Seismic and sequence stratigraphy of Upper ...

Seismic and sequence stratigraphy of Upper Cretaceous–Tertiary succession, eastern Abu-Gharadig Basin, Western Desert, Egypt Mohamed Boukhary1, Samah El Nahas2 , Ahmed Abd El Naby1, Mohamed Hamed Abdel Aal3, Mohamed Mahsoub3, and Mahmoud Faris4 Faculty of Science, Ain Shams University, email: [email protected]; [email protected] Egyptian General Petroleum Company (EGPC), 8 Dr. Moustafa Abu Zahra Street, Nasr City, Cairo, Egypt, email: [email protected] Faculty of Education, Ain Shams University, email: [email protected]; [email protected] Faculty of Science, Tanta University, Tanta, Egypt email: [email protected]

ABSTRACT: This work deals with the sequence stratigraphy of the subsurface Upper Cretaceous and Cenozoic succession of the eastern Abu Gharadig Basin in the Western Desert of Egypt. The micropaleontological inspection of the cuttings from four wells: WD14/1, East Mubarak-1, East Mubarak-2, East Mubarak-3, revealed 23 foraminiferal biozones and six calcareous nannofossil zones and the presence of several hiatuses. The information obtained from biostratigraphic analysis, well data and seismic interpretation for the studied area has enabled the classification the Upper Cretaceous and Cenozoic succession into five major depositional sequences and these units were then correlated with those recorded in the north Western Desert and elsewhere Most of the major sequence boundaries and the unconformity surfaces inbetween compared well with those of Kharga Oasis, Farafra Oasis, the global cycle chart of Haq et al. (1988), the Western European sea-level curve of Hardenbol et al. (1998) and with the sequence boundaries, flooding surfaces and the sea-level curve of Haq and Al-Qahtani 2005, indicating that most of them are caused by global eustasy and some of the sequence boundaries are related to local tectonism. Three of the identified Upper Cretaceous-Cenozoic major sequences coincide with those of Haq and Al-Qahtani 2005 along the Arabian Platform, while two of them were formed due to local tectonic events.

Key words: Sequence stratigraphy, seismic interpretation, Upper Cretaceous, Cenozoic, Abu Gharadig Basin, Western Desert, Egypt.

INTRODUCTION

The Western Desert of Egypt covers an area of approximately 700,000 sq km, which represents two-thirds of the total area of Egypt (Mahsoub et al. 2012). The Abu Gharadig Basin is located in the central northern part of the Western Desert. The study area is located east of Abu Gharadig Basin in the north Western Desert of Egypt between latitudes 29°00’N and 30°12’N and longitudes 29°00’E and 29°54’E. The studied wells, from east to west, are S. Tiba-1A, East Mubarak-1, East Mubarak-2, East Mubarak-3, WD14/1, WD12/1, West Halif-1 and Rabat-E-1 (Text-fig. 1). The intent of the present work is to determine the sedimentary sequences and environments of deposition by using the seismic profiles and available well data to integrate both the sequence stratigraphy and biostratigraphy data of the Upper Cretaceous and Cenozoic interval. Abu Roash, Khoman and Apollonia formations source rocks are mature with respect to oil generation in the Abu Gharadig/Natrun/Gindi areas and may have generated commercial oil in those areas (EGPC 1992). GEOLOGIC SETTING OF THE STUDY AREA

Based on the subsurface data interpretation, lithostratigraphic units in the northern part of the Western Desert comprise most of the sedimentary section from Proterozoic basement rocks to recent deposits. The total thickness of sedimentary section measures about 14,000 feet (Younes 2003). Text-figure 2 summarizes the main stratigraphic units of the Western Desert.

In Egypt, the Upper Cretaceous marks a major marine transgression which resulted in the deposition of a dominantly carbonate section in the study area. The Upper Cretaceous succession is subdivided into three lithostratigraphic units, from base to top, Bahariya, Abu Roash, Khoman formations (Issawi et al. 1999). The sedimentary rocks of the Upper Cretaceous are present in three basins in the Western Desert; Abu Gharadig, Shushan, and Gindi, basins (Text-fig. 1), which include the most important hydrocarbon resources in the Western Desert. Bahariya Formation, Lower Cenomanian

The formation was described by Stromer (1914) and named by Said (1962) after the Bahariya Oasis , where the type locality is situated in Gabel El Dist. In the type section the base of the formation is not exposed and it consists of argillaceous sandstone with minor beds of carbonates deposited in a fluviomarine setting. It is overlain by the Abu Roash Formation. The maximum thickness occurs in the Kattaniya-1 Well (1,143 m). Darwish et al. (1994) subdivided the Bahariya Formation into two members. The lower Bahariya Member is a single sandstone/ siltstone lithofacies, reflecting fluvio-marine conditions. The upper Bahariya Member is made up of three lithofacies units: A basal shale–carbonate lithofacies deposited under shoals to subtidal flat conditions.

Stratigraphy, vol. 11, no. 2, pp. 109–141, text-figures 1–21, tables 1–3, plates 1–6, 2014

109

Mohamed Boukhary et al.: Seismic and sequence stratigraphy of Upper Cretaceous–Tertiary succession, eastern Abu-Gharadig Basin

TEXT-FIGURE 1 A- Dimensional index map showing the spatial distribution of the main east-west sedimentary basins and major tectonic features in the north Western Desert, Egypt (modified after Bayoumi 1996; El Diasty and Moldowan, 2012). B- The study area (rectangle, including location of the wells) lies east of Abu Gharadig basin in the north Western Desert of Egypt.

TEXT-FIGURE 2 Generalized lithostratigraphic column of the Abu Gharadig Basin (modified after Qarun Petroleum Company, Mahsoub et al. 2012).

Khoman Formation

A median sandstone–siltstone deposited under nearshore to outer shoreface conditions. An upper mixed shale–siltstone to carbonate lithofacies reflecting shallow-marine conditions. Abu Roash Formation

The type locality of Abu Roash Formation is north of the Pyramids of Giza. This unit is subdivided into seven lithostratigraphic members, termed from top to base as A, B, C, D, E, F and G, which extend from Upper Cenomanian to Santonian time. Most of the sediments were deposited under marine neritic to open basinal conditions that prevailed in the northern Western Desert. This unit represents the alternation of transgressive and regressive phases, which are characterized by: Shallow to deeper marine carbonates on highs. The limestones were dolomitized and have both inter-crystalline and fracture porosity. Shallow deposits, consisting of alternating shale and sandstone. During the Turonian time, an evaporitic sequence was deposited in some areas. 110

The type section of this unit is located at Ain Khoman (Le Roy 1953), southwest of the Bahariya Oasis. Sediments of this unit were deposited in an open marine facies that prevailed in the north Western Desert during the Campanian–Maastrichtian ages. This unit unconformably overlies Abu-Roash Formation, particularly in the structurally high areas. Lithologically, this formation consists of members, the lower unit is mostly limestone interbedded with shale, while the upper unit consists of chalky limestone with chert bands. Cenozoic rocks

Cenozoic rocks consist of the following formations, from base to top, as follows: Apollonia Formation: Paleocene to Eocene (Hanter 1990): The formation consists of limestone with subordinate shale. The type locality is located south of Sussa village in Libya, where it is 250m thick and made up of massive siliceous limestones with numerous chert bands. The formation has been informally subdivided by several authors into lithostratigraphic units, from top to base: A to D, among them units B and D are thinner and dominated by shale.

Stratigraphy, vol. 11, no. 2, 2014

TEXT-FIGURE 3 Correlation of the biostratigraphic zonal schemes for the Upper Cretaceous–Tertiary as used in the present study in Well East Mubarak-1.

The Dabaa Formation: Norton (1967)

The type section is the interval 579 to 1021m of the Dabaa-1 well. It consists of gray and greenish gray clay and claystone with subordinate thin beds of limestone with glauconite and pyrite, of Upper Eocene to Oligocene age. Moghra Formation: Said (1962)

The type section is the classic surface section of Moghra at the extreme eastern point of the Qattara Depression, where it attains a 230m section Said (1962). It is a clastic fluvio-marine deltafront facies of Early Miocene age. Marmarica Formation: Said (1962)

The type locality of the Marmarica Formation is located at the northern escarpment of the Siwa Oasis. The Formation attains 78m in thickness (Said 1962a, b). It consists of limestone and marl with some sandy limestone intercalated with shale of shallow neritic environment belonging to the Middle Miocene. Quaternary deposits unconformably overlie the Miocene rocks and consist of Plio-Pleistocene continental sands. STRUCTURAL SETTING

Western Desert lies within the mobile belt of the tectonic framework of the Egyptian Territory (Said 1962). The preMiocene rocks were the most markedly affected by folding and faulting. However, the tectonic instability of the mobile belt, continued during the Miocene and post Miocene times. Shata (1955) mentioned that the regional structural setting of the Northern Western Desert is characterized by a series of

alternating positive and negative subsurface structures, trending NE-SW (Syrian arc system) with a minor NNE-SSW trends. Abu El-Ata and Abd El-Nabi (1985) denoted that Cretaceous sequence of the Abu Gharadig basin is dissected by mostly NWSE and WNW-ESE faults. They also suggested the presence of four major E-W trending faults, two of which to the north and the other two to the south. Interpretation of gravity data shows that the Western Desert, which encloses the Abu-Gharadig Basin, is essentially part of a Jurassic–Cenomanian divergent (“passive”) continental margin (El Emam et al.) which evolved as such in relation to the opening and development of the Tethys Sea (Textfig. 21). This restricted extensional basin may be superimposed on a failed suture that was reactivated as the Pangea supercontinent began to split into Gondwana and Laurasia. The extensional nature of the Abu Gharadig Basin is evidenced by the thinning of its underlying crust (El Emam et al.), and it is even used as an example of such restricted and highly subsiding basin which may be related to processes of rifting that commenced in the Jurassic (Ibrahim 1990; Ibrahim and Aly 1994). Sultan and Halim (1988) denoted that the most predominant structural trends in the North Western Desert of Egypt are: The NE to ENE folding trend is associated with reverse faulting and initiated during the Late Cretaceous period (Syrian arc system). The NW to WNW extensional faults, which seem to be relatively abundant in the northern Western Desert. Most of these faults initiated during Late Cretaceous to Early Tertiary times. The E-W trending strike-slip faults.

111



MATERIALS AND METHODS

The aim of the present work is to carry out a detailed paleontologic and sequence-stratigraphic study of a restricted part of the Abu Gharadig Basin by using conventional subsurface stratigraphic methods and interpretation of geophysical measurements. Thirty-seven seismic lines, supported by the composite, velocity and the vertical seismic profile (VSP) logs of five selected wells (WD14/1, East Mubarak-1, East Mubarak-2, East Mubarak-3, ST1A), were used. Cuttings from four wells (WD14/1, East Mubarak-1, East Mubarak-2 and East Mubarak-3) were selected for biostratigraphic studies that include several species of foraminifera. BIOSTRATIGRAPHY

This part deals with the biostratigraphy of the Upper Cretaceous– Tertiary sequence in Abu Gharadig Basin. Three distinct zonal schemes have been considered for biostratigraphic studies: A zonal scheme based mainly on Nummulites for Paleogene sequences, following Blondeau 1972, Schaub 1981 and SerraKiel et al. (1998). A zonal scheme based on planktonic foraminifera, following Caron 1985 for the Cretaceous planktonic foraminifera and 112

biozones of Toumarkine and Lüterbacher 1985 for the Paleocene and Eocene planktonic foraminifera in Bolli et al. 1985. These biozones are compared to those of Berggren and Pearson 2005; Berggren and Pearson 2006. A zonal scheme based on ostracoda, following Bassiouni 1969. The illustrated foraminifera used in the present biozonation are illustrated in Plates (1–5). Biozones Based on Larger Foraminifera

The biozones of larger foraminifera match well with those of Schaub (1981) and Serra-Kiel et al. (1998) from Early to Middle Eocene sequences. The biozones of larger foraminifera, which were defined from the presently studied boreholes, are shown in Table (1). These biozones are briefly discussed, from base to top, as follows: Nummulites ornatus Zone = SBZ 9 (Late Ilerdian)

This interval is characterized by the presence of Nummulites ornatus. This zone is recorded from well East Mubarak-2 (Textfig. 4) while it is missing in wells East Mubarak-1, East Mubarak-3 and WD 14/1 (Table 1). The thickness of this biozone is 63m in well East Mubarak-2. This biozone spans the base of the Apollonia Formation in well East Mubarak-2 and it is conformably overlain by zone SBZ 10.



Nummulites luterbacheri / N. distans / N. bakhchisaraiensis Zone = SBZ 10 (Lower Cuisian)

and East Mubarak-3 (Table 1). The SBZ 15, which is equated with the Middle Lutetian 2 of Schaub 1981 is missing.

The foraminiferal assemblages of this biozone include Nummulites distans, N. praediscorbinus, Nummulites syrticus, Nummulites luterbacheri and Nummulites praelucasi. It is worth mentioning that N. luterbacheri was found by Boukhary et al. (1995) associated with N. fraasi, the supposed primitive Nummulites species. This biozone is documented in wells East Mubarak-2 (Text-fig. 4) and WD 14/1(Text-fig. 6) while it is missing in well East Mubarak-1 (Text-fig. 3) and East Mubarak-3 (Text-fig. 5). The thickness of this zone ranges from 100m in well WD 14/1 to 257m in well East Mubarak-2. This biozone spans the base of the Apollonia Formation and it is unconformably overlain by the zone SBZ 14 in wells East Mubarak-2 and the zone SBZ 16 in well WD 14/1 (table 1). This biozone is conformably underlain by zone SBZ 9 in well East Mubarak-2. The SBZ 11, SBZ 12 and SBZ 13 zones, which are equated with the MiddleLate Cuisian–Early Lutetian of Schaub 1981 are missing.

Nummulites discorbinus / N. cf. gizehensis / N. bullatus Zone = SBZ 16 (Late Lutetian)

Nummulites beneharnensis Zone = SBZ 14 (Middle Lutetian 1)

The foraminiferal assemblages of this biozone include Nummulites beneharnensis, Nummulites discorbinus, Nummulites cf. gizehensis and Nummulites cf. boussaci. This zone is documented in wells East Mubarak-2 (Text-fig. 4) and East Mubarak-3 (Textfig. 5) while it is missing in wells East Mubarak-1 (Text-fig. 3) and WD 14/1(Text-fig. 6). The thickness of this zone ranges from 286m in well East Mubarak-2 to 338m in well East Mubarak-3. This biozone spans the upper part of the Apollonia Formation in wells East Mubarak-2 and East Mubarak-3. It is unconformably overlain by SBZ 17–18 in well and East Mubarak-2 and by SBZ 16 in well East Mubarak-3 (Table 1). This biozone is unconformably underlain by SBZ 10 in wells East Mubarak-2

The foraminiferal assemblages of this biozone include Nummulites bayhariensis, Nummulites cf. lehneri, Nummulites bullatus, Nummulites cf. cyrenaicus, Nummulites pachoi, Nummulites aff. pulchellus and Nummulites cf. gizehensis. This biozone is documented in wells East Mubarak-3 (Text-fig. 5) and WD 14/1 (Text-fig. 6) while it is missing in wells East Mubarak-1 (Text-fig. 3) and East Mubarak-2 (Text-fig. 4). The thickness of this biozone ranges from 250m in well East Mubarak-3 to 220m in well WD 14/1. This biozone spans the upper part of the Apollonia Formation in wells East Mubarak-3 and WD 14/1 and it is unconformably overlain by SBZ 19 in wells WD 14/1 and by SBZ 17 in well East Mubarak-3 (Table 1). This biozone is unconformably underlain by SBZ 10 in well WD 14/1 and by SBZ 14 in well East Mubarak-3 (Table 1). Reticulina heluanensis Zone = SBZ 17 / 18 (Ostracod zone, Bartonian)

The foraminiferal assemblages of this biozone include Nummulites rutimeyeri, Nummulites cf. gizehensis, Nummulites aff. cyrenaicus and Nummulites cf. boulangeri. The presence of an assemblage of ostracods such as: Reticulina heluanensis, Novocypris eocenana and Paracypris s.p. indicate a Bartonian age, see Bassiouni 1969. This biozone is recorded only in well East Mubarak-1 (Text-fig. 3). The thickness of this biozone is 50m. The biozone spans the upper part of the Apollonia Formation in well East Mubarak-1 and it is unconformably overlain by SBZ 19. 113


TEXT-FIGURE 6 Correlation of the biostratigraphic zonal schemes for the Upper Cretaceous–Tertiary as used in the present study in Well W.D 14/1.

Gaziryina pulchellus / N. retiatus Zone / N. chavannesi = SBZ 19 / 20 (Priabonian)

The foraminiferal assemblages of this biozone include Nummulites retiatus, Nummulites chavannesi, Gaziryina pulchellus, Nummulites rutimeyeri, Nummulites cunialensis, Nummulites incrassatus ramondiformis, Nummulites cf. boulangeri, Baggina cojimarensis, Cancris mauryae, Bulimina sculpitils, Astrocyclina stellata, and Discocyclina pratti. This zone is recorded in the four wells (Text-fig.s. 3–6) and it is marked in wells East Mubarak-2 and East Mubarak-3 by the presence of Asymmetricythere hiltermanni. The thickness of this zone ranges from 60m in well WD 14/to 114m in well East Mubarak-2. This biozone spans the uppermost part of the Apollonia Formation in wells East Mubarak-1 and WD 14/1 and the lower part of Dabaa Formation in wells East Mubarak-2 and East Mubarak-3. It is conformably overlain by Cyclammina cancellata Zone in wells D 14/1, East Mubarak-2 and East Mubarak-3 while it is unconformably overlain by Pliocene deposits in well East Mubarak-1. This biozone is unconformably underlain by SBZ 14 in wells East Mubarak-2, by SBZ 16 in WD 14/1 and East Mubarak-3 and by SZB 18 in East Mubarak-1. Cyclammina Zone (Oligocene)

The foraminiferal assemblages of this biozone include Cyclammina sp., Uvigerina ssp., and arenaceous assemblage. This zone is recorded from wells East Mubarak-2 (Text-fig. 4), East Mubarak-3 (Text-fig. 5) and WD 14/1 (Text-fig. 6) while it is missing in well East Mubarak-1. The thickness of this zone ranges from 57m in well East Mubarak-2 to 40m in well WD 14/1. This biozone spans 114

the uppermost part of Dabaa Formation in wells East Mubarak-2, East Mubarak-3 and well WD 14/1 and it is unconformably overlain by the Operculina complanata Biozone in wells East Mubarak-2, East Mubarak-3 and well WD 14/1. It is unconformably underlain by SBZ 18 in well East Mubarak-2 and by SBZ 20 in wells East Mubarak-3 and well WD 14/1. Operculina complanata Zone (Early Miocene)

This biozone is based on the presence of Operculina complanata and it is recorded from wells East Mubarak-2 (Text-fig. 4) and in well WD 14/1 (Text-fig. 6) while it is missing in wells East Mubarak-1 (Text-fig. 3) and East Mubarak-3 (Text-fig. 5). The thickness of this zone ranges from 18m in well WD 14/1 to 20m in well East Mubarak-2. This biozone spans the base of the Moghra Formation in wells East Mubarak-2and WD 14/1. This is conformably underlain by Cyclammina cancellata biozone in wells East Mubarak-2 and well WD 14/1. Planktonic Foraminiferal Biozones:

The biozones of planktonic foraminifera determined in this work corresponds to the biozones of Caron 1985 for the Cretaceous planktonic foraminifera and biozones of Toumarkine and Lüterbacher 1985 for the Paleocene and Eocene planktonic foraminifera in Bolli et al. 1985. The biozones of planktonic foraminifera recognized in the studied boreholes are represented in Table 2. These biozones are briefly discussed from base to top as follows:


TEXT-FIGURE 7 Location map of the study area: exploration wells, seismic lines with shot points, trace of the correlation scheme (in text-figure 7).

Heterohelix globulosa Zone

Author: Caron (1978)

Heterohelix globulosa Ehrenberg 1840

Definition: Interval from first occurrence of Dicarinella primitive to first occurrence of Dicarinella concavata.

Age: Turonian This zone is recorded from the four studied wells (Text-fig. 17). The thickness of this zone is 165m in well W.D 14/1. This biozone spans Abu Roash F and the lower part of Abu Roash E (Text-fig. 17) and it is overlain by Ammomarginulina assemblage zone in wells W.D 14/1, East Mubarak-1 and East Mubarak-2, while it is unconformably overlain by Discorbis turonicus Zone in well East Mubarak-3. The appearance of Heterohelix globulosa delineates the boundary between Cenomanian and Turonian (Ismail and Soliman 1997). Globotruncana concavata Zone (= Dicarinella concavata Zone) Category: Interval zone Age: Late Coniacian to Early Santonian

Remarks: This zone is recorded from wells WD 14/1 and East Mubarak-3 (Text-fig. 17) while it is missing in wells East Mubarak-1 and East Mubarak-2. The thickness of this biozone ranges from 691m in well W.D 14/1 to 571m in well East Mubarak-3 and it spans the lower part of the Khoman Formation (Text-fig. 17). The Globotruncana elevata Zone in well East Mubarak-3 and the Contusotruncana contusa / Racemguemblina fructicosa Zone in well W.D 14/1 unconformably overlie this zone (Text-fig. 17). Globotruncana elevata Zone Category: Partial range zone Age: Early Campanian Author: Postuma (1971)

115


TEXT-FIGURE 8 Interpreted sequences in seismic profile WGS-84-117 (in NE-SW direction, for location see text-figure 7). This figure shows the eastward erosion of ERS depositional sequence especially, where the well South Tiba-1 is present at uplifted fault block.

TEXT-FIGURE 9 Interpreted sequences in seismic profile WMT (in E-W direction, for location see text-figure 7).

TEXT-FIGURE 10 Interpreted sequences in seismic profile PR18 (in NE-SW direction, for location see text-figure 7).

116


TEXT-FIGURE 11 Interpreted sequences in seismic profile WQ85-51b (in SE-NW direction, for location see text-figure 7).

TEXT-FIGURE 12 Interpreted sequences in seismic profile WQ-86-61C (in SENW direction, for location see text-figure 7). Black arrows show toplap at SB4 of Upper Cretaceous sequence (UCS3), which is represented by Khoman Formation.

TEXT-FIGURE 13 Interpreted sequences in seismic profile WFK (in NE-SW direction, for location see text-figure 7) showing decrease of the thickness of UCS3 at the central part of the study area.

117


TEXT-FIGURE 14 Interpreted sequences in seismic profile WFP (in NW-SE direction, for location see text-figure 7).

TEXT-FIGURE 15 Interpreted sequences in seismic profile SJ82-8 (in N-S direction, for location see text-figure 7) showing westward decrease of the thickness of UCS3.

Definition: Interval, with Globotruncanita elevata, from last occurrence of Dicarinella asymetrica to first occurrence of Globotruncana ventricosa.

and it spans the lower part of the Khoman Formation (Textfig. 17). The Globotruncana aegyptiaca Zone unconformably overlies this zone (Text-fig. 17).

Remarks: This zone is recorded from wells East Mubarak-1, East Mubarak-2 and East Mubarak-3 (Text-fig. 17) while it is missing in well W.D 14/1. The thickness of this biozone ranges from 705m in well East Mubarak-1 to 400m in well East Mubarak-2

Globotruncana aegyptiaca Biozone

118

Category: Interval zone


TEXT-FIGURE 16 Interpreted sequences in seismic profile SJ84-5 (in ESE–WNW direction, for location see text-figure 7).

Age: Early Maastrichtian Author: Caron 1985 Definition: Interval from first occurrence of Globotruncana aegyptiaca to first occurrence of Gansserina gansseri. Remarks: The foraminiferal assemblages of this biozone in the study area include Globotruncana aegyptiaca, Contusotruncana fornicata, Globotruncana arca, Heterohelix globulosa and Bolivinoides draco miliaris. This zone is found in wells East Mubarak-1, East Mubarak-2 and East Mubarak-3 while it is missing in well WD 14/1 (Text-fig. 17). The thickness of this zone ranges from 82m in well East Mubarak-2 to 33m in well East Mubarak-1and it spans the upper part of the Khoman Formation. It is conformably overlain by the Gansserina gansseri Zone. Gansserina gansseri Zone Category: Interval zone Age: Late Maastrichtian Author: Brönnimann 1952 Definition: Interval from first occurrence of Gansserina gansseri to first occurrence of Abathomphalus mayaroensis. Remarks: The foraminiferal assemblages found in this biozone include Gansserina gansseri, Pseudoguemblina excolata, Globotruncana arca, Pseudotextularia elgans, Contusotruncana contusa, Ventilabrella eggeri and Racemiguembelina fructicosa. This zone is recorded in wells East Mubarak-1, East Mubarak-2 and East Mubarak-3, while it is missing in well WD 14/1 (Text-

fig. 17). The thickness of this biozone ranges from 273m in well East Mubarak-2 to 125m in well East Mubarak-3. This biozone is unconformably overlained by P1(c.) (Morozovella trinidadensis) Zone (Text-fig. 17). Contusotruncana contusa/Racemiguembelina Zone (= Abathomphalus mayaroensis Zone).

fructicosa

Category: Total range zone Age: Uppermost part of Late Maastrichtian Author: Brönnimann (1952) Definition: Interval of total range of Abathomphalus mayaroensis. Remarks: The foraminiferal assemblages of this biozone include Contusotruncana contusa, Racemiguembelina fructicosa,Globotruncana ssp., Heterohelix sp. and Pseudogumbelina costulata. This zone is found in well WD 14/1 (Text-fig. 6) while it is missing in wells East Mubarak-1, East Mubarak-2 and East Mubarak-3 and (Table 2). The thickness of this zone is 120m and it spans the top of the Khoman Formation in well WD 14/1 (Text-fig.s 6, 7). This zone is characterized by the presence of Contusotruncana contusa and Racemiguembelina fructicosa of Late Maastrichtian age. P1 Morozovella trinidadensis Zone Category: Interval zone Age: Early Paleocene

119


TEXT-FIGURE 17 Biostratigraphic and lithostratigraphic correlation of the four studied wells W.D 14/1, East Mubarak-1, East Mubarak-3 and East Mubarak-2 in E-W direction.

Author: Bolli 1957a

Age: Early Eocene

Definition: Interval from first occurrence of Morozovella trinidadensis to first occurrence of Morozovella uncinata.

Author: The name Globorotalia subbotinae Zone has been used by Soviet authors (e.g. Anonymous 1963); the definition given here follows Luterbacher and Premoli Silva (in Caron et al. 1975).

Remarks: This zone is equivalent to Globanomalina compressa / Praemurica inconstans (P1c) Subzone (early Paleocene (mid-late Danian) of Berggren et al. 1995; Berggren and Pearson 2005). The foraminiferal assemblages of this biozone are Morozovella trinidadensis, Globoconusa daubjergensis, Cibicidoides succedens, Morozovella pseudobulloides and Planorotalites planoconica. This zone is recorded from wells East Mubarak-2 (Text-fig. 4) and East Mubarak-3 (Text-fig. 5) while it is missing in wells East Mubarak-1 and WD 14/1 (Table 2). The thickness of this zone ranges from 100m in well East Mubarak-2 to 13 in well East Mubarak-3. This biozone spans the base of the Apollonia Formation. It is unconformably overlain by P6 (Morozovella subbotinae) biozone and unconformably underlain by the Gansserina gansseri biozone (Text-fig. 17). P6 Morozovella subbotinae Zone Category: Interval zone 120

Definition: Interval from last occurrence of Morozovella edgari to first occurrence of Morozovella aragonensis. Remarks: This zone is equivalent to Morozovella formosa (E4) Zone (Early Eocene (early Ypresian) of Berggren and Pearson 2005; Berggren and Pearson 2006. The foraminiferal assemblages of this biozone are Morozovella subbotinae and Morozovella formosa gracilis. This zone is recorded from well East Mubarak-3 while it is missing in wells East Mubarak-1, East Mubarak-2 and WD 14/1 (Table 2). The thickness of this zone is 100m in well East Mubarak-3. This biozone spans the base of the Apollonia Formation in well East Mubarak-3. It is unconformably overlain by zone P9 Acarinina pentacamerata and underlain by P1 Morozovella trinidadensis Biozone.


TEXT-FIGURE 18 Interpreted sequences in seismic profile WGS-84-117 (in NESW direction, for location see Figure 7) illustrates the tie with well South Tiba-1 to detect the major depositional sequence boundaries correlated with the Arabian Plate Cycle Chart (modified after Haq and Al-Qahtani 2005).

TEXT-FIGURE 19 Interpreted sequences in seismic profile WFK (in NE-SW direction, for location see text-figure 7) reveals the tie with well W.D 12/1 to detect the major depositional sequence boundaries correlated with the Arabian Plate Cycle Chart (modified after Haq and Al-Qahtani 2005).

P9 Acarinina pentacamerata Zone Category: Interval zone Age: Early Eocene Author: Krasheninnikov (1965) Definition: Interval from first occurrence of Turborotalia cerroazulensis frontosa to first occurrence of representatives of the genus Hantkenina. Remarks: This zone is equivalent to Acarinina pentacamerata (E6) Zone (late Early Eocene (late Ypresian) of Berggren and

Pearson 2005; Berggren and Pearson 2006. The foraminiferal assemblages of this biozone are Morozovella sp. cf. caucasica, Acarinina pentacamerata and Truncorotaloides collactea. This zone is recorded from well East Mubarak-3 (Text-fig. 3) while it is missing in wells East Mubarak-1, East Mubarak-2 and WD 14/1 (Table 2). The thickness of this zone is 275m. This biozone spans the lower part of the Apollonia Formation and it is unconformably overlain by zone SBZ 14 and underlain by P6 Morozovella subbotinae Zone. The top of this zone corresponds to the boundary between the Early and the Middle Eocene and it corresponds to the first occurrence of representatives of the genus Hantkenina of typical Middle Eocene as adopted by the majority of authors (Bolli et al. 1985).

121


TEXT-FIGURE 20 Interpreted sequences in seismic profile SJ82-8 (in N-S direction, for location see text-figure 7) shows the tie with well Rabat East-1 and a synthetic seismogram to detect the major depositional sequence boundaries correlated with the Arabian Plate Cycle Chart (modified after Haq and Al-Qahtani 2005).

Benthic Foraminiferal Biozones:

The biozones of benthic foraminifera determined in this work corresponds to the biozones of well East Mubarak-1 (the General Petroleum Company 1973), well East Mubarak-2 (the General Petroleum Company 1974), well East Mubarak-3 (the General Petroleum Company 1975) and well W.D 14/1 (the General Petroleum Company 1976). These biozones are briefly discussed from base to top as follows: Thomasinella fragmentaria Zone Thomasinella fragmentaria Omara 1956 Age: Early-Late Cenomanian This zone is recorded from wells W.D 14/1 and East Mubarak-1 (Text-fig. 17) while it is undifferentiated from the overlying Thomasinella punica Zone in wells East Mubarak-3 and East Mubarak-2. The thickness of this zone is 183m in well East Mubarak-1. This biozone spans the Bahariya Formation and the lower part of Abu Roash G (Text-fig. 17) and it is overlain by Thomasinella punica Zone. Thomasinella fragmentaria was recorded by Ismail and Akarish 2000 from Late Cenomanian Galala Formation of the northern Eastern Desert of Egypt. Thomasinella punica Zone Thomasinella punica Schlumberger 1893 Age: Late Cenomanian This zone is recorded from wells W.D 14/1 and East Mubarak1(Text-fig. 17) while it is undifferentiated from the underlying Thomasinella fragmentaria Zone in wells East Mubarak-3 and 122

East Mubarak-2. The thickness of this zone is 133m in well W.D 14/1. This biozone spans the upper part of Abu Roash G (Text-fig. 17) and it is overlain by Heterohelix globulosa Zone. Thomasinella punica was recorded by Ismail and Soliman 1997 from the Cenomanian Bahariya Formation of north Western Desert of Egypt and by Ismail and Akarish 2000 from Late Cenomanian Galala Formation of the northern Eastern Desert of Egypt. Ammomarginulina assemblage Zone

Age: Turonian This zone is recorded from wells W.D 14/1, East Mubarak-1 and East Mubarak-2 (Text-fig. 17) while it is missing in well East Mubarak-3. The thickness of this zone is 473m in well East Mubarak-3. This biozone spans the upper part of Abu Roash E, Abu Roash D and the lower part of Abu Roash A in Well W.D 14/1 while it spans small part of Abu Roash E in well East Mubarak-1 and it ranges from the upper part of Abu Roash E to Abu Roash B in well East Mubarak-2 (Text-fig. 17). It is overlain by Discorbis turonicus Zone. Discorbis turonicus Zone Discorbis turonicus Said and Kenawy 1957 Age: Turonian This zone is recorded from the four studied wells (Text-fig. 17). The thickness of this zone is 667m in well East Mubarak-1. This biozone spans the upper part of Abu Roash A in Well W.D 14/1 while it spans the upper part of Abu Roash E, Abu Roash D and Abu Roash A in well East Mubarak-1 and it ranges from


TEXT-FIGURE 21 Index map of the area investigated with major global geological features (from Geochronique 2001, v. 79, simplified).

the upper part of Abu Roash E to Abu Roash A in well East Mubarak-3 (Text-fig. 17). It represents Abu Roash A in well East Mubarak-2 (Text-fig. 17). This zone is overlain by Globotruncana concavata Zone in wells W.D 14/1 and East Mubarak-3, while it is unconformably overlain by Globotruncana elevata Zone in wells East Mubarak-1 and East Mubarak-3. Discorbis turonicus was recorded by Ismail and Soliman 1997 from the Turonian Abu Roash Formation of north Western Desert of Egypt and by Ismail and Akarish 2000 from Early-Late Turonian Maghara el Hadida Formation of the northern Eastern Desert of Egypt. It was also recorded by Ismail 2000 from Late Turonian Wata Formation of the western part of the Gulf of Aqaba, east Sinai, Egypt. DETAILED SEQUENCE STRATIGRAPHIC ANALYSIS

The studied Cenomanian–Recent succession in the East AbuGharadig Basin of the Western Desert is subdivided into five second-order depositional sequences: Upper Cretaceous sequence (UCS1), (UCS2), (UCS3), Paleocene Eocene sequence (PES) and Upper Eocene to Recent sequence (ERS) based on the interpretation of 37 seismic sections (laid out in NS, EW, NW-SE and NE-SW directions, Text-fig. 7), four composite logs and the foraminiferal content (Text-fig. 17). The identified depositional sequences are bounded with five sequence boundaries marked from base to top as: SB1, SB2, SB3, SB4 and SB5 (Text-figs. 8–16). These sequences are of Type 2 sequence boundaries (Van Wagoner et al. 1988; Emery

and Myers 1996) that may pass laterally into a Type 1 sequence boundary depending on the tectonic subsidence pattern in the basin. However, if the rate of relative sea level fall is slow, there is a gradual but widespread denudation without substantial river incision, giving Type 2 unconformities. The different seismic surveys in the study area are shown in Table 3. Three of the identified sequence boundaries (SB3, SB4 and SB5) coincide with those of Haq and AlQahtani 2005 (Text-figs. 18-20). Also, UCS3, PES and ERS major depositional sequences are correlated well with AP9, AP10 and AP11 tectonostratigraphic megasequences of Haq and Al-Qahtani 2005 (Text-figs. 18-20) along the Arabian Gulf. Upper Cretaceous Sequence 1 (UCS1), Lower Cenomanian

The first sequence (UCS1) is represented by the Upper Cretaceous rocks is the oldest depositional sequence in the examined successions which includes the Bahariya Formation (Text-figs. 8–16). UCS1 is bounded by SB1 at the base and SB2 at the top. SB2 represents the boundary between the Abu Roash-G Member and the underlying Bahariya Formation. The UCS1 constitutes the lower part of AP8 tectonostratigraphic megasequence of Haq and Al-Qahtani 2005 (Text-figs. 18-20), indicating local tectonism. Locally the top of this sequence extends along the study area, indicating a regional unconformity between the Abu Roash Formation and the underlying Bahariya Formation of the second123


TABLE 1 Larger foraminifera shallow benthic zones (SBZ) in the studied wells from West to East.

order depositional sequence boundary (El Bassyouny 1970; Catuneanu et al. 2006). UCS1 displays discontinuous, moderate to low amplitude reflectors. Internal configurations including onlap, toplap, downlap and parallel reflectors were recognized. The external form of this sedimentary body appears either as sheet-like or wedge-shaped units. The principal internal configurations appear to be parallel to subparallel. Interpretations

Clear differences between the moderate to low amplitude reflectors in this unit testify to the existence of at least two different lithologies. Shale to siltstone beds which have high amplitude and display parallel to divergent reflector terminations. The other lithological composition are the sandstone beds, which have a low to moderate amplitude and are characterized by discontinuous reflectors. According to Darwish et al. (1994) and Ismail et al. (1989), the Bahariya Formation was deposited in a shallow marine to fluvio-marine environment with alternating high and low energy.

124

Upper Cretaceous Sequence 2 (UCS2), Late Cenomanian–Turonian

Abu Roash-G Member (Late Cenomanian) Based on the interpretation of seismic lines, the Abu Roash-G Member can be subdivided into two main parts. The lower part is characterized by low to moderate amplitude and moderate continuity reflectors. The seismic facies of this part is marked by parallel reflectors, which seems to represent elongated wedge-shaped beds. High amplitude and continuous reflectors characterize the seismic facies of the upper part of the Abu Roash-G Member. Generally, the internal reflection geometry at the upper sequence boundary is considered as concordant and runs parallel to the sequence boundary. Interpretations

The characteristic configuration of the seismic facies in the lower part of the Abu Roash-G Member is interpreted as sand bars. The low amplitude and discontinuity of the seismic reflectors support this interpretation. These sand beds may represent deposits of a prograding delta system, with offshore (pro-delta)

Stratigraphy, vol. 11, no. 2, 2014 TABLE 2 Plankton biozones in the studied well from West to East.

125


TABLE 3 Different Seismic surveys conducted in the study area.

silty mudstones at the base overlain by (in ascending order) lower, middle and upper shoreface sandstone, distributarymouth bar sandstone (see also Mahsoub et al. 2012). The internal configuration of parallel reflectors in the upper part is interpreted as homogenous sediments, which are arranged in parallel thin beds. These features exhibit cycles of mudstone, glauconitic siltstone, limestone, and sandstone deposits. The depositional environment of Abu Roash-G Member is considered to be delta to shallow-marine environment (Mark et al. 2009). Abu Roash A, B, C, D, E and F Members (Turonian)

The Abu Roash Formation is generally characterized by several strong correlated internal reflectors representing the contacts between its members. The parallel reflectors alternate with weak to moderate internal reflectors, which show chaotic to hummocky internal configurations (Text-fig. 10). The external forms of these members (A, B, C, D, E and F) display different geometries such as sheet-like and wedge-shaped forms, which can be indicated by parallel to divergent internal reflection configuration. Interpretations

According to Barakat et al. (1987), these facies features exhibit cycles of shallow marine limestone, sandy limestone and shale of the Abu Roash A, shallow marine of the Abu Roash B Member, relatively restricted deep marine shale, sandstone and limestone of the Abu Roash C Member, the limestone and shale of Abu Roash D, shallow marine sand and shale of the Abu Roash E Member, and the deep marine limestone and shale of the Abu Roash F Member (Text-fig. 17). The alternation between weak –moderate and high amplitude internal reflectors suggests at least two different lithological units. The marked parallel reflectors are interpreted as shale beds. The low amplitude reflectors have a chaotic to hummocky internal configurations, which indicate impure limestone or highly bioturbated sandstone beds. The Abu Roash Formation of Turonian age consists of limestone with shales and sandstone intercalations providing a good source, reservoir and cap rocks for hydrocarbons (Bayoumi et al. 1987). According to Barakat et al. (1987) the habitats of the faunal assemblage together with the occurrence of detrital quartz grains in the Abu Roash F-A 126

Members suggest a shallow marine environment of the neritic zone. Furthermore, the Abu Roash Formation was deposited in shallow-shelf to open-marine conditions (Barakat et al. 1987; Bayoumi 1994, 1996). The UCS2 also constitutes the uppermost part of AP8 tectonostratigraphic megasequence of Haq and Al-Qahtani 2005 (Text-figs. 18-20), indicating local tectonism. Upper Cretaceous Sequence (UCS3), Late Coniacian– Maastrichtian

The Upper Cretaceous sequence comprises the sediments of the seismic facies which is represented by the Khoman Formation (Text-figs. 8–15). It displays an overall transgressive trend according to the presence of planktonic foraminifera along the studied wells (Text-figs. 3, 5, 6); this sequence is composed entirely of chalky limestone, cherty in parts. It is clearly traced on the seismic reflection profiles based on well data. This sequence displays variable thicknesses ranging from 246m to 1,178m with increase in thickness towards the east (Text-figs. 8–12) and decrease in thickness towards the center and west (Text-figs. 13–16). The tectonic framework of the area and the irregularities of the SB3 play a major role in this variation. The UCS3 is bounded by SB3 below and the SB4 above (Text-figs. 8–16). Detailed analysis of SB3 reveals that it is of Type 2 of Van Wagoner et al. (1988). In the central and northern parts, it displays concordant relation with the internal reflectors of the overlying and underlying sequences, indicating only a basinward shift of shorline. The shelf offlap break was never exposed, indicating a Type 2 boundary extends in the study area. This boundary changes to Type 1 in the southern part (Text-fig. 12). SB3 is at the end of Turonian and it is characterized by partial erosion of the Coniacian and Santonian between the Khoman and the top of the Abu Roash Formation, as shown by truncation of the top Abu Roash and the base Khoman (Text-fig. 17) especially in structurally uplifted places (Bayoumi and Lotfy 1989). It is an important disconformity recorded in all the Cretaceous-Tertiary successions of Egypt (Hewaidy et al. 2006; Mahsoub et al. 2012). SB3 can be traced on the examined seismic reflections between TWT 0.7 sec and 1.85 sec (Text-figs. 8–16). This surface generally dips to the southwest with a wide range of irregularities due to a series of NW-SE trending faults (Mahsoub et


al. 2012). UCS3 depositional sequence is toplapped at SB4 (Text-fig. 12) at the southward direction in the area of study with some beds onlapping upward so it is may be a Type 1 sequence boundary. This sequence is equivalent to the Maastrichtian DKSQ1 and DKSQ2 depositional sequences of Dakhla Formation recorded along the eastern escarpment face of the Kharga Oasis (El-Azabi and Farouk 2011). These sequences were recorded by El-Azabi and El-Araby (2000) in the west Dakhla-Farafra area in their study of Dakhla Formation facies characteristics and cyclicity. UCS3 depositional sequence also coincides with the AP9 tectonostratigraphic megasequence of Haq and Al-Qahtani 2005 (Text-figs. 18-20) along the Arabian Gulf. The reflectors of the UCS3 are characterized by moderate amplitude, frequency and continuity. The sequence also exhibits parallel reflection in the north to oblique reflection in the south constituting a toplap along SB4 and displaying sheet to basin fill external forms (Text-fig. 12) and from basin fill to wedge (Text-fig. 11). Two main features of the picked reflectors are considered:

displays concordant relation with the internal reflectors of the overlying and underlying sequences (Text-fig. 14) indicating basinward shift of shoreline, which was never exposed of the shelf offlap break. It changes to Type 1 in the southern part of the study area (Text-fig. 12). SB4 can be traced on the examined seismic reflection profiles between TWT 0.45 sec and 1.85 sec (Text-figs. 8–16). This surface has wide range of irregularities due to a series of NW-SE faults (Mahsoub et al. 2012). PES depositional sequence is toplapped by the SB3 boundary towards the south in the area of study, with some beds onlap upward so it is may change to Type 1 sequence boundary (Text-fig. 12). According to the foraminiferal data there is also unconformity surface within this sequence (Text-figs. 8–20) due to erosion of SBZ11 to SBZ13 zones of the Middle Eocene (Early-Middle Lutetian) age (Table 1; Text-figs. 4–6). The reflectors of the Paleocene-Eocene sequence are characterized by two main features:

The reflectors of the Upper Cretaceous facies in the central part are moderate in continuity, amplitude, and frequency. This seismic facies laterally changes to discontinuous, low amplitude and high frequency facies.

The reflectors of the Paleocene-Eocene facies in the central part of the area are moderate in continuity, amplitude and frequency. It also exhibits parallel northward to oblique southward forming toplap and show a sheet to wedge shaped external form (Text-fig. 12). The Paleocene-Eocene facies laterally change to discontinuous with low amplitude and high frequency.

The reflectors of the Upper Cretaceous facies decrease downward both in continuity and in amplitude (Text-fig. 11).

The reflectors of the Paleocene-Eocene facies increase downward in both continuity and amplitude.

Interpretations

Interpretation

The characteristics of the seismic reflectors of the Upper Cretaceous facies suggest that the central area is more massive (less rich in pores) than the surrounding parts. The decrease in continuity of the Upper Cretaceous facies recommend that the depositional condition in the region changed from inner shelf at the base to outer shelf at the top of the Upper Cretaceous facies (see also El-Azabi and Farouk 2011). The Khoman Formation consists mainly of chalky limestone with pyritic, cherty interbeds in lower part and interbeds of shale in the upper part (Barakat et al. 1984; Abdel Hamid 1985; Ghanem 1985).

The characteristics of the seismic reflectors of this seismic facies suggest that the central area is more massive (less rich in pores) than the surrounding parts. The low amplitude reflectors in the lower part reveal the heterogeneous lithology, which may be related to mixed pure carbonate sediments containing also cherty nodules. The increase of continuity and amplitude of the seismic reflectors in the lower part of this sequence suggest that the depositional condition in the region changed from outer shelf at the base to inner shelf at the top of the Paleocene-Eocene sequence (see also El-Azabi and Farouk 2011).

Paleocene-Eocene Sequence (PES)

Upper Eocene to Recent Sequence (ERS)

The Paleocene-Eocene sequence (PES) includes the sediments of the seismic facies which is represented by the Apollonia Formation (Text-figs. 8–16). It is developed with an overall transgressive trend. This sequence is composed entirely of limestone according to the composite data in all of the studied wells. The thickness of the PES is variable, ranging between 279m to 1,763m with increase toward the east. The tectonic framework and the irregularity of the SB4 play a major role in this variation.

The sediments of the uppermost part of Apollonia Formation (Text-figs. 11, 17), Dabaa Formation in the lower part and Moghra Formation at the top as well as the overlying deposits of the interpreted seismic profiles (Text-figs. 8–16) represent ERS sequence in the study area. These formations build up a complete sequence. They cannot be differentiated in the eastern part of the study area (Text-figs. 8–12) compared with the central and western parts (Text-figs. 13–16). The lower boundary of this sequence is represented by the sequence boundary (SB5), whereas the upper boundary represents the top of the all interpreted seismic lines in the study area. SB5 is recorded in the limestones of the uppermost part of Apollonia Formation at wells W.D 14-1 and East Mubarak-1 (Text-figs. 11, 17) and it extends along the boundary between Apollonia and Dabaa formations southeastwards (Text-fig. 11). SB5 unconformity surface represents eastward uplift and erosion of ERS depositional sequence especially, where Dabaa Formation is completely eroded at well South Tiba 1 (Text-fig. 8).

The PES is bounded by SB4 below and the SB5 above (Textfigs. 8–16). SB4 is located at the end of the Upper Cretaceous. Based on fossil content, the available data and former geological studies the lower part of this sequence boundary is affected by submarine erosion causing disappearance of the uppermost part of the Maastrichtian and the Early Paleocene (Text-figs. 3, 5, 6, 17). Accordingly, this sequence may be equivalent to the Paleocene-Lower Eocene DKSQ3, DKSQ4, T/EsSQ5, EsSQ6 and Es/ThSQ7 depositional sequences of El-Azabi and Farouk 2011. PES depositional sequence is also equivalent with the AP10 tectonostratigraphic megasequence of Haq and Al-Qahtani 2005 (Text-figs. 18-20) along the Arabian Gulf. Detailed analysis of SB4, like SB3, reveals that it is of Type 2. It

SB5 is characterized by continuous, high amplitude, and low frequency reflections. Thus, it can be identified and traced in all examined seismic profiles between TWT 0.15 sec and 0.55 sec (Text-figs. 8–16). This surface dips eastward as well as westward with wide range of irregularities due to a series of NW-SE faults (Mahsoub et al. 2012). ERS depositional sequence is equivalent 127


with the AP11 tectonostratigraphic megasequence of Haq and AlQahtani 2005 (Text-figs. 18-20) along the Arabian Gulf. The reflectors of the Upper Eocene to Recent facies are characterized by: The reflectors of the upper part are chaotic, discontinuous and are of high frequency and composed of sandstone beds. The reflectors of the lower part of the ERS display an increase in both continuity and amplitude but decrease in frequency compared with those of the upper part. Interpretation

The characteristic features of the upper top facies of Upper Eocene– Recent sequence (ERS) of the Dabaa and Moghra formations suggest a change from shallow marine inner shelf environment at the base to fluvial facies of continental environment at the top. DISCUSSION

The detailed sequence-stratigraphic analysis and the composite logs of the Cenomanian–Recent sediments in the area east of Abu Gharadig Basin (Text-fig. 17) have revealed that the examined succession was deposited under fluctuating sea level, as indicated in the following: During the Early Cenomanian, the available data indicate a maximum fall in sea level, which is widely recognized across the Western Desert (see also Mahsoub et al. 2012). This fall started with the deposition of the coarse clastics (sandstone) of the Bahariya Formation (UCS1), continued, and increased with deposition of more clastics and carbonates. UCS1 is underlain by SB1 and overlain by the second-order depositional sequence of the Abu Roash Formation, being truncated at the top by the SB2 sequence boundary (subaerial unconformity). The late Cenomanian rocks were deposited under delta to shallow marine conditions (Mark et al. 2009) sandstones, siltstones, shales and limestones of Abu Roash G Member of the lower part of UCS2 (Text-fig. 17). According to Barakat et al. (1987); Bayoumi (1994, 1996) and Mahsoub et al. (2012), the Abu Roash F-A members were deposited in shallow-shelf to open-marine conditions during Turonian. These members constitute the upper part of UCS2 (Textfigs. 8–20). UCS2 is directly overlain by SB3 sequence boundary, reflecting Late Turonian erosion that led to erosion of the upper part of the Abu Roash Formation especially in uplifted structures/ palaeobathymetric highs (Text-figs. 17–20). Unconformity surface is recorded at the base of Maastrichtian within the UCS3 as indicated by the planktonic foraminiferal biozones (Table 2, Text-fig. 17). This unconformity may be equivalent to the sequence boundary, Ca/MaKh1 of El-Azabi and Farouk 2011, recorded at the base of the Dakhla Formation, which was defined by Hermina (1990) in Kharga due to the absence of early Maastrichtian zones. According to El-Azabi and Farouk 2011, this hiatus was identified in the KhargaBeris stretch (Lüger 1985), west Dakhla-Farafra (El-Azabi and El-Araby 2000), Dakhla (Tantawy et al. 2001), Farafra (Hewaidy et al. 2006) and at El Kef section, north-west Tunisia (Li et al. 1999). This hiatus was also attributed to the uplift of the Bahariya Arch during initiation of the Syrian Arc Fold System. It defines a short-duration regressive event in the early Maastrichtian at the Duwi/Dakhla contact in the Eastern Desert and it coincides with a major global cooling event and eustatic sea-level drop at ca 71 Ma (El-Azabi and Farouk 2011). 128

The relatively deep sea conditions that prevailed by the offset of the Early Cenomanian persisted during the Late Cenomanian– Turonian and attained their peak in the Maastrichtian (Mahsoub et al. 2012), which indicates an increase in sea level in the Western Desert. This transgression led to the deposition of the Upper Cretaceous Khoman Chalk sequence (UCS3). The base of UCS3 is marked by SB3 (Text-figs. 17–20). The recorded planktonic biozones along this sequence indicate that it is deposited in deep marine environment (see also Younes 2003; Text-fig. 17). The decrease of the thickness of UCS3 westwards (Text-figs. 18–20) indicates uplift and erosion of this sequence in this direction. The top of UCS3 is marked by SB4 sequence boundary (Textfigs. 17–20). The SB4 is associated with no definite record of the upper part of the Maastrichtian and the base of the Early Paleocene rocks at wells W.D 14/1, East Mubarak-1 and East Mubarak-2. It is accompanied also by the absence of the upper part of the Maastrichtian and very small thickness of Paleocene rocks at well East Mubarak-3 (Text-fig. 17); this is probably due to the uplift and erosion of the area at that time because the sedimentation was continuous in the Western Desert in the structurally low and subsiding areas while some stratigraphic gaps and erosional truncations were common on the preexisting highs, which were reactivated, especially during the Paleocene (El-Azabi and Farouk 2011; Mahsoub et al. 2012). Accordingly, SB4 sequence boundary may be equivalent to the sequence boundary MaKh2 of El-Azabi and Farouk 2011 which was recorded in west Dakhla-Farafra by El-Azabi and El-Araby (2000) and on the Galala plateaux, along the western coast of the Gulf of Suez by Kuss et al. (2000). This sequence boundary may correspond to a worldwide, short-lived sealevel fall during the early late Maastrichtian at the top of the Gansserina gansseri Zone at 68 Ma (Haq et al. 1988; El-Azabi and Farouk 2011; Text-fig. 17). SB4 sequence boundary may be equivalent also to the sequence boundary Ma/DaKh3, which coincides with the Cretaceous-Paleogene boundary as one of the largest recorded sea-level falls in the Kharga succession (El-Azabi and Farouk 2011). This boundary may be correlated with sequence boundary Ma-Sin-Z given by Lüning et al. (1998) in central east Sinai and in north-central Tunisia as well as in north-east Cyrenaica, Libya (Jorry 2004). According to El-Azabi and Farouk 2011, A relative sea-level drop is also recorded during the latest Maastrichtian in the global eustatic cycle charts of Haq et al. (1988) This sea-level lowstand recorded at ca 65.5 Ma is coincident with the latest Maastrichtian maximum cooling (Li and Keller 1998). Moreover, the Apollonia Formation (Text-fig. 17) represents the Paleocene-Eocene sequence (PES), the lower part of the PES is deposited during Paleocene, indicating deposition of outer shelf environment at wells W.D 14/1, East Mubarak-1 and East Mubarak-2 (Text-fig. 17). The lower part of PES is mostly absent at well East Mubarak-3 (Text-fig. 17), this is probably due to uplifting and erosion of the uppermost part of the Maastrichtian and most of the Palaeocene rocks (Mahsoub et al. 2012) as indicated by unconformity surface recorded at the Paleocene-Eocene boundary within the PES (Text-fig. 17). This unconformity, which is indicated from the absence of planktonic biozones (P2-P5, table 2) may be equivalent to the sequence boundary Se/ThKh4 of El-Azabi and Farouk 2011 which was recorded from G. El-Teir/Tarawan, Kharga Oasis (Faris et al. 1999; lack of Zone NP6), Dakhla (Tantawy et al.


2001; lack of Zone NP5), El-Qusaima area, north-east Sinai (Ayyad et al. 2003; lack of Zone NP6) and in Farafra (Hewaidy et al. 2006, lack of P4a and P4b). This boundary coincides with the SelGal2 sequence boundary of Kuss et al. (2000) and with the Th1 sequence boundary of the Western European sea-level curve of Hardenbol et al. (1998) and it is also synchronous with a major eustatic sea-level fall at the base of Zone P4 in the Paleocene cycle chart of Haq et al. (1988). The unconformity surface recorded at the Paleocene-Eocene boundary within the PES (Text-fig. 17) may also be equivalent to the sequence boundary, Th/SpKh of El-Azabi and Farouk 2011, recorded near the base of the Esna Formation and marking the P/E boundary as a major hiatus in Farafra Oasis (Hewaidy et al. 2006). This sequence boundary may coincide with sequence boundaries ThGal2 and Th6 of Kuss et al. (2000) and Hardenbol et al. (1998), and the worldwide, short-lived sea-level fall within Zone P5 in the Eocene cycle chart of Haq et al. (1988) and of Miller et al. (2005). The almost absence of planktonic foraminiferal biozones (P6 and P7, table 2) indicates that the recorded unconformity surface recorded at the Paleocene-Eocene boundary within the PES (Text-fig. 17) may also be equivalent to the sequence boundary, YpKh7 of El-Azabi and Farouk 2011, defined in the top middle part of the Esna Formation in Farafra Oasis. According to YpKh7 of El-Azabi and Farouk 2011, it is also recorded from the central east Sinai by Lüning et al. (1998, YpSin-1) and from the Galala plateaux by Kuss et al. (2000, YpGal1). A correlatable sequence boundary exists at the base of Sub-zone P6b (now Zone E4, sensu Berggren and Pearson 2005) in the global eustatic sea-level chart of Haq et al. (1988) and in the New Jersey sea-level curve of Miller et al. (2005). Unconformity surface was recorded at the Early EoceneMiddle Eocene (Middle-Late Lutetian) boundary within the PES (Text-fig. 17). This unconformity, which is indicated from the absence of planktonic biozone (P9, table 2) may be equivalent to the sequence boundary YpKh8 of El-Azabi and Farouk 2011 located near the top of the Thebes Formation. It is also identified in the upper part of the Lower Eocene Farafra Limestone at El Quss Abu Said and at Ain Maqfi (Hewaidy et al. 2006). This unconformity could be correlated with the SB1 sequence boundary detected by Jorry (2004) at the top of Zone P9 (Table 2) in north-east Cyrenaica, Libya, which corresponds to the Ypresian/Lutetian contact (El-Azabi and Farouk 2011). It coincides with the youngest eustatic sea-level drop recorded in the late Early Eocene, close to the Ypresian-Lutetian boundary (Haq et al. 1988 cycle charts; Miller et al. 2005 sea-level curve). The planktonic foraminifera, which is recorded from the limestone intervals of PES at well East Mubarak-3 indicate a deep marine environment during the Early Eocene (Ypresian). The shallow benthic zones SBZ 10 at well W.D 14/1 and SBZ 9 and SBZ 10 at well East Mubarak-2 indicate shallow marine environment, while the absence of the Early Eocene sediments at well East Mubarak-1 is probably due to uplifting of the area at that time (Text-fig. 17). The absence of the Early Lutetian sediments along the study area (Text-fig. 17) indicates uplifting and erosion of the area at that time and shows a lacuna within the PES along the seismic profiles (Text-figs. 17–20). The Middle Lutetian sediments are deposited at wells East Mubarak-3 and East Mubarak-2 in shallow marine environments as indicated from the shallow benthic zone SBZ 14 (Text-fig. 17) while they are absent at wells W.D 14/1 and East Mubarak-1 indicating uplifting and erosion westwards. The Late Lutetian sediments are deposited at wells W.D 14/1 and East Mubarak-3 in a shallow marine environment as indicated from the shallow benthic zone

SBZ 16 (Text-fig. 17). These sediments are absent at wells East Mubarak-1 and East Mubarak-2 which indicate uplifting and erosion of the area at that time. The Bartonian sediments of PES, which is terminated by SB5 sequence boundary, are only recorded at well East Mubarak-1 while the absence of these sediments at the other wells reflects uplifting and erosion of the area at that time. The Upper Eocene to Recent sequence (ERS), which is underlain by SB5, includes the uppermost part of Apollonia, Dabaa and Moghra formations as well as Recent deposits. The transgression of sea level that continued during the Priabonian led to deposition of shallow marine limestone (uppermost part of Apollonia Formation) at well W.D 14/1, changed to shallow marine shale of the lower part of Dabaa Formation eastwards at wells East Mubarak-3 and East Mubarak-2 (Text-fig. 17). These sediments are absent at East Mubarak-1 reflecting uplifting and erosion of the area at that time. The rate of sea level rise began to decrease during the Oligocene led to the deposition of shallow marine shale of the upper part of Dabaa Formation and continued to more and more decrease in the sea level (fluvial to coastal) during the Early Miocene where the Moghra Formation was laid down. SUMMARY AND CONCLUSIONS

The foraminiferal contents and sequence-stratigraphic analysis have enabled to date the different lithostratigraphic units and to detect some hiatuses and or lacunae within the sedimentary record as follows: The Early Cenomanian second-order depositional sequence UCS1 of Bahariya Formation is underlain by SB1 and overlain by SB2 sequence boundary (subaerial unconformity). UCS1 shows a maximum fall in sea level, which is widely recognized across the Western Desert. The Late Cenomanian-Turonian second-order depositional sequence UCS2 is underlain by SB2 and overlain by SB3 and it is represented by Late Cenomanian Abu Roash G Member below, which was deposited under delta to shallow marine conditions and the Abu Roash F-A members above which were deposited in shallow-shelf to open-marine conditions during Turonian. SB3 sequence boundary of the Upper Cretaceous sequence (UCS3) is located at the end of Turonian and it is affected by submarine erosion causing erosion of some members of the underlying Abu Roash Formation, resulting in a major unconformity, which may point to tectonic instability due to pulses of epeirogenic movements affecting the area. The lower part of Paleocene-Eocene sequence (PES), which is represented by Apollonia Formation, is affected by the complete submarine erosion of the uppermost part of the Maastrichtian and the Early Paleocene. According to foraminiferal content, there is unconformity surface inside PES as indicated by absence of SBZ11 to SBZ13 zones of the Middle Eocene (Early-Middle Lutetian) age. The boundary between the Apollonia Formation and the overlying Dabaa Formation is represented by an unconformity (Sequence Boundary SB4) and it could be time-transgressive unconformity. SB5 unconformity surface represents uplift with non-deposition of ERS depositional sequence especially in the eastern part of the study area, as recorded in the well South Tiba 1A. SB5 is 129


determined in the limestones of the uppermost part of Apollonia Formation and extends along the boundary between Apollonia and Dabaa formations southeastwards (Text-fig. 11). The Upper Cretaceous–Tertiary succession for the studied area can be subdivided into five major second-order depositional sequences (UCS1, UCS2, UCS3, PES and ERS), separated by five major depositional sequence boundaries (SB1, SB2, SB3, SB4 and SB5). These sequences are Type 2 and may be changed to Type 1 in the south. Most of these sequences and depositional sequence boundaries compared well with those of Kharga Oasis, Farafra Oasis, the global cycle chart of Haq et al. (1988), the Western European sea-level curve of Hardenbol et al. (1998) and with the major sequences, sequence boundaries, flooding surfaces and the sea-level curve of Haq and Al-Qahtani 2005, indicating that most of them are caused by global eustasy and some of the sequence boundaries are related to local tectonism. Three of

the identified Upper Cretaceous-Cenozoic major depositional sequences (UCS3, PES and ERS) coincide with AP9, AP10 and AP11 tectonostratigraphic megasequences of Haq and Al-Qahtani 2005 along the Arabian Plateform, while two of them (UCS1 and UCS2) are of local tectonism. ACKNOWLEDGMENTS

The authors thank Egyptian General Petroleum Corporation (EGPC) for providing the subsurface data, and their permission to publish this work. These thanks are extended to Ain Shams University for supporting this work. With deep gratitude the authors thank Professor Dr.sc. Bruno Saftic, Faculty of Mining, Geology and Petroleum Engineering, University of Zagreb for reviewing the manuscript, his comments enhanced the quality of the manuscript substantially.

PLATE 1 Cyclammina sp., equatorial view, from well EM(3), depth (471/474), Dabaa Formation, late Oligocene, scale bar =mm; Voloshinovella aquisgranensis (Beissel 1889), equatorial view, from well WD14/1, depth (1203/1206), Khoman Formation, Late Companion, scale bar =mm;

1 Cyclammina sp., equatorial view, from well EM(3), depth (471/474), Dabaa Formation, late Oligocene, scale bar =mm; 2

3

4

Voloshinovella aquisgranensis (Beissel 1889), equatorial view, from well WD14/1, depth (1203/1206), Khoman Formation, Late Companion, scale bar =mm; Neoflabellina delicatissima Plummer 1926, from well EM(3), depth (1674/1677), Khoman Formation, Maastrichtian, scale bar =100µm; Heterohelix globulosa (Ehrenberg 1843), side view, from well EM(1), depth (783/786), Khoman Formation, Maastrichtian, scale bar = 100µm;

5–7 Pseudotextularia elgans (Rzehak 1891), Khoman Formation, Maastrichtian, Figure 5 from well EM(1), depth (786/789), side view. Figure 6 from well EM(1), depth (768/771), side view and Figure 7 from well EM(1), depth (753/756), scale bar = 100µm;

17, 18 Globotruncana arca (Cushman 1926), ventral view, Khoman Formation, Maastrichtian, scale bar = 100µm; 19 Globoconusa daubjergensis (Brönnimann 1953), ventral view, from well EM(3), depth (1578/1581), Apollonia Formation, Early Paleocene, scale bar = 100µm; 20 Planorotalites planoconica (Subbotina 1953), ventral view, from well EM(3), depth (1578/1581), Apollonia Formation, Early Paleocene, scale bar = 100µm; 21 Turborotalia cerroazulensis cocoaensis (Cushman 1928), ventral view, from well WD14/1, depth (549/552), Apollonia Formation, Late Eocene, scale bar = 100µm; 22

Acarinina pentacamerata (Subbotina 1947), ventral view, from well EM(3), depth (1392/1395), Apollonia Formation, Early Eocene, scale bar = 200µm;

8 Ventilabrella eggeri Cushman 1928, from well EM(3), depth (1674/1677), Khoman Formation, Maastrichtian, scale bar =100µm;

23 Morozovella argonensis (Nuttall 1930), ventral view, from well EM(3), depth (1440/1443), Apollonia Formation, Early Eocene, scale bar = 200µm;

9 Pseudoguembelina costulata (Cushman 1938), from well WD14/1, depth (1203/1206), Khoman Formation, Late Companion, scale bar = 100µm;

24 Morozovella formosa gracilis (Bolli 1957), ventral view, from well EM(3), depth (1530/1533), Apollonia Formation, Early Eocene, scale bar = 100µm;

10

Pseudoguembelina excolata (Cushman 1926), from well EM(3), depth (1674/1677), Khoman Formation, Maastrichtian, scale bar =100µm;

25 Morozovella pseudobulloides (Plummer 1926), ventral view, from well EM(3), depth (1578/1581), Apollonia Formation, Early Paleocene, scale bar = 200µm;

11 Contusotruncana fornicata (Plummer 1931), ventral view, from well EM(1), depth (786/789), Khoman Formation, Maastrichtian, scale bar = 100µm;

26 Morozovella subbotinae (Morozova 1929), ventral view, from well EM(3), depth (1530/1533), Apollonia Formation, Early Eocene, Scale bar = 200µm;

12–14

Gansserina gansseri (Bolli 1951), from well EM(1), depth (786/789), Khoman Formation, Maastrichtian, Figure 12 dorsal view, Figure 13 ventral view and Figure 14 side view, scale bar = 100µm;

15, 16

Globotruncana aegyptica Nakkady 1950, from well EM(1), depth (783/786), Khoman Formation, Maastrich-

130

tian, Figure 15 ventral view and Figure 16 side view, scale bar = 100µm;

27 Morozovella trinidadensis (Bolli 1957), ventral view, from well EM(3), depth (1578/1581), Apollonia Formation, Early Paleocene, scale bar = 200µm; 28 Morozovella sp. ventral view, from well EM(3), depth (1578/1581), Apollonia Formation, Early Paleocene, scale bar = 100µm.

Mohamed Boukhary et al.

stratigraphy, vol. 11, no. 2, 2014

Plate 1

131


REFERENCES ABDEL HAMID, M. L., 1985. “Contribution to the Geology of Upper Cretaceous with special emphasis on Turonian– Senonian sedimentation patterns and hydrocarbon potentials in the Abu Gharadig Area, North Western Desert.” Unpubl. PhD Thesis, Cairo University, 189 p. ABU EL-ATA, A. S. A. and ABD EL-NABI, S. H., 1985. Two-dimensional gravity modelling of simple and complex mass distributions in relation to the inferred tectonic model of the Qattara Depression area, Western Desert, Egypt. Egyptian Geological Survey, Annals, 1985: 269–284. AL FAR, D. M., 1966. Geology and coal deposits of Gebel Maghara, (north Sinai). Cairo: Egypt Geological Survey. Paper 37, 59 pp. BARAKAT, M. G., DARWISH, M. and ABDEL HAMID, M. L., 1984. Detection and delineation of reservoir potential within Abu Roash Formation, East Abu Gharadig Area, North Western Desert, Egypt. In: Eds., Abstracts of papers presented at the twenty-second Annual, Meeting, Geological Society of Egypt, 1. –––––, 1987. Hydrocarbon source rock evaluation of Upper Cretaceous “Abu Roash Formation” east Abu Gharadig area; Northwestern Desert, Egypt.– In: M.E.R.C., Ain Shams University, Earth Science Series, 1: 120–150. BASSIOUNI, M. A., 1969. Einige Costa und Carinocythereis (Reticulina). Arten aus dem Palaozan und Eozan von Jordanian (Ostracoda). Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, v. 134, no. 1, p. 1–16.

BAYOUMI, A. I. and LOTFY, H. I., 1989. Modes of structural evolution of Abu Gharadig Basin. Journal of African Earth Sciences, 9: 273–287. BAYOUMI, A. I., DARWISH, Y. A. and LOTFY, H. I., 1987. Acoustic characteristics of the Abu Gharadig Basin sediments. Journal of African Earth Sciences, 6: 399–405. BERGGREN,W. A., KENT, D. V., SWISHER, C. C. and AUBRY, M. P., 1995. A revised Cenozoic geochronology and chronostratigraphy. In: Berggren, W. A., Kent, D. V., Aubry, M.-P. and Hardenbol, J., Eds., Geochronology, time scales and global stratigraphic correlations: A unified temporal framework for historical geology, 129– 212. Tulsa: Society of Economic Paleontologists and Mineralogists (SEPM). Special Publication 54. BERGGREN, W. A. and PEARSON, P. N., 2005. A revised tropical to subtropical Paleogene planktonic foraminiferal zonation: Journal of Foraminiferal Research, 35: 279–298. –––––, 2006. Tropical to subtropical planktonic foraminiferal zonation of the Eocene and the Oligocene. In: Pearson, P. N. et al., Eds. Atlas of Eocene Planktonic Foraminiferas. Cushman Foundation Special Publication, 41: 29–40. BLONDEAU, A., 1972. Les Nummulites.Volume 1. Vuibert, Paris, 254 p. BOLLI, H. M., 1957. The genera Globigerina and Globorotalia in the Paleocene–Lower Eocene Lizard Springs Formation of Trinidad, BWI. United States National Museum Bulletin, 215, 61–81.

PLATE 2

1

Globanomalina micra Cole 1927, from well EM(3), depth (591/594), Dabaa Formation, Late Eocene, scale bar = 100µm;

2

Hantkenina alabamensis Cushman 1925a, from well EM(3), depth (579/582), Dabaa Formation, Late Eocene, scale bar = 100µm;

3

4

Globigerina sp., ventral view, from well EM(1), depth (522/525), Apollonia Formation, Middle Eocene, scale bar = 100µm;

5

Globigerinatheka index tropicalis (Blow and Banner 1962), side view, from well EM(3), depth (591/594), Dabaa Formation, Late Eocene, scale bar = 100µm;

6,7

Bolivinoides draco miliaris Hiltermann and Koch 1950, from well EM(1), depth (786/789), Khoman Formation, Maastrichtian, scale bar =100µm;

8

Coryphostoma sp. from well EM(3), depth (1578/1581), Apollonia Formation, Early Paleocene, scale bar = 200µm;

9

132

Globigerina sp., ventral view, from well EM(1), depth (522/525), Apollonia Formation, Middle Eocene, scale bar = 100µm;

Asterigerina carinata Orbigny 1839, equatorial view, from well WD14/1, depth (510/513), Apollonia Formation, Late Eocene, scale bar = 0.5mm;

10–12 Stensioeina exculpta gracilis Brotzen 1945, Khoman Formation, Late Campanian, Figure 10 from well WD14/1, depth (1218/1221), dorsal view and Figures 11, 12 from well WD14/1, depth (1203/1206), ventral views, scale bar =mm; 13

Karreria sp. dorsal view, from well EM(3), depth (1578/1581), Apollonia Formation, Early Paleocene, scale bar = 100µm;

14

Lepidorbitoides minor Schlumberger 1902, equatorial view, megalospheric, from well EM(3), depth (1626/1629), Khoman Formation, Maastrichtian, scale bar = 0.25mm;

15

Penoperculoides sp. axial section, megalospheric, from well EM(3), depth (1479/1482), Apollonia Formation, Early Eocene, scale bar = 0.25mm;

16–22

Cuvillierina sp. From well EM(3), depth (1479/1482), Apollonia Formation, Early Eocene. 16 microspheric, internal structure, Figure 17 A form, external. Figures 16, 17 Scale bar = 200µm and Figures 18–22 megalospheric, Figures 18–20 equatorial views and Figures 21, 22 axial sections, Figures 18–22 scale bar = 0.5mm.

23

Rotalita trochidiformis Lamarck 1804, equatorial view, From well EM(3), depth (1479/1482), Apollonia Formation, Early Eocene, scale bar = 0.5mm.



Plate 2

133


BOLLI, H. M., SAUNDERS, J. B. and PERCH–NIELSEN, K., Eds., 1985. Plankton stratigraphy. Cambridge: Cambridge University Press. BOUKHARY, M., BASSIOUNI, M. E. and HUSSEIN–KAMEL, Y., 1995. Nummulites luterbacheri n.sp. Unexpected Large Nummulites from El Quss Abu Said, Farafra Oasis, Western Desert, Egypt. Revue de Micropaléontolgie, 38: 285–298. BRÖNNIMANN, P., 1952. Globigerinidae from the upper Cretaceous (Cenomanian–Maestrichtian) of Trinidad, BWI. Bulletin of American Paleontology, 34: 5–71. CARON, M., 1985. Cretaceous planktic foraminifera. In Bolli, H. M., Saunders J. B. and Perch–Nielsen, K. Eds., Plankton stratigraphy, 17–86. Cambrdge: Cambridge University Press CARON, M., LUTERBACHER, H., PERCH–NIELSEN, K., PREMOLI SILVA, I., RIEDEL, W.Ŕ. and SANFILIPPO, A., 1975. Zonati à l’aide de microfossiles pélagiques du Paléocène supérieur et de l’Eocène inférieur. Bulletin de la Société Géologique de France, v. 17, p. 125–147. DARWISH, M., ABU KHADRAH, A. M., ABDEL HAMID, M. L. and HAMED, T. A., 1994. Sedimentology, environmental conditions and hydrocarbon habitat of the Bahariya Formation, central Abu Gharadig Basin, Western Desert, Egypt. Proceedings of the 12th Petroleum Exploration and Production Conference, Cairo, Egypt, Nov, 12–15, 1994 Volume 1, 429–449. Cairo: Egyption General Petroleum Corporation. CATUNEANU, O., KHALIFA, M. A. and WANAS, H. A., 2006. Sequence stratigraphy of the Lower Cenomanian Bahariya Formation, Bahariya Oasis, Western Desert, Egypt.–Sedimentary Geology, 190, 121–137. doi:10.1016/j.sedgeo.2006.05.010 EGPC, 1992. Western Desert oil and gas fields (a comprehensive overview). EGPC – 11th Exploration Conference. Cairo: Egyptian General Petroleum Company, 431 pp. EL-AZABI, M. H. and EL-ARABY, A., 2000. Depositional cycles, an approach to the sequence stratigraphy of the Dakhla Formation, west Dakhla–Farafra stretch, Western Desert, Egypt. Journal of African Earth Sciences, 30: 971–996.

EL-AZABI M. H. and FAROUK, S., 2011. High-resolution sequence stratigraphy of the Maastrichtian– Ypresian succession along the eastern scarp face of Kharga Oasis, southern Western Desert, Egypt. Sedimentology, 58: 579–617. EL BASSYOUNY, A. A., 1970. “Geology of the area between Gara El Hamra of Ball–Qur Lyons and Ghard El Moharrik, and its correlation with El Harra area, Bahariya Oasis, Egypt.” Unpubl. MSc Thesis, Cairo University, 180 p. EL DIASTY, W. SH. and MOLDOWAN, J. M., 2012. Application of biological markers in the recognition of the geochemical characteristics of some crude oils from Abu Gharadig Basin, north Western Desert–Egypt. Marine and Petroleum Geology, [VOLUME??]: 28–40. El EMAM, A., D. BISHOPP and I. DUNDERDALE 1992. The hydrocarbon potential of the west Gindi area, Western Desert, Egypt. Proceedings of the 10th Petroleum Exploration and Production Conference, Cairo, 1990. Egyptian General Petroleum Corporation, v. 2, p. 229-256. EL GEZEERY, M. N., MOHSEN, S. M. and FARID, M., 1972. Sedimentary basins of Egypt and their petroleum prospects. Proceedings of the 8th Arab Petroleum Congress, Algiers, p. 1–15. ELOUI, M. and ABDINE, S., 1972. Rock units correlation chart of northern Western Desert, Egypt. Cairo: WEPCO, 158 p. EMERY, D. and MYERS, K. J., 1996. Sequence stratigraphy. Oxford: Blackwell Science, 297 p. GHANEM, M. F., 1985. “Subsurface geology of the Cretaceous sediments in the North Western Desert of Egypt and its hydrocarbon potentialities.” Unpubl. PhD Thesis, Faculty of Science, Cairo University, 131 p. FARIS, M., ABD EL-HAMEED, A. T., MARZOUK, A. M. and GHANDOUR, I. M., 1999. Early Paleogene calcareous nannofossils and planktonic foraminiferal biostratigraphy in central Egypt. Neues Jahrbuch der Geologische u. Paläaontologische Abhandlungen, 213: 261–288.

PLATE 3

1–7

8, 9

N. beneharnensis De la Harpe 1926, megalospheric, Apollonia Formation, Middle Eocene, 1, 7 from well EM(2), depth (813/816), Figures 2, 4 from well EM(2), depth (855/858), Figures 3, 5, 6 from well EM(2), depth (747/750), Figures 1–3 external views and Figures 4–7 equateorial views, scale bar =mm; N. cf. lehneri Schaub 1962, megalospheric, From well WD14/1, depth (696/699), Apollonia Formation, Middle Eocene, Figure 8 external view and Figure 9 half section, scale bar =mm;

10–14 N. bakhchissaraiesis Rozlozsnik 1929, megalospheric, From well WD14/1, depth (801/804), Apollonia Formation, Early Eocene, Figure 10 external view, Figures 11, 12 equatorial views and Figures 13, 14 axial sections, scale bar =mm; 15–18

134

N. sp. cf. praelorioli Herb and Schaub 1963, Megalospheric, From well EM(2), depth (963/966), Apollonia

Formation, Middle Eocene, Figure 15 external view, Figure 16 half section, Figure 17 equatorial view and Figure 18 axial section, scale bar =mm; 19–23

mN. cf. boussaci Rozlozsnik 1924, Apollonia Formation, Middle Eocene, Figure 19 Microspheric, external view, Figures 20–23 Megalosheric, Figures 20–22 external views and Figure 23 half section. Figures 19, 20, 23 from well EM(2), depth (702/705) and Figures 21, 22 from well EM(2), depth (651/654), scale bar =mm;

24–31

N. ornatus Schaub 1951, From well EM(2), depth (1110/1113), Apollonia Formation, Early Eocene, Figures 24, 25 microspheric, Figure 24 external view, Figure 25 equatorial view, Figures 26–31 megalospheric, Figures 26, 27 external views, Figures 28–31 equatorial views, scale bar =mm.



Plate 3

135


HAQ, B. U. and AL-QAHTANI, A. M., 2005. Phanerozoic cycles of sealevel change on the Arabian Platform. GeoArabia, 10: 127–160.

analysis of some Cenomanian–Turonian exposures in the north eastern Desert, Egypt. Egyptian Journal of Geology, 44:. 277–294.

HAQ, B. U., HARDENBOL, J. and VAIL, P. R., 1988. Mesozoic and Cenozoic chronostratigraphy and cycles of sea-level change. In: Wilgus, C. K., et al., Eds., Sea-level changes – An integrated approach, 71–108 Tulsa: Society of Economic Paleontologists and Mineralogists. Special Publication 42.

ISMAIL, A. A. and SOLIMAN, S. I., 1997. Cenomanian–Santonian foraminifera and ostracods from Horus Well-1, North Western Desert, Egypt. Micropaleontology, 43: 165–183.

HANTAR, G., 1990. North Western Desert. In: Said, R., Ed., The geology of Egypt, 293–319. Rotterdam: Balkema. HARDENBOL, J., THIERRY, J., FARLEY, M. B., JACQUIN, T., DE GRACIANSKY, P. C. and VAIL, P. R., 1998. Mesozoic–Cenozoic sequence chronostratigraphy framework of European basins. In: de Graciansky, P. C., Hardenbol, J., Jacquin, T. and Vail, P. R., Eds., Sequence stratigraphy of European basins, 3–14. Tulsa: Society of Economic Palentologists and Mineralogists. Special Publication 60. HERMINA, M. H., 1990. The surroundings of Kharga, Dakhla and Farafra oases. In: Said, R., Ed., The Geology of Egypt, 259–292. Rotterdam: Balkema. HEWAIDY, A. A., EL-AZABI, M. H. and FAROUK, S., 2006. Facies associations and sequence stratigraphy of the Upper Cretaceous– Lower Eocene succession in the Farafra Oasis, Western Desert, Egypt. In: Eds., 8th International Conference on the Geology of the Arab World (GAW 8), Cairo University, Egypt, vol. II, 569–599., Cairo. IBRAHIM, M., 1990. Review of the stratigraphic and tectonic framework of the west El Gindi area, Western Desert, Egypt: implications for hydrocarbon occurrence. 10th Egyptian General Petroelum Corporation Seminar, vol. 2, pp. 190–228., Cairo. IBRAHIM, M. and ALI, M., 1994. The impact of environmental problems on open hole log evaluation of Bahariya Formation, Western Desert, Egypt. Proceedings of the 12th Petroleum Exploration and Production Conference, Cairo, 1994. Egyptian General Petroleum Corporation, v. 2, p. 369-386. ISMAIL, A. A., 2000. Upper Cretaceous stratigraphy and micropaleontology of the western part of the Gulf of Aqaba, East Sinai, Egypt. M.E.R.C. Ain Shams University, Earth Science Series, 14: 239–261. ISMAIL, A. A. and AKARISH, A. I. M., 2000. Stratigraphy and facies

ISMAIL, M. M., EL NOZAHY, F. A. and SADEEK, K. N., 1989. A contribution to the geology of the Bahariya Oasis, Western Desert, Egypt. Geological Journal, 18: 379–391. ISSAWI, B., EL HINNAWI, M., FRANCIS, M. and MAZHAR, A., 1999. The Phanerozoic geology of Egypt a geodynamic approach. Cairo: Egyptian Geological Survey. Special Publication 76, 462 pp. JORRY, S., 2004. The Eocene Nummulite carbonates (Central Tunisia and NE Libya): sedimentology, depositional environments, and application to oil reservoirs. Geneva: University of Geneva. PhD Thesis, Terre and Environment, vol. 48, 206 pp. KRASHENINNIKOV, V. A., 1965. Zonal stratigraphy of the Paleogene in the eastern Mediterranean. Moscow: Academia Nauk SSSR, Geologicky Institut. Trudy 133, 76 pp. (In Russian). KUSS, J., SCHEIBNER, C. and GIETL, R., 2000. Carbonate platform to basin transition along an Upper Cretaceous to lower Tertiary Syrian Arc uplift, Galala Plateau, Eastern Desert, Egypt. GeoArabia, 5: 405–424. LE ROY, L. W., 1953. Biostratigraphy of the Maqfi section, Egypt, In: R. C. Moore, Ed. Treatise on Invertebrate Paleontology. Part C. 1–73., Boulder: Geological Society of America. Memoir 54. LI, L. and KELLER, G., 1998. Diversification and extinction in Campanian–Maastrichtian planktic foraminifera of northwest Tunisia. Eclogae Geologica Helvetiae, 91: 75–102. LI, L., KELLER, G. and STINNESBECK, W., 1999. The Late Campanian and Maastrichtian in northwestern Tunisia: paleoenvironmental inferences from lithology, macrofauna and benthic foraminifera. Cretaceous Research, 20: 231–252. LOUTIT, T. S., HARDENBOL, J., VAIL, P. R. and BAUM, G. R., 1988. Condensed sections: the key to age dating and correlation of conti-

PLATE 4

1-4

N. syrticus Schaub 1981, megalospheric, From well EM(2), depth (900/903), Apollonia Formation, Middle Eocene, Figure 1 external view and Figures 2–4 half sections, scale bar = 0.5mm;

15

N. praelucasi Douvillé 1924, megalospheric, external view, From well WD14/1, depth (801/804), Apollonia Formation, Early Eocene, scale bar = 0.25mm;

16, 17

N. retiatus Roveda 1959, megalospheric, Apollonia Formation, Middle Eocene, Figure 16 from well WD14/1, depth (531/534), external view and Figure 17 from well WD14/1, depth (549/552), Figure 16 equatorial view, scale bar = 0.33mm;

18, 19

N. bullatus Azzaroli 1952, megalospheric, From well WD14/1, depth (558/561), Apollonia Formation, Middle Eocene, Figure 18 external view and Figure 19 half section, scale bar = 0.25mm.

5–8 N. pachoi Said 1951, megalospheric, From well EM(3), depth (657/660), Apollonia Formation, Middle Eocene, Figures 5, 6 equatorial views and Figures 7, 8 axial sections, scale bar =mm; 9–14

136

N. cf. gizehensis Forskål 1775, Apollonia Formation, Middle Eocene, Figures 9, 11, 14 from well WD14/1, depth (576/579), Figures 10, 12, 13 from well EM(3), depth (657/660), Figure 9 microspheric, half section, Figures 10–14 megalospheric, Figures 10, 11 external views and Figures 12–14 half sections, scale bar =mm;



Plate 4

137


nental margin sequences. In: Wilgus, C. K., et al., Eds., Sea–level changes – an integrated approach, 183–215. Tulsa: Society of Economic Paleontologists and Mineralogists. Special Paper 42.

PROTODECIMA, F. and BOLLI, H. M., 1970. Evolution and variability of Orbulinoides beckmanni (Saito). Ecoglae geologicae Helvetiae, 63: 883–905.

LÜGER, P., 1985. Stratigraphie der marinen Oberkreide und des Alttertiars im Sudwestlichen Obernil–Becken (SW-Aegypten) unterbesonderer berucksichtigung der mikropaläontologie, paläoekologie und paläogeographie. Berliner Geowissenschaftliche Abhandlungen, 63: 1–150.

ROBERTSON RESEARCH INTERNATIONAL LIMITED (RRI), 1982. “Petroleum potential evaluation, Western Desert, Egypt.” In unpubl. report, 55–162. Cairo: Egyptian General Petroleum Corporation (EGPC).

LÜNING, S., MARZOUK, A. and KUSS, J., 1998. The Paleocene of central east Sinai, Egypt: ‘sequence stratigraphy’ in monotonous hemipelagites. Journal of Foraminiferal Reserch, 28: 19–39. MAHSOUB, M., ABUL NASR, R., BOUKHARY, M., ABD EL AAL, H. and FARIS, M., 2012. Bio– and sequence stratigraphy of Upper Cretaceous–Paleogene rocks, East Bahariya Concession, Western Desert, Egypt. Geologia Croatica, 65: 109–138. MARK, A. P., GABE, A., OSAMA, N., and JOE, C., 2009. Depositional facies control on reservoir characteristics in the middle and lower Abu Roash “G” Sandstones, Western Desert, Egypt. Search and Discovery, Art. #50181. (Adapted from oral presentation at AAPG International Conference and Exhibition, Cape Town, South Africa, October 26–29, 2008). MILLER, K. G., KOMINZ, M. A., BROWNING, J. V., WRIGHT, J. D., MOUNTAIN, G. S., KATZ, M. E., SUGARMAN, P. J., CRAMER, B. S., CHRISTIE-BLICK, N. and PEKAR, S. F., 2005. The Phanerozoic record of global sea-level change. Science, 310: 1293–1298. MUFTAH, A. M. and BOUKHARY, M. (2013).- New Late Eocene genus Gaziryina (Foraminifera) from the Al Bayda Formation (ShahhatMarl Member), Al Jabal al Akhdar, Northern Cyrenaica, Libya. Micropaleontology, vol. 59, nos. 2–3, text-figures 1–5, plate 1, pp. 103–109. NORTON, P., 1967. Rock-stratigraph/ic nomenclatures of the Western Desert, Egypt. Cairo: Egyptian Petroleum Corporation, 557 p.

SAID, R., 1962a. Über das Miozän in der westlichen wüste Ägyptens. Geologisches Jahrbuch, 80: 349–366. –––––, 1962b. The Geology of Egypt. Amsterdam: Elsevier, 377 p. SAID, R. and KENAWY, A., 1957. Foraminifera from the Turonian rocks of Abu Roash Egypt. Contributions from the Cushman Foundation for Foraminiferal Research, 8: 77–86. SAUNDERS, J.B. & BOLLI, H.M. (1985) Trinidad’s contribution to world biostratigraphy. In Carr-Brown, B. & Christian,J.T. (eds.) Transactions of the Fourth Latin American Geological Conference, July 7–15, 1979, 781-95, Geological Society of Trinidad and Tobago, Port-of-Spain. SCHAUB, H., 1981. Nummulites et Assilines de la Téthys paléogène. Taxinomie, phylogenèse et biostatigraphie. Mémoires Suisses de Paleontologie, 104: 1–236 (Atlas I); 106 (Atlas II). SERRA-KIEL, J., HOTTINGER, L., CAUS, E., et al., 1998. Larger foraminiferal biostratigraphy of the Tethyan Paleocene and Eocene. Bulletin de la Société Géologique de France, 169: 281–299. SHATA, A., 1955. An introductory note on the geology of the northern portion of Western Desert of Egypt. Bulletin of the Desert Institute of Egypt, 5(4): 96–106. STROMER, E., 1914. Die Togographie und Geologie der Strecke Gharaq– Baharije nebest Ausfuhrungen ueber die geologische Geschichte Ae-

PLATE 5

1-4

N. discorbinus Schlotheim 1820, From well EM(2), depth (813/816), Apollonia Formation, Middle Eocene, Figure 1 microspheric, half section and Figures 2–4 megalospheric; Figure 2 external view; Figures 3, 4 half sections, scale bar =mm;

5, 6

N. chavannesi De La Harpe (1878), From well EM(1), depth (483/486), Apollonia Formation, Late Eocene, Figure 5 microspheric, equatorial view and Figure 6 megalospheric, equatorial view, scale bar =mm.

7–9

N. incrassatus ramondiformis De La Harpe in Herb and Hekel (1975), megalospheric, From well WD14/1, depth (510/513), Apollonia Formation, Late Eocene, Figures 7, 8 equatorial view and Figure 9 axial section, scale bar =mm;

10–13

138

N. pulchellus Hantken in De La Harpe (1883), From well WD14/1, depth (531/534), Apollonia Formation, Late Eocene, Figure 10 microspheric, equatorial view and Figures 11–13 megalospheric, equatorial views, scale bar =mm;

14–16

N. rutimeyeri De La Harpe (1883), megalospheric, From well EM(3), depth (561/564), Apollonia Formation, Late Eocene, Figure 14 external view, Figure 15 equatorial view and Figure 16 axial section, scale bar =mm;

17–22

N. sp. cf. boulangeri Schaub 1981, megalospheric, From well EM(2), depth (525/528), Apollonia Formation, Late Eocene, Figures 17–20 external view and Figures 21, 22 half section, scale bar =mm;

23, 24

N. bayhariensis Checchia and Rispoli 1911, megalospheric, From well WD14/1, depth (696/699), Apollonia Formation, Middle Eocene, Figure 23 external view and Figure 24 half section, scale bar =mm;

25

N. luterbacheri Boukhary et al. 1995, megalospheric, axial section, From well EM(3), depth (1050/1053), Apollonia Formation, Early Eocene, scale bar =mm;

26–29

N. distans Deshayes 1838, megalospheric, From well EM(2), depth (1020/1023), Apollonia Formation, Early Eocene, Figure 26 external view and Figures 27–29 equatorial views, scale bar =mm.



Plate 5

139


gyptens. Abhandlung Bayrischer, Akademischer Wissenschaften, Mathematisch–Naturwissenschaftliche Kl., v. 11, p.1–78.

Perch–Nielsen, K., Eds., Plankton stratigraphy, Cambridge University, New York: Cambridge University Press, pp. 87-154.

SULTAN, N. and HALIM, M. A., 1988. Tectonic framework of Northern Western Desert, Egypt and its effect on hydrocarbon accumulations. Proceedings of the 9th Exploration Conference, Egyptian General Petroleum Corporation, Cairo, 1988, v. 2, p. 1–22.

VAN WAGONER, J. C., POSAMENTIER, H. W., MITCHUM, R. M., VAIL, P. R., SARG, J. F., LOUTIT, T. S. and HARDENBOL, J., 1988. An overview of the fundamentals of sequence stratigraphy and key definitions. In: Wilgus, C. K., et al., Eds., Sea–level changes: An integrated approach, 39–45. Tulsa: Society of Economic Paleontologists and Mineralogists. Special Publication 42.

TANTAWY, A. A., KELLER, G., ADATTE, T., STINNESBECK, W., KASSAB, A. and SCHULTE, P., 2001. Maastrichtian to Paleocene depositional environment of the Dakhla Formation, Western Desert, Egypt: sedimentology, mineralogy, and integrated micro– and macrofossil biostratigraphies. Cretaceous Research, 22, 795–827.

YOUNES, M. A., 2003. Alamein Basin hydrocarbon potentials,Northern Western Desert, Egypt Eds., American Association of Petroleum Geologists Annual Convention, May 11–14, 2003, Salt Lake City, Utah, Abstracts, 6. Tulsa: American Association of Petroleum Geologists.

TOUMARKINE, M. and LÜTERBACHER, H., 1985. Paleocene and Eocene planktic foraminifera. In: Bolli, H. M., Saunders, J. B. and

PLATE 6 Figs. 1-40 Scale bar =10 µm.

1-3

Arkhangelskiella cymbiformis Vekshina 1959, from well EM (1), depth (786/789), Khoman Formation, Maastrichtian.

21, 22

Microrhabdulus decoratus Deflandre (1959), from well WD14/1, depth (1218/1221), Khoman Formation, Maastrichtian.

4,5

Braarudosphaera bigelowii Gran and Braarud 1935, from Well WD 14/1, depth (996/999), Apollonia Formation, Paleocene.

23

Micula decussate Vekshina 1959, from well WD 14/1, depth (1218/1221), Khoman Formation, Maastrichtian.

6

Micranthalithus Vesper Deflandre in Deflandre and Fert 1954, from well EM(1), depth (753/756), Khoman Formation, Maastrichtian.

24, 25

Micula murus (Martini 1961) Bukry 1973c, from well EM (1), depth (783/786), Khoman Formation, Maastrichtian.

7

Lucianorhabdus cayeuxii Deflandre 1959, from well EM (1), depth (783/786), Khoman Formation, Maastrichtian.

26-28

Pontosphaera multipora (Kamptner 1948) Roth (1970), from well WD14/1, depth (900/903), Apollonia Formation, Early Eocene.

8-11

Chiasmolithus solitus (Bramlette and Sullivan 1961) Locker 1968, from well EM (1), depth (723/726), Khoman Formation, Maastrichtian.

12-13

Coccolithus pelagicus (Wallich 1877) Schiller (1930), from well WD 14/1, depth (996/999), Apollonia Formation, Paleocene.

14-16

Eiffellithus turriseiffelii Deflandre in Deflandre and Fert 1954, from well EM (3), depth (1674/1677), Khoman Formation, Maastrichtian.

17-20

140

Watznaueria barnesae (Black in Black and Barnes 1959) Perch-Nielsen 1968, Khoman Formation, Maastrichtian, Figs. 17, 18 from well EM (3), depth (1698/1071) and Figs. 19, 20 from well WD 14/1, depth (1203/1206).

29-31

Reticulofenestra dictyoda (Deflandre in Deflandre and Pert 1954) Stradner in Stradner and Edwards (1968), from well EM (3), depth (1392/1395), Khoman Formation, Maastrichtian.

32-35

Reticulofenestra umbilica (Levin 1965) Martini and Ritzkowski (1968), from well EM (3), depth (624/627), Apollonia Formation, Middle Eocene.

36,37

Sphenolithus radians Deflandre in Grasse (1952), from well EM (3), depth (1440/1443), Khoman Formation, Maastrichtian.

38-40

Zeugrhabdotus pseudanthophorus (Bramlette and Martini 1964) Perch-Nielsen (1984a), from well EM (1), depth (753/756), Khoman Formation, Maastrichtian.



Plate 6

141