CHAPTER
ONE
INTRODUCTION
1.1. PRELUDE:
The Paleo-Mesozoic sediments are well
exposed in the Wadi Araba area which is located in the northern part of the
Eastern Desert of Egypt. Some important works on the carboniferous - Cenomanian
succession in Wadi Araba area has already been published (e.g. Fourtau, 1900
& 1904; Hume 1911; Abdallah & Adindani 1963; Awad & Abdallah, 1966
and Hewaidy et al. 2003). Most of these works were essentially concerned with
the paleontological considerations and the stratigraphic relationships.
However, little has been paid to the modern sedimentological aspects. These
aspects will be considered herein to emphasize
Paleo-Mesozoic rock units along the easternmost parts of Wadi
Araba.
1.2. THE STUDY AREA:
Wadi Araba is situated at the far north eastern reaches
of the Egyptian Eastern Desert, along the western
coast of Gulf of Suez. The study area lies at the northeastern corner of the
northern bank of Wadi Araba (Fig. 1.1). It extends between
the Lat.: 29° 22' 37"' &
29°29'15'"N and Long.: 32° 32' 42"' & 32° 14' E, Fig. (1.1).
Fig.
1.1
Satellite
image of Wadi Araba including the study area.
1.3. ACCESSIBILITY:
The study area lies between Ain-Sokhna and Zaafrana areas. The area is easily to be arrived by vehicles along
the international asphaltic road run parallel to the coast of the Gulf of Suez
(Ain Sokhna –Zaafrana road), Suez governorate. Inside Wadi Araba itself, the
outcrops are distributed along the floor, and on both banks of the wadi. These
outcrops are in form of low hills and moderate-high cliffs that can be easily
walked and traversed.
1.4.
AIM OF THE WORK:
The aim of the work is to examine a part of the
Paleozoic-Mesozoic sedimentary succession to the north-eastern part of Wadi Araba,
along the southern slopes of the Northern Galala Plateau. The detailed
lithological characteristics will be discussed both in the field outcrops and
in the laboratory. The different sedimentary facies forming the sedimentary
succession and their mutual relationships are to be emphasized. The
depositional interpretations will be given to arrive the evolution of these
sediments. The tectono-sedimentary status of the given succession will be
discussed in terms of the sequence stratigraphic principles.
1.5.
PERVIOUS WORK:
The study area has been treated
geologically long ago. Different geo-topics have been discussed since the early
time of 20th Century. The following is a brief of the
concerned works:
1.5.1.
Stratigraphy:
Carboniferous:
The
Carboniferous rocks along Wadi Araba were first discovered by Schwerin Furth (1883)
at the mouth of Wadi Abu Silla. Walther (1890) described the rocks in detail,
especially those found opposite the exit Wadi Rod El–Hamal. The author (ibid) came
to the conclusion that the marls and limestone beds of Wadi Araba having the
age of “Sub-carbon" or Lower 'Carboniferous. Said (1962) supported the
Lower Carboniferous (Visean) age to Wadi Araba outcrops. Abdallah and Adindani
(1963) stated that the carboniferous rocks in Wadi Araba are represented by Rod
El-Hamal Formation. It is best exposed in the area at the junction of Wadi
Araba and Wadi Rod El-Hamal, comprising of 5 units of different lithological
compositions. The whole succession is overlain by thick red shales. The authors
(ibid) further added that on the basis of the corals and pelecypods present in
the top parts of the Rod El-Hamal, it can be stated to be of Upper
Carboniferous age. Moreover, Abdallah and Adindani (1963) considered the member
5, at the top of the Rod El-Hamal Formation as to be of Pennsylvanian age, thus
the lower members may belong to the Mississippian. Adindani and Shakhov (1970)
stated that in South Sinai, along Ayun Musa wells drilled for coal exploration,
the clastics including the coal seams are regarded to be Carboniferous in age depending
on pollen spores analysis. Kora (1995) stated that Early to Late Carboniferous
in Wadi Araba is represented by Rod El-Hamal Formation.
Permo-Triassic:
Abdallah and Adindani (1963) identified
and described a Permo-Triassic succession, on the basis of the badly preserved
fossils, named by them to as Qiseib Formation along Wadi Qiseib in the Northern
Galala Plateau-western side of the Gulf of Suez. They added that the Qiseib
Formation unconformably underlies the Lower Cretaceous Malha Formation
(Abdallah and Adindani op. cit.). Horowitz 1970 stated that the lower clastic
red beds of the Qiseib Formation include many thin coal seams with rich
palynomorphs suggesting an Early to Middle Triassic age. Druckman (1974) In Abu
Hamth well-I, pointed-out that the Qiseib Formation is 376 m thick; the upper 36
m are made of limestones rich in Middle Triassic marine fossils. El Barkouky
(1986) confirms a Triassic age for the Qiseib Formation in Sinai. Lejal-Nicol (1987)
identified a Lower Permian flora from Wadi Araba. Kora (1992) confirmed this
Lower Permian age of the Qiseib Formation due to the occurrence of the bivalves
Notomya cuneata (Sowerby) and Megadesmus nobilissiinus (De
Koninck). Issawi et al. (1999) further supported that the Qiseib Formation is of
Permo–Triassic age, forming a transition unit between the Paleozoic and the
Mesozoic.
Early
Cretaceous:
Abdallah and Adindani (1963) mapped
the west side of the Gulf of Suez where they first recorded a rich Lower
Cretaceous fauna in a unit below the Cenomanian beds, which they first named as
the Malha Formation. Fawzi and Naim (1964) studied a 174 m Lower Cretaceous
section in Gebel Shabrawet and gave an Albian age to the upper part of the Malha
Formation section. Bartov and Steinitz (1977) at Arif El Naga, North Sinai,
found that the Malha Formation consists of grey, white and variegated
sandstones, cross-bedded and quartzitic in parts with silt interbeds and limonitic
shale beds mainly in the lower part. Mazhar et al. (1979) The clastic beds of
the Malha Formation unconformably overlie red shales of possibly Triassic or
Permo - Triassic age and unconformably underlie the Cenomanian Galala
Formation. Al Ahwani (1982) published that the Lower Cretaceous sediments are
subdivided into four main rock units; two clastic units and two upper carbonate
units, the lower two units are made of sandstones topped by dolomite and
dolomitic limestones. El-Fawal (1988) stated that the Malha Formation along
El-Tih Scarp, South Sinai is generally has Early Cretaceous age on the basis of
it geometrical basis and the enclosing plant remains. The author further added
that this formation is composed of two members; a lower gravelly sandstone
member evolved within active braided channels, and an upper member of thick
intercalation of sandstone and silt- & clay-shale paleosol evolved with a
wide meandering river belt. Jenkins (1990) stated that the Malha Formation unconformably
overlies Jurassic beds. Kerdany and Cherif (1990) pointed out that the lower
sandstone beds formerly called as Nubia Sandstone might be Barrernian in age.
Aboul Ela et al. (1991) stated that the Lower Cretaceous section at Gebel
Shabrawet is correlated here with the Malha Formation and is believed to be of
Albian to Varconian age, though the lower beds of this formation might belong
to the Aptian or even to the Berriasian - Barremian.
Upper Cretaceous (Cenomanian):
Carozzi (1951) early stated that the Galala
Plateau was interpreted as a cycle of decreasing depth of the sea. Hume (1962)
noted that it is remarkable that neither Turonian nor Cenomanian formations are
exposed anywhere along the northern slopes of the Southern Galala range.
Abdallah and Adindani (1963) were the first who applied the name Galala
Formation at the Galala massif, along the western coast of the Gulf of Suez. Al
Ahwani (1982) believes that the Galala Formation in G. Shabrawet area was
deposited in a decreasing water depth on an inner shelf environment.
1.5.2.
Structure:
Said (1962) subdivided
the continental platform area of Egypt into two tectonic domains: a northern
‘Unstable Shelf’ and southern ‘Stable Shelf’ with unstable hinge zone in
between. The stable shelf is included the south of Egypt and is mainly covered
by incomplete continental successions belonging to the Palaozoic and Mesozoic
rocks with simple structural features (Said, 1990). Abdallah et al. (1973)
stated that there are minor anticlines and synclines are recognized in Wadi
Araba particularly in the Paleozoic rocks of the Rod El-Hamal locality, East
Wadi Araba. According to Bandel & Kuss (1987) several structural units
(blocks) can be differentiated in Wadi Araba, Fig (1.2).
Fig. 1.2 Sketch
showing the geological situation in the Wadi Araba area (modified after Kuss,
1989).
Said
(1990) pointed out that there was rapid lateral variation in the lithofacies of
the different stratigraphic units during the Cretaceous, one of the most
interesting features of the north Eastern Desert, could be due to syn-sedimentary
structural control. Abdel-Aal & Lelek (1994) stated that the Galala
plateaus represent a major branch of the Syrian Arc in the Eastern Desert. It
is characterized by Late Cretaceous uplift in the north, and subsidence farther
to the south. Folding &/or uplift of the Syrian Arc began in
post-Cenomanian times.
Stampfli
et al. (1995) stated that the complex uplifts and domal anticlines of
the Syrian Arc Fold Belt were formed during the closure of the Neotethys. Kuss
et al. (2000) stated that the North eastern Egypt is situated at the northern
edge of the African- Arabian Craton. It was affected during the Late Cretaceous
to early Tertiary times by east- northeast-oriented dextral wrench-faulting.
This resulted in transpressive movements and the inversion of the Late Triassic
– Liassic half-grabens that cut east-northeastward across the northern rim of
the African-Arabian Plate. Kuss et al. (2000) stated that the folding &/or
uplift of the Syrian Arc began in post-Cenomanian times, reached its acme
during the Late Cretaceous, Fig. (1.3).
Fig.
1.3 The tectonic features in northeast Egypt showing the distribution
of the Syrian Arc System (modified
after Kuss et al., 2000).
1.5.3. Tectonics:
The Galala mountain
complex represents an isolated late Cretaceous (Maastrichtian) to Eocene
carbonate platform at the southern margin of the Tethys, which is referred to
as the unstable shelf of northern Egypt (Youssef 2003). The evolution of the
carbonate platform is connected closely to the tectonic activity of the ENE–WSW
striking Wadi Araba Fault, which forms part of the Syrian Arc-Fold-Belt (e.g.
Krenkel 1925; Moustafa and Khalil 1995; Hussein and Abd-Allah 2001). During the
Early Eocene, a major phase of tectonic activity occurred along the Syrian
Arc-Fold-Belt (Shahar 1994). Regional uplift and subsidence triggered the
formation of ENE–WSW striking basins, submarine swells and subaerially exposed
plateaus on the unstable shelf (Said 1990; Schütz 1994). According to regional
tectono-sedimentary constraints, three major depositional units can be
distinguished; (i) the Northern Galala/Wadi Araba High (NGWA), (ii) a
transitional slope zone, and (iii) the Southern Galala Sub-basin (SGS). The
NGWA represents shallow-marine to probably subaerially exposed inner platform
environments. Due to the syn-sedimentary monoclinal uplift, an erosional phase
started since the Late Cretaceous, thus major inner-ramp deposits were eroded
or intensively altered (Moustafa and Khalil 1995). The Rocks of the northern
platform interior are intensively affected by tectonic displacement, which is a
result of the Miocene opening of the Gulf of Suez. The connection between the
NGWA and the SGS is represented by a transitional slope zone (mid ramp to outer
ramp).
The 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. Formation
and evolution of carbonate platform systems are strongly controlled by eustatic
sea-level changes and the activity of adjacent tectonic provinces (Bosellini
1989; Everts 1991).
Based on the Paleocene record of the
Galala platform, (Scheibner et al. 2003) assume a platform evolution that is
affected more by local tectonic displacements than by eustatically controlled
sea-level changes. Thus, the tectonic activity along the Wadi Araba Fault
system triggered the initial growth of the Galala platform as a coupled effect
of sea-level drop and local tectonic uplift. The geometry and architecture of
platform and slope have undergone repeated changes since the Cretaceous due to
the varying tectono-sedimentary constraints on the unstable Egyptian shelf
(Meshref 1990; Schütz 1994; Youssef 2003).
1.5.4
Geomorphology:
These structural features control the
geomorphology of the study area, where Wadi Araba is bounded in the north by
the Northern Galala Plateau, in the south by the Southern Galala Plateau and in
the east by the Gulf of Suez.Wadi Araba has NE – SW direction, following the
direction of a regional Syrian Arc anticline structure. Wadi Araba is
relatively low compared with the great heights of the surrounding plateaus
(Fig. 1.4). It reaches 30 km width from north to south and extends westward to
the central Eocene limestone plateau of the Eastern Desert. It is traversed by
a large number of drainage lines. Some of these drainage lines are shedding
from the two Galala (NW – SE and SE – NW), forming tributaries of the main WSW
– ENE drainage line of Wadi Araba.Most of these drainage lines are filled with
Plio – Pleistocene deposits (gravel or loose sands) that were transported from
the limestone cliffs by the tributary branches.
1.5.5.
Paleogeography:
Said (1990) stated that the first
major marine transgression in the Cretaceous occurred during the Aptian in
response to a world-wide rise in sea-level. Kuss & Bachmann (1996) added
that the Albian sea encroached further south due to the rising of sea-level,
resulting in conformable Aptian-Albian successions in northern Sinai, while in
the south, the Albian sequences unconformably onlap Aptian and pre-Aptian
siliciclastics. Furthermore, during the Cenomanian, the
Fig. 1.4: The drainage system and elevation of Wadi
Araba and the bounding Galala plateaus
(modified after Conoco, 1987).
ongoing rise of the sea-level corresponds to a
Tethyan-wide high stand (Philip et al., 1993). Kuss & Malchus (1989)
further added that the Late Cenomanian shelf facies of the Eastern Desert and
northern Sinai is characterized by a rich assemblage of benthic foraminifera
and ammonites of the genera Neolobites and Vascoceras. During the
Turonian, Bauer et al. (2003) pointed out that in the Eastern Desert,
shallow-marine, siliciclastic and terrestrial conditions prevailed during the
relative sea-level lowstand across the Turonian – Coniacian boundary. Kuss
& Bachmann (1996) reported a wide calcareous succession of an open marine
chalk and chalky limestone sediments of Campanian–Maastrichtian transgressive
phase. The authors (ibid) stated that
these sediments are widely distributed over the southern Egypt and Sinai. Said (1990)
further added that by the end of the Cretaceous, during the Maastrichtian, the
transgression reached further to the south and covered wide areas mostly with
thick chalk-marl units, shale, and subordinate silts of deeper shelf origin.
https://www.dropbox.com/s/w5mkopxksub4lkm/FACIES%20ANALYSIS%20AND%20SEDIMENTARY%20HISTORY%20OF%20SOME%20PALEO-MESOZOIC%20ROCK%20UNITS%2C%20WADI%20ARABA%2C%20EASTERN%20DESERT%2C%20EGYPT.pdf?dl=0
CHAPTER SEVEN
SUMMARY AND CONCLUSIONS
The present study is concerned with the Paleo/Mesozoic sedimentary
succession exposed at the entrance of Wadi Araba along the southern scarp of
the Northern Galala Plateau, west of the Gulf of Suez. Detailed field studies were
under-taken to establish the vertical and lateral changes in the lithology, the
geometry of sedimentary bodies, the enclosing sedimentary structures, and the paleocurrent
characterizing the examined succession.
The results of these investigations have provided some conclusions
which are summarized in terms of the (1) lithostratigraphy, (2) sedimentary
facies analysis, (3) depositional interpretations, and (4) depositional history
of the examined rock units.
7.1. ROD EL-HAMAL FORMATION:
7.1.1. Lithostratigraphy:
In the
study area as well as the Gulf of Suez region Rod El-Hamal Formation
representing the time span of Upper Carboniferous age. Its lithology ranges
from coarse-grained sandstone and gravelly sandstones to shales, with
occasional basal conglomeratic deposits at the contact with underlying basement
rocks.
7.1.2. Sedimentary facies analysis:
The lithological
successions represented within the different units of the Rod El-Hamal
Formation in the study area have been subdivided into 3 lithofacies
associations which have been identified by means of their lithology, geometry,
grain size and sedimentary structures. These facies include; Crudely-bedded,
Monomineralic Conglomerate, Cross-stratified Sandstone, and Fine-laminated gray
to black silt-shale.
7.1.3. Depositional interpretations:
The facies analysis done for Rod El-Hamal Formation in the study
area have provided that the formation was deposited as a result of mild marine
transgression advanced over the unconformable contact with the underlying
basement rocks. the sediments were collected within shallow intertidal
foreshore as mixed sandy/muddy tidal flat.
7.2. THE QISEIB FORMATION:
7.2.1. Lithostratigraphy:
In the study area, the Qiseib Formation represents the
depositional episode of Permo-Triassic age.
Its lithology varies between gravelly sandstones to mudstones and
claystones. The Qiseib Formation exhibits different colors including white,
yellow, gray, green, chocolate-brown, deep violet, olive, and red mottling with
variable sedimentary structures. Features of subaerial exposure, including
mottling and iron crusts in the siltstones and claystone of the formation are common.
The rock succession of the examined formation displays definite depositional
stacking regime in form of regular successive fining-upward sequences.
7.2.2. Sedimentary facies analysis:
The
Qiseib Formation is divided into three major lithofacies, each of which is
characterized by specific lithology and sedimentary structures. These
lithofacies are recorded within the rock succession of the examined formation
displaying definite depositional stacking regime in form of regular successive
fining-upward sequences. Each sequence varies in thickness from 2.0 m to about
5.0, and commences with lag-conglomerates, whereas terminates by the mudstones
/mud-shales. These sedimentary facies include basal conglomerates trough
cross-stratified sandstones, and varicolored, mottled silt-shale.
7.2.3. Depositional interpretations:
Based upon the sedimentary facies analysis done for the Qiseib
Formation in the study area, it can be concluded that the formation was deposited
under continental fluvial environment within a wide belt of meandering rivers.
7.3. THE MALHA FORMATION:
7.3.1. Lithostratigraphy:
The Malha Formation crops-out throughout the regions of south
Sinai, southeast Sinai, north Sinai, north central Sinai and west of the Gulf
of Suez. It overlies rock units of different ages indicating a major erosional
phase prior to Malha deposition.
In the study area, the
Malha Formation is subdivided into two members; the Lower Member is gravelly
sandstones, whereas the Upper Member is sandstone/mudstone intercalation.
7.3.2. Sedimentary facies analysis:
The
lithological successions representing the different units of the Malha
Formation in the study area have been subdivided into six sedimentary facies;
which have been identified by means of their lithology, geometry, grain size,
sedimentary structures and paleocurrent patterns. The Lower Member of the
formation consists of four sedimentary facies; including clast supported
conglomerate association, large-scale, trough cross-stratified gravelly
sandstone, large scale, planar tabular cross-stratified gravelly sandstone, and
horizontally laminated sandy mudstone. The Upper Member, on the other hand,
consists of two sedimentary facies including; large-scale, epsilon and trough
cross-stratified sandstone and rooted and burrowed sandy-mudstone.
7.3.3. Depositional interpretations:
The precise
study of the different lithofacies associations has led to the interpretation
of the depositional environments of each of the units as follows:
The sedimentary facies of the Lower Member of the Malha Formation
includes gravelly sandstones and mudstones which are stacked in fining upward
sequences. These were deposited as
successive, widespread fluvial, gravel-rich sandy sheet-floods. These
sheet-floods were laid down within an extensive fluvial network of low
sinuosity braided streams running in a N, NE and NW directions under the
influence of a relatively high paleoslope. Deposition had taken place near to
the hinterlands in the areas dominated by channel influence.
The sedimentary facies of the Upper Member were formed as bedforms deposited mainly by high
sinuosity meandering streams, forming point bars and flood plains. Flood plains
were later subjected to subaerial conditions and developed completely or
partially into prolific paleosols.
7.4. THE GALALA FORMATION:
7.4.1. Lithostratigraphy:
In the study area, the Galala Formation
overlies unconformably the Malha Formation. The upper boundary of the Galala
Formation with the overlying formations is generally conformable relations.
Galala Formation is represented by ~60 m thick of intercalation of
shales, sandstones, limestones, dolostones, and marly limestones with the
characteristic Cenomanian fauna. The basal parts, just overlying the lower
contact, the shales of the Galala Formation are rich in glauconite acquiring
the shale an egg-yellow colours.
7.4.2. Sedimentary facies analysis:
The lithological successions represented
within the different units of the Galala Formation in the study area have been
subdivided into five microfacies associations which have been identified by
means of their petrographical composition:
(1)
Dolomitized Dismicrite Association: Basal parts of the Galala Formation consist
of thick hard massive faint yellow limestones interbedded with thinner vary
colored shale layers, these limestones are consisting of homogenous pale grey
lime-micrite.
(2) Ostracodal biomicrite Association: thick intercalation of grey, medium hard
limestone beds, and thin highly fissile vary colored shale intervals, and rich
with many animal bioturbations.
(3) Foraminiferal biomicrite Association:
recorded at the lower part, consists of hard light grey argillaceous limestone
with reddish brown bands showing different types of animal burrows.
(4) Dolomitic quartz arenite Association:
recorded at the lower and upper parts, consists of hard, compact, sheet-like
beds of brown sandstone beds vary in thickness intercalating with shale beds at
the upper parts.
(5) Gypsiferous feldspathic quartz arenite
Association: recorded at the uppermost part, consists thick, hard, compact and
massive sandstones.
7.4.3. Depositional interpretations:
The
precise study of the different lithofacies associations has led to the
interpretation of the depositional environments of the given unit as a
sedimentary product of shallow transgressive sea conditions evolved with the
marine transgression covered the northern parts of Egypt during the early
Cenomanian. the sediments were deposited in the realm varying between
supratidal and intertidal foreshore to inner shelf depositional settings.
7.5. THE
DEPOSITIONAL EVOLUTIONARY PHASES OF THE PALEO-MESOZOIC SUCCESSION IN THE STUDY
AREA
The foregoing
sedimentological analyses have enabled that the examined Paleo-Mesozoic
succession in the study area was developed through a series of depositional
phase events that can be summarized as follows:
- Pre - Carboniferous phase
- Carboniferous phase
- Permo-Triassic phase
- Jurassic-Early Cretaceous phase
- Late Cretaceous (Cenomanian) phase
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