Description: Recent hydrocarbon exploration in the northern sector of the Western Desert in Egypt has revealed relatively rich hydrocarbon accumulations, mainly of gas, and demonstrate promising future prospects. In order to improve our understanding of this area and to provide a biostratigraphical framework for the hitherto poorly dated Lower Cretaceous successions, a palynological analysis was carried out on 57 ditch cutting samples from the Abu Tunis 1x borehole. Palynostratigraphic investigation on these samples has enabled the identification of three new palynostratigraphically defined age divisions with three corresponding palynozones defined by first uphole occurrences of gymnosperm and angiosperm pollen and dinoflagellate cysts. Spore and pollen grains recovered from the Abu Tunis 1x borehole show the characteristics of the pre-Albian Dicheiropollis / Afropollis Phytogeographical Province. Discrepancies in the reported range of Dicheiropollis etruscus , when compared with earlier (Berriasian) appearances in West Africa and later (late Hauterivian) appearances in East Africa, may be attributed to palaeoecological factors. Dicheiropollis etruscus is accepted as having a cheirolepidiacean conifer affinity and is regarded as having been produced by a thermophilous plant. Here, we suggest that Dicheiropollis etruscus was adapted to arid conditions. Dicheiropollis etruscus thus first appeared in hot, dry palaeo-subtropical African regions, but as Western Gondwana broke up and the African Plate moved northeast during/after the Late Jurassic, the region that is now present-day Egypt, Libya and Sudan had moved by the late Hauterivian into a subtropical position; the ensuing increased aridity thus allowed Dicheiropollis etruscus to migrate into these areas.

Description: The Miocene Marnoso-arenacea Formation (Italy) is the only ancient sequence where deposits of individual submarine density flow deposits have been mapped in detail for long (〉100 km) distances, thereby providing unique information on how such flows evolve. These beds were deposited by large and infrequent flows in a low-relief basin plain. An almost complete lack of bed amalgamation aids bed correlation, and resembles some modern abyssal plains, but contrasts with ubiquitous bed amalgamation seen in fan-lobe deposits worldwide. Despite the subdued topography of this basin plain, the beds have a complicated character. Previous work showed that a single flow can commonly comprise both turbidity current and cohesive mud-rich debris flows. The debris flows were highly mobile on low gradients, but their deposits are absent in outcrops nearest to source. Similar hybrid beds have been documented in numerous distal fan deposits worldwide, and they represent an important process for delivering sediment into the deep ocean. It is therefore important to understand their origin and flow dynamics. To account for the absence of debrites in proximal Marnoso-arenacea Formation outcrops, it was proposed that debris flows originated within the study area due to erosion of mud-rich seafloor; we show that this is incorrect. Clast and matrix composition show that sediment within the cohesive debris flows originated outside the study area. Previous work showed that intermediate and low strength debris flows produced different downflow-trending facies tracts. Here, we show that intermediate strength debris flows entered the study area as debris flows, while low strength (clast poor) debris flows most likely formed through local transformation from an initially turbulent mud-rich suspension. New field data document debrite planform shape across the basin plain. Predicting this shape is important for subsurface oil and gas reservoirs. Low strength and intermediate strength debrites have substantially different planform shapes. However, the shape of each type of debrite is consistent. Low strength debrites occur in two tongues at the margins of the outcrop area, while intermediate strength debrite forms a single tongue near the basin center. Intermediate strength debrites are underlain by a thin layer of structureless clean sandstone that may have settled out from the debris flow at a late stage, as seen in laboratory experiments, or been deposited by a forerunning turbidity current that is closely linked to the debris flow. Low strength debrites can infill relief created by underlying dune crests, suggesting gentle emplacement. Dewatering of basal clean sand did not cause a long runout of debris flows in this location. Hybrid beds are common in a much thicker stratigraphic interval than was studied previously, and the same two types of debrite occur there. Hybrid flows transported large volumes (as much as 10 km 3 per flow) of sediment into this basin plain, over a prolonged period of time.

Description: A palynological analysis has been conducted on the Cretaceous sediments of the Abu Tunis 1x borehole, in the northern Western Desert, Egypt. The palynomorphs recovered have been analysed both qualitatively and quantitatively, and permit a refinement of the original stratigraphy with the identification of four time-rock units. These have been divided into four informal sporomorph units and one dinoflagellate cyst palynozone. These biozones are, from oldest to youngest: the Afropollis jardinus-Tricolporopollenites-Elaterosporites klaszii Assemblage Zone (early–mid Albian), the Elaterosporites verrucatus-Sofrepites legouxae-Cretacaeiporites Assemblage Zone (late Albian–early Cenomanian), the Sofrepites legouxae Partial Range Zone (early–?mid Cenomanian), the Proteacidites cf. africaensis Total Range Zone (mid–late Cenomanian) and the Canningia senonica Total Range Zone (early? Santonian). A barren interzone has been identified immediately below the youngest palynozone, and this may be related to the unfavourable lithology (i.e., limestone and dolostone). The absolute abundances of spores and pollen represent the first quantitative description of an Egyptian Albian–Cenomanian palynofloral, a flora that is characteristic of the Albian–Cenomanian Elaterate Phytogeographical Province. The early Santonian palynoflora is exclusively marine phytoplankton; terrestrial palynomorphs representative of the Senonian Palmae Province are completely absent. The quantitative and semi-quantitative distributions of Afropollis jardinus are compared with similar semi-quantitative distributions of this species from other wells in the northern Western Desert of Egypt, and this permitted the identification of a mid Albian–early Cenomanian Afropollis jardinus ‘acme’ as an important local biostratigraphical event in the mid Cretaceous.