Geology of Egypt by dr /allam

this topic writen by prof/A.Allam
geology department
helwan university

I. THE WESTERN DESERT OF EGYPT (LIBYAN DESERT):
A. Allam,1986: A regional and paleoenvironmental study on the Upper Cretaceous deposits of the Bahariya Oasis, Libyan Desert, Egypt.- Journal of African Earth Sciences, Pergamon Press, Vol.5,No.4,pp.407-412.

Abstract: The Bahariya Oasis represents an anticline with major prevailing NE-SW major fault system. The present regional geological study proved that the Earth movement has undergone large changes in the sedimentary facies as well as lateral variation in the thickness of strata. These sedimentary rocks range in age from Cenomanian to Oligocene: Bahariya Fm. (L. Cenomanian), El-Heiz Fm.(U. Cenomanian), El-Hefhuf Fm.(Turonian-Santonian), Ain Giffara Fm.(Campanian), Khoman Chalk (Maastrichtian), Plateau Limestone (Eocene), and Radwan Fm. (Oligocene).
The chronological sequence of the studied beds as well as the structure of the oasis are dealt with. The distribution of the sediment and its faunal association in the Upper Cretaceous deposits led to the distinction of three major phases of sedimentation which are also discussed in detail.

Results: Within the depression, the main structural feature is the NE-SW fault zone cutting across the centre and separating two completely different lanscapes. A number of synclines of El-Heiz and El-Hefhuf Formations are preserved along this fault zone. The fault zone is variously mapped with a throw to the north and a throw to the south; the inclination of the adjacent strata suggests uplift of the southern block, but the author believes that there has been movement in both dorections on the fault zone at different times. It is possible on a fault pattern model to suggest that the lateral movement was responsible for the compressional synclinal features. The succession of El-Hefhuf syncline contains chalky limestones of Maastrichtian age, demonstrating that the age of the movement resulting in the compressional features was post-Senonian and pre-Yepresian. Earlier Upper Cretaceous distinct series of faulting have been proposed. However, the present study indicates that the central transverse fault zone has neen active, at least, since the Cenomanian.
The present study attributed variations in lithology with marked changes. The facies analysis demostrates that in the Bahariya Oasis an apparent draping of sediments took place over the northern block by gradual subsidence of the southern, landward block during the sedimentation. The three models of sedimentation recognized in the exposures of the depression are:
3. Transgressive model (Campanian-Maastrichtian)
2. Regressive model (Turonian-Santonian)
1. Transgressive model (Upper Cenomanian)
Generally , the depositional environment which results from the facies analysis is one of a belt of a shallow marine environment along the central fault zone separating a terrestrially dominated environment in the south from the pure marine dominated environment in the north of the oasis during the Late Cretaceous. The climate conditions prevailing during the Late Cretaceous in the investgated area were also responsible for such a depositional environment. These conditions have been proved to be subtropical. Recent paleogeographic reconstruction has indicated that Egypt was in a near equator position.
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A. Allam, K. Shamah and A. Zalat, 1991: Biostratigraphy of the Middle Eocene Succession at Gebel Mishgigah, Wadi Rayan, Libyan Desert, Egypt.- Journal of African Earth Sciences, Pergamon Press, Vol.12, No.3, pp.449-459.

Abstract: The present study deals with the biozonation of exposed section at Gebel Mishgigah, which is mainly composed of highly fossiliferous limestones, dolostones and marls. These deposits belong to Mishgigah Member of Wadi Rayan Formation and are of Late Lutetian to Bartonian (Late Middle Eocene) age. The collected samples were investigated for their microfaunal and nannofloral content. Different associations of calcareous nannoplankton, planktonic foraminifers, ostracods and bryozoans were detected. The depositional environments and paleoecologic factors that prevailed during the sedimentation were also interpreted.

Results: Gebel Mishgigah belongs, geographically to the Fayoum Province; it lies at the eastern scarp of Wadi Rayan Depression. The oldest exposed rocks , at Wadi Rayan, are of Middle Eocene age. They are divisible into two units: the Wadi Rayan Formation and the overlying Gehannam Formation. The studied section at Gebel Mishgigah is the stratotype of the Mishgigah Member of Wadi Rayan Formation. It is of Late Lutetian to Bartonian (Late Middle Eocene) age.
This distribution of sediments and the faunal associations in the Mishgigah deposits led to the distinction of two major depositional environments: 1) Alternating shallow, reefal and comparatively deep marine conditions of the neritic zone during the late Lutetian time, 2) Fairly shallow marine conditions during the early Bartonian time to shallow littoral marine environment during the late Bartonian time.
It seems also that within the regressive phase of the Tethys sea, during the late Middle Eocene time, a slight transgression took place at the top of the Upper lutetian. In an inland pelagic sea, white chalky limestones were doposited.
A micropaleontological study of the Mishgigah Member, at its type locality, led to the recognition of two calcareous nannoplankton biozones, three planktonic foraminiferal biozones, two bryozoan biozones and two ostracodal biozones. Thus, the Upper Lutetian part of the Mishgigah Member at Gebel Mishgigah is characterized by the presence of the older part of the nannofloral Reticulofenestra umbilica Zone (NP 16), the planktonic foraminiferal Morozovella lehneri Zone (P 12), the bryozoan Tremogastrina fourtaui - Steginoporella delicata Zone, and the older part of the ostracodal Loxoconcha vetustopunctatella Zone. Whereas, the Bartonian part of the rock unit is occupied by the younger part of the nannofloral Retculofenestra umbilica (NP 16) and the overlying Discoaster saipanensis Zone (NP 17), the planktonic foraminiferal Truncorotaloides pseudodobius Zone (P 13) and the overlying Truncorotaloides topilensis Zone (P 14), the bryozoan Tremogastrina fourtaui Zone, and the younger part of the ostracodal Loxoconcha vetustopunctatalla Zone and the overlying Trachyleberis nodosus nodosus Zone.The boundary between the Upper Lutetian and the Lower Bartonian lies on the top of the Morozovella lehnerti Zone.
The present biostratigraphic zonation can be correlated with the Middle Eocene type locality in Egypt, at Gebel Mokattam, East Cairo. The Mishgigah Member of Wadi Rayan Formation in the Libyan Desert is the stratigraphic equivalent to the Nummulites gizehensis, Buildingstone and Guishi Members of the Mokattam Formation as well as the Bartonian part of the Maadi Formation described by Allam et al. (1988).
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II. THE NILE VALLEY AND DELTA

A. Allam, M. Bassiouni and A. Zalat, 1988: Calcareous nannoplankton from Middle and Upper Eocene rocks at Gebel Mokattam, East-Cairo, Egypt.- Journal of African Earth Sciences, Pergamon Press, Vol.7, No.1, pp.201-211.

Abstract: This paper discusses the stratigraphic significance and illustrates the calcareous nannoplankton separated from the Middle and Late Eocene sediments at the type area, Gebel Mokattam, East-Cairo, Egypt.
Six nannofloral biozones were recorded: the Middle Eocene Discoaster sublodoensis Zone, Reticulofenstra umbilica Zone, Discoaster saipanensis Zone and Chiasmolithus oamaruensis Zone; the Late Eocene Isthmolithus recurvus Zone and Ericsonia subdisticha Zone. These zones correspond closely to those established in other regions, and correlated well with the standard Eocene zones.

Presented at: "14th COLLOQUIUM OF AFRICAN GEOLOGY", Technische Universitaet Berlin-Germany, 18-22 August 1987"
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M.A.Bassiouni, A.Allam, M.Boukhary and A.Zalat 1988: On The Occurrence Of Nummulites ptukhiani KACHARAVA At The Base Of Maadi Formation (Bartonian), Gebel Mokattam, East of Cairo, Egypt.- Revue de Paleobiologie,Benthos 86, 3eme Symposium International sur les Foraminiferes Benthiques, Museum de Historie Naturelle, Geneve-Suisse, 22-28 Septembre 1986, Vol.Spec.No.2, pp.615-620.

Abstract: This paper deals with the study of the benthonic foraminifer Nummulites ptukhiani KACHARAVA, in samples collected from Gebel Mokattam, which is regarded as the type locality
of the Middle and Upper Eocene in Egypt.
This species was originally described from Armenia and also is recorded from several tethyan provinces, i.e. Italy, Spain, Libya and Oman. All the auther gave this species an latest Middle Eocene age.
Nummulites ptukhiani KACHARAVA is recorded in this work for the first time in Egypt. It has a taxonomic relationship with N. fabianii group. N. ptukhiani represents the phyletic link between N. bullatus AZZAROLI and N. fabianii (PREVER).
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A. Allam, 1982: On the geologic setting of the Nile Delta, Egypt.- Ain Shams Sci. Bull., No. 24, B, 1982 - 1983, p. 35 - 52.

Abstract: The area of the Nile Delta, as a part of northern Egypt, had been subjected to the same geologic events that affected the whole region during its Pre-Miocene geologic history. The Delta region is bounded on the eastern side by a major upwarp zone which occupies most of North Central Sinai. This zone extends westwards into "Cairo-Suez Anticlinal Horst", and is followed , northwards, by a major downwarp zone which occupies most of the Delta region and its extension into northwest Sinai.

The sedimentary section of the Nile Delta, has an anticipated thickness of the more than 12000 m of which about 5000 m belong to the neogene. The occurrence of such a thick section allows the development of strong gravity faults and structural zones zones particularly in its northern part.

A transition zone from crystalline continental crust to typical oceanic crust occurs along a hinge line extending parallel to the present coast line of Israel and northern Sinai (Ginsburg & Gvirtzman, 1979). The tectonic features interpreted from the overlying sedimentary sequence of both Paleozoic and Mesozoic times suggest the westward extention of the hinge line to cross the Nile Delta, forming an ESE-WNW fault zone between Mid and North Delta. This fault zone follows the steep and rapid plunging of the basement complex, similar to the hinge line of northern Sinai and Israel.

No doubt that the development of the Nile Delta through ages till its present form is related to events occurred since the Precambrian. The Precambrian crystalline rocks underlying the Paleozoic and the Mesozoic sediments are expected at a depth more than 11000 m. The fault zone follows the steep and rapid plunging surface of the basement complex. These Late Cretaceous step faults dominate in Mid-Delta. Anhydrite and gypsum deposits were formed during Messinian due to subsidence of Mediterranean Sea. Finally, a tectonic movement during the Late Miocene caused a lowering of the Sea bottom and thick clinoform sequence of clastic sediments were deposited. Since then, the Nile Delta acquired its present form.

III. THE EASTERN DESERT OF EGYPT (ARABIAN DESERT), GULF OF SUEZ, AND THE EGYPTIAN RED SEA COAST:

A. Allam, 1988: Depositional Environment and Diagenesis of the Late Cretaceous Phosphorites in the Duwi (Phosphate) Formation, Hamrawein Area, Arabian Desert, Egypt.- UNESCO, IUGS/IGCP, Regional Meeting on Cretaceous and Tertiary Phosphorites, Amman-Jordan, 3-5 April, Book of Abstracts, pp. 17-18.

Abstract: The late Senonian Duwi (Phosphate) Formation and its lateral equivalents occur as a thin wide-spreed shallow marine deposits with reside in an east-west trending belt spanning the lower middle latitudes of Egypt. These Egyptian phosphorites lie near the base of a generally transgressive marine squence that was deposited on the outer fringes of the Arabo-Nubian Craton in Cretaceous-Tertiary time. However, the studied phosphorites were laid down within shallow epeiric sea which flanked southern portion of the Tethyan trough.
This study concentrates upon the Duwi (Phosphate) Formation at Wadi Teban, Hamrawein area, along the Red Sea coast of the Arabian Desert of Egypt, where the unit is particularly well exposed. The porpose of this study is to reconstruct the depositional and diagenetic histories of the entire formation in this area. Particular attention was given to the phosphatic rocks, which occur in the study succession, as four beds interbedded with limestones, dolostones, mudstones, sandstones, and chert.
Textural and lithofacial studies of Wadi Teban phosphorites show that the cryptocrystalline varieties of apatite (collophane), fluorine rich variety of apatite, most likely francolits, and fish debris are the major phosphate components. Microfacial analysis showed that these rocks are classified as clastic phosphate rocks because of the dominance of detrital phosphatic and quartz clasts. A mixture of subangular to subrounded quartz grains and rounded phosphatic pellets and nodules may indicate the complex origin of the phosphorites.The phosphatic pellets were, for the most part, internally structurless, and they may be interpreted as detrital or may have formed diagenetically. The quantity of silica , which varies considerably from sample to another, is related primarly to the presence of allogenic minerals (detrital quartz). The cement is formed of fine-grained phosphatic grains (collophane), carbonates (mainly dolomite) and less commonly silica.
Examination by the scanning electron microscope revealed that apatite appears to favour certain types of surfaces for nucleation. For example, apatite seems to grow actively on the surface of primarily formed phosphatic minerals, replacing biogenic components and within skeletal materials. It seems that part of the phosphatic deposits were formed diagenetically,evidences of replacement of previously existing materials (mainly carbonates) by apatite are observed. Other parts of the phosphorites were formed authigenically; e.g. by direct precipitation from sea water. The euhedral crystal forms and growth of apatite on the surfaces of minerals support formation by precipitation rather than by replacement. Furthermore, the examination of organic materials and algal coated grains revealed that the oxidation of these organic matters during SO4, reduction is main source of dissolved phosphate.
The studied phosphate succession was deposited during the Late Cretaceous time. During that time, global sea levels reached a second-order maxima at approximately 71 m.y. ago; this maxima is superimposed upon the great first order (supercycle) sea level rise of the Late Senonian. Following this Late Campanian maxima, relative global sea levels dropped, and continued to fall well into Early Maastrichtian time. The concentration of the intially precipated apatite into indurated phosphate rocks is probably brought about by physical processes such as winniwing and reworking. During the period of low sea level, the fine-grained fraction of the sediments is eroded away, concentrating the phosphorite initially into coarse-grained sediments and ultimately into nodular deposits.
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A. Allam and K. Shamah, 1986: Microfacial Analysis and Environmental Development of the Duwi (Phosphate) Formation, Quseir-Safaga District, Eastern Desert, Egypt.- Acta Mineralogica-Petrographica, Szeged-Hungaria,Vol. XXVIII, pp. 11-20.

Abstract:Microfacial analysis, based on six stratigraphic sections, were carried out to the Duwi (Phosphate) Formation at the coastal plain of Quseir-Safaga along the Red Sea coast. The study showed that the main rock types are: phosphorite, organic rich shale, siliceous claystone, glauconitic sandstone, chert, dolomite, and oyster limestone. Detailed field and microfacial investigations of these rock types were done.
The paleogeographical distribution of the Duwi (phosphate) Formation was found to be influenced by biological and chemical parameters which was necessary for precipitation of calcium phosphates. Other factors controlling the areal extent include water depth, wave base and current velocity.
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Hilde L.Schwartz and A. Allam, 1985: Preliminary Report on Fishes from the Phosphate Beds of Wadi Teban, Hamrawein Area, Eastern Desert, Egypt.- Egyptian Journal of Geology, Geological Society of Egypt, Vol.29, No.1-2, pp.145-154.

Abstract:A small, preliminary collection of vertebrate remains from the four phosphate beds of the Duwi (Phosphate) Formation includes teeth of both cartilaginous and bony fishes. The collection was made at Wadi Teban, Hamrawein area, in the Eastern Desert of Egypt. At least three types of shark (Isurus sp., Squalicorax sp. and Ginglymostoma) and one holostean (Hadrodus sp.) occur in the field area. The sharks represent both benthic and pelagic forms and support sedimentological evidence that the Duwi (Phosphate) Formation was deposited in a relatively shallow water marine environment.

See also: Delta Journal of Science, A Periodical of Faculty of Science, Tanta University, Tanta-Egypt, Vol.9, Jan.-Jun.1985, pp.184-195.
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A. Allam, 1988: A Lithostratigraphical and Structural Study on Gebel El-Zeit Area, Gulf of Suez, Egypt.- Journal of African Earth Sciences, Pergamon Press, Vol.7, No.7/8, pp.933-944.

Abstract: Gebel El-Zeit area is situated close to the Arabo-Nubian shield, so that it has been affected by Paleozoic (Caledonian and Hercynian) and Mesozoic (Alpine) orogenic movements. This paper deals with the effect of these movements on the facies of the sedimentary rocks. The study has led to two main conclusions: a) the occurrence of four stages of sedimentation each separated by unconformity; b) the existence of complex inter-relationship between rifting and sedimentation, periodic tilting and fracturing of the horst blocks with erosional beveling of older deposits following each stage of sedimentation.

Results: Gebel El-Zeit area provides an ideal model for the regional tectonics and structural relationships to sedimentary history of the Gulf of Suez area.
The Precambrian granite is unconformably overlain by the Cambrian clastic deposits representing the first marine transgression on the Arabo-Nubian Shield (Araba Fm), followed by alluvial plain, continental environment (Naqus Fm). After a subtantial hiatus in sedimentation took place, a Cretaceous sequence of alluvial plain, marginal, and shallow marine sandstones, siltstones and silty shales were laid down (Malha, Galala, Wata and Matulla Fms) representing a clear transition from continental to shallow marine depositional environment. Subsequently, the ranges were extensively faulted, creating a south-westward dip of about 20 degrees in the pre-Tertiary succession. Erosion then beveled the deposits of the eastern edge of the blocks, exposing the basement rocks. The following Miocene marine transgression was accompanied by deposition of marine and non marine-coastal sediments (Nukhul, Ras El-Behar, Belayim and south Gharib-Zeit Fms).
It is believed that Gebel El-Zeit area was structurally high during that time and formed somewhat an island at the Gulf of Suez. Following this, a continued uplift tilted the beds to their present position. During the Pleistocene and Holocene times, the water of the Gulf of Suez advanced over the essentially stationary ranges, leaving subhorizontal limestone terraces and perched beaches. The recent terresterial deposits are primarily coarse clastic alluvial fans, while reefs continued to form off-shore.
Structurally, the oldest clear fracture are the N70E Tethyan trend which is sub-parallel to the pre-tilting land surface. Active faulting along the E-W Mediterranian trend occurred at the beginning of the Cretaceous transgressive cycle, which is evidenced by growth faulting in the basal Cretaceous deposits. After the Cretaceous, normal faulting along the Gulf of Suez trend tilted the horst block about 25 degree to the southwest. Shering was resulted due the oppening of the Red Sea which created swarms of Aqaba trend jouints which cut both the basement and sedimentary rocks. Jointing and faulting along the Suez (Clysmic) trend continued and became dominant with step faulting, parallel to the Gulf of Suez. Arching of the horst created new conjugate cross-faulting, with reactivation of older trends. In general, initial fracture trends in the sedimentary cover were inherited from, or simultaneous with trends in the basement rocks.
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Antar Abdel-Wahab, A. Allam, M. Kholief and A. Salem (1992): Sedimentological and palaeoenvironmental studies on the clastic sequence of Gebel El-Zeit area, Gulf of Suez, Egypt.- Journal of African Earth Sciences, Pergamon Press, Vol.14.

Abstract: The present work deals with the sedimentological and palaeoenvironmental studies of the Palaeozoic clastic sequence (Cambrian) of the Gebel El-Zeit area. The sandstones which build up the major part of this sequence are fine to coarse grained moderately to well sorted, mostly of unimodal patterns, strongly fine skewed to near symmetrical and vary from meso- to very lepto-kurtic.
The grain-size parameters and their bivariate relations do not give an exact environment of deposition, nevertheless, most of them have a fluviatile origin. So, the application of some of the bivariate relations to ancient sediments, which microscopically show mild or no cementation, is still valid if coupled with other parameters, such as sedimentary structures, palaeocurrent analysis and other confirmed data.
The palaeocurrent analysis indicates that these sandstones came from two completely different sources. A marine transgression from the north northeast produced the Araba Formation (Lower Cambrian), whereas the Naqus Formation (Upper Cambrian) has been interpreted as fluvial. The source is situated to the south southwest. The streams were probably very erratic and intermittent.

IV. SINAI
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A. Allam, 1989: The Paleozoic sandstones in Wadi Feiran-El Tor area, Sinai, Egypt.- Journal of African Earth Sciences, Pergamon Press, Vol.9, No.1, pp.49-57.

Abstract: The Paleozoic sandstone succession between Wadi Feiran and El-Tor in southwestern Sinai has been subdivided into five distinct lithostratigraphic units: the Lower Cambrian Araba Formation, the Upper Cambrian Naqus Formation, the Lower Carboniferous Abu Durba Formation, the Upper Carboniferous Aheimer Formation and the Permian Qiseib Formation.
The present study has also proved that the Paleozoic Earth movements have undergone distinct changes in the sedimentary facies, together with lateral variations in the composition and thickness of strata. The distribution of the sediments and their faunal contents point to the existence of five major phases of sedimentation during the Paleozoic Era.

Results: The Lower Cambrian, in the Gulf of Suez region, is marked by the invasion of the Tethys Sea from the north. The Araba Formation includes the first clastic beds of this major marine transgression. It is distributed in the Gulf of Suez region as an E-W parallel body reflecting an undulated surface of the underlying basement.It is thin and uniform in thickness. The presence of bioturbations at the base of the formation, as well as the cross stratification of the following beds and the fossil contents may suggest that the Lower Cambrian sandstones were deposited on a shallow marine platform with low relief, and hinterland to the south and southeast of the studied area.The following Naqus Formation becomes increasingly fluviatile to continental. The unfossiliferous sands and pebbles of this formation were deposited at a regressive phase of the sea. The formation is uniformly thin north of latitude 28 30 N, and increase in thickness towards the south in the subsurface. Further south, the Naqus Formation also thins gradually. It seams that the studied area has been affected by a down to the south fault in the Early/Late Cambrian times, towards the downthrown side, the Naqus Formation was deposited. Therefore, the areas of thick Naqus deposits (southward) are overlain by clastic sediments of Abu Durba Formation, whreas the thin Naqus deposits (northward) are overlain by the carbonates of Um Bogma Formation.
During the Early Caboniferous there was a second north to the south marine transgression (Late Paleozoic transgression) in the Gulf of Suez region. Abu Durba Formation represents this widespread transgression by buff-grey to blue claystones with dateable fossils together with fine medium-grained sandstones. To the north of the studied area, the clastic sediments of the Abu Durba Formation are laterally changed into marine carbonates of the Um Bogma Formation. Therefore, it is believed that the depositional environment of Abu Durba Formation and its equivalents range from inner sublittoral, partly restricted, to outer sublittoral conditions. The degree of variability of depositional environments implies a submarine relief of some magnitudes. Furthermore, the thin carbonates of the Um Bogma Formation seem to be deposited on the upthrown side of the forementioned fault system, whereas, the thick clastic sediments of the Abu Durba Formation were deposited on its down thrown side.
A down to the north fault (or fault system) has affected the studied area at the end of the Carboniferous time. The thick carbonate sediments of Ataqa Formation were deposited in the downthrown side. The upthrown side recieved the marne shales of Aheimer Formation. The Ataqa Formation is restricted north of latitude 29 N and its equivalent to the south is the clastic Aheimer Formation. These two units probably represent the last major transgression of the Tethys Sea during the Paleozoic times. The present Aheimer Formation starts with green shale at the base and ends with sandstone lenses at the top. A lagoonal system could be responsible for the deposition of the marine shales, whereas, the sandstone lenses may represent fluviatile channel deposits. The distribution of sediments may suggest a deposition in a transgressive-regressive sea which is adjacent to the shoreline. Therefore, the Aheimer Formation is most prbably marine at the base and non-marine at the top.
At the close of the Carboniferous and the advent of the Permian the Tethys Sea regressed totally from the studied area. The continental red beds of the Qiseib Formation were deposited in a wide braid plain.

Presented at: "30th INTERNATIONAL GEOLOGICAL CONGRESS(IGC), 4-14 August 1996, Beijing-China"
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A. Allam and H. Khalil, 1989: Geology and Stratigraphy of Gebel Qabeliat Area, Southwestern Sinai, Egypt.- Journal of African Earth Sciences, Pergamon Press, Vol.9, No.1, pp.59-67.

Abstract: The present study is based on 1:40000 scale mapping of the area between Wadi Feiran and El-Tor area, Sinai. The Photo-geological map is more detailed than the previous ones. The study include details on the litho- and biostratigraphy, especially of the Late Cretaceous - Tertiary sequence, and on the facies changes within the outcropping rock-units.

Results: It is well known that the granitic Precambrian shield forms the highland of Sinai. The Cambrian and younger subaerial erosion of this Precambrian shield has led to the deposition of thick and widespread Nubia Sandstone. The absence of any basal conglomerates in the lower sands suggest that the lower Nubia Sandstone was deposited in a shallow marine platform with low relief. A hinterland to the south and a basin to the north is als inferred. The widespread and uniform nature of the lower Nubia Sandstone implies a Paleozoic epicontinental to shallow marine shelf of large dimensions. It is suggested that this shelf may have extended far northward in Sinai throughout the Paleozoic Era.
During the Permo-Carboniferous time there is a north to south widespread marine transgression in the mapped area. The geologic record of this transgression is represented by clastic sediments with dateable fossils. The depositional environment in that time implies a submarine relief of some magnitude. It ranges from inner sublittoral, outer sublittoral to bathyal marine conditions. Earth movements during the Permo-Carboniferous time are suspected. At the end of the Paleozoic Era the sea withdrew from the mapped area.
The characteristics of the Early Mesozoic Nubia Sandstones which are interbedded with fossil soils with root structures and fossil trees, indicate a fluviatile to deltaic depositional environment. The sandstones were probably eroded from the surrounding igneous and metamorphic rocks, so that it would be possible that the depositional environment ranged from braided fluviatile systems to marginal or shallow marine settings in ahigh energy low braided streams.
The Cenomanian begins with the first appearance of marine beds above the Nubia Sandstone. The transition from clastic to an entirely marine section occurs over few metres. The facies characters of the Cenomanian rocks indicate a fairly shallow transgressing sea. The upper part of the succession shows alternating shallow and comparatively deep marine facies. This phenomenon would suggests an oscillating shallow sea, especially during the Late Cenomanian when this sea became gradually deeper at the beginning of the Turonian.
The Late Cretaceous sea continued its transgression during the Turonian, where compratively deeper marine conditions prevailed. This was evidenced by predominance of limestones and dolostones and low clastic ratio. The presence of dolomite indicates a stable sea-margin-environment. However, this Turonian sea was receiving, at interval, subordinate amounts of terrigenous material from a neoghbouring southern landmass.
The abundance of detrital grains and the pelletal nature of the Lower Senonian rocks indicate a predominant shallow marine condition of the neritic zone. This shallowing of the Late Cretaceous sea would suggest a crustal uplift of the sea floor about the end of Turonian time. The clastic sediments of Lower Senonian age is followed by a chalky sequence of Upper Senonian age, which indicate deposition under deeper marine conditions far from any terrigenous material. It means, the shallowing of the Lower Senonian sea was followed by a reversal in the secular oscillation of the sea floor. However, the orogenic movements which affected the northern parts of Egypt along the NW-SE Syrian arcs, were not active at the mapped area because the Paleocene deposits conformably follow the topmost Upper Senonian beds. The Paleocene sediments show open marine outer neritic facies environment. It seems that the marine conditions during the Paleocene time were, more or less, similar to that obtained during the Late Senonian.
The beginning of Early Eocene was the time when the transgression of the sea was either halted or had a slight regression. The crustal stability has produced a deposition of uniform open-sea facies of the limestone with flint. By upper Lower Eocene time a regression of the sea started, and the reefal alveolinid limestone facies was formed under shallow marine conditions. The Late Eocene transgression of the sea must have continued probably to the end of Oligocene time. Therefore, the Middle Eocene sea was gradually regressing, due to the appearance of larger foraminifers above the Lower Eocene beds.
The Oligocene in Sinai was marked by general uplift accompanied by igneous activity. The igneous activity was represented by the Early Tertiary basalt flows which was generally interpreted as related to initial faulting in the Suez rift. The onset of rifting is defined in the present map by unconformity. The erosion which occurred appears to be restricted to the Upper Eocene limestone. A shallow proto-rift depocentre was first formed in which the lower part of the Gharandal Group was deposited. As the sea-level rose through the Aquitanian and Early Burdigalian, successive formations onlapped the margins of the developing depocentre. The subsequent deposition of the upper part of the Gharandal Group, comprise lagoonal and subsequent marginal and shallow marine sequence, and reflects major sea-level changes. The Lower Miocene deposits were succeeded during Middle Eocene (Serravallian) time by prolonged sedimentation of reef building carbonates in the mapped area. These reefs, which constitute the Belayim Formation marks the last occurence of marine fauna in the Miocene. The reefal coditions wre gradually changed to progressive aridity, leading to the prolonged formation of evaporites of Ras Malaab Group during Turtonian and Messinian times. The evaporitic deposits were accumulated under very shallow epicontinental sea.
Finally, at the close of Miocene time, aridity ceased and gave way, during Pliocene-Pleistocene times, to the sedimentation of clastic materials in southwestern Sinai. The Pliocene-Pleistocene deposits, in the mapped area, have mainly terrestrial facies. They are mostly composed of gravels and conglomerates with some anhydrite interbeds. This seems to indicate that occasional marine transgressions covered the area.

A. Allam, M. Faris and H. Khalil, 1986: Planktonic Foraminifera and Calcareous Nannofossil Biostratigraphy of the Lower Eocene Rocks of Gebel Qabeliat, Sinai, Egypt.- Israel Journal of Earth Sciences, Vol.35, pp.167-175.

Abstract: Two planktonic foraminiferal biozones were recorded from the Early Eocene beds of Gebel Qabeliat, Gulf of Suez, Sinai: Morozovella subbotinae Zone and Morozovella formosa formosa Zone. The corresponding calcareous nannofossil biozones are: Tribrachiatus contortus Zone, Discoaster binodosus Zone and Tribrachiatus orthostylus Zone. The near absence of microfossils in the upper Lower Eocene section probably points to a change in the paleoecological conditions in the studied area during that time. Resumption of reefal environment is confirmed by the up-sequence appearance of the larger foraminifers. Early Eocene planktonic foraminifers and calcareous nannofossils zones recognized in the study section for the first time are broadly similar to those recorded in Israel and many parts of the world.
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K.A.Khaled, A.Allam and N.Edress 2001: Organic Geochemical Characteristics of the Black Shale Beds in Carboniferous Ataqa Formation, West Central Sinai, Egypt.- The fifth Conference On Geochemistry, Alexandria University,Egypt,12-13 Sept.,Vol.II,pp.275-292.

Abstract: Several black shale beds are located within the middle part of the Carboniferous sandstone succession of Ataqa Formation at Beaa-Um Thora district in west Central Sinai. The organic geochemical characteristics of these shales have been studied to evaluate their hydrocarbon potential. The obtained results show that black shale beds have a uniform mineralogical composition allover the studied area. The average of carbonate and silicate contents of these shales are 16.04 and 66.39 percent respectively. They contain also high bitumen, organic matter and TOC contents, which are enough to consider them as a potential source rock for generating hydrocarbons. Pyrolysis results indicate that, the organic matter in these shales belongs mainly to mature Type II kerogen with marked amount of types I and III. In addition, these kerogens show a wide range of maturity levels; from low to high mature. The significant variation of maturations attributed to the different geothermal effects in the area. Coal bodies are classified as a humic coal of hard brown coal to bituminous hard coal rank stages of low economic value.
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A. Allam and H. Khalil, 1988: Geology and Stratigraphy of the Arif El-Naga Area, Sinai, Egypt.- Egyptian Journal of Geology, Geological Society of Egypt, Vol.32/1-2, pp.199-218.

Abstract: The sedimentary succession at Gebel Arif El-Naga in northeastern Sinai is subdivided into eleven distinct lithostratigraphic units, which range in age from Triassic to Eocene:the Anisian Arif El-Naqa Fm., the Ladinian to Lower Carnian Abu Nusra Fm., the Hettangian Rajabiah Fm., the Pliensbachian Shusha Fm., the Aptian to Albian Malha Fm., the Cenomanian Halal Fm., the Turonian Wata Fm., the Coniacian Mezera Fm., the Santonian to Maastrichtian Sudr Chalk, the Paleocene Beida Fm., and the Middle Eocene Foyah Foyah Fm.
The Arif El-Naga area is situated close to the Arabo-Nubian Shield, the Suez Graben and the Aqaba-Dead Sea Rift. It has been affected by different tectonic movements from the Senonian onwards. The study deals also with the complex interrelationship between tectonics and sedimentation.It proved that tectonic movements have caused distinct changes in sedimentary facies, exhibited as lateral variations in the composition and thickness of strata. Delineation of the spatial distribution of the rock units was aided by photogeological mapping of the area.
In brief, the Arif El-Naga area is covered by a sedimentary succession predominatly deposited in shallow platform environment.
The Triassic rocks (Arif El-Naqa and Abu Nusra Fms.) are exposed in the core of the anticline. They unconformably underlie the Lower Jurassic beds. It seems that the studied area was folded above the sea at the end of the Triassic. The area formed a regional high from which the upper Triassic deposites were eroded.
The Lower Jurassic exposures at Gebel Arif El-Naga demonstrate an inner shelf clasic series (Rajabiah and Shusha Fms.). The fact that no Middle or Upper Jurassic units are found in the studied area could be taken as an indication that this area was structurally high near the end of the Jurassic. A regional uplifting was probably responsible for the nondeposition or erosional truncation of the Middle and Upper Jurassic sediments.
A regional stratigraphic gap underlies the fluvio-continental deposites of the Lower Cretaceous (Malha Fm.). Following this general regression of the sea, a transgressive carbonate depositional phase was then started (Halal Fm.). It progressively onlapped the Malha Formation in the southward direction. The observed small changes in thickness and facies are probably a result of a tectonic movement during the Cenomanian to Early Turonian.
During the Late Cretaceous, the northern Sinai shelf platform was covered by chalky and marly deposits (Sudr Chalk). Thickness changes are due to local morphotectonic features. It is blieved that the folding during the Campanian further tilted the inclined Cenomanian beds to near verticality and uplifted the southern flank of the Arif El-Naga structure thus exposing it to erosion. The folding was accompanied by intense erosion of the elevated core area down to the Jurassic resulting in a breached anticline.
The Paleocene is represented in the studied area by the Beida Formation. Unconformities and stratigraphic gaps are obseved below and above this formation, probably due to synsedimentary tectonics, in particular to the folding of the Syrian Arc. This folding movement seems to have become strong enough to bring the area above sea level. However, during the Eocene time, the synclinal areas around Arif El-Naga anticline were submerged by schallow water. The deposited Middle Eocene sediments (Foyah Fm.) are thin compared to those known from the Egma (Egypt)and Avedat (Israel) Plateaus. Furthermore, the Foyah Formation unconformably overlaps older sedimentary units of different ages. It is therefore, believed that the folding movement continued during the Eocene and later times.