consist mainly of spores and pollen grains elucidating nonmarine conditions of deposition. Comparison with other relevant microfloras recovered from stratigraphically equivalent units suggests that the Sinai palynomorphs could be linked with the Laurasian European assemblages.

Palynology of the mid-Cretaceous Malha and Galala Formations, Gebel El Minshera, North Sinai, Egypt

Abstract Palynological investigations of the mid-Cretaceous, delta-influenced Malha Formation and superjacent transgressive Galala Formation exposed at Gebel El Minshera, north Sinai, Egypt, have yielded a sparse but biostratigraphically useful record of spores, pollen, and rare dinoflagellate cysts. A representative of the pollen genus Tricolporites, recovered 18 m above the base of the Malha Formation, is post-Aptian in age. An interval comprising the upper Malha Formation and lower Galala Formation is dated as middle Albian/middle Cenomanian based on the occurrence of Elaterosporites klaszii at the base and Afropollis jardinus at the top. A palynoflora from the upper Malha Formation, which includes ephedroids as well as Elaterosporites, has affinities with the Albian–Cenomanian Elaterates Province. The presence of palynomorphs associated with active fluvio-deltaic settings supports a proximal deltaic environment for the deposition of the Malha Formation, with the superjacent Galala Formation representing a subsequent marine flooding of the delta. A distinctive monospecific assemblage of the dinoflagellate cyst Subtilisphaera senegalensis in the upper part (Cenomanian) of the Galala Formation reflects an ecologically stressed, marginal-marine environment. This assemblage constitutes the first record of the mid-Cretaceous Subtilisphaera ecozone in Egypt and indeed east of Morocco, and in deposits as young as Cenomanian. The Malha and lowermost Galala Formations are characterized by type III–VI kerogen, which is gas prone but having little potential to produce hydrocarbons. Spore-pollen color indicates thermal maturity at the transitional to over-mature level, which is anomalously high when compared with equivalent deposits in the region.

Depositional paleoenvironment and hydrocarbon source potential of the Oligocene Dabaa Formation, north Western Desert, Egypt: A palynofacies approach

A detailed palynofacies study was carried out on 24 shale cutting samples from the Oligocene Dabaa Formation, which was penetrated in the Amana-1X well, Abu El Gharadig Basin, north Western Desert, Egypt. The investigation targeted primarily three main groups of palynological elements: phytoclasts, palynomorphs, and amorphous marine organic matter (AMOM), using transmitted light microscopy. Two major marine palynofacies were recognized: the oldest is palynofacies 1, made up mainly of AMOM (average abundance 47.5%), phytoclasts (31.6%), and palynomorphs (20.9%). A suboxic to anoxic outer shelf to upper slope paleoenvironment is suggested for this palynofacies. Palynofacies 2 is characterized by poorly preserved translucent phytoclasts (average abundance 61.2%) in addition to palynomorphs (24%), AMOM (14.8%), and opaques (

Stratigraphic and palaeoenvironmental significance of Eocene palynomorphs from the Rusayl Shale Formation, Al Khawd, northern Oman

Abstract Miospores recovered from the Rusayl Shale Formation of the Al Khawd section, northern Oman, are assigned an Early Eocene age, based on the co-occurrence of pantropical stratigraphic markers such as Proxapertites cursus, Spinizonocolpites echinatus, Rhombipollis geniculatus , and Intratriporopollenites microreticulatus . The sediments were deposited in a marginally marine environment under terrestrial influence, as indicated by the presence of very rare dinocysts and foraminiferal test linings, and significant amounts of cuticular material. The presence of Spinizonocolpites suggests a shoreline inhabited by mangroves. The occurrence of the mangrove taxon Avicennia , which today belongs to a coastal marsh vegetational community, supports the presence of tidal swamps near the area of deposition. The presence of the algal taxon Botryococcus is indicative of freshwater influence. The diversity of the angiosperm palynoflora, which forms the bulk of the assemblage,is thought to indicate a dense lowland vegetation cover.

Geophysical and palynological investigations of the Tell El Dabaa archaeological site, Nile Delta, Egypt

The authors present preliminary results of geophysical and palynological reconnaissance at the Tell El Dabaa, eastern Nile Delta. The geophysical survey reveals the presence of floodbasins, levees and channel deposits. Low palynomorph concentrations probably result from the high sedimentation rate and mean that further work is needed on the methods for palynological study in the region.

Dinoflagellate cyst evidence for the age and palaeoenvironments of the Upper Eocene–Oligocene Dabaa Formation, Qattara Depression, north Western Desert, Egypt

ABSTRACT The palynological investigation of 30 outcrop samples from seven sites in and near the Qattara Depression, north Western Desert, Egypt, has yielded six samples from three sites containing poorly to well-preserved assemblages including dinoflagellate cysts, freshwater algae, acritarchs, pollen and spores. The sites have not been dated previously, but dinoflagellate cyst evidence reveals an early or middle Rupelian (Early Oligocene) age for one sample (overlapping ranges of Tuberculodinium vancampoae and Phthanoperidinium comatum) and early Rupelian or older (occurrence of Lentinia serrata) for another, establishing time equivalence with the Upper Eocene–Oligocene Dabaa Formation. The palynological assemblages reflect fluctuating conditions on the southern margin of the Tethys/Paratethys Ocean, with the frequent co-occurrence of Homotryblium floripes, Pediastrum and Botryococcus reflecting restricted and probably lagoonal marine environments influenced by seasonal river inflow. Despite low global sea levels during the Early Oligocene, marine conditions evidently extended as far south as the southern Qattara Depression. Outcrops in the north Western Desert are typically deeply weathered and barren of palynomorphs, this being the first report of dinoflagellate cysts from surface sections of the Qattara Depression and its surroundings.