The impact of the Syrian Arc Orogeny on the Early Paleogene rocks, western shoulder of the Gulf of Suez, Egypt

Palaeogeography, Palaeoclimatology, Palaeoecology 454 (2016) 30–53

Contents lists available at ScienceDirect

Palaeogeography, Palaeoclimatology, Palaeoecology journal homepage: www.elsevier.com/locate/palaeo

The impact of the Syrian Arc Orogeny on the Early Paleogene rocks, western shoulder of the Gulf of Suez, Egypt Abdalla M. El Ayyat ⁎, Nageh A. Obaidalla Geology Department, Faculty of Science, Assiut University, Assiut 71516, Egypt

a r t i c l e

i n f o

Article history: Received 16 June 2015 Received in revised form 30 November 2015 Accepted 5 April 2016 Available online 16 April 2016 Keywords: Stratigraphy Sedimentology North Eastern Desert Early Paleogene Planktonic foraminifera Syrian Arc Orogeny

a b s t r a c t Integrated biostratigraphical and sedimentological studies on the Early Paleogene rocks (Thebes Formation) at four localities along the western shoulder of the Gulf of Suez, have provided an opportunity to evaluate the stratigraphy and the geological evolution of the sedimentary basins. The carbonate succession of the Thebes Formation represents a general regressive trend, which rests conformably to unconformably on the shales and marls of the Dakhla and Esna formations. The vertical facies change records a transition from deep- to mid-shelf to shoal, to lagoon, into a peritidal zone forming southwest gently-dipping slope to basin transect. Based on the study of the planktonic foraminiferal fossils; four zones have been defined according to the important planktonic foraminiferal taxa: Morozovella aragonensis/Morozovella subbotinae, Acarinina pentacamerata, Acarinina cuneicamerata of Ypresian age and Globigerinatheka kugleri/M. aragonensis of Early Lutetian age. The stratigraphy of the studied rocks is punctuated by three regional syn-depositional tectonic phases. The ages of these phases, have been determined chrono-stratigraphically as: Danian/Early Ypresian, Middle–Late Ypresian and Early Lutetian. Globally, these phases are three pronounced tectonic episodes in the tectonic history of the Syrian Arc Orogeny. The results suggest that the sedimentation regime was mainly controlled by external as well as internal parameters, which formulated the sedimentary basins. © 2016 Elsevier B.V. All rights reserved.

1. Introduction The Early Paleogene in Tethys realm is characterized by tectonism that caused paleogeographic and sea level changes linked with climatic fluctuations. These changes have had impacts on the depositional history in northern Egypt which is a part of the Syrian Arc Orogeny (SAO). The SAO is related to the northward movement of the African craton towards Eurasia in the Late Turonian (Scheibner et al., 2003) as well as the reactivation of Mesozoic fault systems (Hussein and Abd-Allah, 2001). The history of the SAO conditioned the times and intensity of the terrigenous input, the location of the main depocenters and the facies framework modulated by global eustatic sea level changes (Haq et al., 1987). Throughout the Phanerozoic, the importance of tectonically controlled carbonate platform evolution has been described for various environments (Bosence, 2005). Recently, several local circum-Tethyan studies on the evolution of carbonate platform systems during the Early Paleogene have been carried out with special emphasis on environmental conditions (Özgen-Erdem et al., 2005; Adabi et al., 2008; El Ayyat and Obaidalla, 2013), biostratigraphy (Schaub, 1992) and the response to palaeoclimatic change (Pujalte et al., 2009). ⁎ Corresponding author. E-mail addresses: [email protected], [email protected], [email protected] (A.M. El Ayyat), [email protected], [email protected] (N.A. Obaidalla).

http://dx.doi.org/10.1016/j.palaeo.2016.04.011 0031-0182/© 2016 Elsevier B.V. All rights reserved.

The Southern Galala, along the western side of the Gulf of Suez (Fig. 1), represents a playground area for Paleogene carbonate research. The geological evolution of the carbonate platform there is tied strongly to the activity of the SAO, which demonstrates a northeast-southwest striking framework of horsts and grabens at the southern Tethyan shelf. The emergence of the Galala platform has been documented for the Campanian/Maastrichtian (Scheibner et al., 2003). Multiple pulses of tectonic uplift, which are related to the temporarily reactivation of Cretaceous fault systems, caused the repeated reconfiguration of the platform morphology. Although, the focus area represents only a relatively small part of the whole tectonic history of the SAO in northern Egypt, it greatly contributes to the knowledge of the different tectonic mechanisms and associated sea level oscillations in this folding belt. The Early Paleogene sediments have been extensively studied in the north Eastern Desert. Most of the previous studies focused on their lithological and paleontological aspects. In contrast, the impacts of tectonism and sea level oscillations on the stratigraphy and pattern of sedimentation have been only briefly outlined. Basic previous studies include the works of Mazhar et al. (1979), Abu Khadra et al. (1994), Strougo and Faris (1993), Boukhary et al. (1998), Kuss et al. (2000), Morsi and Scheibner (2009) and Höntzsch et al. (2011). The present study focuses on the Thebes Formation since it is highly confused with other rock units with respect to its age and nomenclature as shown in Table 1. The present study is devoted mainly to: 1) provide

A.M. El Ayyat, N.A. Obaidalla / Palaeogeography, Palaeoclimatology, Palaeoecology 454 (2016) 30–53

31

Fig. 1. (A) Location of Egypt in Africa, (B) location of the study area in Egypt and (C) the distribution of the measured sections in the study area. Modified from El Ayyat and Obaidalla (2013).

age determination for the studied sequence, aiming to construct an accurate biostratigraphical zonal scheme. This scheme is used to detect the syn-depositional tectonism of the Early Paleogene; 2) redefine and correlate the Early Paleogene lithostratigraphic subdivisions in northeastern Egypt from Saint Paul Monastery in the north to Gebel Millaha in the south; 3) provide a general view of the sedimentological model as well as reconstruct the depositional history of the slope to basin transect for the study area; and 4) discuss the relationship between the tectonic events identified and the development of the basin, its tectonic history and global events.

2. Materials and methods An area extending between 32° 00′, 33° 30′ East and 27° 30′, 29° 00′ North, west of the Gulf of Suez in Egypt has been chosen and subjected to detailed stratigraphical and sedimentological studies. Four stratigraphical sections have been measured and described in detail bed by bed (Fig. 1). The vertical sample distance varies between 20 cm in shales to more than 1 m in carbonates, depending on the general condition of the outcrop and the degree of alteration. About 200 samples have been taken mainly for detailed thin section analysis. Extra polished cut slabs

32

A.M. El Ayyat, N.A. Obaidalla / Palaeogeography, Palaeoclimatology, Palaeoecology 454 (2016) 30–53

Table 1 Lithostratigraphic correlation of the different proposed rock units of Early Paleogene in north Eastern Desert and surrounding areas.

}

(10 × 15 cm) have been sawn, polished and photographed. For more reasonable results, quantitative analysis was performed by estimation of components and matrix, using the comparison charts of Baccelle and Bosellini (1965) and Schäfer (1969). Staining technique of Katz and Friedman (1965) has been used to differentiate the dolomites. The identification of planktonic foraminiferal taxa is based on Pearson et al. (2006). General legend for symbols used in study is presented in Fig. 2. Carbonate depositional textures following Dunham (1962) and Embry and Klovan (1971) and water energy index (EI) following Plumley et al. (1962) have been applied (Figs. 3-6). Photomicrographs of thin sections have been taken with a camera Zeiss MC 80. Paleoecologic interpretation and basin evolution have been attempted based on the fossil content, litho- and microfacies associations, tectonic behavior of the region and previous related studies. Information from Early Paleogene successions in adjacent areas have been integrated and compared to elucidate the paleogeographic setting of the studied basin and to reconstruct a more precise depositional history. These data form the basis of the regional interpretation of uplift, erosion, sedimentation and renewed subsidence by throwing more light on the syn-depositional tectonism. 3. Stratigraphical setting The Southern Galala is located in the north Eastern Desert and extends from the Gulf of Suez in the northeast inward into the Eastern

Desert due to southeast. By its position, it represents the southern flank of Wadi Araba (Fig. 1). It is an isolated Maastrichtian to Eocene carbonate platform at the southern margin of the Tethys, which is referred to as the unstable shelf of Egypt (Said, 1990). The tectonic activity of Wadi Araba, which forms part of the SAO, contributes significantly in the geological evolution of Eocene carbonate platform (Hussein and Abd-Allah, 2001). Traveling southwest, the basinal succession of the stable shelf comprises a paleobathemetry of up to 600 m (Speijer and Wagner, 2002). The Early Paleogene Galala Mountains are tectonically and depositionally linked to the monoclinal structure of Gebel Somar on west-central Sinai (Moustafa and Khalil, 1995). Both structures were separated during the rifting of the Gulf of Suez in the Late Oligocene and Miocene (Höntzsch et al., 2011). The Early Paleogene sedimentary succession of the Southern Galala includes two rock units, which differ in their stratigraphic range and varying depositional setting within an inner shelf to basin transect. The Esna Formation represents an interval of uppermost Paleocene to Lower Eocene basinal marl and shale of a palaeodepth ~ 200 m (Scheibner et al., 2001). It is followed by alternating chalky marl, dolomitized limestone, chert and calcareous sandstone of the Thebes Formation (Hermina and Lindenberg, 1989), coinciding roughly with the initial occurrence of chalky marl in the Lower Eocene succession of the Galala Mountains. Several authors (e.g., Hermina and Lindenberg,

A.M. El Ayyat, N.A. Obaidalla / Palaeogeography, Palaeoclimatology, Palaeoecology 454 (2016) 30–53

33

and seems to have been governed by the Late Paleocene paleorelief. Several minor and major erosive discontinuity surfaces are recorded within the Thebes Formation, especially at Gebel Millaha and Wadi El Dakhal sites. In the study area, the Thebes Formation consists primarily of laminated to thinly-bedded fine-grained limestone, dolomitized limestone and chalk. Scattered nodules, concretions or bands of chert (flint) can be found throughout, but tend to be most common in its upper part. In general, the carbonate beds lack biogenic sedimentary structures and megafossils are relatively absent. The deposition of the northern sections took place within a marine basin of primarily neritic depths with intermittent rapid deeper water sedimentation. On the contrary, at the extreme south, the thinly-bedded, papery and laminated nature of rocks with planktonic foraminifera, coupled with the scarcity of benthic fossils suggests that the Thebes Formation was formed as a hemipelagic deposit in deep, quiet settings of very low energy environment. Exposures at Gebel Millaha and Wadi El Dakhal sites exhibit slump and slide structures of different types (Plate I5, 6). The formation of shallow water environments and slopes steep enough to generate slump structures may be the result of Early Eocene uplift of fault blocks. This would allow carbonate platform sediments to coexist adjacent to deeper basinal sediments and periodically be deposited downslope into the basin. This heterogeneous accumulation of carbonate lithologies is indicative of progressive shallowing and outward progradation of shallow water depositional environments. On a regional scale, the stratigraphy of the studied succession in the south (e.g. at north Wadi Qena, Plate I7), is represented by complete Upper Cretaceous–Lower Paleogene rocks. On contrary, in the north (e.g. at Saint Paul, Plate I8), the stratigraphy is represented only by the upper part of the Dakhla Formation, followed unconformably by the thinly-bedded limestone of Thebes Formation. 4. Biostratigraphy

Fig. 2. Legend of symbols used in the present study.

1989; Darwish and El Araby, 1993; Höntzsch et al., 2011) have proposed many formational names for the Thebes Formation under study (Table 1). Accordingly, difficulties have been emerged during the interpretation of the stratigraphic position and thickness of the Thebes Formation. Such problems have hampered the reconstruction of the depositional history and facies framework and resulted in a somewhat confusing picture, with discrepancies hindered the recognition of sedimentary sequences and events common to the entire area of northern Egypt. The Thebes Formation (Said, 1962) gained acceptance and wide usage to describe the Lower Eocene rocks in Egypt. Being the main subject of the present study, the Thebes will be retained as a formational name to designate the Lower and Middle Eocene facies under study despite the fact that this name has been elevated to group level by the authors of the new geological map of Egypt. The Thebes Formation rests conformably to unconformably (Fig. 7) over the laminated shale and marl of the underlying Dakhla and Esna formations (Plates I2, 3, 4). The unconformable contact is of great extension

The biostratigraphy of Thebes Formation (Figs. 8 and 9) herein is based on the study of the planktonic foraminiferal fossils and follows the zonal scheme of Wade et al. (2011) for the Ypresian–Lutetian age (Fig. 10). According to the important planktonic foraminiferal taxa (Plates II and III), four zones have been defined, in stratigraphic order are: Morozovella aragonensis/Morozovella subbotinae, Acarinina pentacamerata, Acarinina cuneicamerata of Ypresian age and Globigerinatheka kugleri/M. aragonensis of Early Lutetian age. They unconformably rest on the Early Danian Praemurica inconstans (P1c) Zone, the Latest Thanetian Morozovella velascoensis (P5) Zone and the Early Ypresian M. subbotinae (E3) Zone at Saint Paul, Wadi El Dakhal and Gebel Millaha, respectively. On contrary, these zones rest conformably on the late Early Ypresian M. formosa (E4) Zone at north Wadi Qena. 4.1. M. aragonensis/M. subbotinae (E5) Zone It was originally defined by Berggren and Pearson (2005) as a concurrent range zone to cover the interval from the LO of M. aragonensis (Nuttall) and the HO of M. subbotinae (Morozova). This zone is defined over all the study area. It is conformably overlain by the A. pentacamerata Zone of late Middle Ypresian age at north Wadi Qena section, but it is unconformably overlain by A. cuneicamerata Zone of Late Ypresian age at the remainder sections. 4.2. A. pentacamerata (E6) Zone It was originally defined by Berggren and Pearson (2005) as a partial range zone of nominate taxon to cover the interval between the HO of M. subbotinae (Morozova) and the LO of A. cuneicamerata (Blow). This zone is only defined at north Wadi Qena and is overlain conformably by the A. cuneicamerata Zone of Late Ypresian age. At the remainder

34

A.M. El Ayyat, N.A. Obaidalla / Palaeogeography, Palaeoclimatology, Palaeoecology 454 (2016) 30–53

Fig. 3. Vertical distribution of the main components, depositional textures, energy index (EI) and sedimentary environments of the Thebes Formation at Saint Paul section (legend in Fig. 2).

A.M. El Ayyat, N.A. Obaidalla / Palaeogeography, Palaeoclimatology, Palaeoecology 454 (2016) 30–53

35

Fig. 4. Vertical distribution of the main components, depositional textures, energy index (EI) and sedimentary environments of the Thebes Formation at Wadi El Dakhal section (legend in Fig. 2).

sections, A. pentacamerata Zone is absent because of a hiatus at the Middle/Late Ypresian boundary. 4.3. A. cuneicamerata (E7) Zone It was originally defined as lowest occurrence zone by Berggren and Pearson (2006) to mark the Late Ypresian between the LO of the nominate taxon and the LO of Guembelitrioides nuttalli (Hamilton). Berggren and Pearson (2006) also used G. nuttalli (Hamilton) as a marker for the Earliest Lutetian and defined the Ypresian/Lutetian boundary at the A. cuneicamerata/G. nuttalli zonal boundary. Recently, Molina et al. (2011), in their study on the GSSP of Ypresian/Lutetian boundary in Spain, subdivided E7 Zone (= A. cuneicamerata Zone) into three subzones namely: Acarinina bullbrooki at the base, Turborotalia frontosa at the middle and Morozovella gorrondatxensis (partim) at the top. At the same time, Wade et al. (2011) subdivided the

A. cuneicamerata (E7) Zone into two subzones namely: A. cuneicamerata at the base and T. frontosa at the top. All of them placed the Ypesian/ Lutetian boundary within the lower part of the T. frontosa Subzone. With respect to the G. nuttalli taxon, Wade et al. (2011) and Molina et al. (2011) used its LO as a marker for the lower boundary of E8 Zone (=G. nuttalli Zone) at higher stratigraphic level than the Ypresian/ Lutetian boundary. In the present study, the Latest Ypresian A. cuneicamerata (E7) Zone is defined all over the study area and is overlain unconformably by the G. kugleri/M. aragonensis Zone of Early Lutetian age at Wadi El Dakhal and north Wadi Qena. At Saint Paul and Gebel Millaha sites, this zone occupies the uppermost part of Thebes Formation. Stratigraphically and according to the successive LOs of the nominate taxa the A. cuneicamerata Zone has been subdivided here into three subzones: A. cuneicamerata, Astrorotalia palmerae and T. frontosa.

36

A.M. El Ayyat, N.A. Obaidalla / Palaeogeography, Palaeoclimatology, Palaeoecology 454 (2016) 30–53

Fig. 5. Vertical distribution of the main components, depositional textures, energy index (EI) and sedimentary environments of the Thebes Formation at north Wadi Qena section (legend in Fig. 2).

4.3.1. A. cuneicamerata (E7a) Subzone It is here defined as a lowest occurrence subzone to cover the interval from the lowest occurrence of the nominate taxon to the LO of A. palmerae (Cushman and Bermŭdez). It is equivalent to the lower part of both A. bullbrooki Subzone of Molina et al. (2011) and A. cuneicamerata Subzone of Wade et al. (2011). It is

overlain conformably by the A. palmerae Subzone of Late Ypresian age. 4.3.2. A. palmerae (E7b) Subzone It was originally defined by Berggren et al. (1995) as a lowest occurrence subzone to define the interval from the LO of the nominate taxon

A.M. El Ayyat, N.A. Obaidalla / Palaeogeography, Palaeoclimatology, Palaeoecology 454 (2016) 30–53

37

Fig. 6. Vertical distribution of the main components, depositional textures, energy index (EI) and sedimentary environments of the Thebes Formation at Gebel Millaha section (legend in Fig. 2).

to the LO of Hantkenina nuttalli Toumarkine to cover the Latest Ypresian interval. The HO of A. palmerae (Cushman and Bermŭdez) lies stratigraphically at lower level than the Ypressian/Lutetian boundary (Wade et al., 2011). This subzone is defined here as a lowest occurrence subzone to cover the interval from the LO of A. palmerae (Cushman and Bermŭdez) to the LO of T. frontosa (Subbotina). Molina et al. (2011) at the GSSP of the Ypressian/Lutetian boundary (Spain) used T. frontosa (Subbotina) to cover the Latest Ypresian–Earliest Lutetian interval

from its LO to LO of G. nuttalli of the Early Lutetian. It is equivalent to the upper part of both A. bullbrooki Subzone of Molina et al. (2011) and A. cuneicamerata Subzone of Wade et al. (2011). It is overlain conformably by the T. frontosa Subzone of Latest Ypresian age. 4.3.3. T. frontosa (E7c) Subzone This subzone was originally defined by Wade et al. (2011) as a lowest occurrence zone to cover the stratigraphic interval from the LO of the

38

A.M. El Ayyat, N.A. Obaidalla / Palaeogeography, Palaeoclimatology, Palaeoecology 454 (2016) 30–53

Fig. 7. Spatial and temporal distribution of the Thebes Formation and the nature of its contacts with the underlying Esna and Dakhla formations along the NNE–SSW correlation trend.

nominate taxon to the LO of G. nuttalli (Hamilton). T. frontosa (Subbotina) is defined here from the uppermost part of Thebes Formation, which represents the Late Ypresian age all over the study area. The upper boundary of T. frontosa (Subbotina) is marked by the occurrence of a hiatus which led to absence of the transition interval between the Ypresian and Lutetian time at Wadi El Dakhal and north Wadi Qena. It is equivalent to the lower part of the T. frontosa Subzone of both Molina et al. (2011) and Wade et al. (2011). It is overlain unconformably by G. kugleri/M. aragonensis Zone of Early Lutetian age.

5. Sedimentology Based on the characteristic lithology, fauna and sedimentary structures, eight facies belts have been identified. They fashioned nearly in east–west parallel belts on a gently south-southwest dipping ramp, which intersect the western shoulder of the Gulf of Suez (Figs. 3–6, Table 2).

5.1. Open marine facies belt 4.4. G. kugleri/M. aragonensis (E9) Zone It was originally defined by Berggren et al. (1995) as a concurrent range zone of the nominate taxa between the LO of G. kugleri (Bolli, Loeblich and Tappan) and the HO of M. aragonensis (Nuttall). In the present work, G. kugleri/M. aragonensis Zone covers the uppermost part of the Thebes Formation, which represents the Early Lutetian age at Wadi El Dakhal and north Wadi Qena (Figs. 8 and 9). Accordingly, the upper boundary of this zone is approximately coincides here with the upper surface of Thebes Formation at these localities.

It has been recorded in the central part at north Wadi Qena and Wadi El Dakhal localities (Figs. 4 and 5). It consists of laminated to thinlybedded, fine-grained limestone (Plate I1). Scattered nodules or concretions of flint are common. Rhythmic bedding is the most striking feature, which marked by alternations of clay-rich and clay-poor sediment. In thin section, this facies contains well-preserved planktonic foraminifera (5–17%) in limemudstone and wackestone depositional textures. These components are embedded in argillaceous micrite, which shows different degrees of recrystallization (Plate IV1).

Plate I. 1) 2) 3) 4) 5) 6) 7) 8)

Bioclastic and dolomitic limestone of the Thebes Formation interbedded with flint nodules and lenses. North Wadi Qena section. Phosphatic irregular contact between the Thebes Formation and the underlying Dakhla Formation. Saint Paul section. Gradational contact between the Thebes Formation and calcareous shale to marl of the underlying Esna Formation. North Wadi Qena section. Irregular contact between the Thebes Formation and the underlying shale of the Esna Formation. The contact rests directly on red paleosol horizon. The underlying shale is structurally deformed. Gebel Millaha section. Graded calcareous sandstone (fining upward) at the base of the Thebes Formation (white arrows) overlying unconformably calcareous shale of the Esna Formation. Soft sediment deformation on the right of photo scale (scale height = 4 cm). Wadi El Dakhal section. Slump channel lag deposits at the lower part of Gebel Millaha section. The basal part of the structure is phosphatic with scattered collophane grains. Complete Upper Cretaceous-Paleogene succession at southwestern parts (north Wadi Qena). Sudr Formation (Campanian/Maastrichtian) at the base and Thebes Formation (Early to Middle Eocene) at the top. Thin to medium bedded limestone of the Thebes Formation in a deformed tilted block. Saint Paul section.

A.M. El Ayyat, N.A. Obaidalla / Palaeogeography, Palaeoclimatology, Palaeoecology 454 (2016) 30–53

39

40

A.M. El Ayyat, N.A. Obaidalla / Palaeogeography, Palaeoclimatology, Palaeoecology 454 (2016) 30–53

The thin-bedded to laminated nature implies deposition in a low energy depositional environment. The abundance of planktonic foraminifera and scarcity of benthic fossils suggest deposition in deep calm water, in an open marine environment, normally below the range of current activity. The rhythmic bedding may be caused by fluctuations in the depositional environment, including variations in siliciclastic input and water depth. The most conspicuous microfacies types include foraminiferal limemudstone to bioclastic foraminiferal limemudstone to wackestones, which accumulated in low energy to intermittently agitated water conditions ((EI = I to II, Figs. 4 and 5).

responsible for the formation and fabric of the nummulites bank. The nummulites bank has little associated micro- or macrofauna, suggesting that deposition took place in a nutrient-poor (oligotrophic) environment. Imbrication of nummulites changed from isolate to chaotic stacking upward, suggesting an increase in energy due to shallowing and a change from current to wave-dominated processes (Aigner, 1983). The nummulites bank was deposited in intermittently to slightly agitated (EI = II to III) water conditions (Table 2).

5.2. Slope facies belt

It is exposed only at Gebel Millaha section (Fig. 6) as reddish gray, lenticular, bedded foraminiferal grainstone (0.3 to 0.9 m thick). Lower contact is sharp and erosive, whilst upper one is gradational. Beds are often massive or contain only parallel laminations. Worn and abraded foraminifera (37–52%) and bioclasts (8–13%) are the main components cemented by blocky sparite (Plate IV4). Many of the bioclasts show over packing and micritization with good sorting and absence of carbonate mud. Such shoal facies is common in middle shelf settings (Wilson and Jordan, 1983). The foraminiferal grainstone reflects a gradual increase from low-energy tidal flats northwards to high-energy shoal conditions on a carbonate shelf southwards. Planktonic foraminifera are very susceptible to mechanical breakage during transport. During his study on the Thebes Formation in the Red Sea region, Snavely et al. (1979) recorded cross-bedded planktonic foraminiferal lime sand that had been winnowed and concentrated as a result of current action. The lack of interparticle fines suggests deposition in a relatively high-energy environment. Packing of foraminiferal tests is probably a result of early solution. The most common microfacies (Table 2) is represented by bioclastic foraminiferal grainstone, which accumulated in slightly agitated water conditions (EI = III).

It occurs at Gebel Millaha and Wadi El Dakhal sites, where it crops out at the upper part of the Thebes succession (Figs. 4 and 6). Three different types of slump and slide structures could be differentiated: 1) slump-folded beds (Plate I5); 2) slide blocks rest on large intraformational truncation surface; and 3) slump channel lag deposits (0.2 to 0.5 m thick, Plate I6). The main components are represented mainly by collophane grains (5–8%); lithoclasts (9–17%); quartz grains (14–18%); planktonic foraminifera (29–44%) and bioclasts (18–25%) embedded in a mixture of sparite and micrite. Grain size of these components ranges from fine to medium sand (Plate IV2). The syn-sedimentary slump and slide could be developed by down slope, short periods of catastrophic gravitational sliding and slumping on a steep ramp which was subjected to tectonic subsidence and progressive tilting. The bedding is intensively deformed, suggesting plastic deformation during transport. McIlreath and James (1979) suggested that extensive syn-sedimentary distortion of bedding can be developed by creep in thin to very thin- bedded, upper basinal slope peri-platform lime mudstone. Syn-sedimentary slumping is particularly conspicuous in the Thebes Formation beds (Bandel and Kuss, 1987; Keheila, 2000), where it is largely related to topographic slopes inherited from the prevailing nummulites bank and shoal complex. Slump channel lag deposits, commonly interpreted to have been transported by debris flows, which confined to relatively narrow, erosional channels with little evidence of meandering (Plate I6). Turbidity currents and debris flows appear to be the dominant transport mechanisms for the down slope movements of coarse detritus on carbonate slopes. Examples of folded slump deposits are described from the Permian Bell Canyon and Cherry formations, west Texas and New Mexico by Rigby (1958). Quite to intermittently agitated water conditions (EI = I to II) controlled the deposition of this facies (Table 2). 5.3. Nummulites bank facies belt It crops mainly out at Saint Paul and Wadi El Dakhal (Figs. 3 and 4). The bank possesses a sheet- like or very low amplitude bank-like geometry. Generally, it is medium to thick-bedded (0.9 to 3 m thick) nummulites rudstones and floatstones (Plate IV3). The fauna consist exclusively of nummulite tests (73–91%). The smaller A-forms dominate over the larger B-forms with bimodal grain size distribution. Faunal elements other than nummulites include echinodermal fragments and bioclasts of pelecypods (6–12%). A variety of physically controlled structures can be observed such as erosional and scoured contacts between beds; erosive pockets and pot holes filled with rudstones and floatstones; densely packed and edgewise imbricated nummulite accumulation and sheets of nummulites rudstones. The nummulites bank developed in two successive stages. The first stage (Early Eocene) has been recorded at Saint Paul (Boukhary et al., 1998), but the second one (Middle Eocene) has been recorded at the top of Wadi El Dakhal section. Nummulites development is optimal in well-aerated, warm and shallow water (Blondeau, 1972). Such conditions are likely to have predominated on top of a submarine swell (represented by isolated local horsts formed as a result of block faulting). Biological (reproduction) and physical (winnowing by storms) processes are thought to be

5.4. Shoal facies belt

5.5. Back-bank/lagoonal facies belt It is well exposed at Saint Paul and Wadi El Dakhal (2.5 to 6 m thick, Figs. 3 and 4). It crops out as hard, medium to thick-bedded, laminated, distinctly caverneous, dark gray limestone. Bioturbated wackestones and packstones dominate the sequence, but mudstones are also abundant. Components are represented by fragmented nummulites (8–12%), orbitolites (6–11%), miliolids (6–9%), green algae (9–14%), operculines (3–6%), alveolines (9–13%), textularid foraminifera (4–7%), quartz grains (4–8%), fine bioclasts (14–21%) and peloids (13–15%) of different shapes and nearly same size are scattered in the micrite (Plate IV5). Most components show micritization and/or micrite coating. The sedimentological characteristics, stratigraphic position and fauna suggest deposition in semi-restricted environment – a lagoon – probably with low current activity, where most of muds were laid down from suspension (Table 2). The incursions of siliciclastics into back-bank/lagoonal environment are probably due to mild distant tectonic uplift and erosion or climate change on a distant landmass (might be Wadi Araba uplift) due to north of the studied localities (Fig. 1). The Eocene genus (alveolines) assumed to thrive in fore- and back-reef zones; prolific growth of this form is possible in clear protected areas in the back-reef regions (Ghose, 1977). Operculines have been reported from the deeper parts of lagoons where the water is quiet (McKee et al., 1959). Textularid foraminifera are common in the lagoon, back-reef regions and nearshore areas, while near-reef areas are rich in miliolids (Newell, 1956). The abundance of dasyclads, peloids, alveolines and fragmented nummulites suggests sedimentation on a marine carbonate platform in a lagoonal-back bank setting with tropical, warm, clear, and shallow waters showing a slight tendency towards hypersalinity. Biofacies comparable to the Egyptian assemblage are known in Tunisia offshore (Bismuth and Bonnefous, 1981); Oman (de Bourdillon, 1988); Iraq (Al Hashimi, 1975). The sediments of this facies have been accumulated in intermittently agitated water conditions

A.M. El Ayyat, N.A. Obaidalla / Palaeogeography, Palaeoclimatology, Palaeoecology 454 (2016) 30–53

41

Fig. 8. Biostratigraphic ranges of the important planktonic foraminiferal species at Saint Paul and Wadi El Dakhal sections.

(EI = II) and comprising several microfacies such as quartzose foraminiferal pelloidal wackestone to packstone, alveolines nummulites wackestones to packstone and orbitolites bioclastic foraminiferal wackestones.

5.6. Shallow subtidal facies belt It crops out in the middle and southwestern parts as thin to mediumbedded, whitish to grayish white, chalky limestone, moderately indurated

Fig. 9. Biostratigraphic ranges of the important planktonic foraminiferal species at north Wadi Qena and Gebel Millaha sections.

42

A.M. El Ayyat, N.A. Obaidalla / Palaeogeography, Palaeoclimatology, Palaeoecology 454 (2016) 30–53

Fig. 10. Biocorrelation diagram for each of the three tectonic episodes showing the distribution of the main planktonic foraminiferal biozones. Biozones and age assignment are based on Wade et al. (2011).

with scattered chert nodules and lenses (5–8 cm in diameter). Graded laminations are recorded at some levels, sometimes disrupted by strong bioturbation. Fauna are sparse with low diversity (Plate IV6) and represented mainly by fragmented and intact planktonic forams (3–10%), ostracods (1–3%) and fine bioclasts of silt size (up to 17%) embedded in slightly dolomitized micrite matrix. Limemudstones and wackestones are predominant, but packstones and grainstones, with erosional lower contacts, are frequently encountered (Table 2). The absence or scarcity of this facies due to north is attributed to the general shallowing in that direction (nearshore). The sparsely fossiliferous lime mudstones and wackestones reflect deposition in a moderately shallow, low-energy subtidal setting on an open carbonate shelf. The presence of fossiliferous packstone and grainstone beds with erosional lower contacts may reflect high-energy events that disrupted substrates and deposited planktonic coquina as lags. The most common microfacies are dolomitized bioclastic limemudstone, bioclastic foraminiferal wackestone and foraminiferal wacke/packstone. This facies was deposited under quite to intermittently agitated water energies (EI = I to II).

thick). It is composed of grayish white, large-scale even, thinlybedded, pure and dolomitized limestone with chert nodules (Plate I8). In thin section, it consists of fine-grained, pelletal limemudstone showing slight to moderate dolomitization. Very few fossils, represented mainly by fragmented planktonic chambers (5–11%). Plant remains are recorded at certain levels (Plate IV7). Vertical bioturbation tubes are common at certain levels. This facies belt is considered as a part of wide inner shelf environment. Restriction in fauna may reflect stressful environmental conditions. The fragmented planktonic fauna cannot be used as indicators for recognizing the depositional environment but are considered as bio- and lithoclasts because of bad preservation (due to worn and external abrasion); fragmentation into isolated chambers and filling of some chambers with dark lime-mud, coarse crystalline calcite or dolomite, collophane or silica. Bioclastic limemudstone, foraminiferal limemud/ wackestone and bioclastic wackestone are the predominant microfacies types. The sediments of this facies were accumulated in quite water conditions (EI = I) with short intervals of intermittently agitated (EI = II) water conditions.

5.7. Intertidal flat facies belt

5.8. Supratidal facies belt

It is represented all over the focus area (Figs. 3-6) and increases in thickness due to north, where it measures nearly 38 m at Saint Paul locality. On contrary, it decreases in thickness at Gebel Millaha (6 m

It crops out at Gebel Millaha locality, mostly underlying unconformity surfaces (Fig. 6). Prevailing rock types are yellowish gray, interlaminated dolomite and dolomitic limestone, thick bedded (1–6.5 m thick), hard

A.M. El Ayyat, N.A. Obaidalla / Palaeogeography, Palaeoclimatology, Palaeoecology 454 (2016) 30–53

and moderately porous. Irregular laminations with cracks and/or microfolds are common. Randomly distributed bubble-shaped fenestral voids are common (Plate IV8). The rock is composed of dolomite rhombs, which can be differentiated into two types. The first type is represented by fine-grained rhombs ranging from 10 to 50 μm with lime mud matrix. The dolomite rhombs do not develop zoning but have a cloudy appearance due to the presence of very fine opaque inclusions. The second type is less abundant and ranges in size from 90 to 200 μm and is hypidiotopic to xenotopic in fabric. Where sediment has been totally dolomitized, the rhombic shape of the dolomite crystals in thin section may no longer be apparent. Birdseye vugs, generally the bubble-like variety, may occur in the lower supratidal and/or upper intertidal zone in those areas where algal mats are lacking. The first type of fine-grained dolomite rhombs was originally laid down as micrite, deposited in supratidal zone of marginal marine environment. The second type of coarse dolomite rhombs is a probably neomorphic product of the fine ones (Sibley and Gregg, 1987). The petrographic evidences confirm the replacement (secondary) origin for dolomite in the study area. These evidences are: 1) different sizes of the dolomite crystals are in the range 10–200 μm. These grain sizes are typically characteristic of dolomite of secondary origin (Friedman and Sanders, 1987); 2) the predominance of the subhedral to euhedral shape of the grains substantiates the secondary origin; and 3) obliteration of the original features and structures due to the dolomitization process adds further evidence. In the study area, it is believed that during compaction, the swelled smectite which is a major clay mineral component of the underlying Esna Formation, may convert into the unswelled more stable illite with release of Mg2+ (McHargue and Price, 1982). This clay conversion might result in mass dolomitization of the overlying carbonates (the Thebes Formation, Table 2). Recorded microfacies are represented by dolomitized bioclastic mudstone and fenestral dolomitized limemud/wackestone. These microfacies types were accumulated in quite water conditions (EI = I).

6. The syn-depositional tectonic events and basin evolution Event stratigraphy is an excellent tool for subdividing stratigraphic records and establishing high resolution correlations between coeval successions of different depositional settings in a sedimentary basin (Martin-Chivlet and Chacon, 2007). It is particularly useful for: 1) the analysis of thick, relatively homogeneous, deep marine successions, where sea level changes are not clearly recorded and biostratigraphic studies are incompatible with high resolution stratigraphy; and 2) detailed correlations between such homogeneous successions and their correlative shallow marine sequences, in the absence of a well preserved platform to basin transition. Many authors (e.g. Hussein and Abd-Allah, 2001) believe that the geological history of the Egyptian Paleogene was dominated by tectonic events, which have been continued steadily or episodically into the Paleogene from Late Cretaceous tectonism. Kuss (1989) pointed to Paleocene–Early Eocene uplift and related it to the later graben forming processes of the Red Sea/Gulf of Suez. Abu Khadra et al. (1994) recorded syntectonic events of Early and Middle Eocene age in the Southern Galala and suggested that the central part of the Gulf of Suez was tectonically active site during the Eocene epoch. Integrated facies analysis and biostratigraphic studies demonstrated that the long term stratigraphy of the studied sequence is punctuated by three regional tectonic phases of the SAO (Figs. 10 and 11), which induced rapid changes in palaeogeography and regional tectonics. Each phase configured a new genetic scenario for sedimentation, which lasted until the next tectonic reorganization and, in turn, controlled the deposition of the stratigraphic record. The ages of these events have been determined as: Danian/Early Ypresian, Middle–Late Ypresian and Early Lutetian (Table 3). Facies analysis permitted the characterization of sedimentary environments and their changes throughout the investigated area. Moreover, the biostratigraphic studies, mainly based on the distribution of planktonic foraminifera (Fig. 10), have allowed the precise age dating

Plate II. (see on page 44) 1–3) Turborotalia frontosa (Subbotina, 1953): Figs. 1 and 2, north Wadi Qena section, sample no. 42. Fig. 3, Wadi El Dakhal section, sample no. 50. 4, 5) Turborotalia possagnoensis (Toumarkine and Bolli, 1970), north Wadi Qena section, sample no. 50. 6, 7) Acarinina bullbrooki (Bolli, 1957), north Wadi Qena section, sample no. 30. 8, 9) Globigerinatheka kugleri (Bolli, Loeblich and Tappan, 1957), north Wadi Qena section, sample no. 52. 10, 11) Acarinina cuneicamerata (Blow, 1979), Wadi El Dakhal section, sample no. 36. 12) Guembelitrioides nuttalli (Hamilton, 1953), north Wadi Qena section, sample no. 52. 13, 14) Igorina broedermanni (Cushman and Bermúdez, 1949), north Wadi Qena section, sample no. 40. 15, 16) Planorotalites capdevilensis (Cushman and Ponton, 1949), north Wadi Qena section, sample no. 34. 17, 18) Astrorotalia palmerae (Cushman and Bermúdez, 1937), north Wadi Qena section, sample no. 37. 19, 20) Planorotalites pseudoscitula (Gloessner, 1937), Wadi El Dakhal section, sample no. 41. Plate III. (see on page 45) 1) Hantkenina duemblei (Weinzierl and Applin, 1929), north Wadi Qena section, sample no. 59. 2, 3) Morozovella velascoensis (Cushman, 1953), Wadi El Dakhal section, sample no. 3. 4, 5) Morozovella formosa (Bolli, 1957), north Wadi Qena section, sample no. 3. 6, 7) Morozovella aragonensis (Nuttall, 1930), Gebel Millaha section, sample no. 20. 8, 9) Morozovella subbotinae (Morozova, 1929), Gebel Millaha section, sample no. 2. Globigerinatheka subconglobata (Shutskaya, 1958), Wadi El Dakhal section, sample no. 58. 11, 12) Acarinina praetopilensis (Blow, 1979), north Wadi Qena section, sample no. 50. 13: Praemurica inconstans (Subbotina, 1953), Saint Paul section, sample no. 2. 14, 15) Acarinina pentacamerata (Subbotina, 1947), north Wadi Qena section, sample no. 26. 16) Subbotina senni (Beckmann, 1953), north Wadi Qena section, sample no. 49. 17, 18) Acarinina rohri (Brönnimann and Bermúdez, 1953), north Wadi Qena section, sample no. 55. 19, 20) Subbotina hagni (Gohrbandt, 1967), Wadi El Dakhal section, sample no. 57.

43

44

A.M. El Ayyat, N.A. Obaidalla / Palaeogeography, Palaeoclimatology, Palaeoecology 454 (2016) 30–53

Plate II. (caption on page 43).

A.M. El Ayyat, N.A. Obaidalla / Palaeogeography, Palaeoclimatology, Palaeoecology 454 (2016) 30–53

Plate III. (caption on page 43).

45

46

A.M. El Ayyat, N.A. Obaidalla / Palaeogeography, Palaeoclimatology, Palaeoecology 454 (2016) 30–53

Table 2 Summary of the most diagnostic features of the different types of depositional environments. Facies belt

Occurrence

Thickness

Description

Interpretation

Open marine facies

At north Wadi Qena and Wadi El Dakhal sites.

14 to 31 m thick.

Continental slope facies

At Gebel Millaha and Wadi El Dakhal sites, (the upper part of the Thebes Formation).

3.5 to 10.5 m with an increase due to north.

Thin-bedded to laminated nature implies a very low energy environment. The scarcity of benthonic fossils suggests a hemipelagic deposition in deep calm water, in an open marine site, normally below the range of current activity. Abundance of chert may be a function of the volume of silica available in the sediment or could reflect a greater amount of diagenesis and dissolution of silica from the sediment. Planktonic foraminifera theoretically could live anywhere in the sea but are most numerous away from shore over deep water due to less competition from benthonic organisms for nutrients. Quite to intermittently (EI = I to II) agitated water conditions controlled the deposition of this facies. Slump and slide beds may be developed by down slope, short periods of catastrophic sliding and slumping on a steep ramp which was subjected to tectonic subsidence and progressive tilting. The bedding is intensively deformed, suggesting plastic deformation during transport. Turbidity currents and debris flows appear to be the dominant transport mechanisms for the down slope movements of coarse detritus on carbonate slopes. Quite to intermittently (EI = I to II) agitated water conditions controlled the deposition of this facies.

Nummulites bank facies

At Wadi El Dakhal and Saint Paul sites.

0.9 to 3 m thick.

Shoal facies

It is exposed at Gebel Millaha site.

0.30 to 0.90

Laminated to thinly bedded, fine-grained limestone and chalky limestone. Scattered nodules or concretions of flint (chert) can be found throughout, but tend to be most in its upper portion. The most striking structures are rhythmic bedding between clay rich and clay poor sediment or by zones of chert nodules and fine plane laminations. It consists of well-preserved planktonic forams and bioclasts forming mudstones and wackestones. Components are embedded in argillaceous micrite, which recrystallized later into microsparite. 3 types of slump and slide structures: i) slump-folded beds, ii) slide blocks rest on large intraformational truncation surface: iii) slump channel lag deposits. The components include lithoclasts; collophane grains; planktonic forams and bioclasts. Groundmass is a mixture of sparite and micrite. The sediments indicate that the direction of slumping and slopes were oriented towards the centers of basin due south and southwest. A sheet like or very low amplitude bank like geometry. Medium to thick bedded, nummulites rudstones and floatstones. Nummulites occur in rock-forming quantities in massive, poorly bedded bioclastic limestones. The fauna consists of nummulite with smaller A-forms dominate over the larger B-forms. Other sparse fauna include fragments of echinoderms and pelecypodal fragments. Sedimentary structures include erosional and scoured contacts between beds; erosive pockets and pot holes filled with rudstones and floatstones; densely packed and edgewise imbricated nummulite accumulation and sheets of nummulites rudstones. Reddish gray, lenticular-bedded foraminiferal grainstone. Beds are often massive or contain only parallel laminations. Worn and abraded foraminifera and bioclasts are the main constituents cemented by a mosaic of blocky sparite. Many of the bioclasts show over packing and micritization with good sorting. The surface of components is stained with thin film of iron oxides.

Back-bank lagoonal facies

It is well exposed in the northern parts at Saint Paul and Wadi El Dakhal sites.

2.5 to 6 m thick.

Shallow subtidal facies

At the middle 0.75 to 5.5 m and southern thick. localities.

Intertidal flat facies

All studied localities, with increase in thickness due to north.

6 to 38 m thick.

Supratidal

At Gebel

1 to 6.5 m

m thick.

Hard, medium to thick-bedded, laminated, distinctly caverneous, dark gray limestone. Burrow and bioturbation are common. Wackestones and packstones dominate the sequence, but mudstones are also abundant in certain horizons. Components are fragmented nummulite tests, mostly of A-forms, discocyclines, algae, operculines, alveolines, biserial forams, quartz grains and fine bioclasts. Peloids of different shapes and nearly same size are scattered in the micrite. Components show micritization and/or micrite coating. Thin to medium bedded, whitish to grayish white, chalky limestone, with scattered chert nodules and lenses. Horizontal and/or oblique bioturbation is common. Fine-scale, graded laminations are recorded at some levels. Shelly fossils are represented by planktonic forams, ostracods and bioclasts. Several minor and major erosive surfaces are recording within this facies, especially at Wadi El Dakhal locality. Phosphatic foraminiferal packstone and grainstone as condensed horizons overlying erosive surfaces.

Nummulite development is optimal in well aerated, warm and shallow water (predominated on top of a submarine swell). Biological and physical processes are thought to be responsible for the formation and fabric of this facies. Nummulites have little associated micro- or macrofauna, suggesting that deposition took place in a nutrient-poor environment. This facies cannot be considered true reefs since they did not have an organic framework; nor can be described as shoals, which are formed purely by physical processes. The nummulite shells were deposited in intermittently to slightly agitated (EI = II to III) water conditions.

It reflects a gradual increase from low-energy tidal flats to high-energy shoal conditions. Staining with iron oxides may indicate deposition within the shoals after an individual history of formation. The occurrence of polished, intact and broken foraminifera indicates that the fauna has undergone reworking without substantial transport and concentrated by current action. The massive nature of beds may be the result of bioturbation. The blocky calcite cement perhaps is of late diagenetic origin. The most common microfacies is foraminiferal grainstone, which accumulates in slightly agitated water conditions (EI = III). Alveolines are shallow-water forms. They assumed to thrive in fore- and back-reef zones. Operculines have been reported from the deeper parts of lagoons where the water is quiet. Textularid foraminifera are common in the lagoon, back-reef regions and nearshore areas, while near-reef areas are rich in miliolids. The abundance of dasyclads, peloids, alveolines and biserial forams suggests a lagoonal-back bank site with tropical, warm, clear, and very shallow waters with a slight tendency towards hypersalinity. This facies was accumulated in intermittently agitated water conditions (EI = II) and including several microfacies (arenaceous foraminiferal pelloidal wackestone to packstone, alveolines nummulites wackestones to packstone and bioclastic foraminiferal wackestones). Absence of this facies due to north is attributed to the general shallowing in that direction. Laminations may generally result from tides or storm deposition, and the presence of such laminations is indirectly controlled by burrowing organisms. The fossiliferous lime mudstones, wackestones and packstones reflect deposition in a moderately shallow, low-energy subtidal setting on an open carbonate shelf. Packstone and grainstone beds with erosional lower contacts are inferred to reflect high-energy. Features indicative of subaerial exposure are absent, suggesting continuous submergence. This facies was deposited under quite to intermittently water energies (EI = I to II). Depositional textures are represented mainly by lime mudstones and wackestones with high-energy pulses of packstones and packstone/grainstones. It is considered as a part of wide inner shelf environment. Fenestrae are mainly formed by desiccation and shrinkage or air and gas bubble formation. Birdseye vugs, may occur in the upper intertidal zone where algal mats are lacking. Restriction in fauna may reflect stressful environmental condition. It was accumulated in quite water conditions (EI = I) with short intervals of intermittently agitated (EI = II) conditions. Limemudstone is common, but wackestone of short duration is often encountered.

Grayish white, large-scale even, thinly bedded, bioturbated, pure and dolomitized limestone with chert nodules. It consists of fine-grained, dolomitized pelletal limemudstone. Randomly distributed bubble-shaped fenestral voids are common. Very few fossils, represented mainly by fragmented forams are scattered in the groundmass. Plant remains are recorded at certain levels. Vertical burrows destroyed and churned the sediment structures. Yellowish gray interlaminated dolomite and First type dolomite was originally laid down as micrite, deposited in

A.M. El Ayyat, N.A. Obaidalla / Palaeogeography, Palaeoclimatology, Palaeoecology 454 (2016) 30–53

47

Table 2 (continued) Facies belt flat facies

Occurrence

Thickness

Description

Interpretation

Millaha site, occasionally underlying erosive surface.

thick.

dolomitic limestone, thick bedded, hard and moderately porous. In thin section, the rock consists of dolomite rhombs of two types. The first type is fine-grained (10–50 μm) in micrite matrix with idiotopic to hypidiotopic fabric and inequigranular texture. The second one (90–200 μm) with hypidiotopic to xenotopic fabric. Some rhombs show zoning in dark to brownish cores with thin clear outer rims. Some evaporites were leached by weathering leaving pore spaces. Total dolomitization obliterated the rhombic shape of the dolomite crystals.

supratidal zone of marginal marine environment. The second type is a probably neomorphic product of the fine one. Evaporites are often present during the dry season but disappear during the wet season. The petrographic evidences confirm the replacement origin for dolomite because of the different sizes of crystals is in the range 10–200 μm; subhedral to euhedral shape of the grains and obliteration of the original features. During compaction, the swelled smectite of the underlying Esna Formation converted into the unswelled stable illite with release of Mg2+. This clay conversion led to mass dolomitization of the overlying carbonates of the Thebes Formation.

for the studied successions. The recorded tectonic episodes have been characterized (Table 3), dated and correlated (Fig. 12). The same event can be traced at different locations in the basin as a sedimentary bed; as an unconformity; as a hiatal surface; or as a rapid change in the sedimentary facies or fossil assemblages. Such events can also cause abrupt changes in sedimentation, ecology, biology, geography and accommodation. There are many evidences supporting tectonic unrest in the study area. These evidences are mainly indicated by: 1) the partial missing of the upper part of both Dakhla Formation at Saint Paul and Esna Formation at Gebel Millaha and Wadi El Dakhal localities; 2) complete missing of the Tarawan and Esna formations, which directly overlie the Dakhla Formation at Saint Paul locality (El Ayyat and Obaidalla, 2013); 3) the complete absence of some remarkable planktonic foraminiferal zones at different stratigraphic levels; 4) the major unconformity surfaces between superimposed rock units (i.e. at the contact of Esna and Dakhla with Thebes Formation) as well as within the same rock unit (i.e. within Thebes Formation at Gebel Millaha and Wadi El Dakhal sites); 5) the pronounced changes in the style of sedimentation regimes on the level of rock units (i.e. from shales of Esna to carbonates of the Thebes) as well as in the same rock unit (i.e. from shallower to deeper facies in the Thebes Formation; 6) vertical as well as lateral variations in the thickness of the same rock unit from one locality to another in areas geographically nearby each other; and 7) variations in the age of the Thebes Formation from shallower areas in the north to deeper areas in the south. 6.1. Syrian Arc tectonic phase 1 (Danian–Early Ypresian) It took place at the contact between the Thebes Formation and the fine siliciclastic shales of both the Dakhla Formation at Saint Paul and the Esna Formation at the rest of investigated localities (Fig. 12). By its situation, it represents the oldest tectonic movement (Table 3) and has the most complex and inhomogeneous tectonic and depositional history. It covers areas with long range hiatuses (e.g. Saint Paul) and others with short ranges (e.g. Gebel Millaha) with a remarkable increase in magnitude and duration due to northeast. Around Gebel Millaha site (Fig. 10), the hiatus is indicated by the complete absence of M. formosa Zone spanning nearly 1.7 My, where the Middle Ypresian M. aragonensis/M. subbotinae Zone rests unconformably on the Early Ypresian M. subbotinae Zone. The unconformity surface is marked by the presence of a red paleosol horizon separates between the Thebes and the Esna formations (Plate I4). Accordingly, the basal part of the Thebes Formation is enriched with phosphate grains and reworked lithoclasts forming phosphatic packstone and pack/grainstones. Traveling northward, its time elapse becoming longer, which estimated as nearly 3.3 My at Wadi El Dakhal, whereas the Middle Ypresian M. aragonensis/M. subbotinae Zone rests unconformably on Late Thanetian M. velascoensis Zone. Erosive surface with pronounced relief is cutting erosively into marls and shales of the Esna Formation. Phosphate grains of different sizes scattered into the basal

part of the Thebes Formation directly over the erosive surface. At Saint Paul, this tectonic event records the longest hiatus in the study area (9.1 My), whereas Middle Ypresian M. aragonensis/M. subbotinae Zone rests unconformably on the Middle Danian P. inconstans Zone. Moreover, an irregular surface at the basal part of the Thebes Formation delineates its contact with the underlying Dakhla Formation. The reason for these different depositional histories may lie in the fact that these areas were differently affected by SAO, which led to formation of local horsts and grabens. By the effect of this tectonic event, the floor of the open marine basin of the Esna and Dakhla formations reconfigured to shelf platform of the Thebes Formation. Moreover, the regional pattern of sedimentation suddenly changed from siliciclastic shales to carbonates. Fig. 12 reflects that the construction of the depositional basin of the Thebes Formation was controlled by major and regional subsidence and uplift movements all over north Eastern Desert due to the impact of this tectonic episode. On contrary, the paleorelief of the Thebes basin at north Wadi Qena closely follows that of the Esna Formation. The paleorelief and geometry of that basin is regular, simple, wide and featureless without marked relief except wide and gentle subsidence. Therefore, the Thebes Formation overlies conformably the Esna Formation with a gradational contact, whereas Middle Ypresian M. aragonensis/M. subbotinae Zone rests conformably on the Early Ypresian M. subbotinae Zone. On the scale of sea level changes, at Saint Paul area (Fig. 11), sea level curve of the present area shows a good similarity to the eustatic one (Haq et al., 1987) during the time interval of the Danian P. inconstans Zone at the upper part of the Dakhla Formation. Afterwards, a major fall in sea level took place spanning the Latest Danian to earliest Late Ypresian interval. This event led to drop in sea level and subsequently lowstand conditions controlled the depositional conditions of the uppermost part of the Dakhla Formation and the lowermost part of the Thebes Formation. Here, it could possible to estimate the lower and upper boundaries of this hiatus on exact biostratigraphical investigations, which refers to a long lasting period of non deposition and/or erosion due to uplift (Figs. 11 and 12). The echo of this hiatus is represented by undulating erosional contact separating Dakhla Formation below from the overlying Thebes Formation (Plate I2) with a time duration between 9.1 and 1.7 My (Syrian Arc tectonic phase 1). Around Wadi El Dakhal, the sea level regime and its fluctuations during the Thanetian M. velascoensis Zone are here compared with eustatic curve as given by Haq et al. (1987). Both long and short term eustatic curves of these authors reveal a complete correlation with the relative curve of the studied Esna Formation. A pronounced peak of sea level rise took place during the deposition of open marine Esna Formation. Later on, the highstand conditions are followed, in the present area, by a remarkable drop in sea level from 55 to 51.2 My. Accordingly, Thebes Formation rests on the Esna with an irregular surface, which may refer to a marked tectonic phase (Syrian Arc tectonic phase 1). Comparatively, this gap corresponds to a transgressive episode in Haq et al. (1987) curve, which supports the uplifting of the northern belt of the focus area at both Saint Paul and Wadi El Dakhal sites during that time.

48

A.M. El Ayyat, N.A. Obaidalla / Palaeogeography, Palaeoclimatology, Palaeoecology 454 (2016) 30–53

Plate IV.

A.M. El Ayyat, N.A. Obaidalla / Palaeogeography, Palaeoclimatology, Palaeoecology 454 (2016) 30–53

Highstand conditions at north Wadi Qena promoted the deposition of open marine Esna shale during Early Ypresian (M. formosa Zone). The same conditions of sea level rise continued upward during deposition of the Thebes Formation that overlies conformably Esna Formation (Plate I3). Correlation between short term oscillations on relative curves and their counterparts of eustatic curves of Haq et al. (1987) are constructed. The latter shows five sea level falls of variable decline magnitudes before the onset of Syrian Arc phase 2 (Fig. 11). These falls are correlatable well with six fall peaks on the relative curve of the studied area for the same time interval with a general shallowing up trend. It is apparent that the southern part of the study area at Gebel Millaha was a structural paleohigh. A salient pervasive high area is indicated by a relatively thin section of Eocene sediments (Fig. 6). The structural style of this high area is not clear, whether it is fault ridge or horst block. This view is supported by paraconformities and discontinuities that occur at various levels within the stratigraphic record and used for the interpretation of sequence boundaries (Scheibner et al., 2000). The same is true in areas that are more basinal where the absence of individual subzones suggests an incomplete stratigraphic record. Nearly at 54 My, a drop in sea level took place due to differential movements on fault blocks. This movement led to erosion of the upper part of Esna Formation and the open marine outer shelf of the Esna reconfigured to carbonate platform and slope of the Thebes Formation. Comparing this sea level fall (54 to 50.9 My) with eustatic curves of Haq et al. (1987) shows opposite relationships (Fig. 11), which add more support for local uplift. The first lowstand of the Early Paleocene and its corresponding sequence boundary were interpreted by Kulbrok (1996) and may coincide with that of eastern Sinai. The same author reported two earlier Paleocene sea level falls, also known from outcrops in the Nile Valley (Speijer and Schmitz, 1998), but not discernible in the Galala Plateaus. 6.2. Syrian Arc tectonic phase 2 (Middle–Late Ypresian) This phase (intra-Ypresian) took place at the Middle–Late Ypresian boundary (Table 3). It extends over most of the study area except at north Wadi Qena site (Figs. 10 and 12). Sedimentologically, the record of this event does not reflect the development of a sedimentary disconformity and no well developed hardground has been detected, but increase in bioturbation was observed towards the top of the underlying facies and a rapid rise in the argillaceous content plus small lithoclasts, incorporated in the level of the overlying facies. On contrary, in basinal areas such as the case of north Wadi Qena section, the Middle–Late Ypresian transition has a very complete record and no substantial erosion occurred. Biostratigraphically, it was indicated by the complete absence of A. pentacamerata Zone, where A. cuneicamerata Zone of Late Ypresian overlying unconformably M. aragonensis/M. subbotinae Zone of Middle Ypresian age. This episode lasted for a short time with constant duration (nearly 0.4 My). In spite of its short duration, the presence of this event during deposition of the Thebes Formation indicates clearly that the depositional basin of the later did not enjoy quiescence in spite of the apparent uniformity in sedimentation style.

49

Around 52.3 My, sedimentation started at Saint Paul with a general rise of sea level as indicated by the long term curve that shallowed up slowly. Regardless of a minor deviation, there is a general correspondence (Fig. 11) between the curve of the study area and the eustatic one during the time span from 52.3 to 50.8 My (Middle Ypresian M. aragonensis/M. subbotinae Zone). On the scale of short term oscillations, a regular oscillation in sea level of the study area is correlatable with that on the short term curve. Two remarkable regressive/transgressive peaks on the relative curve of the study area are correlatable well with their counterparts on the eustatic curve. In the focus area, the third upper peak on the eustatic curve counterparts the second Syrian Arc tectonic phase (Middle–Late Ypresian). Afterwards, the sedimentation started again with normal marine conditions due to rise in sea level. From 51.2 to 49.8 My, sedimentation of the Thebes Formation at Wadi El Dakhal was laid down in a morpho-tectonic basin generated as a result of the SAO. This basin interbedded with slump and slide deposits at the lower parts and became shallower upward. Correlation between the relative and eustatic curves (Haq et al., 1987) shows a positive correlation on the long term curves and minor deviations on the short terms (Fig. 11). Generally, sedimentation during this period is characterized by shallowing upward regime punctuated by discontinuities of much shorter duration, which are indicated by the penecontemporaneous reworking of the sediments and the absence of individual subzones resulting in an incomplete stratigraphic record (Scheibner et al., 2000). Afterwards, a regional drop in sea level took place from 50.8 to 50.4 My. This fall in sea level is corresponding to second tectonic phase. Open marine sedimentation started at Gebel Millaha during the period from 52.3 to 50.8 My with a general rise in sea level, which is marked by good correlations between relative and short curves (Middle Ypresian M. aragonensis/M. subbotinae Zone). Four regressive/ transgressive peaks on the relative curve are correlatable well with their counterparts on the eustatic curve. The upper peak, on the eustatic curve, counterparts the second SAO phase (Middle–Late Ypresian). Upsection, normal marine conditions took place with a relatively slow rate of shallowing. 6.3. Syrian Arc tectonic phase 3 (Early Lutetian) During Early Lutetian, the studied area was affected by the last third phase of the SAO. The diastrophic impact of this event is concentrated in the central part at north Wadi Qena and Wadi El Dakhal (Table 3). Its time duration (nearly 3.9 My) is constant all over the studied localities. Its biostratigraphical impact is indicated by the partial absence (upper part) of T. frontosa Zone and complete absence of G. nuttalli Zone, where G. kugleri/M. aragonensis Zone rests unconformably on T. frontosa Zone. The ample lithological impact is represented by condensed sedimentation at the end of the Late Ypresian. Moreover, the depositional regime shallowed upward and changed vertically from outer shelf sedimentation during Ypresian to middle and inner

Plate IV. 1) Planktonic foraminiferal wacke-to packstone of open marine origin. Uneven distribution of components is related to bioturbation. North Wadi Qena section. 2) Quartzose wacke-to packstone of continental slope setting. Most planktonic shells are fragmented with isolated chambers filled with collophane and/or lime mud. Gebel Millaha section. 3) Nummulites pack-to-floatstones of both A and B-forms. The smaller A-forms dominate over the larger B-forms. Edge-wise and imbricated structures are visible. Wadi El Dakhal section. 4) Bioclastic foraminiferal grainstone with worn and abraded shells cemented by blocky sparite. Shoal facies belt. Gebel Millaha section. 5) Quartzose wacke-to packstone of back-bank lagoonal facies. Some components suffered from micritization. Wadi El Dakhal section. 6) Bioclastic foraminiferal wacke-to-packstone. Distribution of components is controlled by bioturbation. Fine dolomite rhombs scattered in the matrix. Shallow subtidal facies. Wadi El Dakhal section. 7) Dolomitized foraminiferal mudstones. Fragmented shells are randomly scattered in dolomitized matrix. Note the well-sided dolomite rhombs replacing the micrite. Photo inset shows plant remains. Intertidal flat facies. Gebel Millaha section. 8) Moderately porous, dolomitic limemudstone containing sparse foraminiferal chambers and fine bioclasts. Polished slab (photo inset) shows randomly distributed bubble-shaped fenestral voids. Supratidal flat facies. Gebel Millaha section.

50

A.M. El Ayyat, N.A. Obaidalla / Palaeogeography, Palaeoclimatology, Palaeoecology 454 (2016) 30–53

Fig. 11. Spatial and temporal impacts of the Syrian Arc tectonic phases as well as relative and eustatic sea level changes in the study area.

shelf in Lutetian. At Saint Paul and Gebel Millaha, sediments belonging to Lutetian age are totally missed. This missing may be attributed to intensive erosion and/or nondeposition by the effect of this event. It is postulated here that the rejuvenation of SAO associated with differential block faulting is the main reason for interpreting such events. Moustafa and Khalil (1995) stated that the age of folding in Wadi Araba and the South Galala Plateau is certainly pre-Middle

Eocene and most probably Late Cretaceous (early Late Senonian and later). Taking the sea level changes in consideration, a relative sea level fall took place from 48.3 to 44.4 My at both Wadi El Dakhal and north Wadi Qena. This fall in sea level is corresponding to third tectonic phase. Subsequently, rise in global sea level led to normal marine sedimentation. Around 50.4 My, the area of Wadi El Dakhal and north Wadi Qena

A.M. El Ayyat, N.A. Obaidalla / Palaeogeography, Palaeoclimatology, Palaeoecology 454 (2016) 30–53

51

Table 3 Sedimentological, paleontological and paleogeographical impacts of the Syrian Arc tectonic events during the Early Paleogene on the western shoulder of the Gulf of Suez, Egypt. Event

Occurrence

Duration

Paleontological impacts

Sedimentological impacts

Early Lutetian tectonic event (SAO phase 3)

In the central part, at north Wadi Qena and Wadi El Dakhal.

Constant duration all over the study area (nearly 3.9 My).

Partial absence of T. frontosa Zone and complete absence of G. nuttalli Zone, where G. kugleri/M. aragonensis Zone rests unconformably on T. frontosa Zone.

Middle–Late Ypresian tectonic event (SAO phase 2)

It extends over most of the area, except at north Wadi Qena site.

Short time with constant duration (nearly 0.4 My).

Danian-Early Ypresian tectonic event (SAO phase 1)

At the contact between the Thebes and both the Dakhla Formation at Saint Paul and the Esna Formation at the rest of investigated localities.

Varies from place to place with a remarkable increase in magnitude and time due to NNE (1.7 to 9.1 My).

Complete absence of A. pentacamerata Zone, where A. bullbrooki Zone of Late Ypresian overlying unconformably M. aragonensis/M. subbotinae Zone of Middle Ypresian age. Around Gebel Millaha, a complete absence of M. formosa Zone, where the Middle Ypresian M. aragonensis/M. subbotinae Zone rests unconformably on the Early Ypresian M. subbotinae Zone. At Wadi El Dakhal, the Middle Ypresian M. aragonensis/M. subbotinae Zone rests unconformably on Late Thanetian M. velascoensis Zone. At Saint Paul, a Middle Ypresian M. aragonensis/M. subbotinae Zone rests unconformably on the Middle Danian P. inconstans Zone.

Condensed sedimentation at the end of late Ypresian. The depositional regime shallowed upward and changed vertically from outer shelf sedimentation during Ypresian to middle and inner shelf in Lutetian. At Saint Paul and Gebel Millaha, sediments belonging to Middle Eocene age are totally missed. This missing may be attributed to intensive erosion and/or nondeposition by the effect of this event. It does not reflect the development of a sedimentary disconformity, but a net increase in bioturbation was observed towards the top of the underlying facies and a rapid rise in the argillaceous content. On contrary, at north Wadi Qena, the Middle–Late Ypresian transition has a very complete record and no marked erosion took place. Around Gebel Millaha, a red paleosol horizon separates between the Thebes and the Esna formations. The basal part of the Thebes Formation is enriched with phosphate grains and reworked lithoclasts forming phosphatic packstone to pack/grainstone facies. At Wadi El Dakhal, erosive surface with pronounced relief cut into marls and shales of the Esna Formation. Phosphate grains scattered into the basal part of the Thebes Formation. At Saint Paul, an irregular surface at the basal part of the Thebes Formation delineates its contact with the underlying Dakhla Formation. By the effect of this tectonic event, the floor of the open marine basin of the Esna and Dakhla formations reconfigured to shelf platform of the Thebes Formation. Moreover, the regional pattern of sedimentation suddenly changed from siliciclastic shales to limestone of the Thebes Formation.

Fig. 12. Oriented stratigraphic cross-section (NNE–SSW), reconstructed at different geologic times, showing the lateral and vertical lithofacies distributions at each time unit, as well as the effects of the different Syrian Arc tectonic phases. Biozones and age assignment are based on Wade et al. (2011).

52

A.M. El Ayyat, N.A. Obaidalla / Palaeogeography, Palaeoclimatology, Palaeoecology 454 (2016) 30–53

were covered with the sea and a pronounced sea level rise in the Early Lutetian (G. kugleri/M. aragonensis Zone) took place. Relative curves are in contemporaneous with the global curves and both types of curves indicate slight shallowing upward. The development of the SAO herein was formulated in three tectonic phases from Early Paleocene (Danian) to Middle Eocene (Lutetian). Each one caused abrupt changes in sea level, paleogeography, environmental conditions and sedimentary facies, as well as significant depositional gaps, variations in sedimentation rates, and enhanced synsedimentary tectonics (Table 3). Additionally, they suggest important reconfiguration of the basins architecture that took place at time intervals shorter than the chrono-stratigraphy is able to resolve. Practically, this shows the importance of event stratigraphy for analyzing large sedimentary basins and making extrabasin correlations. Sestini (1984) indicated that the Syrian Arc deformations continued up to Middle Eocene in other parts of Egypt. They are contemporaneous with the development stages of the Neotethyan Sea in northern Egypt. The compressive forces of these events in north Egypt are related to rejuvenation of the SAO, which could be tentatively traced as far as northeast Libya (Goudarzi, 1980) and also continue offshore of the Mediterranean Sea (Sestini, 1984). It is assumed that these tectonic events are pronounced phases in the tectonic history of the SAO, the collision of the Afro-Arabian and Eurasian plates and the closure of the Tethys Sea. 7. Summary and conclusions Southern Galala Plateau is considered a suitable area for Cenozoic carbonate research. Its geology and stratigraphy is controlled mainly by the activity of the SAO at the southern Tethyan shelf. The focus area represents a small part of the whole tectonic history of the SAO in northern Egypt, which throws some light on the knowledge of the different tectonic mechanisms and associated sea level oscillations in this folding belt. The sedimentary succession of the Early to Middle Eocene age in the Southern Galala includes one rock unit (Thebes Formation), which differs in its stratigraphic range and varying depositional setting within an inner platform to basin transect. Stratigraphically, the Thebes Formation rests unconformable to conformable over the underlying Dakhla and Esna formations, respectively. The Thebes Formation consists primarily of laminated to thinlybedded, fine-grained limestone, dolomitized limestone and chalk. Scattered nodules, concretions or bands of chert can be found throughout. At Wadi El Dakhal section, the basal part of the sequence is interbedded with thin to medium bedded, calcareous sandstone and mixed carbonate-siliciclastic beds. Besides, exposures at Gebel Millaha and Wadi El Dakhal sites are intermeddling with syn-sedimentary slump structures of different types. Field observations and sedimentological analyses revealed the predominance of eight sedimentary facies belts forming a southwest gently dipping carbonate shelf. This shelf could be classified into two major structural and sedimentological provinces: 1) a distal stable outer shelf in the southern parts, which is characterized by planktonic rich, fine grained limestone with scattered flint bands and nodules; and: 2) an unstable inner shelf, which covers the middle and northern parts. On this shelf the thickness and biofacies of the Eocene carbonates changed widely in areas geographically near to one another. The arrangement of the facies belts takes the form of east–west oriented parallel belts intersecting the western shoulder of the Gulf of Suez. This distribution might be controlled chiefly by the paleorelief inherited from the Early Ypresian tectonism due to the rejuvenation and growth of the SAO, as well as to collision of Afro-Arabian plates and closing of the Tethys Sea. Tectonically, the studied sequence is punctuated by three syndepositional tectonic episodes, which have their imprints on basin relief and regional tectonics. Furthermore, they also controlled the deposition

of the stratigraphic record. These tectonic episodes took place during Danian–Early Ypresian, Middle–Late Ypresian and Early Lutetian. It is postulated that the tectonic events are pronounced phases in the tectonic history of the SAO, the collision of the Afro-Arabian and Eurasian plates and the closure of the Tethys Sea. Comparing the relative sea level changes in the study area with the global curves at the same time interval demonstrates a good correlation with shifts at certain levels in the stratigraphic record. The sea level shifts were mainly tectonically controlled (due to impacts of SAO) and interpreted as local phenomena. Accordingly, interpretation of the relative sea level changes and the tectonic instability in the study area as a result of eustatic sea level changes is not completely true. It is evident that, the sedimentation in the north Eastern Desert during Early Paleogene was highly affected externally by the north–south compressional regime as a consequence of the convergence of the African and Eurasian plates, which commenced just after the Late Cretaceous and continued until the Eocene. The basin fill was also affected internally by the sedimentary factors or processes, such as provenance, basin topography, sedimentary input and climate.

Acknowledgements The authors are indebted to late Prof. Ahmed S. Kassab, Geology Department, Assiut University for field assistance, guidance and encouragement. Prof. Dr. A. Ibrahim is thanked for improving English spelling and grammar. The authors are grateful to Prof. Dr. Thierry Corrège (editor in chief) for his constructive comments and suggestions which have greatly improved the earlier version of the manuscript. The authors wish to thank the reviewers for their helpful and constructive comments. Funding by Assiut University (Egypt) is gratefully acknowledged. References Abu Khadra, A.M., Darwish, A.M., El Azabi, M.H., 1994. Contribution to the faulted down Eocene limestones of the Southern Galala plateau (Saint Paul), Gulf of Suez, Egypt. Second International Conference on the Geology of the Arab World, Cairo University, pp. 418–437. Adabi, M.H., Zohdi, A., Ghabeishavi, A., Amiri-Bakhtiyar, H., 2008. Applications of nummulitids and other larger benthic foraminifera in depositional environment and sequence stratigraphy: an example from the Eocene deposits in Zagros basin, SW Iran. Facies 54, 499–512. Aigner, T., 1983. Facies and origin of nummulitic buildups: an example from the Giza Pyramids Plateau (Middle Eocene, Egypt). Neues Jahrb. Geol. Palaontol. Abh. 166, 347–368. Al Hashimi, H.A., 1975. Contribution to the stratigraphy and micropaleontology of the Naopurdan Shaly Group in Chuwarta area, Northwestern Iraq. J. Geol. Soc. Iraq Spec. Issue 27–36. Baccelle, L., Bosellini, A., 1965. Diagrammi per la stima viviva della composizine percentuale nelle rocce sedimentary, Annali dell'Universita di ferrara (Nuova Serie), Sezione IX. Sci. Geol. Paleontol. 1, 117–153. Bandel, K., Kuss, J., 1987. Depositional environment of the pre-rift sediments of the Galala heights (Gulf of Suez, Egypt). Berl. Geowiss. Abh. 78, 1–48. Berggren, W.A., Pearson, P.N., 2005. A revised tropical to subtropical Paleogene planktonic foraminiferal zonation. J. Foraminifer. Res. 35, 279–298. Berggren, W.A., Pearson, P.N., 2006. Taxonomy, biostratigraphy, and phylogeny of Eocene Morozovella. Cushman Found. Spec. Publ. 41, 343–376. Berggren, W., Kent, D.V., Swisher, C.C., Aubry, M.A., 1995. A revised Cenozoic geochronology and chronostratigraphy. SEPM Spec. Publ. 54, 129–212. Bismuth, H., Bonnefous, J., 1981. The biostratigraphy of carbonate deposits of the Middle and Upper Eocene in northeastern offshore Tunisia. Palaeogeogr. Palaeoclimatol. Palaeoecol. 36, 191–211. Blondeau, A., 1972. Les Nummulites, de l' enseignment a la Teichert. Vuibert library, Paris (254 pp.). Bosence, D., 2005. A genetic classification of carbonate platforms based on their basinal and tectonic setting in the Cenozoic. Sediment. Geol. 175, 49–72. Boukhary, M., Kulbrok, F., Kuss, J., 1998. New nummulitids from Lower Eocene limestone of Egypt (Monastery of Saint Paul, Eastern Desert). Micropaleontology 44, 99–108. Darwish, M., El Araby, A., 1993. Petrography and diagenetic aspects of some siliciclastic hydrocarbon reservoirs in relation to rifting of the Gulf of Suez, Egypt. In: Philobbos, E., Purser, B.H. (Eds.), Geodynamics and Sedimentation of the Red Sea– Gulf of Aden Rift System. Geological Survey of Egypt, Special Publication Vol. 1, pp. 155–187.

A.M. El Ayyat, N.A. Obaidalla / Palaeogeography, Palaeoclimatology, Palaeoecology 454 (2016) 30–53 Bourdillon de, Grissac Ch., 1988. Les Foraminiferes benthiques de le Eocene moyen ou superier du Dhofar, Sultanat de Oman. Interet biostratigraphique, paleoecologiques et paleogeographique. Rev. Paléobiol. 2, 621–622. Dunham, E.J., 1962. Classification of carbonate rocks according to depositional texture. In: Ham, W.E. (Ed.), Classification of Carbonate Rocks. American Association of Petroleum Geologists Memoirs Vol. 1, pp. 108–121. El Ayyat, A.M., Obaidalla, N.A., 2013. Stratigraphy, sedimentology and tectonic evolution of the Upper Cretaceous/Paleogene succession in north Eastern Desert, Egypt. J. Afr. Earth Sci. 81, 35–59. Embry, A.F., Klovan, E.J., 1971. A Late Devonian reef traced on northeastern bank island, northwest Territories. Can. Pet. Geol. Bull. 19, 730–781. Friedman, G.M., Sanders, J.E., 1987. Origin and occurrence of dolomite. In: Chilinger, G.V., Bissell, H.J., Fairbridge, R.W. (Eds.), Developments in Sedimentology 9A. Carbonate rocks, Elsevier, New York. Ghose, B.K., 1977. Paleoecology of the Cenozoic reefal foraminifers and algae — a brief review. Palaeogeogr. Palaeoclimatol. Palaeoecol. 22, 231–256. Goudarzi, G.H., 1980. Structure of Libya. In: Salem, M., Busrewil, M. (Eds.), The Geology of Libya Vol. 3. Academic Press, pp. 879–892. Haq, B.U., Hardenbol, J., Vail, P., 1987. Chronology of fluctuating sea levels since the Triassic. Science 235, 1156–1167. Hermina, M., Lindenberg, H.G., 1989. The Tertiary. In: Hermina, M., Klitzsch, E., List, F.K. (Eds.), Stratigraphic Lexicon and Explanatory Notes to the Geological Map of Egypt, 1:500,000, CONOCO, Cairo, pp. 141–217. Höntzsch, S., Schneiber, C., Kuss, J., Marzouk, A.M., Rasser, M.W., 2011. Tectonically driven carbonate ramp evolution at the southern Tethyan shelf: the Lower Eocene succession of the Galala Mountains, Egypt. Facies 57, 51–72. Hussein, I.M., Abd-Allah, A.M., 2001. Tectonic evolution of the northeastern part of the African continental margin, Egypt. J. Afr. Earth Sci. 33, 49–68. Katz, A., Friedman, G.M., 1965. The preparation of stained acetate peels for the study of carbonate rocks. J. Sediment. Petrol. 35, 248–249. Keheila, E., 2000. Lower Eocene facies, environments and evolution of sedimentary basins in southern Galala, Egypt: Evidence for global coastal onlap and tectonics. Second International Conference on Basic Science and Technology, Assiut, Egypt, pp. 75–104. Kulbrok, F., 1996. Biostratigraphie, Fazies und Sequenzstratigraphie einer Karbonatrampe in den Schichten der Oberkreide und des Alttertiaers Nordost-Ägyptens (Eastern Desert, Nord Golf von Suez, West Sinai). Berichte aus dem Fachbereich Geowissenschaften der Universität Bremen Vol. 81, pp. 1–153. Kuss, J., 1989. Facies and paleogeographic importance of the pre-rift limestones from NE Egypt and Sinai. Geol. Rundsch. 87 (2), 487–498. Kuss, J., Scheibner, C., Gietl, R., 2000. Carbonate platform to basin transition along an Upper Cretaceous to Lower Tertiary Syrian Arc uplift, Galala Plateaus, Eastern Desert, Egypt. GeoArabia 5, 405–424. Martin-Chivlet, J., Chacon, B., 2007. Event stratigraphy of the Upper Cretaceous to Lower Eocene hemipelagic sequences of the Prebetic zone (SE Spain): record of the onset of tectonic convergence in a passive continental margin. Sediment. Geol. 197, 141–163. Mazhar, A., Enany, N., Abdel Kader, Y., 1979. Contribution to the Cretaceous–Early Tertiary stratigraphy of El Galala El Qibliya Plateau. Ann. Geol. Surv. Egypt 9, 377–387. McHargue, T.R., Price, B., 1982. Dolomite from clay in argillaceous or shale-associated marine carbonates. J. Sediment. Petrol. 52, 873–886. McIlreath, I.A., James, N.P., 1979. Carbonate slopes. In: Walker, R.G., James, N.P. (Eds.), Facies Models, Response to Sea Level Change. Geological Association of Canada, pp. 133–144. McKee, E.D., Chronic, J., Leopold, E.B., 1959. Sedimentary belts in lagoon of Kapingamarangi Atoll. Bull. Am. Assoc. Pet. Geol. 43, 501–562. Molina, E., Alegret, L., Apellaniz, E., Bernaola, G., Caballero, F., Dinarès-Turell, J., Hardenbol, J., Heilman-Clausen, C., Larrasoaña, J.C., Luterbacher, H., Monechi, S., Ortiz, S., OrueEtxebarria, X., Payros, A., Pujalte, V., Rodríguez-Tovar, F.J., Tori, F., Tosquella, J., Uchman, A., 2011. The Global Standard Stratotype-section and Point (GSSP) for the base of the Lutetian Stage at the Gorrondatxe section, Spain. Episodes 34 (2), 86–108.

53

Morsi, A.M., Scheibner, C., 2009. Paleocene–Early Eocene ostracods from the Southern Galala Plateau (Eastern Desert, Egypt): taxonomy, impact of paleobathymetric changes. Rev. Paleontol. 52, 149–192. Moustafa, A., Khalil, H.M., 1995. Superposed deformation in the northern Suez rift, Egypt: relevance to hydrocarbon exploration. J. Pet. Geol. 18 (3), 245–266. Newell, N.D., 1956. Geological reconnaissance of Raroia (Kon Tiki) Atoll, Tuamota Archiopelago. Bull. Am. Mus. Nat. Hist. 109, 317–372. Özgen-Erdem, N., Inan, N., Ajyazi, M., Tunoglu, C., 2005. Benthic foraminiferal assemblages and microfacies analysis of Paleocene–Eocene carbonate rocks in the Kastamonu region, northern Turkey. J. Asian Earth Sci. 25, 403–417. Pearson, P.N., Olsson, R.K., Huber, B.T., Hemleben, C., Berggren, W.A., 2006. Atlas of Eocene planktonic foraminifera. Cushman Found. Spec. Publ. 41 (514 pp.). Plumley, W.J., Risley, G.A., Graves, R.W., Kaley, M.E., 1962. Energy index for limestone interpretation and classification. In: Ham, W.E. (Ed.)Classification of Carbonate Rocks, American Association of Petroleum Geologists, Special Publication Vol. 1, pp. 85–107. Pujalte, V., Schmitz, B., Baceta, J.I., Orue-Etxebarria, X., Bernola, G., Dinares-Turell, J., Payros, A., Apellaniz, E., Caballero, F., 2009. Correlation of the Thanetian–Illerdian turnover of larger foraminifera and the Paleocene–Eocene thermal maximum: confirming evidence from the Campo area (Pyrenees, Spain). Geol. Acta 7, 161–175. Rigby, K., 1958. Two new Paleozoic Hydrozoans. J. Paleontol. 46, 509–519. Said, R., 1962. The Geology of Egypt. Elsevier Publishing Company, Amsterdam (377 pp.). Said, R., 1990. The Geology of Egypt. Balkema, Rotterdam (734 pp.). Schäfer, K., 1969. Vergleichs Schaubilder zur Bestimmung des Allochemgehalts bioklastiscer Karbonatgesteine. Neues Jb. Geol. Paläontol. Monat. 46, 173–184. Schaub, H., 1992. The Campo section (NE Spain) a Tethyan parastratotype of the Cuisian. Neues Jahrb. Geol. Palaontol. Abh. 186, 63–70. Scheibner, C., Kuss, J., Marzouk, A.M., 2000. Slope sediments of a Paleocene ramp-to-basin transition in NE Egypt. Int. J. Earth Sci. 88, 708–724. Scheibner, C., Marzouk, A.M., Kuss, J., 2001. Shelf architectures of an isolated Late Cretaceous carbonate platform margin, Galala Mountains (Eastern Desert, Egypt). Sediment. Geol. 145, 23–43. Scheibner, C., Reijmer, J.J., Marzouk, A.M., Speijer, R.P., Kuss, J., 2003. From platform to basin: the evolution of a Paleocene carbonate margin (Eastern Desert, Egypt). Int. J. Earth Sci. 92, 624–640. Sestini, G., 1984. Tectonic and sedimentary history of NE African margin (Egypt/Libya). In: Dixon, J., Robertson, A. (Eds.), The Geological Evolution of the Eastern Mediterranean. Blackwell Scientific Publishers, Oxford, pp. 161–175. Sibley, D.E., Gregg, J.M., 1987. Classification of dolomite rock texture. J. Sediment. Petrol. 57, 967–075. Snavely, P.D., Garrison, R.E., Meguid, A.A., 1979. Stratigraphy and regional depositional history of the Thebes Formation (Lower Eocene), Egypt. Ann. Geol. Surv. Egypt 9, 344–362. Speijer, R.P., Schmitz, B., 1998. A benthic foraminiferal record of Paleocene sea level and trophic/redox conditions at Gebel Aweina, Egypt. Palaeogeogr. Palaeoclimatol. Palaeoecol. 137, 79–101. Speijer, R.P., Wagner, R., 2002. Sea level changes and black shales associated with the Late Paleocene thermal maximum; organic-geochemical and micropaleontologic evidence from the southern Tethyan margin (Egypt-Israel). In: Köberl, C., MacLeod, K.G. (Eds.), Catastrophic Events and Mass Extinctions: Impacts and Beyond. Geological Society of America, Special Paper, pp. 533–549. Strougo, A., Faris, M., 1993. Paleocene–Eocene stratigraphy of Wadi El Dakhal, Southern Galala Plateau. Earth Science Series Vol. 7. Middle East Research Center, Ain Shams University, pp. 49–62. Wade, B.S., Pearson, P.N., Berggren, W.A., Pälike, H., 2011. Review and revision of Cenozoic tropical planktonic foraminiferal biostratigraphy and calibration to the geomagnetic polarity and astronomical time scale. Earth-Sci. Rev. 104, 111–142. Wilson, J.L., Jordan, C., 1983. Middle shelf. In: Scholle, P.A., Bebout, D.G., Moore, C.H. (Eds.), Carbonate Depositional Environments. American Association of Petroleum Geologists, Memoir Vol. 33, pp. 297–347.