Most of the palynological research conducted on Egyptian Cretaceous successions has been based on deep borehole samples taken from exploratory wells. These boreholes were drilled as a result of intensive exploration activities for hydrocarbons in the northern part of Egypt, especially the northern part of the Western Desert. Examples of work on borehole samples are: Abdelmalik et al.
(1981), Penny (1986, 1988a, 1992), Omran et al. (1990), Schrank & Ibrahim (1995) and Mahmoud & Deaf (2007). Hence washed ditch cutting samples were and still are the most widely accessible and routinely used material for Egyptian Cretaceous palynological research. However, core samples have sometimes been available for palynostratigraphers to use, for example in the papers of Abdelmalik et al. (1981), El-Beialy (1994a, 1994b, 1994c) and Ibrahim (1996, 2002a). In the southern part of the Western Desert, ditch cutting and core samples from shallow hydrological boreholes drilled during governmental reclamation projects has been the main source for palynological investigations. Examples of work based on such material are those of Schrank (1982, 1983), Schrank & Mahmoud (1998, 2000, 2002) and Mahmoud (2003). In southern Egypt, mining activities centred on the Upper Cretaceous phosphate deposits of the Duwi Formation have also enabled some palynological research to be carried out (e.g. Schrank, 1984a-b). The reason productive samples are generally restricted to borehole samples results from present day environmental conditions. Egypt is located in the subtropical arid zone and all the Cretaceous and younger outcrops are have been subjected to extensive deep weathering, and as a result they have been found to be palynologically barren (e.g. Schrank, 1983). Personal observations of samples taken from black and green
phy and palynozonation for proliferation of planktonic forams and nannofossils. Consequently, no independent age control is available for these successions. The upper Cretaceous interval is generally composed of pre-Campanian middle to upper shelf deposits, and of deeper upper to middle slope deposits for the Campanian-Maastrichtian interval, which is mainly represented by thick carbonate successions (Kerdany &
Cherif, 1990; Said, 1990). The planktonic foraminifera-calibrated palynological work of Abdel-Kireem et al. (1996) on upper Cretaceous (Cenomanian-Maastrichtian) subsurface samples from the Kahraman-1 and Abu Gharadiq-1 boreholes in the northern Western Desert is one of the few attempts to provide micropalaeontologically calibrated palynological work (Fig. 5.1). Most of the independently calibrated palynological work has been done by oil exploration companies and has not been published.
As most of the Egyptian palynological work has been carried out on ditch cutting samples where no independent age control was available, palynostratigraphers have identified different palynomorph assemblages, which have then been correlated with similar assemblages from other palaeogeographically related areas in order to date the Egyptian Cretaceous successions. As a result, several informal palynological zonal schemes (Fig. 5.2) and age assignments for different rock units have been proposed for the Cretaceous rocks of Egypt. The informal zones proposed by Schrank & Ibrahim (1995)
represent the most complete palynological zonal scheme for the Egyptian upper lower and upper Cretaceous sedimentary sequence (Fig. 5.2).
Figure 5.1 Cretaceous palynological assemblages and foraminiferal biozones in the north Western Desert of Egypt (Abdel-Kireem et al., 1996).
Chapter V Palynostratigra
Figure 5.2 (part) Correlation of most of the important palynozones for the Cretaceous of the northern Egyptian deser
phy and palynozonation Chapter V Palynostratigra
Correlation of most of the important palynozones for the Cretaceous of the northern Egyptian deserts. (W.D. = Western Desert).
phy and palynozonation
Correlation of most of the important palynozones for the ts. (W.D. = Western Desert).
Figure 5.2 (continued).
Figure 5.2 (continued).
Chapter V Palynostratigra
Figure 5.2 (continued).
phy and palynozonation Chapter V Palynostratigra
Figure 5.2 (continued).
phy and palynozonation
Figure 5.2 (continued).
phy and palynozonation Chapter V Palynostratigra
The Cretaceous biostratigraphic work of Schrank & Mahmoud (1998) in the Dakhla Basin in Central Egypt contributed to the understanding of this basin, where successions below the well-known Duwi Phosphate Formation had received little geological study, usually being referred to as the Nubian Sandstone Formation.
Later work by Schrank & Mahmoud (2000) on the Cenomanian of the Dakhla Basin resulted in the identification of new spore and angiosperm pollen species, and revealed the geological importance of this area, whereas the northern Western Desert was the research focus for palynostratigraphers studying early angiosperm pollen (e.g. Penny, 1988a, 1988b, 1989, 1991). The palynological work of Schrank
& Mahmoud (2002) in the Barremian of the Dakhla Basin also yielded new early angiosperm pollen. All of the new species described in the latter work are recognised in the present study of the Cretaceous succession of the Western Desert, providing better correlation between the Barremian of Central Egypt and that of the north Western Desert. It is thus possible to put the lower Cretaceous of Central Egypt into the framework of the regional Egyptian Cretaceous, previously best known from the Western Desert.
Perhaps the most important development for Egyptian palynology has been the development of the scanning electron microscope (SEM) which has been used to erect several dozen new angiosperm species (Schrank, 1982, 1983; Penny, 1986, 1988a, 1988b, 1989, 1991; Schrank & Ibrahim, 1995; Ibrahim, 1996; Ibrahim
& Abdel-Kireem, 1997; Kedves, 1998; Schrank & Mahmoud, 1998; Kedves, 1999;
Schrank & Mahmoud, 2000, 2002; Ibrahim, 2002a). The use of the SEM to study early angiosperm pollen from Lower Cretaceous successions has revealed the diverse nature of these angiosperm assemblages (Penny, 1992; Ibrahim, 2002a).
The resultant high resolution SEM-driven taxonomy has provided much information about the evolutionary trends of certain early angiosperm pollen taxa, for example
the Afropollis complex (Fig. 5.3), and hence increased their biostratigraphic importance.
In the past most palynostratigraphers Afropollis specimens to
investigations. Later SEM studies carried out by Schrank & Ibrahim Ibrahim (1996, 2002a)
provided better SEM microphotographs of previously described
Figure 5.3 Phylogenetic relationships between different Doyle et al. (1982)
complex (Fig. 5.3), and hence increased their biostratigraphic
In the past most palynostratigraphers (e.g. Omran et al., 1990)
specimens to Afropollis spp. based on routine light microscopic Later SEM studies carried out by Schrank & Ibrahim
(1996, 2002a) resulted in identification of new Afropollis provided better SEM microphotographs of previously described Afropollis
Phylogenetic relationships between different Afropollis
(1982). Dotted line: possible evolutionary trends according to complex (Fig. 5.3), and hence increased their biostratigraphic
ran et al., 1990) assigned spp. based on routine light microscopic Later SEM studies carried out by Schrank & Ibrahim (1995) and
Afropollis species and Afropollis species.
Afropollis species of d line: possible evolutionary trends according to
phy and palynozonation Chapter V Palynostratigra
The SEM (e.g. Schrank, 1983; Penny, 1986, 1988a, 1989) has also contributed toward a better understanding of the palaeolatitudinal migration of early angiosperm pollen producing plants (Doyle et al., 1977; Doyle, 1992; Penny, 1992).
Doyle (1992) compared his lower Potomac (USA) Zone I palynological assemblage of possible Aptian age to late Barremian and Aptian “Southern Laurasian”
Cerebropollenites assemblages of England and supposed late Barremian and Aptian assemblages of Gabon from the Dicheiropollis etruscus/Afropollis Province.
A gap in the early Aptian assemblage of Gabon has been filled by the better represented Egyptian early Aptian assemblage described by Schrank (1983) from the Mawhoub West 2 borehole in the southern part of the Western Desert, and by Penny (1986, 1988a, 1988b, 1989) from the Mersa Matruh-1 borehole in the northern Western Desert. The Egyptian palynoflora has permitted a better correlation between the Cerebropollenites and the Dicheiropollis etruscus/Afropollis provinces, and provided more evidence that Northern Gondwana was the main centre of early angiosperm radiation.