Haytham El Atfy

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.

A fungal proliferation near the probable Oligocene/Miocene boundary, Nukhul Formation, Gulf of Suez, Egypt

Moderately to well-preserved palynomorph assemblages were recorded from thirty samples of the Nukhul Formation (GH 404-2A Well), southern Gulf of Suez, Egypt. The taxa are dominated by highly diverse fungi, freshwater algae (e.g. Botryococcus, Pediastrum) beside a sparse record of spores and pollen. Marine palynomorphs, such as dinoflagellate cysts (dinocysts), are very rare. The stratigraphy and age of the Nukhul Formation is highly debated due to lack of diagnostic fossils (e.g. foraminifera, nannoplankton). It has been referred mostly to the Early Miocene; however, some recent publications interpret it as being of latest Oligocene–Early Miocene age. A prominent fungal proliferation composed of diverse and moderately well-preserved fungal spores, fungal fragments, fructifications and hyphae is recorded. This fungi-rich interval occurs mainly from 11370 to 11430 ft in the GH 404-2A Well. Such an observation has not been noted previously within the Nukhul Formation or its stratigraphic equivalents in Egypt. This putative ‘eco-event’ is probably associated with the well-known eustatic sea-level fall in the latest Chattian to early Aquitanian or at the Oligocene/Miocene boundary (OMB). It also seems possible that it may represent a more local event related to the rifting of the Gulf of Suez during this period. The high diversity of fossil fungi is interpreted herein as an indication of an episodic prevalence of humid climate at the end of a regressive phase, as also indicated by a lithological change near the top of the Shoab Ali Member of the Nukhul Formation. In addition, the co-occurrence of freshwater algae, mainly Botryococcus and Pediastrum, together with some aquatic fungal genera, such as Involutisporonites, Paragrantisporites, Quilonia, Striadiporites and Reduviasporonites, suggests the temporary existence of shallow, pond- or lake-like aquatic habitats, possibly related to tectonic activity.

Paleoecologic and stratigraphic significance of the freshwater algae Pediastrum in the Upper Cretaceous (Turonian) marine deposits, north Western Desert, Egypt

Palynological investigations of samples collected from the Abu Roash Formation, Faghur Hj5-1 well, north Western Desert, Egypt show a low diversity in palynomorph assemblage. This assemblage is mainly dominated by a clear proliferation of Pediastrum (and other allied algal forms, e.g., Scenedesmus and Botryococcus) which today lives exclusively in freshwater. Such a prominent record within the current marine deposits could be considered a good biostratigraphic datum in the Upper Cretaceous (Turonian) period rather than an ecologic event in the north Western Desert, Egypt. The influence of freshwater input on the studied deposits is proven by the presence of heavy minerals including kyanite, zircon, staurolite, and amphiboles encountered in siliciclastic sediments. Most of these minerals are sub-rounded to rounded so they were derived probably from sedimentary rocks. In the studied succession, the presence of Pediastrum reflects sea level fall (i.e., lowstand systems tracts). The occurrence of Pediastrum and other algae in such marine deposits reflects the predominant deposition of fluviatile sediments related to the discharge of rivers into shelf seas.KurzfassungEine palynologische Untersuchung von Spülproben aus der Abu Roash-Formation (Bohrung Faghur Hj5-1, nördliche Libysche Wüste, Ägypten) lieferte eine wenig diverse Palynoflora. Diese Flora ist gekennzeichnet durch ein Massenvorkommen von Pediastrum und anderen Algenformen, wie etwa Scenedesmus und Botryococcus, die heute ausschließlich im Süßwasser vorkommen. Ein dermaßen charakteristisches Vorkommen in den hier untersuchten marinen Abfolgen kann (für die Oberkreide: Turonium der nördliche Libyschen Wüste Ägyptens) möglicherweise eher als ein biostratigraphisches, denn als ein ökologisches Ereignis interpretiert werden. Der Einfluss eines Süßwassereintrags in den untersuchten siliziklastischen Ablagerungen wird belegt durch das Vorkommen der Schwerminerale Kyanit, Zirkon, Staurolith und Amphibol. Die meisten dieser Minerale sind kantengerundet, so dass angenommen werden kann, dass sie aus sedimentären Ablagerungen stammen. In der untersuchten Abfolge repräsentiert das Vorkommen von Pediastrum einen Meeresspiegeltiefstand. Das Vorkommen von Pediastrum und anderen Algen in solchen marinen Ablagerungen spiegelt die vorherrschende Ablagerung von fluviatilen Sedimenten im Zusammenhang mit dem Abfluss von Flüssen in Schelfmeere wider.

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.

Pre-Quaternary wood decay ‘caught in the act’ by fire – examples of plant-microbe-interactions preserved in charcoal from clastic sediments

Abstract The fossil record contains abundant evidence for the activity of microorganisms in the form of characteristic decay structures within fossil plant remains. Despite an abundance of charcoal in many sedimentary environments, there is little published evidence of such decay structures within charcoal from pre-Quaternary clastic deposits. The present contribution presents some examples of pre-Quaternary charcoal from clastic sediments which exhibit pre-charring decay structures, stratigraphically reaching from the Permian up to the Oligocene. Examples include specimens affected by the principle types of wood rot known from modern ecosystems (i.e. brown-rot, white rot and soft-rot) as well as a peculiar decay pattern resembling an atypical type of white-rot, which is only rarely known from modern wood. Theoretically there are different, so far hypothetical, scenarios which could be used to explain the scarcity of published reports on such material. Besides taphonomical biases directly influencing the sedimentary record of charcoal towards material not affected by microbial decay, it is conceivable that the lack of reports of such material from pre-Quaternary clastic deposits represents a, maybe unintentional, bias introduced by scientists working on pre-Quaternary charcoal.