The regional stratigraphy is continuous across North Africa and have been controlled by the tectonic history of individual basins. Deformational events in the region, most of them minor, are recorded by unconformities reflecting basin tilting, uplift, and erosion of intracratonic structural axes at various throughout the Phanerozoic. The main old deformational events occured in the Precambrian to Early Cambrian, Late Silurian to Early Devonian, Carboniferous to Permian.
Throughout most of Paleozoic, North Africa was a single depositional basin on the northern shelf of the African craton. The basin generally deepened northward where deposition and marine influence were greater. In the Late Silurian and Early Devonian, Laurasia separated from Gondwana resulting in minor deformation, uplift, and lokal erosion. Many of the basins and uplifts preserved today were initially developed during this event from ealier structures. Later, in the Middle to Late Devonian, the initial collision of Laurasia and Gondwana began resulting in erosion and further modification of preexisting structures. The Hercynian orogeny (Carboniferous to Permian) marks the collision between Laurasia and Gondwana and caused regional uplift, folding, and erosion. Paleozoic basins that were delineated by earlier tectonic events were modified, resulting in the development of several intracratonic sag and foreland basins.
Several transgressive-regressive cycles occurred throughout the Paleozoic. Two major flooding events, one in the Silurian and other in the Carboniferous. Many of the prograding fluvial, esturine, deltaic, and shallow marine sands that were deposited during these cycles.

Another basin developed northeast of the Howar-Uweinat uplift in Egypt. This Dakhla Basin is filled with Mesozoic strata . The Dakhla region was probably in the Paleozoic period mostly a highland. A separation of the Kufra Basin from the Dakhla Basin is evident, because the Dakhla Basin is a younger depression filled predominantly with sediments of the Cretaceous age of maximal 3,000 meters in thickness.
The origin of an other uplift (Uweinat-Bir Safsaf-Aswan uplift) is not clear. The whole area from directly east of Djebel Uweinat to Aswan formed a regional high from which Paleozoic and older Mesozoic strata were generally not present, or they were eroded and then transported to south (Lakia Formation in Sudan).
During the Paleozoic, most of the area between northwestern Sudan, southeastern Libya and southwestern Egypt was a stable part of the African craton without much structural differentiation. There was, however, a zone of strong subsidence along the eastern edge of the Kufra basin, the Howar-Uweinat uplift. This area became subsidence during the Early Paleozoic and continued until to the Devonian age. The Howar-Uweinat uplift forms the eastern border of the deep Kufra Basin in Libya. The meaning of the Howar-Uweinat uplift documents itself through the enormous difference of the Basement base between uplift and Kufra Basin of up to >3,000 m. At the eastern edge of the uplift is the difference with <500 m essentially lesser. It is evident, that in maximum of two times probably parts on this structure was uplifted and sediments were eroded. The last significant ascent happened by the Bretonian event of the Upper Devonian age.
The Kufra Basin in southeast Libya forms an elongate depression oriented northeast-southwest, with an aerial extent of about 400,000 km2. The Kufra Basin began in the Early Paleozoic. By marine transgression during the Lower Silurian and Upper Carboniferous, which intercalated the far-reaching continental sedimentation, thick, vastly differentiated predominantly Paleozoic sediments are found here. The basin fill attains a maximum thickness of 3,000 m and comprises a sequence of Paleozoic sediments unconformably overlain by Mesozoic strata and has remained land since the end of Paleozoic times. The centre oft he basin is sand covered and except for a few small isolated hills of Cretaceous Nubian sandstone outcrops are limited to the southeast and southwest of the Kufra oasis. The base of the Paleozoic succession is exposed only in the north, southeast and southwest where it rests unconformably on Precambrian basement. See also International Conference, Cairo 2007

The area between Djebel Uweinat and Gilf Kebir (incl. Jabal Asba, Djebel Kamil, Djebel Kissu etc.) is an area on the Howar-Uweinat uplift. The Basement reaches an evenly altitude to the earth's surface. The first uplifting of the area resulted probably already in the Early Paleozoic (late Silurian). The second uplifting resulted probably in the Upper Devonian age (Bretonian event). The third uplifting resulted probably in the Carboniferous age (Sudetian event).
This high structure was since the first uplift then more a area of denudation and fewer a area of sedimentation. The whole sedimentary block over the Basement reaches both in the Gilf Kebir as well as in the Djebel Uweinat a maximum thickness of 400 m. The Basement outcrop between Uweinat and Gilf Kebir is approximately of + 600 m NN. The Gilf Kebir block has a high of +1000 m NN. The hardened mountain ridge of the Hassanein-Bey plateau of the Djebel Uweinat (+1800 m NN) is built by a tertiary magmatic intrusion and a followed uplift of the sedimentary block of Ordovician and Devonian strata. On top of the mountain ridge is placed a striking crater with a basaltic bottom. The Carboniferous strata at the Uweinat and surrounding are a near-shore facies of a transgression from the southern Kufra basin. The strata overlain unconformably the northeastern to southeastern foothills of the already uplifted mountain range of the Djebel Uweinat. The sediments of the Lower Carboniferous age in the Abdel-Malik Plateau (northern Gilf Kebir) and Jabal Asba, specially from the Wadi Abdel Malik, are the result of an advance of the Carboniferous transgression over the eroded side of the plateau, from the northern Kufra basin coming.
In the uplifted area, between Gilf Kebir and Djebel Uweinat, deposits of the Lower Cretaceous occure as remains. Specially sediments nearby the Aqaba passage and in the Wadi Wassa represent the most extensive expansion of early sediments of Cretaceous age, from the Abu Ballas area coming. More complete Cretaceous deposits are found in edge-position of the uplift southwest of Abu Ballas (Djebel Kamil and surroundig).

1. Paleozoic Sedimentation
    Djebel Uweinat and surrounding areas
    Abdel-Malik Plateau (= northern Gilf Kebir)
    Kemal-el-Din Plateau (= southern Gilf Kebir)
    Jabal Asba (Libya)
    Jabal Zalmah/Dalma (Libya)

2. Early Cretaceous Sedimentation (Gilf Kebir Formation)
    Gilf Kebir and surrounding
    Djebel Kamil and surrounding
 

1. Paleozoic Sedimentation
    (in sense KLITZSCH, E. & SCHANDELMEIER, H., in Geology of Egypt, 1990)

The best exposures of Paleozoic strata are to be seen in the Gilf Kebir - Djebel Uweinat area:  At the southwestern ridge of Gilf Kebir plateaus (especially Abu Ras, Wadi Sura), the Um Ras area (near the Libyan border), Wadi Talh (part of the Abdel-Malik Plateau), and at the northeastem, eastern and southeastern edge of Djebel Uweinat including Karkur Talh and Karkur Murr.

Ordovician Sedimentation
Along the southern foreland areas of the Abdel-Malik Plateau further Ordovician strata can be studied. There, fine to medium and partly coarse-grained white sandstone of fluvial and deltaic origin is interbedded with nearshore marine sandstone, beach sand and silty shale to clayey silt-stone. Several beds are intensively burrowed by trace fossils (Scolithos, Harlania/Arthrophycus, Cruziana). This so called  Um-Ras Formation reaches above the Precambrian Basement a maximum thickness of approximately 100 meters. It builds the eroded lower part of the Gilf Kebir Plateau.

In the entire Djebel Uweinat shallow marine to fluvial sandstone forms the lower sandstone unit directly overlying the Precambrian Basement (for example to seen at Karkur Talh). These strata are, in parts, highly burrowed by trace fossils (Scolithos , Harlania/Arthrophycus, Cruziana). These Sediments are very similar to strata found near the Um Ras Passage along the Libyan border and strata found southeast of Djebel Kissu. The thickness of this strata  is less than 100 m in the Djebel Uweinat.

The only place where older Paleozoic strata is known in the investigated area of Djebel Uweinat.  SEILACHER identified Cruziana cf. rouaulti LEBESCONTE which was found by MONOD on sandstone just above basement around 21°58'N and 25°08’E in Northern Sudan. This trilobite track indicates an Ear1y Ordovician age. It is from nearshore marine sandstone which contains abundant Skolithos sp. in some beds. This formation is called Karkur Talh Formation. It is exposed at both sides of Karkur Talh in the eastern part of Djebel Uweinat. Several ten meters of interbedded fluvial sandstone and conglomeratic sandstone are intercalated with highly bioturbated marine sandstone. The formation unconformably overlies Precambrian metamorphics and is unconformably overlain by marine and fluvial sandstone of Ordovician age (Um-Ras Formation).

At the outliers and small plateaus, directly east of Djebel Uweinat along the Sudanese border, the basal part of the strata consists of  Ordovician strata, as around Karkur Talh.
The massive sandstone outcrops at the edges of the granite-domes of the Jabal Arkenu and Jabal Babein are likewise probably of Ordovician age, standing as hardened remainders.
 

Silurian Sedimentation
Up to now the Silurian age on the uplift structure is represented by a gap. It were detected no layers that can be correlated with the Silurian strata in the Jabal Asba. Between the Ordovician and Devonian strata must be an unconformity exist in the Gilf Kebir and the Jebel Uweinat consequently.

Devonian Sedimentation
Devonian strata are exposed on surface in the Jabal Asba (Libya), the Gilf Kebir (Abdel-Malik and Kemal-el-Din Plateau), at the northern part of Djebel Uweinat etc. Unfortunately, no paleontological proof has been found until now within southwest Egypt. The stratigraphical interpretation is based on the position of these sediments between underlain strata of proven Ordovician age and  overlain strata of proven Carboniferous age. This sandstone is very similar in appearance to the Tadrart Sandstone of Libya.
The Devonian sediments consists of mainly tabular cross-bedded fine-to coarse-grained sandstone, partly slightly conglomeratic, frequently with convolute bedding. These are also present in lesser thicknesses southeast of Djebel Kissu in Sudan.

Carboniferous Sedimentation
The Wadi Malik Formation more or less conformably overlies the Devonian beds in the middle part of the southwestern and western Abu Ras escarpment. It is, however, best exposed all along the Wadi Abdel Malik and its side wadis (Wadi Talh) which reach from the southern and southwestern part of this 60 x 120 km large plateau towards its relatively flat northern end. The approximately 100  m thick Wadi Malik Formation consists of marine sandstone, siltstone and shale interbedded with fluvial, deltaic and tidal sandstone. In marine beds, brachiopods (Camerotoechia sp.), trace fossils (like tracks of tribolites) and starfish (Asteriacites) or burrows like Bifungitis fezzanensis DESIO are frequent. Other forms (Scolicia, Neonereites, Zoophycus, Phycosiphon) provide no time signature, while they may be used as indicating marine conditions. Several non-marine beds contain frequent plant remains including many different plant remains of Visean age (for example Triphyllopteris, Eremopteris, Rhodea, Rhacopteris) .
In north Wadi Abdel Malik, the Wadi Malik Formation underlies unconformably a 30 to 60 m thick bed of an chaotic sediment, consisting of clay, sand, gravel, blocks of older strata up to house size. Southward, in the middle and southern parts of Wadi Malik and its side wadis, these strata are replaced by fluvial sandstone, conglomerate and sandstone with isolated blocks of older strata (erratic boulders). The thickness of this fluvio-glacial unit is several tens of meters. It is overlain by cross-bedded and parallel-bedded sandstone containing plants of Stephanian age in the central parts of the Abdel-Malik Plateau, for example Cordaites sp., was found in sandstone directly overlying the fluvio-glacial North Wadi Malik Formation.
Both in the southeastern part of Djebel Uweinat at Karkur Murr and in the northeast at Karkur Talh, and also directly east of the mountain area, Carboniferous strata are present in varying thickness and facies. The lower 50 to 120 m of the Carboniferous section are mainly made up of sandstone, siltstone and some shale deposited in shallow marine, coastal floodplain or fluvial environment. Parts of the strata are intensively burrowed and brachiopods as well as plant remains of Early Carboniferous age are common. At Karkur Murr these strata rest directly on Precambrian rocks, while at Karkur Talh, as well as east of Djebel Uweinat, they overlie older Paleozoic strata. In most locations, they more or less conformably overlie the Devonian Tadrart Sandstone formation.
Above these partly marine strata, a unit of very heterogeneous Sediments follows. It is made up of fluvial sandstone which is interbedded with a very regularly-laminated siltstone (similar to varve Sediments) in some locations, for example the section at Karkur Murr; the base of this unit is made up of several meters of a chaotic sediment similar to Tillite.  At Karkur Talh and southeast of Djebel Uweinat in Sudan, the varve-type siltstone dominates the whole formation. It occupies the same stratigraphic position of the Tillite and the fluvio-glacial sandstone of the northern Wadi Malik and is, therefore, called the North Wadi Malik Formation. Previously, the varve-type sediments were called Lake Beds Formation.

Remark: Varve-like siltstones the author found also at western edge of the Gilf Kebir plateau (near Wadi Sura) as valley-filling.

The Ordovician shallow marine to fluvial sandstones forms the lower unit directly overlying the Precambrian Basement in the Djebel Uweinat. These strata are, in parts, highly burrowed by trace fossils (Scolithos, Harlania/Arthrophycus, Cruziana). They exposed on surface at the eastern part of Djebel Uweinat as a markedly silty sandstone layer.

In 2009 Andras Zboray found on the northern part of the plateau the Ordovician trace fossils Arthrophycus again. The find-layer is the same as in the eastern part of the Uweinat.

    
Ichnofossils from southern Karkur Thal (3) and northern plateau (1). Photos: Andras Zboray, 2008 and 2009


Ichnofossils from the southern (2) and upper end of western Karkur Thal (1). Photos: The autor, 2006

 
Strata very similar to the Um-Ras Formation also overlie the basement in Northern Sudan south and east of Djebel Kissu. Southward and eastward the continental influence of this sediment increases. Nevertheless, Harlania harlani DESIO and Cruziana acacensis SEILACHER are found 50 kilometers SSE of Djebel Kissu, and Skolithos sp. within the same formation approximately 100 kilometers east of Djebel Kissu.

Devonian strata are exposed on surface at the northern part of Djebel Uweinat. Unfortunately, no paleontological proof has been found until now within southwest Egypt. This sandstone is very similar in appearance to the Tadrart Sandstone of Libya. The Devonian sediments consists of mainly tabular cross-bedded fine-to coarse-grained sandstone, partly slightly conglomeratic, frequently with convolute bedding.
 

The presence of Lower Carboniferous strata has been known for a long time from Karkur Murr and Karkur Talh at the eastern side of Djebel Uweinat. It was already known, that the so-named Karkur Murr/Wadi Waddan Formation  (now Wadi Malik Formation in sense KLITZSCH) consist of sandy shales and include often numerous well-preserved plant remains.

The Carboniferous strata of this Wadi Malik Formation are present in varying thickness and facies. It is normally several 10 meters thick and it consists of  crossbedded to flaserbedded sandstone, siltstone and some shale deposited in shallow marine, coastal floodplain or fluvial environment. Parts of the strata are intensively burrowed and brachiopods as well as plant remains of Lower Carboniferous age are common. At Karkur Murr these strata rest directly on methamorphic Precambrian rocks, while at Karkur Talh, as well as east of Djebel Uweinat, they overlie older Paleozoic strata.
The Carboniferous strata at the Uweinat and surrounding areas are a near-shore facies of a transgression from the southern Kufra basin. The strata overlain  unconformably the northeastern to southeastern  foothills of the already uplifted mountain range the Uweinat. Remains of strata from the Carboniferous transgression also were found extensive at the northern Clayton Craters and approximately 100 kilometers southeast of Djebel Kissu.

On the eastern side of the Uweinat massif, at Karkur Murr, it is possible to see a good exposure of the contact between the metamorphic basement and the lowermost Carboniferous. The basement is formed of schists and gneisses, reddish-grey, folded, with numerous quartz veins; it is unconformably overlain by a thin bed of sandstone and approximately 10 m of rhyolite. These volcanics are followed by 15 m of shale and sandstone interbeddings and, subsequently, approximately 35 m of cross-bedded sandstones with rare shale interbeddings. The lower sandy shales often yield numerous, well-preserved plant remains.

At Djebel Uweinat (Karkur Murr and Karkur Talh) the Wadi Malik Formation contains the following flora of Lower Carboniferous age:
Cyclostigma ungeri JONGMANS
Lepidodendropsis aff. rhombiformis DE ROUVRE
Lepidodendropsis cf. vandergrachti JONGMANS
Precyclostigma tadrartense LEJAL-NICOL

Directly east and southeast of Djebel Uweinat as well as approximately 100 kilometers east of Djebel Kissu, both in northwestern Sudan, the following flora was found:
Triphyllopteris cf. rhombifolia DABER.
Lepidodendron veltheimi STERNBERG
Lepidodendropsis vandergrachti JONGMANS
Prelepidodendron aff. lepidodendropsis LEJAL
Lepidosigillaria intermedia LEJAL
Archaeosigillaria vanuxemi KIDSTON
Precyclostigma sp.

Without exact statements to the place of discovery in the Djebel Uweinat and surrounding are finds mentioned of
Rhodea aff. lotzensis STOCKMANS
Cordaites cf. angulostriatus GRAND'EURY
Eskdalia africana LEJAL-NICOL
Eskdalia malikense LEJAL-NICOL
Eremopteris elegans E.L.
Ursodendron aegyptiacum LEJAL-NICOL
Archaeocalamites sp.

In recent years, and especially in 2008, 2009 and 2010 by Andras Zboray, were found fossil plants on the northern part of the Uweinat plateau. The plant-remains of the types "Lepidodendron" and "Sigillaria" are usually not well preserved. The barely layered deposits have a fine-grained or coarse-grained facies. The finds were deposited on intra-Devonian level. It is likely that this deposits are terrestrial, this means, products of the intra-erosion of the Devonian mountains. This facies differs from the shallow-marine or coastal facies on the eastern side of the Uweinat (e.g. Karkur Murr). The plant-remains are preserved almost in situ. In contrast, the plant-remains in shallow-marine deposits are allochthon of origin at the eastern part of the Uweinat.

         
In the foreground terrestrial Carboniferous layers with plant-remains

Along the southwestern ridge of the Gilf Kebir Plateau can be studied Paleozoic strata at many places. The Ordovician Um-Ras Formation reaches a thickness of approximately 100 m between the Um Ras area and Wadi Sura. It consists mainly of fluvial and deltaic white sandstone, intercalated with interbeds of shallow marine siltstone, some shale and burrowed sandstone. These beds contain Harlania harlani DESIO, Cruziana cf. acacensis SEILACHER, Scolithos sp. and other trace fossils at several levels. This Um-Ras Formation reaches as far east to the southern Gilf Kebir plateau, but by erosion reduced thickness.
At the type locality, the Um-Ras Formation directly overlies Precambrian basement. South of the Um Ras passage, the trilobite tracks of Ordovician age occur only some meters above basement. At the Um Ras passage they occur also in the upper part of the section. The facies of this formation is very similar to the Akakus Sandstone in Libya.

The Ordovician Um-Ras Formation is overlain by 300 m (maximal) fluvial sandstone similar to the Devonian Tadrart Sandstone, are exposed at the escarpments of the Gilf Kebir Plateau. Trace fossils or plant remains were not found up to now. At the Aqaba Passage the Devonian strata are truncated by the Gilf Kebir Formation of Early Cretaceous age.

At the Wadi Abdel Malik respectively at the western foreland of the Abdel-Malik Plateau (Wadi Talh), shallow marine sandstone, siltstone and shale prevail, containing - apart from plants - brachiopodes, lamellibranchiates and different ichnofossils. These strata reach more than 100 meters of thickness in area and they are called Wadi Malik Formation (KLITZSCH 1979). Here they are overlain by a tillite of up to several 10 meters in thickness. Southward in the southern parts of Wadi Abdel Malik area, the stratigraphical position of the tillite is taken by crossbedded sandstone containing irregular large blocks. This sandstone seems to be of fluvial-glacial origin.

The sediments of the Wadi Malik Formation lie over an eroded base of the Devonian Tadrart sandstone unconformably. They were deposited during a transgressive expansion of the Kufra basin in the Lower Carboniferous age from the northwestern direction.

A rich flora was discovered in the Wadi Abdel Malik/Wadi Talh type area, including: Archaeosigillaria minuta, Lepidodendropsis cf. sinaica, Lepidosigillaria intermedia, Prelepidodendron lepidodendroides, P. rhomboidale, Rhacopteris ovata, Triphyllopteris gothani. This flora proves a Tournaisian to Visean age.

At Wadi Abdel Malik/Wadi Talh, were found this flora several meters below intercalations containing remains of different brachiopods, for example Camerotoechia sp. as well as abundant marine ichnofossils (SEILACHER, 1983) including Asteriacites gugelhupf, Bifungites fezzanensis, Spirophyton sp., Cruziana sp. and many others.

The upper part of Carboniferous strata, which is mainly made up of diamictites, occurs in three different facies, which interfinger and which all rest unconformably upon the Wadi Malik Formation. At central parts of Wadi Abdel Malik, the formation rests above an erosional contact on sandstone of Lower Carboniferous age. The uppermost parts of the underlying strata contain plant remains like Triphyllopteris gothani. The upper part of the formation, which is here approximately 50-55 m thick, is overlain by a thin conglomerate followed by sandstone, containing among others Cordaites angulostriatus, which, according to LEJAL-NICOL (1987) indicates Stephanian age. Moreover, the upper part of the northern Wadi Malik Formation - directly below the conglomerate - contains Rhodea lontzenensis, which indicates Namurian age for the glacial formation.

The whole Gilf Kebir plateau is built by Paleozoic rocks (Devonian strata and probably a strong reduced Ordovician base).  The Aqaba passage is an eroded valley between northern Abdel-Malik Plateau and southern Kemal-el-Din Plateau. Is is partially filled with Early Cretaceous layers of the Gilf Kebir Formation (fossil plants).

Sources:

KLITZSCH, E. & LEJAL-NICOL, A. (1984): Flora and fauna from strata in southern Egypt and northern Sudan (Nubia and surrounding areas).
Berliner geowiss. Abh., (A) 50, p. 47-79.
KLITZSCH, E. (1984): Northwestern Sudan and bordering areas: Geological development since Cambrian time.
Berliner geowiss. Abh., (A) 50, p. 23-45.
KLITZSCH, E. & WYCISK, P. (1987): Geology of sedimentary basins of northern Sudan and bordering areas.
Berliner geowiss. Abh., (A) 75.1, p. 97-136.
LEJAL-NICOL, A. (1987): Flores nouvelles du Paleozoique et du Mesozoique d’Egypte et du Soudan septentrional.
Berliner geowiss. Abh., (A) 75.1, p. 151-248.
 

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A. A. Balkema, Rotterdam, 1990
 

"The Geology of Libya", Volume I
M. J. Salem & M. T. Busrewil, Academic Press, 1980