Ismail.indd 1 �AB STRA CT Three wells (Naf-2, Naf-3 and Naf-101), were described and sampled in order to increase understanding of the strati- graphy and micropaleontology of the North Abu Qir Field, Nile Delta, Egypt. Lithostratigraphic studies aided rec- ognition of the following Miocene-Pliocene rock formations (from base to top); Qantara Formation, Sidi Salim For- mation, Qawasim Formation, Rosetta Formation, Abu Madi Formation, Kafr El Sheikh Formation, Baltim Formation, Mit Ghamr Formation, and Bilqas Formation. Biostratigraphic studies were based on the distribution of foraminifera through the Miocene-Pliocene succession. The environmental conditions of the Neogene rocks of the studied wells are interpreted using the results of palaeoecological parameters (e.g. the total number of foraminifera (T.N.F) and planktonic/benthonic ratio (P/B). Keywords: Stratigraphy, Neogene, foraminifera, North Abu Qir area, Nile Delta, Egypt Subsurface stratigraphy and micropaleontology of the Neogene rocks, Nile Delta, Egypt � Ahmed A. Ismail, Mohamed Boukhary and Ahmed I. Abdel Naby Department of Geology, Faculty of Science, Ain Shams University, Abassia 11566, Cairo, Egypt; (aaaismail2002@yahoo.com; moboukhary@yahoo.com and zowail2000@yahoo.com) doi: 104154/gc.2010.01 Geologia Croatica 63/1 1–26 15 Figs. 1 Tab. 4 Pls. Zagreb 2010 Geologia CroaticaGeologia Croatica 1. INTRODUCTION The Nile Delta is one of the most well known deltas of the world, and has attracted the attention of many geologists due to its potential gas reserves. The considerable rise of oil and gas prices has lead to further exploration in order to locate new hydrocarbon fi elds. The Nile Delta has in general, a feature- less surface with a northward slope, except for some limited topographic features such as the Khatatba positive structural and topographic features, and the westward Wadi El-Natrun negative element. Generally, no outcrops occur on the Delta surface, being mainly covered with recent mud and alluvial deposits (AZZAM, 1994), and also with some sand accumu- lations known as the Turtle-backs. The structural setting of the Nile Delta region occupies a key position within the plate tectonic development of the eastern Mediterranean and the Levant. It lies on the northern margin of the African Plate, which extends from the subduc- tion zone adjacent to the Cretan and Cyprus arcs, to the Red Sea where it drifted apart from the Arabian plate. The Abu Qir Field consists of two culminations western and eastern. The western culmination is a four-way dip closure and the eastern culmination is a three-way dip closure and sealed from the eastern direction (cross-fault sealing) by the Kafr El Sheikh Shales, which were brought in juxtaposition with the Abu Madi Sands on the upthrown side of the fault. To the southeast, the West Abu Qir structure is separated from the Abu Qir Gas Field by a northeast-southwest narrow com- plex graben. This graben was formed by a northeast-south- west trending group of faults (BADRAN, 1996). Structur- ally, the Abu Qir and West Abu Qir fi elds were possibly formed in the same way, each being a rollover feature result- ing from the slumping of post-Miocene deltaic sediments within the giant graben, which was bounded by almost two east-west major growth faults (BADRAN, 1996). Geologia Croatica 63/1Geologia Croatica 2 wasim Formation, with a marked unconformity. It is a marine deposit of Early Pliocene age. The shale content increas es upward and the contact with the overlying Kafr El Sheikh Formation is gradational in the studied wells. The type sec- tion is present in the Abu Madi well 1, between 3007 to 3229 m depth. The Abu Madi Formation is the gas-producing hor- izont of the Nile Delta (E.G.P.C., 1994). The Kafr El Sheikh Formation is composed of soft clays with a few interbeds of poorly consolidated sands with a clay ey matrix. The development of this series appears to be rather constant over the entire Delta area. Its upper boundary is mark ed by the fi rst appearance of the El-Wastani sands which have a typical littoral fauna. The Kafr El Sheikh is dated as Early to Middle Pliocene age, according to palaeontological evidence (BARAKAT, 1982). The section has been penetrated in the Kafr El Sheikh well, located some 40 km SSW of the Abu Madi gas fi eld, in the south-central part of the onshore delta area. Its thickness is 1458 m (ISMAIL, 1984). The El Wastani Formation consists of thick quartzose sandstone interbedded with thin clays which thin towards the top. The upper boundary of this formation is uncertain, but it is delineated where the series becomes more sandy for several tens of metres. This formation is assigned to the Late Pliocene (BARAKAT, 1982), and is 123 m thick in the El Wastani well 1 (ISMAIL, 1984). Pleistocene–Holocene rocks are subdivided by (E.G.P.C., 1994) into two formations; the Mit Ghamr Formation at the base, and the Bilqas Formation at the top. The Mit Ghamr Formation is composed of thick layers of sands and pebbles at its base with clay interbeds. This formation grades into the overlying? Bilqas Formation by the increase of interbedded clays with sands, rich in peat, and fossiliferous, with a coastal or lagoonal fauna. The Bilqas Formation constitutes the top basin fi ll with coastal sands and deposits from the Nile fl oods. It was encountered between 20 and 484 m in the Mit Ghamr well, located in the southern part of the Delta, on the east side of the Damietta branch (SCHLUMBERGER, 1984). The Holocene rocks are represented by the intermittent ma- rine transgressions that give rise to a few metres of marine sediments. Both constitute the Bilqas Formation. Plant re- mains and peat deposits are frequent (E.G.P.C., 1994). 3. MATERIAL AND METHODS The Abu Qir North Field, Nile Delta, Egypt, is located to the north west of the Rosetta branch of the Nile River, and is bounded between latitudes 31° 34’ N & 31° 52’ N and lon- gitudes 30° 04’ E & 30° 26’ E (Fig. 1). The number and depth of ditch cutting samples (in metres) for each well are given in Table 1 below. 2. GEOLOGIC SETTING The Miocene rocks in the Nile Delta region were subdivided by E.G.P.C., (1994) into three formations, from base to top: the Sidi Salim, Qawasim and Rosetta. The Sidi Salem For- mation is mainly composed of green-grey clays with a few interbeds of dolomitic marls, and rare occurrences of quart- zose sandstones with calcareous cement and siltstones (BA- RAKAT, 1982). The age of this formation ranges from Lan- ghi an to Tortonian. The lower limit is not known in the central part of the Delta, but was encountered in the western off- shore area (Abu Qir) E.G.P.C. (1994) and also in the south and southeast. It probably overlies the Moghra Formation or older rocks (BARAKAT, 1982). The type section of this for- mation is represented by the bottom sequence at the Sidi Salim well 1 (located south of Lake Burullus), from 3592 to 4038 m depth. The upper limit is defi ned by the base of the thick conglomeratic series of the Qawasim Formation. Off- shore the Sidi Salim is overlain directly either by the Rosetta Anhydrite or by the Lower Pliocene clays of the Kafr El Sheikh Formation. Extensive facies changes, both lateral and up-dip, occur within the Sidi Salim Formation in particular, and in Miocene sequence in general (E.G.P.C., 1994). The Qawasim Formation overlies the Sidi Salem For- mation, and underlies the Rosetta Formation. It is composed of a thick, sandy, and conglomeratic sequence, containing a typical rare Messinian fauna of the Mediterranean basin (E.G.P.C., 1994). The sequence is present in the interval from 2800 to 3733 m in the Qawasim 1 well, located some 14 km east of the Sidi Salim well 1 (SCHLUMBERGER, 1984). The upper boundary of this formation is rather diffi cult to determine if the anhydrites of Rosetta Formation are absent. Locally, it passes laterally to marine clays with Pliocene fauna of Kafr El Sheikh Formation. When the Qawasim For- mation occurs within the basal sands of Abu Madi Forma- tion, where the Rosetta Anhydrite is missing, the criteria of separation are based on palaeontological and sedimentolog- ical evidence (BARAKAT, 1982). Large layers of anhydrite, interbedded with thin clays, represent the Rosetta Formation, observed in offshore well Rosetta 2, NE of the mouth of the Rosetta Nile branch, be- tween 678 to 2718 m depth. The presence of the Rosetta An- hydrite seems to be limited only to the northern and offshore part of the Delta. It has not been encountered in wells drilled on the west fl ank of the Delta (Abu Qir), but was again pre- sent offshore to the north of Alexandria. A Messinian age has been attributed to the Rosetta Anhydrite because of its posi- tion below the marine shales of defi nite Early Pliocene age. The formation indicates a general starvation of the sea that affected the whole Mediterranean area and led to the depo- sition of evaporites SCHLUMBERGER (1984) and HSU et al. (1973, 1977). The Pliocene rocks in the Nile Delta region are subdi- vided by E.G.P.C., (1994) into three formations, from base to top: Abu Madi, Kafr El Sheikh, El Wastani. The Abu Madi Formation is represented by a thick series of sands, in part pebbly, with interbedded thin shales. The formation is cross- bedded and overlies the Rosetta Anhydrite, and/or the Qa- Table 1: Location and number of samples taken from each well in the study area. Wells Depth Interval (m) Number of samples Naf-2 1870–3445 17 Naf-3 1030–3300 30 Naf-101 1540–3550 24 Ismail et al.: Subsurface stratigraphy and micropaleontology of the Neogene rocks, Nile Delta, Egypt Geologia Croatica 3 2. Identifying the foraminifera obtained from the differ- ent horizons and the distribution of the foraminiferal assem- blages, for biostratigraphic studies of the Neogene sequence. 3. Delineation of palaeo-sedimentary environments, and the number of depositional cycles by using several palae- oecological parametres (e.g. the total number of foraminif- era, (T.N.F.) and planktonic/benthic ratio (P/B). 4. STRATIGRAPHY Correlation of the three wells located in the North Abu Qir Field revealed ten lithostratigraphic formations (based on lithological characteristics). These are, from base to top, as follows: Qantara Formation, Sidi Salim Formation, Qawa- sim Formation, Rosetta Formation, Abu Madi Formation, Kafr El Sheikh Formation, El Wastani Formation, Baltim Formation, Mit Ghamr Formation, and Bilqas Formation. Each rock unit is discussed below, taking into consideration the lithologic characters, stratigraphic limits, thickness, and the foraminiferal content when present. 4.1. Qantara Formation The top of the Qantara Formation is only reached by the Naf- 101 well (Figs. 3, 4 and 5), which did not reach the base of this formation. The formation is unconformably overlain by the Sidi Salim Formation. Southward, in the study area, this formation is composed of shale with argillaceous sand and limestone, as revealed by the drilling data in other wells. Northward, the limestone of this formation decreases, and was replaced by clastics (shale and sand). Furthermore, this formation is dated as Early Miocene in age, according to the presence of Globigerinoides primordius as shown in (Fig. 6). This age assignment is confi rmed by the presence of the Early Miocene Dentoglobigerina altispira altispira and Globorotalia These samples were washed, picked, and the different species of foraminifera have been identifi ed and examined. The aim of this study is to analyze the encountered succes- sions stratigraphically, in order to decipher the depositional environment, depositional processes and lateral and vertical facies changes. To achieve these objectives, the following steps were followed: 1. Identifying and recognizing the different rock units of the penetrated Miocene–Pliocene sequence based on the de- scription of the ditch cutting samples and composite logs. Fi gu re 1: A location map showing the studied wells. Fi gu re 2: The Generalized subsurface stratigraphic column of the Nile Delta region. Fi gu re 3: The stratigraphic column of Naf-2 well. Geologia Croatica 63/1Geologia Croatica 4 obesa. Also, there are several other planktonic species asso- ciated with these fossils (e.g. Globigerinoides bisphericus, Neogloboquadrina continuosa, Globorotalia archeomerandii, Globigerina brazieri, Globigerina praebulloides, Orbulina cf. suturalis, Orbulina universa and Globigerinoides trilo- bus immaturus). Moreover, there are several benthic species associated with the previous planktonic species e.g. (Boliv- ina dilatata, Gyroidinoides soldanii, Nonionina scapha, Bu- limina elongata, Lagena sulcata, Globocassidulina elongata, Uvigerina semiornata, Nonionella auris, Lenticulina cultra ta, Cibicides refulgens and Neoeponides sp). 4.2. Sidi Salim Formation This formation unconformably overlies the Qantara Forma- tion and underlies the Qawasim Formation. The bottom of this formation was not reached in two wells (Naf-2 and Naf-3). Its thickness in well Naf-101 is 460 m. This formation is composed of intercalations of shale, sand, clay, with rare oc- currences of white, bioclastic limestone. This limestone oc- curs less frequently and passes gradually towards the north- east of the study area. The formation is of Middle Miocene age, based on the presence of Globigerinoides bollii at the top of this formation, which could represent a useful datum in the Mediterranean region, where the Globigerinoides fohsi lineage is not developed (BOLLI & SAUNDERS, 1985). However, the absence of the three upper biozones of Middle Miocene age (Globigerinoides ruber, Neogloboquadrina may- eri and Globorotalia menardii) biozones indicates a hiatus between the Middle Miocene and the Late Miocene as shown on the distribution chart of the Naf-101 well (Fig. 12). How- ever, the presence of Praeorbulina glomerosa curva and Praeorbulina glomerosa glomerosa species supports the age assignment of this formation, which directly underlies the Upper Miocene sediments. This also indicates a similar hia- tus in the formation as shown in the Naf-3 well (Fig. 11). Accordingly, this formation is dated from the Early Middle Miocene to Late Miocene. Fi gu re 4: The stratigraphic column of Naf-3 well. Fi gu re 5: The stratigraphic column of Naf-101 well. Fi gu re 6: The Miocene–Pliocene planktonic foraminfera zones and sub- zones (after BOLLI & SAUNDERS, 1985). E – Early, M – Middle, L – Late. Ismail et al.: Subsurface stratigraphy and micropaleontology of the Neogene rocks, Nile Delta, Egypt Geologia Croatica 5 Also, there are several planktonic species associated with the above species (e.g. Globigerinoides pseudobesa, Glo- bigerina ciperoensis ciperoensis, Dentoglobigerina venezue- lana, Globigerina woodi, Globigerina nilotica, Orbulina uni- versa, Orbulina bilobata, Globigerinoides trilobus immaturus, Globigerinoides obliquus extremus and Globigerinella obesa). Moreover, there are several benthic species associated with the planktonic taxa listed above (e.g. Quinqueloculina bos- ciana, Bolivina hebes, Ammonia beccarii, Bulimina elon- gata, Asterigerina planorbis, Nonionellina cf. labradorica, Gyroidinoides soldanii, Pullenia quinqueloba, Elphidium macellum and Neoeponides sp.). 4.3. Qawasim Formation This formation overlies the Sidi Salim Formation and under- lies the Rosetta Formation. The thickness of this formation increases northward (25 m in the Naf-101 well, and 100.5 m in the Naf-2 well (Fig. 3)). Also, its thickness is 34 m in Naf-3 well. This formation is composed of sand to sandstone with a few interbeds of clay. Also, there are several plank- tonic species associated with this formation (e.g. Globigeri- noides trilobus immaturus, Globigerinoides bullatus, Glo- bigerinoides obliquus extremus, Globigerina nilotica, and Orbulina universa). Moreover, there are several benthic spe- cies associated with the planktonics (e.g. Cibicides gibbosus, Alabamina sp., Buccella sp., Uvigerina cf. asperula, Boliv- ina hebes, and Nonionina scapha). The formation has been dated as Late Miocene (Messinian), according to its strati- graphic position (AZZAM, 1990; E.G.P.C., 1994; and ABU EL ENEIN, 1990) and also on both lithological and palae- ontological characteristics (ISMAIL, 1984). In the present study, this formation is also dated as Late Miocene accord- ing to its stratigraphic position between the underlying Sidi Salim Formation of Early Middle Miocene to Late Miocene and the overlying Rosetta Formation of Late Miocene. 4.4. Rosetta Formation This formation overlies the Qawasim Formation and under- lies the Abu Madi Formation. The thickness of this forma- tion decreases northward (99 m in Naf-101 well and 28 m in Naf-2 well). Also, its thickness is 50 m in Naf-3 well. It is composed of sand with occurrences of anhydrite and clay. Deposition of evaporites in this formation indicates a gen- eral regression of the Mediterranean, and this also explains the low content of planktonic foraminiferal species (e.g. Glo- bigerinoides tenellus, Globigerinoides obliquus extremus, Globigerina nilotica, Orbulina bilobata and Orbulina uni- versa). Also, there are few benthic species associated with the planktonics (e.g. Gyroidinoides soldanii, Alabamina sp., Uvigerina semiornata and Loxostomum pseudodigitale). The age of the Rosetta Formation is Late Miocene (Messinian) due to its stratigraphic position below the Upper Miocene- Lower Pliocene marine sediments (Abu Madi Formation). Also, the presence of Sphaeroidinellopsis disjuncta in the topmost part of this formation is further evidence for this age assignment. This species of Sphaeroidinellopsis has been used repeatedly as a zonal marker (BOLLI & SAUNDERS, 1985). The highest occurrence of Sphaeroidinellopsis dis- juncta denotes the top of the Miocene (BOLLI & SAUN- DERS, 1985). 4.5. Abu Madi Formation This formation overlies the Rosetta Formation and/or the Sidi Salim Formation with a marked unconformity and un- derlies the Kafr El Sheikh Formation. The thickness of this formation increases northward (138 m in Naf-101 well and 234 m in Naf-2 well). Also, its thickness attains 155 m in Naf-3 well (Fig. 4). It is mainly composed of intercalations of sand, clay, and shale. The age assignment of this forma- tion is controversial, where it is dated as Late Miocene (Mes- sinian), on a sedimentological basis, by EFFAT & GEZEIRY (1986) and DEIBIS et al. (1986). However, ABU EL ENEIN (1990) stated that the transgression in the Early Pliocene was responsible for deposition of the Abu Madi Formation. In the present study, this formation is dated as Early Pliocene in the studied three wells, according to the presence of Glo- borotalia margaritae, which is a widely recognized index species for the Pliocene (BOLLI & SAUNDERS, 1985). On palaeomagnetic evidence (CITA, 1975 and LOURENS et al., 2004), the age of this species ranges from 5.01 to 4.14 Ma. It is a cosmopolitan species occurring in both deep and shallow waters (BOLLI & SAUNDERS, 1985). The pres- ence of Globorotalia exilis with Globorotalia margaritae terminates the Early Pliocene according to BOLLI & SAUN- DERS (1985). The occurrence of Sphaeroidinellopsis dis- juncta in the top of the Abu Madi Formation in the Naf-2 well suggests that this formation is of Late Miocene age. This age assignment is confi rmed by the occurrence of Globorotalia margaritae margaritae at the base of the over- lying Kafr El Sheikh Formation. Also, there are several plank- tonic species associated with the species listed above (e.g. Globigerinoides quadrilobatus, Globigerinoides obliquus extremus, Globigerinoides ruber, Globigerinoides bulloi- deus, Globigerinoides tenellus, Globigerinoides trilobus im- maturus, Globigerina quinqueloba, Globigerina nilotica, Globigerina apertura, Globigerinella obesa, Orbulina uni- versa and Catapsydrax parvulus). Moreover, there are sev- eral benthic species associated with the planktonic taxa (e.g. Bolivina dilatata, Loxostomum perforatum, Buccella sp., No- nionina scapha, Lenticulina smiley, Alabamina sp., Cibici- doides sp., Eponides polygonus, Asterigerina planorbis and Bulimina elongata). From the previous discussion, this forma- tion could be classifi ed as Late Miocene–Early Plio cene. 4.6. Kafr El Sheikh Formation This formation overlies the Abu Madi Formation and under- lies the El Wastani Formation. The thickness of this forma- tion is 1121 m in the Naf-101 well and 1149 m in the Naf-2 well. Also, its thickness attains 1282 m in the Naf-3 well. The formation is composed of shale-clay intercalations with some minor occurrences? of sands, siltstones, argillaceous limestones, and dolomites. Also, there are several planktonic species present in this formation (e.g. Globigerinoides obli- qua, Globigerinoides trilobus trilobus, Globigerina falcon- Geologia Croatica 63/1Geologia Croatica 6 ensis, Globigerina nilotica, Globigerina apertura, Turboro- talia humilis, Globorotalia exilis, Globorotalia acostaensis acostaensis, Bella praedigitata and Catapsydrax parvulus). Moreover, there are several benthic species associated with the planktonics (e.g. Nonion affi nis, Anomalina grosseru- gosa, Bulimina elongata, Gyroidinoides soldanii, Bolivina hebes, Ammonia beccarii, Cibicidoides sp., Cassidulina bro- cha, Pullenia osloensis and Uvigerina semiornata). The Kafr El Sheikh Formation is dated as Early-Middle Pliocene according to palaeontological (BARAKAT, 1982) and geophysical data by BADRAN (1996). It is worthmentioning that during Early-Middle Pliocene, the marine transgression that began during the Early Pliocene, had been extended over the entire Mediterranean area (AZZAM, 1994). The Kafr El Sheikh Formation is ascribed to Early-Late Pliocene (DEIBIS et al., 1986). Also, EFFAT & GEZEIRY (1986) assigned the same age, to the formation based on lithology and wireline logs. RIZZINI et al. (1978) mentioned that the upper part of this for- mation belongs to the Middle Pliocene. 4.7. El Wastani Formation This formation overlies the Kafr El Sheikh Formation and underlies the Baltim Formation. The thickness of this forma- tion increases northward (156 m in Naf-101 well, and 301 m in Naf-2 well). Also, its thickness attains 124 m in Naf-3 well. This formation is composed of intercalations of sand, shale, clay, with some dolomite and limestone. The non- clastic facies (carbonates) increase northward. There are seve- Fi gu re 7: The planktonic foraminiferal distribution chart of Naf-2 well. Ismail et al.: Subsurface stratigraphy and micropaleontology of the Neogene rocks, Nile Delta, Egypt Geologia Croatica 7 ral planktonic species present in this formation (e.g. Globi- gerinoides elongatus, Globigerinoides trilobus sacculifer, Globigerina rubescens, Glo bigerina bulloides, Orbulina uni- versa and Globigerinella obesa). There are also several ben- thic species associated with the planktonic forms (e.g. Non- ion asterizans, Ammonia tepida, Natlandia cf. secasensis, Eponidella cf. libertadensis, Lenticulina reedi, Bulimina elon- gata, Cassidulina brocha, Ammonia umbonata, Bolivina hebes and Pullenia osloensis). The age of this formation is Late Pliocene, based on geo- physical data (BADRAN, 1996 and AZZAM, 1994). These authors mentioned that the regression of the sea heralded the end of the sedimentation cycle of the Pliocene. 4.8. Baltim Formation This formation overlies the El Wastani Formation and un- derlies the Mit Ghamr Formation. The thickness of this for- mation is 690 m in Naf-101 well, 986 m in Naf-2 well and 1492 m in the Naf-3 well. The Baltim Formation is com- posed of intercalations of clay, sand, shale, with thin bioclas- tic limestones. Planktonic foraminiferal species present in this formation include; Globigerinella obesa, Globigerino ides quadrilobatus, Globigerinoides trilobus immaturus, Glo bi- gerinoides trilobus trilobus, Globigerinoides obliquus ex- tremus, Globigerinoides ruber, Globorotalia acostaensis aco- staensis, Globigerina falconensis, Globigerina quinqueloba and Orbulina universa. There are also several benthic speci es Fi gu re 8: The planktonic foraminiferal distribution chart of Naf-3 well. Geologia Croatica 63/1Geologia Croatica 8 associated with the planktonics (e.g. Elphidium macellum, Lenticulina hughesi, Buccella sp., Bolivina hebes, Cibici- doides sp., Uvigerina semiornata, Bulimina elongata, Am- monia beccarii, Asterigerina planorbis and Nonionina sca pha). These foraminiferal species are shown on the distribution charts (Figs. 7, 8, 9, 10, 11 and 12). The formation has been dated as Early Pleistocene based on palaeontological studies (DEIBIS et al., 1986). In the North Abu Qir area, the age of this formation ranges from Pleistocene to Recent as recorded in the two wells (Naf-3 well & Naf-101 well). 4.9. Mit Ghamr Formation This formation overlies the Baltim Formation and underlies the Bilqas Formation. The thickness of this formation de- creases northward (661 m in Naf-101 well and 482.5 m in Naf-2 well). Also, its thickness attains 624 m in the Naf-3 well. This formation is composed of intercalations of clay, sand, and silt, with some limestone. No foraminifera have been recorded in this formation which may be partly due to the number of samples. ISMAIL (1984) dated this formation Fi gu re 9: The planktonic foraminiferal distribution chart of Naf-101 well. Ismail et al.: Subsurface stratigraphy and micropaleontology of the Neogene rocks, Nile Delta, Egypt Geologia Croatica 9 as Late Pliocene to Quaternary, while AZZAM (1994) as- cribed it to the Pleistocene age. Moreover, BADRAN (1996) dated it as Late Pliocene to Pleistocene in age. In the study area, this formation is dated Pleistocene to Recent through- out, based on correlation with neighbouring areas. 4.10. Bilqas Formation This formation covers the whole Delta region. In the study area, it is present at the top of all wells. However, it is dif- fi cult to differentiate it from the underlying Mit Ghamr For- mation. This formation is composed of sand interbedded with clay rich in molluscan fragments. The clays contain vegetable remains and carbonaceous matter. It is dated as Holocene by BARAKAT (1982) and BADRAN (1996). AZ- ZAM (1994) mentioned that during the Holocene a marine transgression covered most of the Northern Delta area and gave rise to a few metres of marine sediments capped by ag- ricultural soil. RIZZINI et al. (1976) and ABU EL ENEIN (1990) ascribed this formation to the same age, based on the faunal association. In the study area, this formation is dated as being Pleistocene to Recent in age. Fi gu re 10: The benthic foraminiferal distribution chart of Naf-2 well. Geologia Croatica 63/1Geologia Croatica 10 5. TAXONOMIC LIST Order Foraminiferida Eichwald, 1830 Quinqueloculina bosciana D’ORBIGNY, 1938 (Pl. 1, Fig. 1) 1938. Quinqueloculina bosciana D’ORBIGNY, p. 191, pl. 11, fi gs. 11–24 1990. Quinqueloculina bosciana D’ORBIGNY-ABU EL ENEIN, pl. 2, fi g. 13 Nodosaria raphanistrum (LINNE), 1758 (Pl. 1, Fig. 2) 1758. Nautilus raphanistrum LINNE, p. 710. 1930. Nodosaria raphanistrum (LINNE)-MACFADYEN, p. 74, pl. 2, fi g. 36 Lagena striata (D’ORBIGNY), 1839 (Pl. 1, Fig. 3) 1839. Oolina striata D’ORBIGNY, p. 21, pl. 5, fi g. 12 1996. Lagena striata (D’ORBIGNY)-OSMAN, pl. 2, fi g.9 Fi gu re 11: The benthic foraminiferal distribution chart of Naf-3 well. Ismail et al.: Subsurface stratigraphy and micropaleontology of the Neogene rocks, Nile Delta, Egypt Geologia Croatica 11 Lagena sulcata (WALKER AND JACOB), 1798 (Pl. 1, Fig. 4) 1798. Serpula sulcata WALKER AND JACOB, p. 634, pl. 14, fi g. 18 1985. Lagena sulcata (WALKER AND JACOB)-LUGER, p. 81, pl. 4, fi g.6 Globorotalia acostaensis acostaensis BLOW, 1959 (Pl. 1, Figs. 5–6) 1959. Globorotalia acostaensis BLOW, p. 208, pl. 17, fi gs. 106a–c 1985. Globorotalia acostaensis acostaensis BLOW-BOLLI & SAUNDERS, p. 210, pl. 27, fi gs. 10–11, pl. 28, fi gs. 16–24 Globorotalia archeomenardii BOLLI, 1957 (Pl. 1, Fig. 7) 1957. Globorotalia archeomenardii BOLLI, p. 119, pl. 28, fi gs. 11a–c 1983. Globorotalia archeomenardii BOLLI-KENNETT & SRINIVASAN, pl. 28, fi gs. 3–5 Fi gu re 12: The benthic foraminiferal distribution chart of Naf-101 well. Geologia Croatica 63/1Geologia Croatica 12 Ismail et al.: Subsurface stratigraphy and micropaleontology of the Neogene rocks, Nile Delta, Egypt Geologia Croatica 13 Neogloboquadrina continuosa (Blow, 1959) (Pl. 1, Figs. 8–9) 1959. Globorotalia opima Bolli subsp. continuosa BLOW, p. 218, pl. 19, fi gs. 125a–c 1985. Globorotalia continuosa BLOW-BOLLI et al., p. 204, pl. 28, fi gs. 8–14. Globorotalia exilis BLOW, 1969 (Pl. 1, Fig.10) 1969. Globorotalia cultrata exilis BLOW, p. 396, pl. 7, fi gs. 1–3, pl. 42, fi gs. 1–5 1983. Globorotalia exilis, BLOW-BOLLI et al., p. 228, fi gs. 33.4, 35.9–11 Globorotalia humerosa humerosa TAKAYANAGI & SAITO, 1962 (Pl. 1, Figs. 11–13) 1962. Globorotalia humerosa humerosa TAKAYANAGI & SAITO, p. 78, pl. 28, fi gs. 1a–c 1985. Globorotalia humerosa humerosa TAKAYANAGI & SAITO-BOLLI et al, p. 208, fi gs. 27.8a–c, p. 209, fi gs. 28.15a–c Globorotalia margaritae margaritae BOLLI & BERMUDEZ, 1965 (Pl. 1, Figs. 14–16) 1965. Globorotalia margaritae BOLLI & BERMUDEZ, p. 132, pl. 1, fi gs. 16–18 1985. Globorotalia margaritae margaritae BOLLI & BER- MUDEZ-BOLLI et al., p. 218, fi gs. 30.9–14G Globorotalia peripheroronda BLOW & BANNER, 1966 (Pl. 1, Figs. 17–18) 1966. Globorotalia peripheroronda BLOW & BANNER, p. 294, pl. 1, fi gs. 1a–c 1983. Globorotalia peripheroronda BLOW & BANNER- KENNETT & SRINIVASAN, pl. 22, fi gs. 1–3 Globorotalia pseudopima BLOW, 1969 (Pl. 2, Fig. 19) 1969. Globorotalia acostaensis pseudopima BLOW, p. 387, pl. 35, fi gs. 1–3 1985. Globorotalia pseudopima BLOW-BOLLI et al., p. 208, fi g. 27.7G, p. 209, fi gs. 28.10–12G Plate 1 Bar scale = 100 µm 1 Quinqueloculina bosciana, (D’Orbigny 1839), Pleistocene-Recent, Baltim, sample from 1030 m, Naf-3 well. 2 Nodosaria raphanistrum, Linne 1758, Pleistocene-Recent, Baltim, sample from 1030 m, Naf-3 well. 3 Lagena striata, (D’Orbigny, 1839), Pliocene, Kafr El Sheikh, sample from 1790 m, Naf-3 well. 4 Lagena sulcata, (Walker and Jacob, 1798), Early Miocene, Qantara, sample from 3550 m, Naf-101 well. 5–6 Globorotalia acostaensis acostaensis, Blow 1959, 5. Ventral view, Pleistocene-Recent, Baltim, sample from 1320m, Naf-3 well. 6. Dorsal view, Early Pliocene, Kafr El Sheikh, sample from 3075m, Naf-2 well. 7 Globorotalia archeomenardii, Bolli 1957, ventral view, Pliocene, Kafr El Sheikh, sample from 2680 m, Naf-101 well. 8–9 Neogloboquadrina continuosa, Blow 1959, 8. Ventral view, Early Miocene, Qantara, sample from 3530m, Naf-101 well. 9. Dorsal view, Early Miocene, Qantara, sample from 3530m, Naf-101 well. 10 Globorotalia exilis, Blow 1969, ventral view, Pliocene, Kafr El Sheikh, sample from 2680 m, Naf-101 well. 11–13 Globorotalia humerosa humerosa, Takayanagi & Saito 1962, 11. Ventral view, Early Miocene, Qantara, sample from 3530m, Naf-101 well. 12. Side view, Early Miocene, Qantara, sample from 3530m, Naf-101 well. 13. Dorsal view, Early Miocene, Qantara, sample from 3530m, Naf-101 well. 14–16 Globorotalia margaritae margaritae, Bolli & Bermudez 1965, 14. Ventral view, Pliocene, Kafr El Sheikh, sample from 2680 m, Naf-101 well. 15. Side view, Pliocene, Kafr El Sheikh, sample from 3075 m, Naf-2 well. 16. Dorsal view, Pliocene, Abu Madi, sample from 2800 m, Naf-3 well. 17–18 Globorotalia peripheroronda, Blow & Banner 1966, 17. Ventral view, Pliocene, Kafr El Sheikh, sample from 1980m, Naf-101 well. 18. Dorsal view, Pliocene, Kafr El Sheikh, sample from 19800m, Naf-101 well. 19 Globorotalia pseudopima, Blow 1969, ventral view, Pliocene, Kafr El Sheikh, sample from1980 m, Naf-101 well. 20 Globorotalia scitula praescitula, Blow 1959, ventral view, Early Pliocene, Kafr El Sheikh, sample from2775 m, Naf-2 well. 21 Globorotalia scitula scitula, Brady 1884, ventral view, Early Miocene, Qantara, sample from 3530 m, Naf-101 well. 22 Dentoglobigerina altispira altispira, Cushman & Jarvis 1936, ventral view, Early Miocene, Qantara, sample from 3550 m, Naf-101 well. 23 Globigerina ciperoensis ciperoensis, Bolli 1954, ventral view, Middle Miocene, Sidi Salim, sample from 3300 m, Naf-3 well. Geologia Croatica 63/1Geologia Croatica 14 Ismail et al.: Subsurface stratigraphy and micropaleontology of the Neogene rocks, Nile Delta, Egypt Geologia Croatica 15 Globorotalia scitula praescitula BLOW, 1959 (Pl. 2, Fig. 20) 1957. Globorotalia scitula praescitula BLOW, p. 221, pl. 19, fi gs. 128a–c 1985. Globorotalia scitula praescitula BLOW-BOLLI et al., p. 219, fi gs. 31.6a–c Globorotalia scitula scitula (BRADY, 1884) (Pl. 2, Fig. 21) 1882. Pulvinulina scitula BRADY, p. 716. 1884. Globorotalia scitula scitula BRADY, pl. 103, fi gs. 7a–c 1985. Globorotalia scitula scitula BRADY-BOLLI et al., p. 219, fi gs. 31.3–4G Dentoglobigerina altispira altispira, (CUSHMAN & JARVIS 1936) (Pl. 2, Fig. 22) 1936. Globoquadrina altispira CUSHMAN & JARVIS, p. 5, pl. 1, fi gs. 13a–c 1983. Globoquadrina altispira altispira CUSHMAN & JARVIS-BOLLI & SAUNDERS, p. 183, fi g. 15 Globigerina ciperoensis ciperoensis BOLLI, 1957 (Pl. 2, Fig. 23) 1957. Globigerina ciperoensis angustiumbilicata BOLLI, p. 109, pl. 22, fi gs. 12a–c 1985. Globigerina ciperoensis ciperoensis BOLLI-BOLLI et al., p. 178, fi gs. 13.1–3G Globigerina nilotica VIOTTI & MANSOUR, 1969 | (Pl. 2, Figs. 1–3) 1969. Globigerina nilotica VIOTTI & MANSOUR, p. 447, pl. 6, fi gs. 1–7 Globigerina praebulloides BLOW, 1959 (Pl. 2, Fig. 4–6) 1957. Globigerina praebulloides BLOW, p. 180, pl. 8 fi gs. 47a–c; pl. 9, fi g. 48 1983. Globigerina praebulloides BLOW-KENNETT & SRINIVASAN, pl. 6, fi gs. 1–3 Plate 2 Bar scale = 100 µm 1–3 Globigerina nilotica, Viotti & Mansour, 1969, 1. Ventral view, Pliocene, El Wastani, sample from 1540, Naf-101 well. 2. Side view, Late Miocene, Rosetta, sample from 2970, Naf-3 well. 3. Dorsal view, Late Miocene, Rosetta, sample from 2970, Naf-3 well. 4–6 Globigerina praebulloides, Blow 1959, 4. Ventral view, Middle Miocene, Sidi Salim, sample from 3300, Naf-3 well. 5. Side view, Mid.-Lat. Miocene, Qawasim, sample from 3300, Naf-3 well. 6. Dorsal view, Middle Miocene, Rosetta, sample from 3030, Naf-101 well. 7–8 Globigerina rubescens, Honza, 1980, 7. Ventral view, Late Pliocene, Kafr El Sheikh, sample from 1960 m, Naf-2 well. 8. Dorsal view, Late Pliocene, Kafr El Sheikh, sample from 1960 m, Naf-2 well. 9–12 Globigerinoides bisphericus, Todd 1954, 9. Ventral view, Early Miocene, Qantara, sample from 3530 m, Naf-101 well. 10. Dorsal view, Early Miocene, Qantara, sample from 3530 m, Naf-101 well. 11. Side view, Early Miocene, Qantara, sample from 3530 m, Naf-101 well. 12. Side view, Early Miocene, Qantara, sample from 3530 m, Naf-101 well. 13–14 Globigerinoides bollii, Blow 1959, 13. Ventral view, Middle Pliocene, Kafr El Sheikh, sample from 2370 m, Naf-2 well. 14. Dorsal view, Late Pliocene, Kafr El Sheikh, sample 1960 m, Naf-2 well. 15–16 Globigerinoides elongatus, D’Orbigny 1926, 15. Ventral view, Late Pliocene, Kafr El Sheikh, sample from 1960 m, Naf-2 well. 16. Dorsal view, Late Pliocene, Kafr El Sheikh, sample from 1960 m, Naf-2 well. 17–19 Globigerinoides obliquus extremus, Bolli & Bermudez 1965, 17. Ventral view, Late Miocene, Rosetta, sample from 3030, Naf-101 well. 18. Side view, Late Pliocene, Kafr El Sheikh, sample from 1960m, Naf-2 well. 19. Dorsal view, Late Pliocene, Kafr El Sheikh, sample from 1969m, Naf-2 well. 20 Globigerinoides obliquus obliquus, Bolli 1957, ventral view, Pliocene, Kafr El Sheikh, sample from 2680 m, Naf-101 well. 21 Globigerinoides primordius, Blow & Banner 1962, ventral view, Early Miocene, Qantara, sample from 3550 m, Naf-101 well. 22–23 Globigerinoides ruber, D’Orbigny 1839, 22. Ventral view, Early Pliocene, Kafr El Sheikh, sample from2625 m, Naf-2 well. 23. Dorsal view, Middle Miocene, Sidi Salim, sample from 3300m, Naf-3 well. 24–25 Globigerinoides trilobus immaturus, Le Roy 1939, 24. Ventral view, Middle Miocene, Sidi Salim, sample from 3300m, Naf-3 well. 25. Dorsal view, Middle Miocene, Sidi Salim, sample from 3300 m, Naf-3 well. Geologia Croatica 63/1Geologia Croatica 16 Globigerina rubescens HOFKER, 1956 (Pl. 2, Figs. 7–8) 1956. Globigerina rubescens HOFKER, p. 234, pl. 32, fi g. 26; pl. 35, fi gs. 18–21 1983. Globigerina rubescens HOFKER-KENNETT & SRI- NIVASAN, pl. 9, fi gs. 7–9 Globigerinoides bisphericus TODD, 1954 (Pl. 2, Figs. 9–12) 1954. Globigerinoides bispherica TODD, p. 681, pl.1, fi gs. 1a–c 1983. Globigerinoides bisphericus TODD-BOLLI & SA- UNDERS, p. 199, fi gs. 24.8; 7,9,12 Globigerinoides bollii BLOW, 1959 (Pl. 2, Figs. 13–14) 1957. Globigerinoides bollii BLOW, p. 189, pl. 10, fi gs. 65a–c 1983. Globigerinoides bollii BLOW-BOLLI et al., p. 193, fi gs. 20.8a–c Globigerinoides elongatus (D’ORBIGNY), 1926 (Pl. 2, Figs. 15–16) 1926. Globigerina elongata D’ORBIGNY, p. 277. 1985. Globigerinoides elongatus (D’ORBIGNY)-BOLLI et al., p. 193, fi gs. 20.4a–c Globigerinoides obliquus extremus BOLLI & BERMUDEZ, 1965 (Pl. 2, Figs. 17–19) 1965. Globigerinoides obliquus extremus BOLLI & BER- MUDEZ, p. 139, pl. 1, fi gs. 10–12 1985. Globigerinoides obliquus extremus BOLLI & BER- MUDEZ-BOLLI & SAUNDERS, p. 194, pl. 20, fi g. 11 Globigerinoides obliquus obliquus BOLLI, 1957 (Pl. 2, Fig. 20) 1957. Globigerinoides obliquus BOLLI, p. 113, pl.25, fi gs. 19a–c 1983. Globigerinoides obliquus obliquus BOLLI-BOLLI & SAUNDERS, p. 194, pl. 20, fi g. 12 Globigerinoides primordius BLOW & BANNER, 1962 (Pl. 2, Fig. 21) 1962. Globigerinoides primordius BLOW & BANNER, p. 15, pl. ix, fi gs. Dd–Ff 1983. Globigerinoides primordius BLOW & BANNER- KENNETT & SRINIVASAN, pl. 11, fi gs. 1–3 Globigerinoides ruber D’ORBIGNY, 1839 (Pl. 2, Figs. 22–23) 1839. Globigerinoides ruber D’ORBIGNY, p. 19, pl. 3, fi gs. 8a–c 1983. Globigerinoides ruber D’ORBIGNY-BOLLI et al., p. 193, fi gs. 20.1, 2 Globigerinoides trilobus immaturus LE ROY, 1939 (Pl. 2, Figs. 24–25; Pl. 3, Fig. 1) 1939. Globigerinoides sacculifer (Brandy) var. immaturus LE ROY, p. 263, pl. 3, fi gs. 19–21 1983. Globigerinoides trilobus immaturus LEROY-BOLLI et al., p. 193, fi gs. 20.14a–c Globigerinoides trilobus sacculifer BRADY, 1877 (Pl. 3, Fig. 2) 1877. Globigerina sacculifera BRADY, p. 535. 1985. Globigerinoides trilobus sacculifer BRADY-BOLLI et al., p. 193, fi gs. 20.13a–b Globigerinoides trilobus trilobus (REUSS), 1850 (Pl. 3, Figs. 3–5) 1850. Globigerina triloba REUSS, p. 374, pl. 47, fi gs. 11a–c 1985. Globigerinoides trilobus trilobus (REUSS)-BOLLI et al., p. 193, fi gs. 20.15a–b Sphaeroidinellopsis disjuncta FINLAY, 1940 (Pl. 3, Figs. 6–8) 1939. Sphaeroidinellopsis disjuncta FINLAY, p. 467, pl. 67, fi gs. 224–228 1983. Sphaeroidinellopsis disjuncta FINLAY-KENNETT & SRINIVASAN, pl. 51, fi gs. 3–5 Orbulina bilobata D’ORBIGNY, 1846 (Pl. 3, Fig. 9) 1846. Orbulina bilobata D’ORBIGNY, p. 164, pl. 9, fi gs. 11–14 1983. Orbulina bilobata D’ORBIGNY, KENNETT & SRI- NIVASAN, p. 88, pl. 20, fi gs. 7–9 Orbulina cf. suturalis BRONNIMANN (Pl. 3, Fig. 10) 1951 Orbulina suturalis BRONNIMANN, p. 135, fi gs. 2–4 1985 Orbulina suturalis BRONNIMANN-BOLLI & SAUN- DERS, p. 201, fi g. 23 (2) Orbulina universa D’ORBIGNY, 1839 (Pl. 3, Fig. 11) 1839. Orbulina universa D’ORBIGNY, p. 3, pl. 1, fi g. 1 1983. Orbulina universa D’ORBIGNY-KENNETT & SRINIVASAN, pl. 18, fi g. 2; pl. 20, fi gs. 4–6 Praeorbulina glomerosa curva BLOW, 1956 (Pl. 3, Figs. 12–13) 1956. Praeorbulina glomerosa curva BLOW, p. 62, Text fi g. 1, no. 9–14 Ismail et al.: Subsurface stratigraphy and micropaleontology of the Neogene rocks, Nile Delta, Egypt Geologia Croatica 17 1983. Praeorbulina glomerosa curva BLOW-KENNETT & SRINIVASAN, pl. 18, fi gs. 3–4 Praeorbulina glomerosa glomerosa BLOW, 1956 (Pl. 3, Figs. 14) 1956. Praeorbulina glomerosa glomerosa BLOW, p. 64, Text fi g. 1, 15–19. fi g. 2, 1–2 1983. Praeorbulina glomerosa glomerosa BLOW-KEN- NETT & SRINIVASAN, pl. 18, fi gs. 5–7 Bolivina hebes MACFADYEN, 1930 (Pl. 3, Fig. 15) 1930. Bolivina hebes MACKFADYEN p. 59, pl. II, fi gs. 5a–c 1999. Bolivina hebes MACKFADYEN-ABUL-NASR & SALAMA, p. 127, fi g. 17 (13) Cassidulina laevigata D’ORBIGNY, 1826 (Pl. 3, Fig. 16) 1826 Cassidulina laevigata D’ORBIGNY, p. 282, pl. XV, fi gs. 4–5 1999 Cassidulina laevigata D’ORBIGNY-ABUL-NASR & SALAMA, p. 127, fi g. 17 (20) Globocassidulina oblonga (REUSS), 1850 (Pl. 3, Fig. 17) 1850. Cassidulina oblonga, REUSS, p. 376, pl. 48, fi gs. 5–6 1982. Globocassidulina oblonga (REUSS)-AGIP, p. 43, fi g. 7 Bulimina elongata D’ORBIGNY, 1826 (Pl. 3, Fig. 18) 1826. Bulimina elongata D’ORBIGNY, p. 269 1990. Bulimina elongata D’ORBIGNY-ABU EL ENEIN, pl. 8, fi g. 19 Uvigerina cf. asperula CZJZEK, 1848 (Pl. 3, Fig. 19) 1848 Uvigerina asperula CZJZEK, p. 146, pl. 13, fi gs. 14–15 1965 Uvigerina asperula CZJZEK –SOUAYA, p. 317, pl. 2, fi g. 26 Uvigerina semiornata, D’ ORBIGNY 1840 (Pl. 3, Fig. 20) 1840 Uvigerina semiornata, D’ ORBIGNY, p. 16. 1999 Uvigerina semiornata, D’ ORBIGNY-ABUL-NASR & SALAMA, p. 129, fi g. 18 (9). Fursenkoina schreibersiana (CZJZEK, 1848) (Pl. 3, Fig. 21) 1999 Fursenkoina schreibersiana (CZJZEK)-ABUL-NASR &SALAMA, p. 129, fi g. 18 (2) Nodosarella sp. (Pl. 3, Fig. 22) Cancris auriculus (FICHTEL & MOLL), 1798 (Pl. 3, Fig. 23) 1798. Nautilus auriculus FICHTEL & MOLL 1798, p. 108, pl. 20, fi gs. a–c 1985. Cancris auriculus (FICHTEL & MOLL 1798)-PAPP & SCHMID, p. 61, pl. 52, fi gs. 7–13 Natlandia cf. secasensis MCCULLOCH 1977 (Pl. 3, Fig. 24) 1977. Natlandia secasensis MCCULLOCH, p. 346 Valvulineria complanata (D’ORBIGNY, 1846) (Pl. 3, Figs. 25–26) 1846. Rosalina complanata D’ORBIGNY, p. 175, pl. 10, fi gs. 13–15 1965. Valvulineria complanata (D’ORBIGNY)-SOUAYA, p. 44, pl. 1, fi gs. 9a–b Neoeponides sp. (Pl. 3, Fig. 27; Pl. 4, Fig. 1) Cibicidoides sp. (Pl. 4, Fig. 2) Eponidella cf. libertadensis CUSHMAN & HEDBERG, 1935 (Pl. 4, Fig. 3) 1935 Eponidella libertadensis CUSHMAN & HEDBERG, p. 13 Asterigerina planorbis D’Orbigny, 1846b (Pl. 4, Figs. 4–5) 1846. Asterigerina planorbis D’Orbigny, p. 205, pl. 11, fi gs. 1–3 1931. Discorbis planorbis (D’Orbigny)-Macfadyen, p. 97, pl. 4, fi gs. 8a–c 1965. Asterigerina planorbis D’Orbigny-Souaya, p.34. Nonionellina labradorica (DAWSON, 1860) (Pl. 4, Figs. 6–7) 1860. Nonionina labradorica DAWSON, p. 191 1988. Nonionellina labradorica (DAWSON)-LOEBLICH & TAPPAN, p. 617, pl. 689, fi gs. 8–17 Melonis pompiliodes (FICHTEL & MOLL, 1798) (Pl. 4, Figs. 8–9) 1798. Natilus pompiliodes FICHTEL & MOLL, p. 31, pl. 2, fi gs. a–c 1969. Nonion pompiliodes (FICHTEL & MOLL)-OMARA & OUDA, p.586, pl. 2, fi gs. 31–32 Geologia Croatica 63/1Geologia Croatica 18 Ismail et al.: Subsurface stratigraphy and micropaleontology of the Neogene rocks, Nile Delta, Egypt Geologia Croatica 19 1999 Melonis pompiliodes (FICHTEL & MOLL)-ABUL- NASR & SALAMA, p. 130, fi g. 19 (13–14) Pullenia osloensis FEYLING & HASSAN, 1954 (Pl. 4, Figs. 10–11) 1954. Pullenia osloensis FEYLING & HASSAN, p. 194, pl. 1, fi gs. 33–35 1983. Pullenia osloensis FEYLING & HASSAN-BELAN- GER & BERGGREN, p. 341, pl. 5, fi gs. 2a–3b Pullenia quinqueloba (REUSS) 1851, (Pl. 4, Fig.12) 1851. Pullenia quinqueloba REUSS, p. 71, pl, v, fi g. 31 1884. Pullenia quinqueloba (REUSS)-BRADY, p. 617, pl. 1xxxiv, fi gs. 14–15 Alabamina sp. (Pl. 4, Fig. 13) Gyroidinoides soldanii D’ORBIGNY 1825, (Pl. 4, Figs. 14–15) 1825. Gyroidina soldanii D’ORBIGNY, p. 278 1990. Gyroidina soldanii D’ORBIGNY-ABU EL ENEIN, pl. 12, fi g. 12 Buccella sp. (Pl. 4, Fig. 16) Ammonia beccarii (LINNE), 1758 (Pl. 4, Figs. 17–20) 1758. Nautilus beccarii LINNE, p. 1162 1930. Rotalia beccarii (LINNE)-MACFADYEN, p. 103 1990. Ammonia beccarii (LINNE)-ABU EL ENEIN, pl. 13, fi g. 4 Ammonia ikebei (INOUE & NAKASEKO), 1951 (Pl. 4, Figs. 21–22) 1949. Rotalia ikebei INOUE & NAKASEKO, p. 10, fi gs. 4a–c 1980. Ammonia ikebei (INOUE & NAKASEKO)-BILL- MAN et al., p. 88, pl. 11, fi g. 16 Plate 3 Bar scale = 100 µm 1 Globigerinoides trilobus immaturus, Le Roy 1939, side view, Middle Miocene, Sidi Salim, sample from 3300 m, Naf-3 well. 2 Globigerinoides trilobus sacculifer, Brady 1877, ventral view, Late Pliocene, El Wastani, sample from 1630 m, Naf-3 well. 3–5 Globigerinoides trilobus trilobus, Reuss 1850, 3. Ventral view, Early Miocene, Qantara, sample from 3550 m, Naf-101 well. 4. Dorsal view, Late Pliocene, Kafr El Sheikh, sample 1960 m, Naf-2 well. 5. Side view, Late Pliocene, Kafr El Sheikh, sample 1960 m, Naf-2 well. 6–8 Sphaeroidinellopsis disjuncta, Finlay 1940, 6. Ventral view, Late Miocene, Rosetta, sample from 3030 m, Naf-101 well. 7. Dorsal view, Late Miocene, Rosetta, sample from 2970 m, Naf-3 well. 8. Side view, Late Miocene, Rosetta, sample from 2970 m, Naf-3 well. 9 Orbulina bilobata, D’Orbigny 1846, Dorsal view, Early Pliocene, Kafr El Sheikh, sample from 3075 m, Naf-2 well. 10 Orbulina cf. suturalis Bronnimann, 1951 Middle Miocene, Sidi Salim, sample from 3300 m, Naf-3 well. 11 Orbulina universa, D’Orbigny 1939, Middle Miocene, Sidi Salim, sample from 3300 m, Naf-3 well. 12–13 Praeorbulina glomerosa curva, Blow 1956, 12. Ventral view, Pliocene, Kafr El Sheikh, sample from 2680 m, Naf-101 well. 13. Middle Miocene, Sidi Salim, sample from 3300 m, Naf-3 well. 14 Praeorbulina glomerosa glomerosa, Blow 1956, Middle Miocene, Sidi Salim, sample from 3500 m, Naf-101well. 15 Bolivina hebes Macfadyen 1930, Late Pliocene, El Wastani, sample from 1870 m, Naf-2 well. 16 Cassidulina laevigata D’ Orbigny, 1826, Pliocene, Kafr El Sheikh, sample from 1640 m, Naf-3 well. 17 Globocassidulina oblonga, (Reuss 1850), Early Miocene, Qantara, sample from 3550 m, Naf-101 well. 18 Bulimina elongata D’Orbigny 1826, Late Pliocene, El Wastani, sample from 1925 m, Naf-2 well. 19 Uvigerina cf. asperula Czjzek, 1848 Late Pliocene, El Wastani, sample from 1870 m, Naf-2 well. 20 Uvigerina semiornata D’Orbigny, 1840, Pliocene, Kafr El Sheikh, sample from 1790 m, Naf-3 well. 21 Fursenkoina schreibersiana (Czjzek, 1848), Pliocene, Kafr El Sheikh, sample from 1460 m, Naf-3 well. 22 Nodosarella sp., Pliocene, Kafr El Sheikh, sample from 1640 m, Naf-3 well. 23 Cancris auriculus, (Fichtel & Moll 1798), ventral view, Pleistocene-Recent, Baltim, sample from 1550 m, Naf-3 well. 24 Natlandia cf. secasensis McCulloch 1977 Dorsal view, Late Pliocene, Kafr El Sheikh, sample from 1960 m, Naf-2 well 25–26 Valvulineria complanata, (D’Orbigny 1846), 25. Dorsal view, Pleistocene-Recent, Baltim, sample from 1550 m, Naf-3 well. 26. Ventral view, Pliocene, Kafr El Sheikh, sample from 1640 m, Naf-3 well. 27 Neoeponides sp.Ventral view, Pliocene, Kafr El Sheikh, sample from 1680m, Naf-101 well. Geologia Croatica 63/1Geologia Croatica 20 Ismail et al.: Subsurface stratigraphy and micropaleontology of the Neogene rocks, Nile Delta, Egypt Geologia Croatica 21 Ammonia perlucida (HERON ALLAN & EARLAND), 1913 (Pl. 4, Fig. 23–24) 1913. Rotalia perlucida HERON ALLAN & EARLAND, p. 139, pl. 13, fi gs. 7–9 1990. Ammonia perlucida (HERON ALLAN & EARLAND)- ABU EL ENEIN, pl. 13, fi g. 8 Ammonia tepida (CUSHMAN, 1926) (Pl. 4, Figs. 25–26) 1999 Ammonia tepida (CUSHMAN)-ABUL-NASR & SA- LA MA, p. 130, fi g. 19 (29) Ammonia umbonata (LEROY, 1944) (Pl. 4, Figs. 27–28) 1944 Rotalia umbonata LEROY, p. 35, pl. 7, fi g. 16–18 1980 Ammonia umbonata LEROY-BILLMAN et al., p. 87, pls. 6–8 Elphidium macellum (FICHTEL & MOLL), 1798 (Pl. 4, Fig. 29) 1798. Nautilus macellus FICHTEL & MOLL, p. 66, pl. 10, fi gs. e–k 1990. Elphidium macellum (FICHTEL & MOLL)-ABU EL ENEIN, pl. 13, fi g. 9 Nonionina scapha (FICHTEL & MOLL, 1798) (Pl. 4, Fig. 30) 1798. Nautilus scapha FICHTEL & MOLL, p. 105, pl. XIX, fi gs. d–f Plate 4 Bar scale = 100 µm 1 Neoeponides sp. Dorsal view, Middle Miocene, Sidi Salim, sample from 3300 m, Naf-3 well. 2 Cibicidoides sp., Early Pliocene, Kafr E Sheikh, sample from 2625 m, Naf-2 well. 3 Eponidella cf. libertadensis Cushman & Hedberg, 1935 Ventral view, Pleistocene-Recent, Baltim, sample from 1550 m, Naf-3 well. 4–5 Asterigerina planorbis, D’Orbigny 1846, 4. Ventral view, Pliocene, Kafr El Sheikh, sample from 1640 m, Naf-3 well. 5. Dorsal view, Pliocene, Kafr El Sheikh, sample from 1640 m, Naf-3 well. 6–7 Nonionellina labradorica (Dawson, 1860) 6. Lateral view, Pliocene, Kafr El Sheikh, sample from 1980 m, Naf-101 well. 7. Side view, Pliocene, Kafr El Sheikh, sample from 1980 m, Naf-101 well. 8–9 Melonis pompiliodes, (Fichtel & Moll 1798) 8. Lateral view, Late Pliocene, El Wastani, sample from 1540 m, Naf-101 well. 9. Side view, Late Pliocene, El Wastani, sample from 1540 m, Naf-101 well. 10–11 Pullenia osloensis, Feyling & Hassan 1954, 10. Lateral view, Late Pliocene, El Wastani, sample from 1540 m, Naf-101 well. 11. Side view, Late Pliocene, El Wastani, sample from 1540 m, Naf-101 well. 12 Pullenia quinqueloba, (Reuss 1851), Middle Miocene, Sidi Salim, sample from 3300 m, Naf-3 well. 13 Alabamina sp. Ventral view, Pliocene, Kafr El Sheikh, sample from 1640 m, Naf-3 well. 14–15 Gyrodinoides soldanii, (D’Orbigny 1825), 14. Ventral view, Pliocene, Kafr El Sheikh, sample from 1680 m, Naf-101 well. 15. Side view, Pliocene, Kafr El Sheikh, sample from 1680 m, Naf-101 well. 16 Buccella sp. Dorsal view, Pliocene, Kafr El Sheikh, sample from 1640m, Naf-3 well. 17–20 Ammonia beccarii, Linne 1758, 17. Lateral view, Pleistocene-Recent, Baltim, sample from 1320 m, Naf-3 Well. 18. Ventral view, Pliocene, Kafr El Sheikh, sample from 2080 m, Naf-101 well. 19. Side view, Pliocene, Kafr El Sheikh, sample from 2080 m, Naf-101 well. 20. Dorsal view, Pliocene, Kafr El Sheikh, sample from 2080 m, Naf-101 well. 21–22 Ammonia ikebei, (Inoue & Nakaseko 1951), 21. Ventral view, Pleistocene-Recent, Baltim, sample from 1460 m, Naf-3 well. 22. Dorsal view, Pleistocene-Recent, Baltim, sample from 1460 m, Naf-3 well. 23–24 Ammonia perlucida, (Heron Allan & Earland 1913), 23. ventral view, Pleistocene-Recent, Baltim, sample from 1460 m, Naf-3 well. 24. ventral view, Pleistocene-Recent, Baltim, sample from 1460 m, Naf-3 well. 25–26 Ammonia tepida, (Cushman 1926), 25. Ventral view, Pliocene, Kafr El Sheikh, sample from 1980 m, Naf-101 well. 26. Dorsal view, Pliocene, Kafr El Sheikh, sample from 1980 m, Naf-101 well. 27–28 Ammonia umbonata (LeRoy, 1944) 27. Ventral view, Late Pliocene, El Wastani, sample from 1540 m, Naf-101 well. 28. Dorsal view, sample from 1320m, Naf-3 well, Baltim, Pleistocene-Recent. 29 Elphidium macellum, (Fichtel & Moll 1798, Pliocene, Kafr El Sheikh, sample from 1460 m, Naf-3 well. 30 Nonionina scapha, (Fichtel & Moll 1798), Early Miocene, Qantara, sample from 3530 m, Naf-101 well. Geologia Croatica 63/1Geologia Croatica 22 1884. Nonionina scapha (FICHTEL & MOLL)-BRADY, p. 730, pl. IX, fi g. 14–16 1930 Nonionina scapha (FICHTEL & MOLL)-MACFA- DY EN, p. 105, pl. IV, fi g. 17 6. ENVIRONMENTAL IMPLICATIONS The environmental conditions of the Neogene rocks of the studied wells are interpreted by using the results of some pa- laeoecological parametres (e. g. the total number of foramin- ifera (T.N.F.) and planktonic/benthic ratio (P/B). The fi rst parameter (T.N.F) is the number of foraminiferal individu- als in one gram of dry sediments. It increases with increas- ing water depth as mentioned by BANDY & ARNAL (1960). The planktonic/benthic ratio represents the number of plank- tonic foraminiferal individuals divided by the number of benthic foraminifera. It is low in near shore marine environ- ment and increases with depth until the carbonate compen- sation depth (CCD) of approximately 4000 m is reached, below which only agglutinated foraminifera are found (PH- ELEGER, 1960). These parametres are graphically repre- sented to refl ect the vertical distribution of the foraminiferal fauna of the different rock units (Figs. 13, 14 and 15). The en- vironmental conditions for each recognized rock unit are men- tioned below based on these aforementioned parameters. The Qantara Formation was only represented in the Naf- 101 well. It underlies the Sidi Salim Formation. The facies of this formation is of non-marine clastics deposited by river currents and associated marginal marine transport processes, in a high-energy outer shelf environment. Moreover, towards the north, the environment changed to a shallow marine one where clastics and even carbonates were deposited by wave transport processes in a relatively quieter inner shelf envi- ronment. This is shown by the relatively higher values of T.N.F. and high P/B values indicating an increase in water depth as shown on Fig. 15. Also, the occurrence of Bolivina dilatata, Gyroidinoides soldanii, Bulimina elongata and Glo- bocassidulina oblonga indicates an increase of water depth (MURRAY, 1991) as in Fig. 15. The Sidi Salim Formation overlies the Qantara Forma- tion and underlies the Qawasim Formation. The faunal dis- tribution shows considered values of T.N.F., high P/B values Fi gu re 13: The paleoecologic parametres of Naf-2 well. Ismail et al.: Subsurface stratigraphy and micropaleontology of the Neogene rocks, Nile Delta, Egypt Geologia Croatica 23 especially in the upper part of the formation which indicate an increase in water depth. Furthermore, the occurrence of Bolivina hebes, Bulimina elongata, Uvigerina pygmoidea, Gyroidinoides soldanii and Lenticulina antipodum suggests a deep shelf environment (MURRAY, 1991) at the upper part of the Sidi Salem Formation. Moreover, there is a decrease in these values up to the middle of this formation as shown on Fig. 14. The facies of this formation, towards north and northwest directions, can be described as shallow marine clastics deposited primarily by wave transport processes in a relatively low-energy outer shelf environment. Further- more, it gradually changes into a high-energy deltaic envi- ronment, towards the south and southeast, which resulted in clastic deposits being deposited from several channels. The Qawasim Formation overlies the Sidi Salim Forma- tion and underlies the Rosetta Formation. The values of T.N.F. and P/B ratio are relatively low indicating a decrease in water depth during deposition of this formation. It was deposited in a high-energy deltaic environment, towards the south and southeast directions. The occurrence of Ammonia beccarii in the Qawasim formation in the Naf-3 well sug- gests a near-shore environment (VAN DER ZWAAN & JOR- ISSEN, 1991). The Rosetta Formation overlies the Qawasim Formation and underlies the Abu Madi Formation. This unit is extrem ely poor in foraminifera. It refl ects a decrease in water depth during its deposition. Deposition of evaporites in this formati on indicates a general regression of the whole Mediterranean. The top of this formation coincides with a general regression of sea level all over the study area, which is contemporane- ous with the "Messinian Salinity Crisis" phenomenon all over the Mediterranean HSU et al. (1973, 1977). The Abu Madi Formation overlies the Rosetta Anhydrite and underlies the Kafr El Sheikh Formation. The faunal dis- tribution shows an increase of T.N.F. values and high P/B values indicating an increase in water depth during deposi- Fi gu re 14: The paleoecologic parametres of Naf-3 well. Geologia Croatica 63/1Geologia Croatica 24 tion of this formation (Fig. 13). The occurrence of Bolivina hebes (as in Naf-3 well) refl ects a neritic type of bolivines (DOUGLAS, 1979). Furthermore, the occurrence of the cos- tate Uvigerina semiornata (as in the Naf-3 well) that prefers anoxic conditions and fi ne-grained substrate (BOERSMA, 1984) suggests a shallow environment. The Kafr El Sheikh Formation overlies the Abu Madi Formation and underlies the El Wastani Formation. The fau- nal distribution refl ects an increase of T.N.F. values and high P/B values mostly at the top and the base of this formation, if compared to the middle part, indicating a fl uctuating water depth which is lower for the central section of the formation. The occurrence of Cassidulina brocha, Ammonia beccarii, A. tepida, Pullenia osloensis, Bolivina dilatata, Bulimina elongata, Uvigerina pygmoidea and Vulvulineria compla- nata suggests a higher water depth in the lower part of the Kafr El Sheikh Formation. Also, the same conditions pre- vailed in the upper part of the same formation as indicated Fi gu re 15: The paleoecologic parametres of Naf-101 well. Ismail et al.: Subsurface stratigraphy and micropaleontology of the Neogene rocks, Nile Delta, Egypt Geologia Croatica 25 by the occurrence of Elphidium advenum, Quinqueloculina bosciana, Globocassidulina oblonga and Fursenkoina sch- reibersiana. The El Wastani Formation overlies the Kafr El Sheikh Formation and underlies the Baltim Formation. The faunal distribution of this formation refl ects an increase of T.N.F. but low P/B values. This represents a lowering of the water depth during deposition of this formation as shown on Fig. 14. The top of this formation coincides with a regression of sea level all over the study area. Also, the occurrence of Ammo- nia-Elphidium and Valvulineria-Fursenkoina assemblages suggests a near shallow environment and a decrease in water depth through the El Wastani Formation. The Baltim Formation overlies the El Wastani Forma- tion and underlies the Mit Ghamr Formation. The faunal dis- tribution of this formation is only observed for the lower part (Fig. 14) due to a lack of samples. The facies in the southern parts, of the study area, can be described as shallow marine. Intercalations of sand, shales and even carbonates were de- posited, primarily by wave transport processes, in a high en- ergetic outer shelf environment which become more quiet towards the north. The Mit Ghamr Formation overlies the Baltim Forma- tion and underlies the Bilqas Formation. The facies can be described as clastics and even carbonates deposited in a quiet shelf environment, where these sediments were affected by postdepositional processes forming some sort of canyon in the older sediments. Finally, the Bilqas Formation covers the whole delta. AZZAM (1994) mentioned that during this time, the marine transgression covered most of the northern delta area and gave rise to a few metres of marine sediments capped by ag- ricultural soil. This is repetition whereas this section is about the faunal content and depositional environment, where no samples are available in this interval. 7. CONCLUSION The present work deals with the stratigraphy and micropal- eontology of the sedimentary sequence in the North Abu Qir Field, Nile Delta, Egypt. Three wells (Naf-2, Naf-3 and Naf- 101) were described, sampled and micropalaeontologically investigated. The lithostratigraphic studies have been carried out on the study area helped in the recognition of the Mio- cene–Pliocene rock units of the study area. These units are (from base to top) the Qantara Formation, Sidi Salim For- mation, Qawasim Formation, Rosetta Formation, Abu Madi Formation, Kafr El Sheikh Formation, Baltim Formation, Mit Ghamr Formation, and Bilqas Formation. The Qantara Formation is dated as Early Miocene ac- cording to the presence of Globigerinoides primordius. This age assignment is confi rmed by the presence of the Early Miocene forms such as Globoquadrina altispira altispira and Globorotalia obesa (KENNETT & SRINIVASAN, 1983). The Sidi Salim Formation is of Middle Miocene age due to the presence of Globigerinoides bollii, at the top of this formation, which could represent a useful datum in the Mediterranean, where the Globorotalia fohsi lineage is not developed (BOLLI & SAUNDERS, 1985). On the other hand, the absence of the three upper biozones of the Middle Mi- ocene (Globigerinoides ruber, Globorotalia mayeri and Glo- borotalia menardii biozones) indicates a hiatus between the Middle and Late Miocene. However, the presence of Prae- orbulina glomerosa curva and Praeorbulina glomerosa glo- merosa species supports an Early Middle Miocene age for this formation, which is directly overlain by the Upper Mi- ocene sediments. This indicates a hiatus between the Early Middle and Late Miocene. Accordingly, this formation is dated as being from the Early Middle to Late Miocene. The Qawasim Formation is dated to the Late Miocene according to its stratigraphic position between the underlying Sidi Salim Formation of Early Middle Miocene to Late Miocene age and the overlying Rosetta Formation of Late Miocene. 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