CALCAREOUS NANNOFOSSIL BIOSTRATIGRAPHY OF THE SUBSURFACE MIOCENE SEQUENCE, NORTHEAST NILE DELTA, EGYPT

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1 THE FIFTH INTERNATIONAL CONFERENCE ON THE GEOLOGY OF AFRICA Vol. (1), P-P.VII-1 VII-31 (OCT. 2007) ASSIUT-EGYPT CALCAREOUS NANNOFOSSIL BIOSTRATIGRAPHY OF THE SUBSURFACE MIOCENE SEQUENCE, NORTHEAST NILE DELTA, EGYPT Faris, M. 1, Samir, A. M. 2, and Shabaan, M. 3 1) Faculty of Science, Tanta University, mhmfaris@yahoo.com 2) Faculty of Science, Alexandria University 3) Faculty of Education, Kafr El Sheikh University, menaam_shabaan@yahoo.com ABSTRACT Miocene nannofossils were recovered from two offshore wells; Ras El Barr-1 and Bougaz E-1 and one onshore well; Rommana-1X, northeast Nile Delta, Egypt. Eleven calcareous nannofossil biozones were recorded, these are from top to base: Amaurolithus tricorniculatus Zone (NN12), Discoaster quinqueramus Zone (NN11), Discoaster calcaris Zone (NN10), Discoaster hamatus Zone (NN9), Catinaster coalitus Zone (NN8), Discoaster kugleri Zone (NN7), Discoaster exilis Zone (NN6), Sphenolithus heteromorphus Zone (NN5), Helicosphaera ampliaperta Zone (NN4), Sphenolithus belemnos Zone (NN3) and Discoaster druggii Zone (NN2). The Miocene/Pliocene boundary is identified in Bougaz E-1 Well by the first occurrence of Ceratolithus acutus (base of Subzone NN12b) and in both Rommana-1X and Ras El Barr-1 wells within the nannofossil Amaurolithus tricorniculatus Zone (NN12). The middle/late Miocene boundary in Ras El Barr-1 Well is delineated at the first occurrence of Discoaster hamatus (the base of Zone NN9). In Bougaz E-1 Well, this boundary is traced at the first occurrence of the planktonic foraminiferal species Neogloboquadrina acostaensis. The early/middle Miocene boundary is located within the Helicosphaera ampliaperta Zone (NN4) which lies in the Qantara Formation (Bougaz E-1 Well), whereas it is placed at the top of Helicosphaera ampliaperta Zone within the Sidi Salem Formation (Rommana-1 Well). INTRODUCTION This study is intended to illustrate the stratigraphically important Miocene nannofloral assemblages and to demonstrate their considerable promise for biostratigraphic zonations and to discus the Miocene stage boundaries. For this study, the nannofloral content was studied from Miocene sequences in three wells; Ras El Barr-1, Rommana-1X and Bougaz East-1, Nile Delta. The studied wells cover the eastern side of the North Nile Delta embayment extend to northwest Sinai and offshore Mediterranean coast, lies between latitudes to 32 50' N and longitudes 31 00' to 32 50' E (Fig. 1). Numerous studies have been devoted to the taxonomic and stratigraphic application of calcareous nannofossils in the Neogene sediments (Gartner and Bukry, 1975; Raffi and Rio, 1979; Okada and Bukry, 1980; Backman, 1980; Varol, 1982; 1983; 1989; Backman and Shockleton, 1983; Theodoridis, 1984; Perch-Nielsen, 1985; Young, 1990; 1998; Rio et al., 1990; Gartner, 1992; Aubry, 1993; Raffi et al., 1995; Fornaciari and Rio, 1996; Fornociari et al., 1996; 1997; de Kaenel and Villa, 1996; Huang, 1997; Bown, 1998; Siesser, 1998; Sprovieri et al., 1998; Negri et al., 1999; Odin et al., 2001; Marino and Flores, 2002; McGonigal and Wei, 2003; Pospichal, 2003 and Coric and Svabenicka, 2004). On the other hand, calcareous nannoplankton has rarely been considered in stratigraphic investigations of the Miocene sections of the Nile Delta, Egypt.

2 VII-2 Faris, M., Samir, A. M., and Shabaan, M. 31 o Ras El Barr-1 32 o 33 o 34 o 31 o Port Said Rommana-1X Bougaz E-1 N 31 o W. Natrun 30 o CAIRO Suez 30o SINAI Fayum 29 o 29 o Minia 28 o 28o Km RED SEA Assiut 31 o 32 o 33 o 34 o Materials Fig.1: Location map of the studied wells A total of 298 subsurface ditch samples are available from the three studied wells. The Ras El Barr-1 Well (offshore) was drilled to a total depth of 4440 m below sea level and penetrated through the Quaternary to the middle Miocene successions. The well is located in the offshore to the north of Damietta (lat N and long E). The Rommana-1X Well (onshore) is situated on the northwest Sinai (lat N, long E). This well was drilled to a total depth of ft below sea level (Schlumberger, 1980) and penetrated through the Quaternary to Oligocene. The Bougaz E-1 Well (lat N and long E) was drilled to a total depth of 1950 m below sea level by the International Egyptian Oil Company IEOC (1999). Method and techniques A small pieces of the ditch sample were taken for nannofossil investigations. According to the commonly accepted technique suggested by Bramlette and Sullivan (1961) and Hay (1964). The slides were examined using polarizing microscope at x1000 magnification in crosspolarized light. All nannofossils observed were recoded in range chart. Each smear slide was examined for at least 30 min. In that period of time, approximately 100 fields of view (FOV) could be searched.

3 Calcareous nannofossil biostratigraphy of the subsurface miocene sequence, northeast nile, VII-.3 Stratigraphy The Miocene sequence is represented by four rock units arranged from top to bottom, Qawasim, Sidi Salem, Qantara and Tineh formations. This sequence is overlain by the early Pliocene Abu Madi and/or Kafr El Sheik formations. The litho, and biostratigraphy of these rock units in the three wells are shown in Figs Qawasim Formation (late Miocene) This formation was first introduced by Rizzini et al. (1978). The type section is in the Qawasim-1 Well (lat N and long E), Nile Delta area (depth intervals between 2800 to 3765 m). The Qawasim Formation consists essentially of sand/shale section together with conglomerate (Zaghloul et al., 1977). In the present study, this formation unconformably overlies the Sidi Salem Formation and conformably underlies the Kafr El Sheik Formation (Bougaz E-1 Well) and conformably overlies the Abu Madi Formation and unconformably underlain by and the Sidi Salem Formations (Rommana-1X Well). Sidi Salem Formation (early to late Miocene) The Sidi Salem Formation was introduced by the Stratigraphic Subcommittee of the NCGS (1974). The type section was drilled in the Sidi Salem-1 Well (lat N and long E), south of Lake Burullus. This formation rests conformably on the Qantara Formation and/or the marine Oligocene or older rocks. Its upper limit is marked by a thick sandy conglomeratic beds and it is unconformably overlain by the late Miocene Qawasim Formation. In the offshore area, this formation is unconformably overlain by the early Pliocene Abu Madi Formation (Ouda and Obaidallaa, 1995; Zaghloul et al., 1977). Qantara Formation (early-middle Miocene) The Qantara Formation was introduced by the International Egyptian Oil Company (IEOC, internal report). The type section is in Qantara-1 Well (lat N and long E), northeastern side of the Nile Delta area (from depth m). The Qantara Formation conformably overlies the Sidi Salem Formation and underlies the Tineh Formation (Bougaz E-1 Well). Tineh Formation (early Miocene) The Tineh Formation was introduced by IEOC (internal report) to represent the Oligocene and parts of the lower Miocene sediments in the offshore area of North Sinai and the eastern Nile Delta. The present study concerns with the upper member of this formation (Tineh Upper Member). In Bougaz E-1 Well, Tineh Upper Member is conformably overlain by the Qantara Formation. Calcareous Nannofossil Biostratigraphy In the present study, the zonal schemes of Martini (1971) and Okada and Bukry (1980) were adopted, in addition, other bioevents were used to improve nannofossil biostratigraphy (Table 1). The abbreviation used are; FO= first occurrence, LO= last occurrence. In the subsurface wells, examinations of samples are usually downward due to contamination by caving. The LO of more than taxa was used for the determination of zonal boundaries. The ages, nannoplankton zonal assignment, nannoplankton abundance and preservation in the studied wells are shown in Figs Some representative nannofossil taxa are shown in Plates Amaurolithus tricorniculatus Zone (NN12) Gartner (1969), emend. Martini (1971) Age: Miocene/Pliocene boundary Definition: Interval from the LO of Discoaster quinqueramus to the FO of Ceratolithus rugosus and/or the LO of Ceratolithus acutus. Nannofloral association : The most common coccolith species encountered in this zone include: Reticulofenestra pseudoumbilicus, R. minuta, R. minutula, Calcidiscus leptoporus, C. macintyrei, Discoaster brouweri, D. intercalaris, D. surculus, Amaurolithus delicatus, A.

4 VII-4 Faris, M., Samir, A. M., and Shabaan, M. tricorniculatus and Sphenolithus abies. Abundant and well preserved calcareous nannofossils are recorded in Bougaz-E-1 Well, and common to rare taxa are recorded in Ras El Barr and Rommana-1X wells. Table 1: Standard calcareous nannofossil biostratigraphy and the present study bioevents. Age Stage Zanclean Messinian Tortonian Serravallian Langhian Burdigalian Aquitanian Martini (1971) Amaurolithus tricorniculatus (NN12) Discoaster quinqueramus (NN11) Discoaster calcaris (NN10) Discoaster hamatus (NN9) Catinaster coalitus (NN8) Discoaster kugleri (NN7) Discoaster exilis (NN6) Sphenolithus heteromorphus (NN5) Helicosphaera ampliaperta (NN4) Sphenolithus belemnos (NN3) Discoaster druggii (NN2) Triquetrorhabdulus carinatus (NN1) Sphenolithus ciparonsis (NP25) b a Boundary Events C. rugosus D. quinqueramus A. primus D. quinqueramus D. hamatus D. hamatus C. coalitus D. kugleri S. heteromorphus H. ampliaperta S. belemnos T. carinatus D. druggii H. recta Okada and Bukry (1980) C. acutus (CN10b) T. rugosus (CN10a) A. primus (CN9b) D. berggrenii (CN9a) D. neorectus CN8b D. bellus (CN8a) C. calyculus (CN7b) H. carteri (CN7a) C. coalitus (CN6) D. kugleri (CN5b) C. miopelagicus (CN5a) Sphenolithus heteromorphus (CN4) Helicosphaera ampliaperta (CN3) Sphenolithus belemnos (CN2) D. druggii (CN1c) D. deflandrei (CN1b) C. abisectus (CN1a) Diotyococcites bisectus (CP19 b) Boundary Events C. rugosus C. acutus D. quinqueramus A. primus D. berggrenii D. neorectus D. hamatus C. calyculus D. hamatus C. coalitus D. kugleri D. kugleri S. heteromorphus H. ampliaperta S. heteromorphus S. belemnos S. belemnos D. druggii C. abisectus S. ciperoensis Present Study NN11 NN9 NN8 NN7 NN6 NN4 NN3 NN2 b a b a NN5 Bioevents C. rugosus C. acutus D. quinqueramus D. quinqueramus D. bellus D. bollii D. hamatus D. exilis H. walbersdurfensis Cy. floridanus S. heteromorphus H. ampliaperta S. belemnos S. belemnos D. druggii Last occurrence First occurrence Occurrence: The Amaurolithus tricorniculatus Zone (NN12) is recorded in the three studied wells (Ras El Barr-1, Bougaz E-1 and Rommana-1X), Fig Discussion: The FO of Ceratolithus rugosus, as identified here in both Ras El Barr-1 and Rommana-1X wells defines the top of the Zone NN12. This species is rare in many basins world-wide and its FO can hardly be recognized due to the absence of core and side-wall samples (Huang, 1997). For that reason, the LO of Ceratolithus acutus as a bioevent defining the top of the Subzone CN10b by Bukry (1975) was adopted to mark the top of the Zone NN12 for the cutting samples as suggested by Varol (1983) and Womardt et al. (1992). In Bougaz E-1 Well, the FO of Ceratolithus rugosus and/or the LO of C. acutus are not recorded, so, the top of the Zone NN12 can not be detected. The FO of Ceratolithus acutus defines the boundary between the Triquetrorhabdulus rugosus Subzone (CN10a) and the overlying C. acutus Subzone (CN10b) of Bukry (1973). He noted that the nannofossils Subzone CN10a has a very short duration. The LO of T. rugosus and the FO of C. acutus are reported to correlate closely (Berggren et al., 1985; Raffi and Flores, 1995; Gartner and Shyu, 1996; Okada, 2000). The Triquetrorhabdulus rugosus Subzone (NN12a) of the late Miocene is defined as interval from the LO of Discoaster quinqueramus to the FO of Ceratolithus acutus (Okada and Bukry, 1980). This subzone is recorded in Bougaz E-1 Well. 10- Discoaster quinqueramus Zone (NN11) Gartner (1969), emend. Martini (1971) Age: late Miocene Definition: Interval from the FO to the LO of Discoaster quinqueramus and the FO of Discoaster berggrenii and/or the FO of Discoaster surculus to the LO of Discoaster quinqueramus.

5 Calcareous nannofossil biostratigraphy of the subsurface miocene sequence, northeast nile, VII-.5 Nannofloral association: The most common assemblages of Discoaster quinqueramus Zone (NN11) include: Calcidiscus leptoporus, C. macintyrei, Reticulofenestra pseudoumbilicus (large), R. minuta, R. minutula, Discoaster brouweri, D. challengeri, D. neorectus and Sphenolithus abies, in addition to the marker species Discoaster quinqueramus. Abundant and well preserved calcareous nannofossil assemblages are recorded in all samples from this zone at Bougaz E-1 Well. Rare to common with moderately preserved assemblages were recognized at Ras El Barr-1 and Rommana-1X wells. Occurrence: The Discoaster quinqueramus Zone (NN11) is recorded from the three studied wells in the Qawasim Formation of both Bougaz E-1 and Rommana-1X wells and in the Sidi Salem Formation of Ras El Barr-1 Well. Discussion: Okada and Bukry (1980) subdivided the Discoaster quinqueramus Zone into a lower Discoaster berggrenii Subzone (CN9a) and an upper Amaurolithus primus Subzone (CN9b) according to the FO of A. primus (the first horse shoe shaped calcareous nannofossils in the Neogene). Two other significant bioevents in the Zone NN11 are the FO of Amaurolithus delicatus and the LO of Reticulofenestra rotaria. The FO of A. delicatus was proposed by Martini and Müller (1986), and its equivalent to the FO of A. primus proposed by Bukry (1973). The two FOs (A. primus and A. delicatus) were used as markers subdividing the Zone NN11 into the lower NN11a and upper NN11b subzones (Huang, 1997). In the range charts, Discoaster quinqueramus was grouped with Discoaster berggrenii, but typical specimens of the latter become extinct before the LO of D. quinqueramus as noted by Bukry (1973) in some oceanic areas. The top and the base of the Zone NN11 are defined by the LO and the FO of Discoaster quinqueramus, respectively. These bioevents are easily recognized in the three studied wells. Amaurolithus delicatus occurs in many samples than any other Amaurolithus spp. but its appearance was sporadic, so, its FO can not be detected. On the other hand, Amaurolithus primus is recorded only in one sample in Rommana-1X Well. 9- Discoaster calcaris Zone (NN10) Martini (1971) Age: late Miocene Definition: Interval from the LO of Discoaster hamatus to the FO of Discoaster quinqueramus, or the FO of Discoaster berggrenii, or the FO of Discoaster surculus. Nannofloral association: The calcareous nannofossil assemblages are well preserved and abundant in Bougaz E-1 Well, but they are rare to few in Rommana-1X and Ras El Barr-1 wells. The characteristic nannofossils of this zone include: Calcidiscus leptoporus, C. macintyrei, Reticulofenestra pseudoumbilicus, R. minuta, D. brouweri, D. neorectus, D. bellus, D. bollii and D. calcaris Occurrence: Within the Sidi Salem Formation in the Ras El Barr-1 Well. An unconformity is detected in Rommana-1X Well, whereas, the Zone NN10 unconformably overlies the middle Miocene Sphenolithus heteromorphus Zone (NN5). In Bougaz E-1 Well, this zone is located at the base of the Qawasim Formation. An important earliest late Miocene hiatus occurs in Bougaz E-1 Well, where the earliest late Miocene nannofossil Discoaster hamatus Zone (NN9) is missing. Discussion: Bukry (1973) subdivided the Discoaster calcaris Zone (NN10) into a lower Discoaster bellus Subzone (CN8a) and an upper Discoaster neorectus Subzone (CN8b) by the FO of D. neorectus and/or the FO of Discoaster loeblichii. Rio et al. (1990) noted a few specimens of typical D. neorectus from western equatorial Indian Ocean (Leg 115) and recorded D. loeblichii as sporadic species only at higher stratigraphic level, therefore, they don t subdivided this zone as Bukry (1973). The LO of Discoaster loeblichii is used by Bukry (1973) to define the top of Zone CN8. The co-occurrences of D. loeblichii and of D. berggrenii were previously noted by Proto- Decima et al. (1978), Mazzei et al. (1979) and Parker et al. (1985) in the Atlantic Ocean. The D. neorectus is very large, six-rayed discoaster with tapering arms and its range restricted to CN8b of Bukry (1973). The top of Zone NN10 is defined by the FO of Discoaster quinqueramus, as identified here in both Ras El Barr-1 and Rommana-1X wells and the top of the Zone CN8 corresponding to the Zone NN10 (top) is defined by the FO of Discoaster berggrenii.

6 VII-6 Faris, M., Samir, A. M., and Shabaan, M. Therefore, the LO of Discoaster neohamatus is a bioevent slightly below the FO of D. quinqueramus, is used as the marker for the top of NN10 (Varol, 1983). In Bougaz E-1 Well, the LOs of Discoaster bellus and D. bollii are recorded in just below the LO of D. quinqueramus are used to approximate the top of Zone NN10a according to Perch- Nielsen (1985) range chart. Meanwhile, D. neorectus is recorded as scattered specimens in such section. 8- Discoaster hamatus Zone (NN9) Bramlette and Wilcoxon (1967), emend. Martini (1971) Age: late Miocene Definition: Interval from the FO to the LO of Discoaster hamatus. Nannofloral association: Common to rare and very rare calcareous nannofossil assemblages were recorded in this zonal interval. The most common coccolith assemblage encountered in this zone includes: Calcidiscus macintyrei, Reticulofenestra pseudoumbilicus, R. minuta in addition to marker species Discoaster hamatus. Occurrence: This zone is recorded only in Ras El Barr-1 Well within the Sidi Salem Formation. Discussion:The most conspicuous change in this zone is the FO of five-rayed discoasters like the large D. hamatus (with tapering, asymmetrically bifurcated arms) and D. bellus (more or less straight, tapering arms, smaller than D. hamatus), as well as D. prepentaradiatus with its bifurcated arms (Perch-Nielsen, 1985). Bukry (1973) used the FO of Catinaster calyculus to subdivide the D. hamatus Zone (CN7) into a lower Helicosphaera kamptneri/h. carteri Subzone (CN7a) and an upper Catinaster calyculus (CN7b). This subdivision is in disagreement with the observations by Thierstein (1974) and Salis (1984) where they found that C. calyculus appears before D. hamatus in the Indian Ocean and South Atlantic. Parker et al. (1985) found the FO of Catinaster calyculus together with the FO of D. hamatus in the North Atlantic Ocean. Rio et al. (1990) recorded a typical C. calyculus below the FO of D. hamatus, and therefore, they were not able to subdivide Zone CN7. The FO of Discoaster bellus occurs at or just below the FO of D. hamatus (Theodoridis, 1984; Rio et al., 1990; Gartner, 1992). Another feature of the nannofossil assemblage of NN9 Zone is the conspicuous increase in abundance of Reticulofenestra, over 7µm in size coinciding with the decrease of Reticulofenestra, less than 5µm (Huang, 1997). The NN9 Zone is defined here by the total range of Discoaster hamatus as original definition of Martini (1971). 7- Catinaster coalitus Zone (NN8) Bramlette and Wilcoxon (1967), emend. Martini (1971) Age: Middle Miocene Definition: Interval from the FO of Catinaster coalitus to the FO of Discoaster hamatus. Nannofloral association: Abundant to common nannofossil assemblages are recorded in this zone in Bougaz E-1 Well, and common to rare in Ras El Barr-1 Well. The most common assemblages of this zone includes: Reticulofenestra pseudoumbilicus (small), Calcidiscus macintyrei, Discoaster exilis, Helicosphaera carteri and Coccolithus miopelagicus. Occurrence: Within the Sidi Salem Formation in both Ras El Barr-1 and Bougaz E-1 wells. Discussion: Discoaster exilis and Coccolithus miopelagicus usually disappear near the top of this zone (Perch-Nielsen, 1985 and Rio et al., 1990). Rio et al. (1990) recorded that Discoaster brouweri and D. calcaris are common in this interval and D. pseudovariabilis is rare. On the other hand, the LO of Coccolithus miopelagicus is used to approximate the base of the Zone NN8 in the absence of C. coalitus (Raffi and Flores, 1995; Marino and Flores, 2002; McGonigal and Wei, 2003). In the present study, the top of this zone fits the original definition of the same zone by Martini (1971) in Ras El Barr-1 Well (the LO of D. hamatus). On the other hand, the LO of D. exilis is used to approximate the top of the zone according to Perch-Nielsen (1985) and Rio et al. (1990) in Bougaz E-1 Well. 6- Discoaster kugleri Zone (NN7) Bramlette and Wilcoxon (1967), emend. Martini (1971) Age: Middle Miocene. Definition: Interval from the FO of Discoaster kugleri and/or the LO of Cyclicargolithus floridanus to the FO of Catinaster coalitus.

7 Calcareous nannofossil biostratigraphy of the subsurface miocene sequence, northeast nile, VII-.7 Nannofloral association: Common to rare nannofossil assemblages of this zone include: Reticulofenestra pseudoumbilicus, Calcidiscus macintyrei, Discoaster exilis, Helicosphaera kamptneri, H. walbersdurfensis and Coccolithus miopelagicus. Occurrence: The Discoaster kugleri Zone (NN7) is recoded in Bougaz E-1 Well within the Sidi Salem Formation. In Ras El Barr-1 Well, the NN6 and NN7 zones are grouped together to form the NN6/NN7 combined zone. Discussion: Discoaster deflandrei becomes very rare and disappears near the top of the Zone NN7 (Perch-Nielsen, 1985). According to Ellis (1981) and Perch-Nielsen (1985), Discoaster kugleri disappears near the top of Zone NN7. The LO of D. kugleri, an auxiliary bioevent proposed by Bukry (1973), was used to mark the top of the NN7 Zone. Theodoridis (1984) mentioned that the LO of Helicosphaera walbersdurfensis occurs close to the FO of Catinaster coalitus. The LO of H. walbersdurfensis is correlated with the top of NN7 Zone (Fornaciari et al., 1996; Siesser and de Kaenel, 1999). Marino and Flores (2002) used the LO of Coccolithus miopelagicus to roughly approximate the NN7/NN8 boundary. In the present study at Bougaz E-1 Well, the LO of Helicosphaera walbersdurfensis is used to roughly approximate the NN7/NN8 boundary. 5- Discoaster exilis Zone (NN6) Hay (1970) emend. Martini (1974) Age: Middle Miocene Definition: Interval from the LO of Sphenolithus heteromorphus to the FO of Discoaster kugleri and/or the LO of Cyclicargolithus floridanus. Nannofloral association: Abundant to rare diversified and moderately preserved assemblages are recorded in Bougaz E-1 Well. It is characterized by Reticulofenestra pseudoumbilicus, Helicosphaera carteri, Coccolithus miopelagicus, Cyclicargolithus floridanus, Discoaster deflandrei, Calcidiscus tropicus and Sphenolithus moriformis. The LO of Calcidiscus premacintyrei and the first rare presence of C. macintyrei occur within this zone. Occurrence: The Zone NN6 is recorded in Bougaz E-1 Well in the Sidi Salem Formation. Discussion: The LO of Cyclicargolithus floridanus is taken as a secondary marker for the base of CN5b Subzone (Bukry, 1973). Ellis (1981) suggested that as a substitute event of the FO of Discoaster bollii. Gartner and Chow (1985) suggested that the LO of Coronocyclus nitescens may be useful in subdividing interval above the LO of Sphenolithus heteromorphus and below the FO of Catinaster coalitus. Marino and Flores (2002) used the FO of Calcidiscus macintyrei to roughly approximate the top of the Discoaster exilis (NN6) Zone. They mentioned that the LO of Calcidiscus premacintyrei comes together with the FO of Calcidiscus macintyrei, considering that the two bioevents are dated at and Ma (Shackleton et al., 1995), respectively, suggesting the presence of a short hiatus. A short-spaced extinction between Sphenolithus heteromorphus and Cyclicargolithus floridanus is recorded in the Equatorial Pacific and Equatorial Atlantic Oceans (Olafsson, 1989). Parker et al. (1985) observed in the mid-latitude of North Atlantic Ocean (DSDP Site 563) the LO of Cyclicargolithus floridanus occurs well below the FO of Discoaster kugleri. The last common occurrence of Calcidiscus premacintyrei and FO of the large form C. macintyrei have been observed in the Mediterranean sections by Fornaciari et al. (1996) and oceanic areas (Raffi et al., 1995), which occur within NN6 Zone and correlate with MNN6- MNN7 pars of Fornaciari et al. (1996). Martini (1971) used the FO of Discoaster kugleri to define the top of the NN6 Zone. The FO of this species is difficult to recognize in the studied wells. In case of the LO of Cyclicargolithus floridanus, the marker for the top of the CN5a Subzone that proposed by Okada and Bukry (1980), is used here to mark the top of the NN6 Zone following some nannofossil specialists (e.g. Varol, 1983; Huang and Huang, 1984; Huang, 1997; Odin et al., 2001; McGonigal and Wei, 2003 and Pospichal, 2003). 4- Sphenolithus heteromorphus Zone (NN5) Bramlette and Wilcoxon (1967) Age: Middle Miocene Definition: Interval from the LO of Helicosphaera ampliaperta to the LO of Sphenolithus heteromorphus. Nannofloral association: Well to moderate preserved, abundant to common diverse calcareous nannofossil assemblage was obtained from all the studied samples within this zone at Bougaz E-

8 VII-8 Faris, M., Samir, A. M., and Shabaan, M. 1 and Rommana-1X wells. The most common nannofossil assemblage recorded in this interval includes Helicosphaera carteri, H. kamptneri, Reticulofenestra minuta, R. pseudoumbilicus Coccolithus miopelagicus, Cyclicargolithus floridanus, Discoaster druggii, Sphenolithus moriformis, Micrantholithus vesper and Braarudosphaera bigelowii in addition to the marker species Sphenolithus heteromorphus. Occurrence: This zone is recognized in Bougaz E-1 Well in Qantara Formation and Rommana- 1X Well within the Sidi Salem Formation. Discussion: The top of the Zone NN5 is defined by the LO of Sphenolithus heteromorphus, which is the most easily determined bioevent in the Mediterranean areas (Ellis and Lohman, 1979; Fornaciari et al., 1996; Huang, 1997; Tanaka and Takahashi, 1998; Odin et al., 2001; McGonigal and Wei, 2003 and Pospichal, 2003). Bukry (1973) mentioned that the FO of Sphenolithus abies in the Sphenolithus heteromorphus Zone (NN5), while some authors only reported the FO of S. abies from the late Miocene. This may be due to different species concepts and/or regional variations of distribution (Perch-Nielsen, 1985). The first form of Reticulofenestra pseudoumbilicus, owns its first appearance in this zone (Bukry, 1973). According to the zonal scheme of Martini (1971), the top and base of the Sphenolithus heteromorphus Zone (NN5) are defined by the LO of S. heteromorphus and Helicosphaera ampliaperta, respectively. These bioevents are will recognized in the present study. 3- Helicosphaera ampliaperta Zone (NN4) Bramlette and Wilcoxon (1967), emend. Martini (1971) Age: Early/middle Miocene boundary Definition: Interval from the LO of Sphenolithus belemnos to the LO of Helicosphaera ampliaperta. Nannofloral association: The species present include: Sphenolithus heteromorphus, Helicosphaera carteri, H. ampliaperta, H. intermedia, H. mediterranea, H. kamptneri, Discoaster variabilis, D. druggii, D. deflandrei, Calcidiscus premacintyrei, Cyclicargolithus floridanus, Braarudosphaera bigelowii and Coccolithus pelagicus. The Zone NN4 is characterized by the co-occurrence of Sphenolithus heteromorphus and H. ampliaperta. Assemblages are good preserved in Bougaz E-1 Well and moderately preserved at Rommana- 1X. Occurrence: In Bougaz E-1 Well, the Helicosphaera ampliaperta Zone (NN4) is recorded within the Qantara Formation and within the Sidi Salem Formation in Rommana-1X Well. Discussion: In some areas of South Atlantic and the Pacific, Helicosphaera ampliaperta is very rare or absent and thus NN4 and NN5 cannot be distinguished (Martini, 1976). In some instance, the FO of Discoaster exilis can be used to approximate the NN4/NN5 boundary (Martini and Worsley, 1971; Müller, 1974). Ellis (1981) considered this event as difficult to assess because overgrowth on discoasterids makes the distinction between D. exilis and D. variabilis difficult. Helicosphaera euphratis becomes rare and often disappears in the upper part of NN4 Zone. Cyclicargolithus floridanus becomes rare in many areas from the upper part of NN4 upwards, though it is may continue with high frequencies as for example in South Atlantic Ocean (Perch-Nielsen, 1985). Bukry (1973) proposed that the end of Discoaster deflandrei acme, as an alternative event, can be taken to define the NN4/NN5 boundary. Parker et al. (1985) noted that the use of D. deflandrei acme to define a zonal boundary is not generally desirable, because such an event may vary from place to place for a variety of reasons. Jiang and Gartner (1984) in the Walvis Ridge and Parker et al. (1985) in the mid-latitude North Atlantic used the first appearance of long-armed discoasterids (Discoaster variabilis group) to distinguish Zones CN3 and CN4. The top of NN4 Zone is defined by the LO of Helicosphaera ampliaperta. This species has been reported from the western equatorial Indian Ocean and equatorial Atlantic Ocean (Fornaciari et al., 1990), Pearl River Mouth Basin, south China Sea (Huang, 1997), Ras Budran area, Gulf of Suez, Egypt, (Marzouk, 1998) and in other Mediterranean zonation (Slezak et al., 1995; Fornaciari and Rio, 1996).

9 Calcareous nannofossil biostratigraphy of the subsurface miocene sequence, northeast nile, VII-.9 In the present study, the Helicosphaera ampliaperta Zone (NN4) fits the original definition of the same zone by Martini (1971). This zone is easy to recognize since interval occupied by this zone contains together H. ampliaperta and Sphenolithus heteromorphus. 2- Sphenolithus belemnos Zone (NN3) Bramlette and Wilcoxon (1967) emend. Martini (1971) Age: early Miocene Definition: Interval from the LO of Triquetrorhabdulus carinatus to the LO of Sphenolithus belemnos. Nannofloral association: A common to rare and moderately preserved and diverse calcareous nannofossil assemblage was obtained from all the studied material within this zone. Species recovered include: Cyclicargolithus floridanus, D. druggii, Coccolithus miopelagicus, Micrantholithus vesper, Discoaster deflandrei, Sphenolithus moriformis, S. conicus, Helicosphaera mediterranea, Braarudosphaera bigelowii and Reticulofenestra pseudoumbilicus (rare) in addition to the marker species (S. belemnos). Occurrence: This zone is recorded in Bougaz E-1 (lower part of the Qantara Formation and uppermost part of Tineh Formation) and Rommana-1X wells (within Sidi Salem Formation). Discussion: The top of this zone is drawn at the LO of the S. belemnos. This fits the original definition of the same zone by Martini (1971). While the FO of Sphenolithus heteromorphus was used by Bukry (1973) to define the top of CN3 zone (CN2/CN3 boundary). S. heteromorphus is abundantly present in the Mediterranean Miocene record and both the FO and LO are biostratigraphically useful (Müller, 1978; Theodoridis, 1984). On the other hand, the relative ranges of the FO of S. heteromorphus and the LO of S. belemnos are debated. The two species have been reported as co-occurring by some authors (e.g. Bukry, 1973 at DSDP Site 140 in the Atlantic Ocean and Takayama and Sato, 1985 at DSDP Site 610 in the North Atlantic Ocean), while Rio et al. (1990) and Fornaciari et al. (1990; 1993) have shown that the ranges of the two species can hardly be considered to overlap. Olafsson (1991) demonstrated that intervals of high abundance of the two species (Sphenolithus belemnos and S. heteromorphus) do not overlap, but they are present in very low abundances between the last common S. belemnos and the first common S. heteromorphus. Marzouk (1998) used the FO of S. heteromorphus to define the top of Zone NN3 in the Ras Budran area, Gulf of Suez. In the present study, the LO of S. belemnos, which is used in the Martini (1971) zonal scheme to mark the top of the Zone NN3 is used following several authors (e. g. Fornaciari et al., 1997; McGonigal and Wei, 2003). This bioevent occurs slightly below the FO of Sphenolithus heteromorphus. The base of this zone will be discussed later. 1- Discoaster druggii Zone (NN2) Martini and Worsley (1971) Age: early Miocene Definition: Interval from the FO of Discoaster druggii to the LO of Triquetrorhabdulus carinatus. Nannofloral association: Abundant and well preserved calcareous nannofossils are recorded from this zone at Bougaz E-1 Well and moderately preserved at Rommana-1X Well. This interval contains abundant Cyclicargolithus floridanus. The most common coccolith assemblage encountered in this zone includes: Coccolithus miopelagicus, Discoaster deflandrei, Helicosphaera intermedia, Pontosphaera multipora, Sphenolithus conicus and S. moriformis in addition to the marker species D. druggii. Occurrence: The Discoaster druggii Zone (NN2) is recorded in Bougaz E-1 (Tineh Upper Member) and Rommana-1X wells within the Sidi Salem Formation. In Rommana-1X Well, this zone unconformably overlies the Oligocene Sphenolithus ciperonsis Zone (NP25). Discussion: The LO of Triquetrorhabdulus carinatus is the original definition of the top of the Zone NN2 (NN2/NN3 boundary). However, the range of the T. carinatus appears to be paleogeographically controlled. Several workers have proposed the FO of Sphenolithus belemnos as an alternative marker bioevent for the NN2/NN3 boundary (Parker et al., 1985; Olafsson, 1989, 1991; Fornaciari et al., 1993; Fornaciari and Rio, 1996; Marzouk, 1998; McGonigal and Wei, 2003). Many authors have noted that it may be difficult to recognize Discoaster druggii in overgrown material (e. g. Olafsson, 1989). Müller (1977) stated that this species is rare in Indian

10 VII-10 Faris, M., Samir, A. M., and Shabaan, M. Ocean. Rio et al. (1990) recorded that the D. druggii is sporadic. Olafsson (1989) used the FO of Triquetrorhabdulus serratus in Site 667 in the eastern Equatorial Atlantic as an alternative event to define the base of NN2 Zone. In high latitudes, D. druggii, Sphenolithus belemnos and Triquetrorhabdulus carinatus are rare or absent and there are no convenient substitutes to subdivide the NN1 to NN3 interval (Perch-Nielsen, 1985). Moreover, the zonal assignment of the Zone NN2 is based on the FO of Helicosphaera ampliaperta, H. mediterranea, H. carteri and Helicosphaera kamptneri (Martini, 1971; Perch- Nielsen, 1985; Martini and Müller, 1986 and Marzouk, 1998). On the other hand, the FO of Calcidiscus tropicus <6 µm was listed by de Kaenel and Villa (1996) as occurring just above the Zone NN1/NN2 zonal boundary (Martini, 1971). McGonigal and Wei (2003) used the FO of C. tropicus to estimate the base of Zone NN2 (CN1b Subzone) in the ODP Leg 189. The FO of Discoaster druggii, which is used in the Martini (1971) zonal scheme to mark the base of D. druggii Zone (NN2), is well represented in the present samples and so, the FO of Sphenolithus belemnos is used to determine the NN2/NN3 boundary. Stage Boundaries Miocene/Pliocene boundary (Messinian/Zanclean boundary) The Miocene/Pliocene (M/P) boundary has traditionally been considered to be coincident with the first appearance of permanent open marine conditions in the Mediterranean after the late Miocene "Messinian salinity crisis" (Cita, 1975). In the term of calcareous nannoplankton, the Miocene/Pliocene boundary has been placed in the Amaurolithus tricorniculatus Zone (CN10) by Okada and Bukry (1980) and in the overlying Ceratolithus acutus Zone (NN13) by Martini (1971). Bukry (1973) tentatively suggested that the LO of Triquetrorhabdulus rugosus and the FO of Ceratolithus acutus (top of Subzone CN10a) are the best approximation of the Miocene/Pliocene boundary on the basis of correlations with the Mediterranean stratotypes. Because taxa of the genera Ceratolithus and Triquetrorhabdulus are usually rare or absent in many materials worldwide. The LO of Discoaster quinqueramus (top of Discoaster quinqueramus Zone (NN11)) is used to approximate the Miocene/Pliocene boundary (Ellis and Lohman, 1979; Parker et al., 1985; Gartner et al., 1987; Gartner, 1992; Backman and Raffi, 1997; Huang, 1997). However, Martini (1971) and Bukry (1973) placed this bioevent below the boundary. Many calcareous nannoplankton workers all over the world are concerned with the definition of the Miocene/Pliocene boundary. For example, Xu and Wise (1997) at ODP Leg 156, considered the M/P boundary placed at the base of the Ceratolithus acutus Subzone (CN10b), based on the FO of the C. acutus taxa. Shafik et al. (1998) at ODP Leg 159 placed the base of Subzone CN10b, to approximate the M/P boundary using the combination of the first occurrences of Ceratolithus armatus and C. acutus and LO of Triquetrorhabdulus rugosus taxa. Siesser and de Kaenel (1999) at ODP Leg 161 placed the M/P boundary in Zone NN12 below the FO of Ceratolithus rugosus, the LO of C. acutus and the last common occurrence of Helicosphaera intermedia taxa and just above the FO of C. acutus taxa. On the other hand, many workers considered the M/P boundary at the LO of Discoaster quinqueramus taxa in Californian marginal area (Fornaciari, 2000) and at the ODP Leg 177 Sites 1088 and 1090 (Marino and Flores, 2002). The Miocene/Pliocene boundary at ODP Leg 189 can be placed at the level of the LO of T. rugosus and/or the LO of D. quinqueramus (McGonigal and Wei, 2003). In Bougaz E-1 Well, the Miocene/Pliocene boundary is defined at base of the Kafr El Sheikh Formation. The boundary is recognized at the FO of Ceratolithus acutus (base of Zone CN10b). This bioevent, on the other hand, occurs slightly above the LO of Discoaster quinqueramus (top of D. quinqueramus Zone NN11). Based on planktonic foraminifera, the M/P boundary is identified at the same depth (1305 m) at the base of Sphaeroidinellopsis seminulina Zone that immediately overlies the Non-distinctive interval (evaporites) of late Miocene (Table 2). In both Rommana-1X and Ras El Barr-1 wells, and due to unreliability of the FO of calcareous nannoplankton Ceratolithus acutus, the Miocene/Pliocene boundary is identified based on foraminiferal Sphaeroidinellopsis seminulina zonal markers (which falls within the

11 Calcareous nannofossil biostratigraphy of the subsurface miocene sequence, northeast nile, VII-.11 nannofossil Amaurolithus tricorniculatus Zone (NN12) and immediately above the Nondistinctive interval (evaporites) of late Miocene (Table 2). Middle/late Miocene boundary (Serravallian/Tortonian boundary) The middle/late Miocene boundary is generally defined at the base of Tortonian stage (Berggren et al., 1985). The Serravallian/Tortonian boundary stratotype in Sample 4 in Rio Mazzapiedi Section (north Italy) was assigned by Martini (1971, 1975) to the calcareous nannoplankton Discoaster hamatus Zone (NN9) based on the LO of D. hamatus taxa. This is the same level as the FO of planktonic foraminifera Neogloboquadrina acostaensis taxa (Cita et al., 1965). According to magnetochronologic considerations and on the fact that the FO of N. acostaensis occurs in the DSDP Site 563 within Zone (NN8), so, Berggren et al. (1985) placed the Serravallian/Tortonian boundary within the calcareous nannoplankton Catinaster coalitus Zone (NN8). El Heiny and Morsi (1992), in the eastern Nile Delta area placed the middle/late Miocene boundary at the base of D. hamatus Zone (NN9). The middle/late Miocene boundary lies within D. hamatus Zone (CN7) (Xu and Wise, 1997). The first appearance of Neogloboquadrina acostaensis represents a global event that has been clearly recorded in the lower part of the Tortonian stage in its type locality as well as in various land marine sections and deep-sea sequences from the Mediterranean (Haggag and Abu El Enein, 1991 and Ouda and Obaidalla, 1995) and world wide (Heath and McGowran, 1984; Berggren et al., 1995; McGowran and Li, 1997). In the onshore Rommana-1X Well, the calcareous nannoplankton zones NN9-NN6, which are the earliest late to late Middle Miocene, are missing and the middle/late Miocene boundary cannot be placed. This boundary is only detected in the offshore area (Ras El Barr-1 and Bougaz E-1 wells) where continuous sedimentation straddled the middle/late Miocene boundary. An important earliest late Miocene hiatus occurs in Bougaz E-1 Well (base of Qawasim Formation), where earliest late Miocene nannofossil Discoaster hamatus Zone (NN9) is not detected. The boundary is recognized at the first occurrence of planktonic foraminiferal Neogloboquadrina acostaensis taxa. In Ras El Barr-1 Well, the middle/late Miocene boundary is recognized at the base of D. hamatus Zone (NN9). This boundary lies within the Sidi Salem Formation. Early/middle Miocene boundary (Burdigalian/Langhian boundary) The early/middle Miocene boundary is equivalent to the base of the Langhian stage ((Berggren et al., 1985). The base of the Langhian is linked biostratigraphically to the FO of the planktonic foraminiferal Praeorbulina spp. taxa (Berggren et al., 1985), which occur in the stratotype section and world wide above the FO of nannofossil Sphenolithus heteromorphus and just below the LO of the Helicosphaera ampliaperta taxa, as well as, within the upper part of nannofossil Helicosphaera ampliaperta Zone (NN4) of Martini (1971). In terms of calcareous nannoplankton, the early/middle Miocene boundary was placed by many authors at the base of the Sphenolithus heteromorphus Zone (NN5) (e.g. Martini, 1971; Bukry, 1973; Perch-Nielsen, 1972; Miller, 1981). On the other hand, this boundary can only be approximated roughly with the last common occurrence of Helicosphaera ampliaperta in the Mediterranean region or the acme end of Discoaster deflandrei in low-latitude oceanic sediments (Rio et al, 1990; Fornaciari and Rio, 1996). In the Gulf of Suez area, this boundary lies at the level of the LO of Helicosphaera ampliaperta, top of the Rudeis Formation (Marzouk, 1998; Sadek, 2001). The early/middle Miocene boundary is detected only in Bougaz E-1 and Rommana-1X wells, where the Ras El Barr-1 Well is drilled to middle Miocene. In Bougaz E-1 Well, the boundary is recognized at the base of Globorotalia fohsi peripheroronda Zone which falls within Helicosphaera ampliaperta Zone (NN4). This boundary lies within Qantara Formation. In Rommana-1X Well, the early/middle Miocene boundary is placed at the base of Globorotalia fohsi peripheroronda Zone. This bioevent coincides with the level of the top of Helicosphaera ampliaperta Zone (NN4).

12 VII-12 Faris, M., Samir, A. M., and Shabaan, M. Fig. 2: Miocene litho, and bistragraphic units of the Ras El Barr-1well.

13 Calcareous nannofossil biostratigraphy of the subsurface miocene sequence, northeast nile, VII-.13 Fig. 3: Miocene litho, and biostratigraphic units of the Rommana-1X well.

14 VII-14 Faris, M., Samir, A. M., and Shabaan, M. Fig. 4: Miocene litho, and biostratigraphic units of the Bougaz E-1 Well.

15 Calcareous nannofossil biostratigraphy of the subsurface miocene sequence, northeast nile, VII-.15 Fig. 5: Distribution chart of the identified calcareous nannofossils in Ras El Barr-1 Well.

16 VII-16 Faris, M., Samir, A. M., and Shabaan, M. Fig. 6: Distribution chart of the identified calcareous nannofossils in Rommana-1X Well.

17 Calcareous nannofossil biostratigraphy of the subsurface miocene sequence, northeast nile, VII-.17 Fig. 7: Distribution chart of the identified calcareous nannofossils in Bougaz E-1 Well.

18 VII-18 Faris, M., Samir, A. M., and Shabaan, M. Fig. 7: Continue.

19 Calcareous nannofossil biostratigraphy of the subsurface miocene sequence, northeast nile, VII-.19 PLATE 1 Figs. 1-3) Ceratolithus acutus Gartner and Bukry (1974), Bougaz E-1 Well, Depths 1287 m and 1305 m, Amaurolithus tricorniculatus Zone (NN12). 4-6) Amaurolithus delicatus Gartner and Bukry (1975), 4, 5) Bougaz E-1 Well, Depth 1305 m, Amaurolithus tricorniculatus Zone (NN12), 6) Rommana-1X Well, Depth 5260 ft, Discoaster quinqueramus Zone (NN11). 7, 8) Ceratolithus rugosus Bukry and Bramlette (1968), Rommana-1X Well, Depth 4300 ft, NN13/NN14 Zone. 9, 10) Amaurolithus tricorniculatus (Bukry and Percival, 1971) Gartner and Bukry, 1975, Rommana-1X Well, Depth 4820 ft, Discoaster quinqueramus Zone (NN11). 11, 12) Amaurolithus amplificus (Bukry and Percival, 1971) Gartner and Bukry, 1975, Bougaz E-1 Well, Depth 1305 m, Amaurolithus tricorniculatus Zone (NN12). 13, 14) Discoaster intercalaris Bukry (197 l), Bougaz E-1 Well, Depths 1218 and 1305 m, Amaurolithus tricorniculatus Zone (NN12). 15) Discoaster variabilis Martini and Bramlette (1963), Bougaz E-1 Well, Depth 1401 m, Catinaster coalitus Zone (NN8). 16, 17) Discoaster surculus Martini and Bramlette (1963), Rommana-1X Well, Depth 4540 ft, Amaurolithus tricorniculatus Zone (NN12). 18, 19) Discoaster challengeri Bramlette and Riedel (1954), Bougaz E-1 Well, Depth 1305 m, Amaurolithus tricorniculatus Zone (NN12). 20, 21) Discoaster bollii Martini and Bramlette (1963), Bougaz E-1 Well, Depth 1374 m, Discoaster calcaris Zone (NN10). 22, 23) Discoaster exilis Martini and Bramlette (1963), Bougaz E-1 Well, Depth 1401 m, Catinaster coalitus Zone (NN8) ) Discoaster deflandrei Bramlette and Riedel (1954), Bougaz E-1 Well, Depth1803 m, Sphenolithus belemnos Zone (NN3). 27, 28) Discoaster druggii Bramlette and Wilcoxon (1967), Bougaz E-1 Well, Depth 1746 m, Helicosphaera ampliaperta Zone (NN4) ) Discoaster asymmetricus Gartner (1969), 29), Rommana-1X Well, Depths 4620 ft, Amaurolithus tricorniculatus Zone (NN12), 30, 31) Bougaz E-1 Well, Depths 1218 m, Amaurolithus tricorniculatus Zone (NN12). 32, 33) Discoaster pentaradiatus (Tan, 1927) Bramlette and Riedel, 1954, Ras El Barr- 1 Well, Depth 3033 m, Discoaster quinqueramus Zone (NN11). 34, 35) Discoaster quinqueramus Gartner (1969), Bougaz E-1 Well, Depths 1323 m and 1338 m, Discoaster quinqueramus Zone (NN11).

20 VII-20 Faris, M., Samir, A. M., and Shabaan, M.

21 Calcareous nannofossil biostratigraphy of the subsurface miocene sequence, northeast nile, VII-.21 PLATE 2 Figs. 1, 2, 6, 7) Discoaster neorectus Bukry (197 l), 1, 2, 6) Rommana-1X Well Depth 4820 ft, Discoaster quinqueramus Zone (NN11), 7) Bougaz E-1 Well, Depth 1323 m, Discoaster quinqueramus Zone (NN11). 3) Discoaster hamatus Martini and Bramlette (1963), Ras El Barr-1 Well, Depth 3558 m, Discoaster hamatus Zone (NN9). 5) Discoaster surculus Martini and Bramlette (1963), Rommana-1X Well Depth 4620 ft, Amaurolithus tricorniculatus Zone (NN12). 4, 8, 13) Discoaster brouweri (Tan, 1927) Bramlette and Riedel, 1954, 4) Rommana-1X Well Depth 4820 ft, Discoaster quinqueramus Zone (NN11), 8, 13) Bougaz E-1 Well, Depth 1305 m, Amaurolithus tricorniculatus Zone (NN12). 9, 10) Discoaster berggrenii Bukry (1971), 9) Bougaz E-1 Well, Depth 1329 m, Discoaster quinqueramus Zone (NN11), 10) Rommana-1X Well Depth 4820 ft, Discoaster quinqueramus Zone (NN11). 11) Discoaster bellus Bukry and Percival (1971), Rommana-1X Well Depth 6220 ft, Discoaster calcaris Zone (NN10). 12) Discoaster calcaris Gartner (1967), Bougaz E-1 Well, Depth 1374 m, Discoaster calcaris Zone (NN10) ) Sphenolithus abies Deflandre in Deflandre and Fert (1954), 14) Bougaz E-1 Well, Depth 1287, Amaurolithus tricorniculatus Zone (NN12), 15, 16) Rommana-1X Well Depth 5260 ft, Discoaster quinqueramus Zone (NN11) ) Sphenolithus heteromorphus Deflandre (1953), 17-20) Bougaz E-1, Depths 1623 m and 1644 m, Sphenolithus heteromorphus Zone (NN5), 21-23) Rommana-1X Well, Depths 6300 ft and 6460 ft, Sphenolithus heteromorphus Zone (NN5) ) Sphenolithus belemnos Bramlette and Wilcoxon (1967), 24-27) Bougaz E-1 Well, Depth 1767 m, Sphenolithus belemnos Zone (NN3), 28, 29) Rommana-1X Well, Depth 7940 ft, Sphenolithus belemnos Zone (NN3). 30, 31) Sphenolithus moriformis (Brönnimann and Stradner, 1960) Bramlette and Wilcoxon (1967), Bougaz E-1 Well, Depth 1767 m, Sphenolithus belemnos Zone (NN3). 32, 33) Sphenolithus conicus Bukry (1971), Bougaz E-1 Well, Depth 1767 m, Sphenolithus belemnos Zone (NN3). 34) Catinaster coalitus Martini and Bramlette, 1963, Bougaz E-1 Well, Depth 1698 m, Helicosphaera ampliaperta Zone (NN4) ) Helicosphaera carteri (Wallich, 1877) Kampter, (1954), 35) Rommana-1X Well, Depth 6340 ft, Sphenolithus heteromorphus Zone (NN5), 36, 37) Bougaz E-1 Well, Depth 1644 m, Sphenolithus heteromorphus Zone (NN5).

22 VII-22 Faris, M., Samir, A. M., and Shabaan, M.

23 Calcareous nannofossil biostratigraphy of the subsurface miocene sequence, northeast nile, VII-.23 PLATE 3 Figs. 1-4) Calcidiscus macintyrei (Bukry and Bramlette, 1966) Loeblich and Tappan, 1978, 1, 2) Bougaz E-1 Well, 1329 m, Discoaster quinqueramus Zone (NN11). 3, 4) Ras El Barr-1 Well, Depth 2682 m, Amaurolithus tricorniculatus Zone (NN12), 5-8) Calcidiscus leptoporus (Murray and Blackman, 1895) Loeblich and Tappan, 1978, Bougaz E-1 Well, Depths 1269 m and 1305 m, Amaurolithus tricorniculatus Zone (NN12). 9, 10) Calcidiscus premacintyrei Theodoridis (1984), Rommana-1X Well Depth 6420 ft, Sphenolithus heteromorphus Zone (NN5) ) Reticulofenestra pseudoumbilicus (Gartner, 1967) Gartner,1969, 11-14, Ras El Barr-1 Well, Depth 2682 m, Amaurolithus tricorniculatus Zone (NN12), 15) Bougaz E-1 Well, Depth 1401 m, Catinaster coalitus Zone (NN8). 16, 17) Reticulofenestra minutula (Gartner, 1967) Haq and Berggren, 1978, Bougaz E-1 Well, Depth 1305, Amaurolithus tricorniculatus Zone (NN12) ) Helicosphaera sellii (Bukry and Bramlette, 1969) Jafar and Martini 1975, 18, 19) Bougaz E-1 Well, Depth 1209 m, Amaurolithus tricorniculatus Zone (NN12), 20) Rommana-1X Well, Depth 4620 ft, Amaurolithus tricorniculatus Zone (NN12). 21, 22) Coronocyclus nitescens (Kamptner, 1963) Bramlette and Wilcoxon, 1967, Bougaz E-1Well, Depth 1677 m, Helicosphaera ampliaperta Zone (NN4). 23, 24) Helicosphaera walbersdurfensis Müller (1974), Bougaz E-1 Well, Depth 1542 m, Discoaster exilis Zone (NN6) ) Helicosphaera kamptneri Hay and Mohler in Hay et al. (1967), Ras El Barr Well, Depth 3033 m, quinqueramus Zone (NN11). 29, 30) Pontosphaera sp1., Bougaz E-1 Well, Depth 1209 m, Amaurolithus tricorniculatus Zone (NN12). 31) Pontosphaera anisotrema (Kamptner, 1956) Backman (1980), Bougaz E-1 Well, Depth 1269 m, Amaurolithus tricorniculatus Zone (NN12). 32, 33) Helicosphaera intermedia Martini (1965), Bougaz E-1 Well, Depth 1758 m, Helicosphaera ampliaperta Zone (NN4) ) Helicosphaera mediterranea Müller (1981), Bougaz E-1 Well, Depth 1881 m, Discoaster druggii Zone (NN2) ) Helicosphaera ampliaperta Bramlette and Wilcoxon (1967), 38, 39) Bougaz E-1 Well, Depth 1677 m, Helicosphaera ampliaperta Zone (NN4), 40, 41) Rommana-1X Well, Depth 6460 ft, Helicosphaera ampliaperta Zone (NN4) ) Helicosphaera scissura Miller (1981), Rommana-1X Well, Depth 6460 ft, Helicosphaera ampliaperta Zone (NN4). 45, 46) Pontosphaera multipora (Kamptner, 1948) Burns, 1973, Ras El Barr Well, Depth 3558 m, Discoaster hamatus Zone (NN9) ) Cyclicargolithus floridanus (Hay et al., 1967) Bukry, 1971, Bougaz E-1 Well, Depth 1686 m, Helicosphaera ampliaperta Zone (NN4). 51, 52) Cyclicargolithus abisectus Müller (1970), Rommana-1X Well, Depth 9150 ft, NP25 Zone. 53, 54) Reticulofenestra lockeri Müller (1970), Bougaz E-1 Well, Depth 1869 m, Discoaster druggii Zone (NN2).

24 VII-24 Faris, M., Samir, A. M., and Shabaan, M.