Quseir Formation Research Articles

Enhanced geological and radioactive mapping of Gabal Abu Ashayir-Gabal El Bakriyah area, central Eastern Desert, Egypt, using remotely sensing data

AbstractThe primary goal of this work is to integrate airborne gamma-ray spectrometry with multispectral data from ASTER and Landsat-8 for mapping of the geology, radiometric data, and types of alterations of Gabal Abu Ashayir-Gabal El Bakriyah area, central Eastern Desert, Egypt. Utilizing various image processing techniques like color band composites (CBC), principal component analysis (PCA), band ratios (BR), and minimum noise fraction (MNF), it is possible to map the hydrothermal alterations zones and identify the lithological units under investigation. By identifying the various lithological units and alteration types, these results are validated and verified in the field. These methods’ outputs are combined to create an accurate geological map of the research region and tracing the propylitic, phyllic and iron oxy-hydroxides alterations. These rock units are ophiolitic mélange (oldest), arc metavolcanics, arc granitoids, younger gabbro, late-collision granites (monzogranites, syenogranites and alkali feldspar granites) and Nubian Sandstone (Taref formation and Quseir Formation) youngest, Furthermore, the radioactive anomalies are primarily associated with ferrugination zones (iron oxy-hydroxides alteration) at Gabal El Bakriyah monzogranite and alkali feldspar granite. The radioactive minerals are uranothorite, thorite and fergusonite. The opaque minerals that encountered at the rock units of Gabal Abu Ashayir-Gabal El Bakriyah are chromite, ilmenite, magnetite, chalcopyrite and chalcocite, whereas the non-opaque minerals comprises titanite, rutile, fluorite, garnet, zircon, apatite and barite.

A long-snouted dyrosaurid (Crocodyliformes, Mesoeucrocodylia) from the Campanian Quseir Formation of Egypt

Dyrosauridae, a clade of neosuchian crocodyliforms, was a significant component of terrestrial and aquatic ecosystems across the latest Cretaceous to Paleogene of North Africa. Here, we report a dyrosaurid mandibular symphysis recovered from the middle–upper Campanian Quseir Formation near Kharga Oasis in the southern Western Desert of Egypt.This is a partial mandible (MUVP 635), including dentaries and splenials, assigned to Dyrosauridae based on its dental pattern, size, and the shape of the splenial in the symphysis. MUVP 635 exhibits alveolar diameters shorter than the interalveolar distances within the same row. Moreover, the seventh dentary alveolus is significantly large, comparable in size to the fourth dentary alveolus, while the sixth dentary alveolus is positioned close to the seventh dentary alveolus and is as small as the eighth dentary alveolus, which is adjacent to the ninth dentary alveolus. Phylogenetic analysis places MUVP 635 as an early-diverging member of Dyrosauridae, consistent with its middle–late Campanian age. It aligns with a polytomy with Chenanisuchus lateroculi and Anthracosuchus balrogus identified as the most basal members of Dyrosauridae. The discovery of new dyrosaurid material in the Quseir Formation extends the range of Dyrosauridae to the middle Campanian, highlighting the taxonomic richness of the dyrosaurid clade across North Africa and supporting hypotheses of the African origin for this family.

Extraction and restoration of the dinosaur bones of Quseir Formation, Western Desert, Egypt

Extraction and restoration of the dinosaur bones of Quseir Formation, Western Desert, Egypt

A new record of saltasaurids in Africa; new evidence from the Middle Campanian, Western Desert, Egypt

ABSTRACT The Late Cretaceous deposits in the south of the Western Desert in the Dakhla Basin are well exposed, comprising variegated shales which contain a variety of vertebrates. In this contribution, we describe a new sauropod specimen from the Quseir Formation, represented by an almost complete humerus. The humerus shows a set of morphological features that allow us to refer it to the Saltasauridae, such as divided and well-developed distal condyles. Saltasaurids are ones of the smallest sauropod dinosaurs. The saltasaurids are newly recorded in Africa, although it was previously discovered on almost all the other continents in the Late Cretaceous. This study mentions the first record of saltasaurid humerus in Africa.

Paleoenvironmental contribution and visual kerogen assessment of some Upper Cretaceous sediments from southern Egypt

We investigated the palynological organic matter (POM) recovered from shale horizons, intercalating the Nubian-type sandstones in middle Egypt, for paleoenvironmental reconstruction. Our palynofacies are dominated by either amorphous organic matter (AOM) or phytoclasts whereas palynomorphs are relatively rare, but not uncommon. The palynofacies categories revealed two different palynofacies types, reflecting estuarine/tidal and fluvio-lacustrine environments for the Maghrabi and the basal Quseir formations, respectively. The kerogen composition of our investigated material and the colors of the thin-walled spores suggest possible sources of hydrocarbons, which are poorly explored in the middle and southern areas of Egypt. Our findings confirmed the previously described marine origin of the Maghrabi Formation. The complete missing of any marine palynomorphs suggests that the basal sediments of the Quseir Formation are almost exclusively of terrestrial origin. This may reveal that the worldwide Late Cretaceous transgression was not effective during deposition of these basal clastics.

The First Side-Necked Turtle (Pleurodira, Bothremydidae) from the Campanian (Late Cretaceous) of Egypt

The Quseir Formation is an Upper Cretaceous (Campanian) deposit in the Kharga oasis of the Southwestern Desert (Egypt). This formation comprises a clastic sequence of bioturbated mudstone and sandstone intercalations, including rare scattered and fragmented vertebrate remains such as shark teeth, dinosaur remains, and turtle plates. These deposits indicate a supratidal marsh environment. A complete shell of a turtle discovered from the Quseir Formation, at the Kharga oasis, is attributed here to Bothremydini (Pleurodira, Bothremydidae), and determined as a new taxon: Khargachelys caironensis gen. et sp. nov. This form represents the only Bothremydini member currently identified in the Campanian record not only of Egypt but also of North Africa. Therefore, it helps fill the missing evolutionary gap from the Late Cretaceous pleurodires in Egypt and in North Africa.

Bioerosion traces on the Campanian turtle remains: New data from the lagoonal deposits of the Quseir Formation, Kharga Oasis, Egypt

Bioerosion traces on the Campanian turtle remains: New data from the lagoonal deposits of the Quseir Formation, Kharga Oasis, Egypt

A new titanosaurian (Dinosauria: Sauropoda) from the Upper Cretaceous (Campanian) Quseir Formation of the Kharga Oasis, Egypt

ABSTRACT Dinosaur fossils from the latest Cretaceous (Campanian–Maastrichtian) of Africa and the Arabian Peninsula are rare. Most discoveries to date have consisted of limited fossils that have precluded detailed phylogenetic and paleobiogeographic interpretations. Fortunately, recent discoveries such as the informative Egyptian titanosaurian sauropod dinosaur Mansourasaurus shahinae are beginning to address these long-standing issues. Here we describe an associated partial postcranial skeleton of a new titanosaurian taxon from the Upper Cretaceous (Campanian) Quseir Formation of the Kharga Oasis, Western Desert of Egypt. Consisting of five dorsal vertebrae and 12 appendicular elements, Igai semkhu gen. et sp. nov. constitutes one of the most informative dinosaurs yet recovered from the latest Cretaceous of Afro-Arabia. The relatively gracile limb bones and differences in the coracoid and metatarsal I preclude referral of the new specimen to Mansourasaurus. Both model-based Bayesian tip-dating and parsimony-based phylogenetic analyses support the affinities of Igai semkhu with other Late Cretaceous Afro-Eurasian titanosaurs (e.g., Mansourasaurus, Lirainosaurus astibiae, Opisthocoelicaudia skarzynskii), a conclusion supported by posterior dorsal vertebrae that lack a postzygodiapophyseal lamina, for example. Igai semkhu strengthens the hypothesis that northern Africa and Eurasia shared closely related terrestrial tetrapod faunas at the end of the Cretaceous and further differentiates this fauna from penecontemporaneous assemblages elsewhere in Africa, such as the Galula Formation in Tanzania, that exhibit more traditional Gondwanan assemblages. At present, the specific paleobiogeographic signal appears to vary between different dinosaur groups, suggesting that Afro-Arabian Cretaceous biotas may have experienced evolutionary and paleobiogeographic histories that were more complex than previously appreciated.

Evidence for Upper Cretaceous seismites in the Abu Tartur area, Western Desert, Egypt

Upper Cretaceous tidal-flat sediments of the Abu Tartur region, Western Desert of Egypt, contain a variety of soft-sediment deformation structures (SSDSs) in the Mut Member of the Quseir Formation and the overlying Duwi Formation. Here, we document recognition of a set of SSDSs characterized by complex morphology and large size. The SSDS include: 1) water-escape structures, 2) minor recumbent, chevron, and slump folds, 3) syn-sedimentary minor faults, 4) neptunian dykes, 5) regular ball-and-pillow structures, flattened pseudo-nodules, and load casts, 6) syn-sedimentary undulations, 7) fractures and joints, 8) sand injectites, and 9) autoclastic breccia and brecciated siderite clasts. The dimensions of the SSDSs range from a few centimeters to several decimeters. Both extensional and contractional forces appear to have been involved in development of these structures. A detailed analysis of facies relationships, combined with consistent orientations of SSDSs and the regional tectonics of the target area suggests earthquakes as the triggering mechanism for sediment deformation and large-scale mass failure. The deformed strata are consistent with most of the well-known criteria of typical seismites. Thus, syn-sedimentary liquefaction was identified as the primary driving force in most of the observed deformation horizons for these Upper Cretaceous SSDSs in the Abu Tartur area.

Paleoclimatic variability in the southern Tethys, Egypt: Insights from the mineralogy and geochemistry of Upper Cretaceous lacustrine organic-rich deposits

The effect of paleoclimate during global warming periods on Upper Cretaceous lacustrine deposits is not fully understood. In this study, comprehensive sedimentological, mineralogical, and geochemical data were used to unravel the past climatic changes and their influence on the accumulation of Campanian lacustrine organic-rich deposits in Egypt. Three sedimentary lithofacies associations are recorded within the uppermost part of the Quseir Formation. The laminated clay-rich mudstone lithofacies has the highest organic matter (TOC up to 1.2 wt.%). Sedimentological observations indicate that the bulk lithologic assemblage was originated in a shallow lacustrine setting. The studied samples consist of clay minerals, quartz, pyrite, carbonate, fluorapatite, and halite. The siliciclastic content reaches up to 78wt.%, whilst the carbonate content ranges from 3 to 22 wt.%. Compared to Post-Archean Australian shales (PAAS), the studied samples are significantly rich in Mg, Ca, P, Al, V, Ga, and Cr contents. The mudstone samples are characterized by high ratios (C-value, CIA, CIW, Mg/Ca, Fe/Mn, Ga/Rb) and low values (K2O/Al2O3), reflecting relatively warm and humid conditions during deposition of these sediments. The prevalence of smectite, as well as the sedimentary features, support that the lacustrine organic-rich mudstones are mainly deposited under warm seasonal climate (arid/humid). Additionally, the presence of dolomite and halite along with the Sr/Ba ratios (1.30–2.13), strongly suggest a saline water setting. The changes between aridity and humidity periods are probably the main reason for the significant variation in water chemistry, especially salinity. Therefore, the paleoclimatic variations largely controlled the depositional process during the formation of the Upper Cretaceous lacustrine organic-rich mudstones in the southern Tethys.

Dinosaur remains from the Upper Cretaceous (Campanian) of the Western Desert, Egypt

Upper Cretaceous dinosaur remains from Afro-Arabia are rare and mainly restricted to pre-Turonian horizons. Consequently, the discovery of new fossils from Upper Cretaceous deposits in the Western Desert, central Egypt is significant because it adds to the meager record of dinosaurs described from this landmass. The oases of Kharga and Dakhla, Western Desert, Egypt, expose the Quseir Formation (Campanian), with the titanosaurian sauropod Mansourasaurus shahinae as the only currently named dinosaur from strata of this age in the entire region. Numerous (~80) other non-avian dinosaur fossils have also been collected from the Quseir Formation, including material that can be referred to Somphospondyli, Titanosauriformes/Titanosauria, and non-avian Theropoda. Among the discoveries from the Dakhla Oasis are the proximal ends of an associated sauropod tibia and fibula and several sauropod caudal vertebrae representing both sub-adult and adult individuals. Middle caudal vertebrae can be referred to Titanosauria on the basis of procoelous centra and anteriorly displaced neural arches. One caudal vertebra even exhibits pneumatic internal structures rarely observed outside of the Upper Cretaceous South American saltasaurines. Dinosaur fossils recovered from the Kharga Oasis include a partial femur and partial cervical vertebra of a sauropod dinosaur and an isolated proximal fibula of a non-avian theropod dinosaur. Taken together, these findings indicate that Late Cretaceous North African ecosystems supported a diversity of non-avian dinosaurs, some demonstrating affinities with South American forms and others (e.g., Mansourasaurus) with Eurasian groups. Additional exploration of the uppermost Cretaceous units in southern Egypt offers promise for the discovery of important fossils to better characterize Afro-Arabian biotas generally while also providing important perspectives on non-avian dinosaur faunas near the close of the Mesozoic Era.

Three‐Dimensional Structural Modelling and Source Rock Evaluation of the Quseir Formation in the Komombo Basin, Egypt

AbstractThe Quseir Formation consists mainly of dark gray mudstones with a high organic matter content and excellent hydrocarbon‐generating potential. The main objectives of this study are to highlight the dominant structural elements in the Komombo Basin, Egypt, and evaluate the geochemical characteristics of the Quseir Formation. Depth maps and a 3D structural model indicate two normal fault trends NW–SE and ENE–WSW. The NW–SE trend is the dominant one that created the primary half‐graben system. The depth to the top of the Quseir Formation gradually decreases from the eastern and central parts towards the corners of the basin. The thickness of the Quseir Formation ranges from about 300 to 1000 ft. The 3D facies model shows that the shale has a large probability distribution in the study area, compared with the sandstone and siltstone. The source rock potential varies between good in the western part to very good in the eastern part of the basin. The organic‐rich interval is dominated by gas‐prone kerogen type III based on TOC and Rock‐Eval. The pyrolysis data vitrinite reflectance (%Ro) (0.5–0.74%) and Tmax values (406–454C°) suggest a maturity level that ranges from immature to early maturity stage for hydrocarbon generation.

Detection of flow units of Quseir Formation (Lower Campanian) as a potential reservoir using experimental correlations of capillary pressure derived parameters, Gebel el-Silsila, Egypt

Sandstone surface samples were collected from Quseir Fm., a member of Nubian Sandstone at Gebel el-Silsila and subjected to petrographical investigation using polarizing microscope. X-Ray diffraction was carried out to determine mineralogy. Scanning electron microscope also was utilized for the morphological characterization of the rock components. This sandstone petrofacies is mainly quartz arenite. The depositional environment of the studied sandstones is fluvial to fluvial-marine, and they suffered post-depositional alterations. Alterations include diagenesis (clay infiltration and original detrital grains disintegration), weathering, deterioration phenomena as erosion, voids existence due to dissolution and absence of bound materials. Mineralogical characterization indicated that quartz is the main constituent of sandstone in addition to kaolinite clay mineral as a cementing material. Petrophysically, the studied samples subjected to porosity and permeability measurements. The measurements showed that the samples are highly porous and permeable. Permeability–porosity relation displayed two groups (A and B). Although porosity values are close to great extent, permeability is quite different for the two groups due to the different distributions of pore throats, perhaps as a result of uneven clay distribution within the two groups of samples. Many capillary pressure-derived parameters were calculated using experimental correlations. The results confirmed the presence of two flow groups, macroport group (group A) and megaport group (group B) that is the best in terms of reservoir quality. The two groups reflect the excellent properties for the studied potential reservoir.

Paleo-environmental reconstructions of the Upper Cretaceous-Paleogene successions, Safaga, Egypt

The Late Cretaceous-Early Eocene sedimentary sequences in the Central Eastern Desert of Egypt were studied in three shallow boreholes (Wassief, Um El-Huaitat, and Mohamed Rabah). This study focuses on an integrated investigation of biostratigraphy, lithostratigraphy and some geochemical parameters, to provide important clues to the relative sea-level changes and to interpret the prevailed depositional conditions.Micropaleontological study on planktonic foraminifera allows to identify eight zones, ranging in age from Late Cretaceous to Early Eocene. Three hiatal surfaces have been recognized as evidenced by missing formaniniferal zones: The first spans the Late Maastrichtian-Danian regional unconformity. The second one is recorded in the Late Paleocene. The third one is located at the Late Paleocene-Early Eocene (Thanetian-Ypresian) boundary. The environments of the study foraminiferal parameters range from the non-marine to outer neritic-upper bathyal.Petrographically, thirteen Microfacies Types (MFT) have been recorded. Three MFTs constitute the siliciclastic facies; MFT-1; silty to sandy mudstone, MFT-2; organic-rich silty mudstone, and MFT-3; fine-grained sandstone/glauconite intercalations. Two MFTs represent a phosphorite facies which are MFT-4; phosclast packstone to phosclast grainstone and MFT-5; phosooid packstone to phosooid grainstone. Eight MFTs characterize the carbonate facies; MFT-6; non-fossiliferous lime-mudstone, MFT-7; phosphatic foraminiferal pack/grainstone, MFT-8; bioclastic foraminiferal packstone, MFT-9; bioclastic foraminiferal wackestone, MFT-10; glauconitic phosphatic foraminiferal Wack-Packstone, MFT-11; non-fossiliferous dolomitic mudstone, MFT-12; dolomitic glauconitic lime-mudstone, and MFT-13; dolomitic bioclastic wackestone. The depositional environments of the study microfacies range from the terrestrial to open marine outer neritic-upper bathyal.Geochemical parameters have been used to improve the litho- and biostratigraphic framework: the major oxides, TOC wt.% and the Chondrite-normalized REE. Based on the vertical distribution of CaO/P2O5, TiO2/CaO and cerium (Ce)-anomaly, changes in paleo-bottom water redox conditions were reconstructed and correlated with relative sea level changes. Prior to the major transgression during deposition of the Duwi Formation under reducing marine conditions, the prevailing oxic to sub-oxic bottom water terrestrial conditions during deposition of the Quseir Formation.

An enigmatic crocodyliform from the Upper Cretaceous Quseir Formation, central Egypt

Non-marine vertebrates, including many crocodyliform clades, remain poorly documented from uppermost Cretaceous deposits of Africa. Recent exploratory fieldwork in the Upper Cretaceous (middle Campanian) Quseir Formation exposed around Dakhla Oasis (Western Desert of Egypt) has revealed new fossils from continental and marginal marine settings that include abundant crocodyliform remains. In particular, materials of an enigmatic crocodyliform, Wahasuchus egyptensis gen. et sp. nov., represented by both cranial and postcranial remains, suggest the presence of a novel southern Tethyan crocodyliform assemblage from northern Africa during the Late Cretaceous. Materials recovered of this taxon thus far include fragmentary portions of the skull and mandible, amphicoelous dorsal vertebrae, and fragmentary appendicular remains. This form is distinguished by a number of unique features including a domed platyrostral skull; a strongly festooned lateral margin of the maxilla with two waves of tooth enlargement; a deep, sculptured fossa at the base of the postorbital bar; a jugal with an anterior process that is at least three times broader than the posterior process; an orbital margin dorsally overlapping the lateral temporal fenestra; a supraoccipital with a distinct medial tuber and associated ventral fossa; and a robust straight dentary with contribution of the splenial to the symphysis. This new form suggests a potentially unique Late Cretaceous assemblage from northern Africa, markedly different from better-known Late Cretaceous crocodyliform assemblages of South America and Madagascar, or from earlier (pre-Turonian) deposits in Africa. This pattern may reveal a distinct regional fauna along the southern Tethys, or potential Cretaceous relationships with Eurasian neosuchian-dominated assemblages.

New Egyptian sauropod reveals Late Cretaceous dinosaur dispersal between Europe and Africa.

Prominent hypotheses advanced over the past two decades have sought to characterize the Late Cretaceous continental vertebrate palaeobiogeography of Gondwanan landmasses, but have proved difficult to test because terrestrial vertebrates from the final ~30 million years of the Mesozoic are extremely rare and fragmentary on continental Africa (including the then-conjoined Arabian Peninsula but excluding the island of Madagascar). Here we describe a new titanosaurian sauropod dinosaur, Mansourasaurus shahinae gen. et sp. nov., from the Upper Cretaceous (Campanian) Quseir Formation of the Dakhla Oasis of the Egyptian Western Desert. Represented by an associated partial skeleton that includes cranial elements, Mansourasaurus is the most completely preserved land-living vertebrate from the post-Cenomanian Cretaceous (~94-66 million years ago) of the African continent. Phylogenetic analyses demonstrate that Mansourasaurus is nested within a clade of penecontemporaneous titanosaurians from southern Europe and eastern Asia, thereby providing the first unambiguous evidence for a post-Cenomanian Cretaceous continental vertebrate clade that inhabited both Africa and Europe. The close relationship of Mansourasaurus to coeval Eurasian titanosaurians indicates that terrestrial vertebrate dispersal occurred between Eurasia and northern Africa after the tectonic separation of the latter from South America ~100 million years ago. These findings counter hypotheses that dinosaur faunas of the African mainland were completely isolated during the post-Cenomanian Cretaceous.

High-resolution sequence stratigraphy of the Upper Cretaceous-Lower Paleogene succession, Gabal Qreiya area, Upper Egypt

The Upper Cretaceous-Lower Paleogene succession at Gabal Qreiya area that covers six rock units, Quseir, Duwi, Dakhla, Tarawan, Esna, and Thebes formations, is reviewed through a high-resolution sequence stratigraphic analysis. Six third-order depositional sequences and their associated surfaces and systems tracts are recognized based on stratigraphic, sedimentological, and high-resolution foraminiferal studies. The pre-Campanian sequence, comprising the Quseir Formation, was accumulated in inner neritic paleodepths, on marginal to shallow subtidal shelf. The Lower Campanian sequence that covers the Duwi Formation was accumulated in oscillating settings between inner to middle neritic paleodepths, on a shallow subtidal shelf. The Upper Campanian-Maastrichtian sequence that covers the lower part of the Dakhla Formation was accumulated in outer neritic-upper bathyal to middle neritic paleodepths, on a deep subtidal shelf to a shallow subtidal shelf. The Danian sequence that covers the middle part of the Dakhla Formation was accumulated in oscillating conditions between upper bathyal and middle neritic paleodepths, on a deep subtidal and a shallow subtidal shelf. The Selandian-Thanetian sequence that comprises the upper part of the Dakhla, Tarawan, and the lower part of the Esna formations was accumulated in fluctuating conditions from upper bathyal to middle neritic paleodepths, on a deep subtidal to a shallow subtidal shelf. The Ypresian sequence that includes the main parts of Esna and Thebes formations was accumulated in fluctuating settings among middle bathyal and middle neritic paleodepths, on a deep subtidal to a shallow subtidal shelf. Most of the sequence boundaries coincide with the global sea-level curve whereas some of them suggest a local tectonic event.

Uranium migration and favourable sites of potential radioelement concentrations in Gabal Umm Hammad area, Central Eastern Desert, Egypt

Airborne gamma-ray spectrometric data, covering Gabal Umm Hammad area, near Quseir City, in the Eastern Desert of Egypt, has been utilized to identify the uranium migration path, and U, Th and K-favorability indices. The following of the uranium migration technique enabled estimation of the amount of migrated uranium, in and out of the rock units. Investigation of the Taref Formation, Nakhil Formation, Tarawan Formation and Dawi Formation shows large negative amount of uranium migration, indicating that uranium leaching is outward from the geologic body toward surrounding rock units. Moreover, calculation of the U, Th and K-favorability indices has been carried out for the various rock units to locate the rocks having the highest radioelement potentialities. The rock units that possess relatively major probability of uranium potentiality include Mu′tiq Group, weakly deformed granitic rocks, and Trachyte plugs and sheets. Meanwhile, the rock units with major potential of Th-index are Taref Formation, Quseir Formation and Dawi Formation. The rock units with major potential of K-index are Dokhan volcanic and Mu′tiq group.

Oil shale resources in Egypt: the present status and future vision

In Egypt, organic-rich sediments in the Duwi and Dakhla Formations of the Campanian-Danian age are customarily assigned as “oil shale” that occupies the middle latitudes of the country but may extend southward to Kurkur Oases. This oil shale belt has a vast worldwide extension, and it is considered as major oil- and gas-prone source rock in many places, especially in the Middle East. The sedimentation of the oil shale was triggered by the major transgression event that occurred during the Late Cretaceous. The lithology, type of kerogen, organic richness, and thickness of these organic-rich sediments vary markedly both on lateral and vertical scales. In Quseir area, the in-place geological reserves, of oil shale of the 800-kcal/kg quality, is estimated to be more than 9 billion tons that can produce 5.48 bbls equivalent upon retorting. Very optimistic resources are expected in the unexplored Nile Valley region. The factor analysis of data rank representing 1176 core samples and analysis of 58 major and trace elements besides Rock-Eval analyses point to five main controlling factors that control deposition of oil shale. The terrestrial indicators Al2O3, TiO2, Fe2O3, and K2O and the marine indicators Ca and Sr are oppositely loaded in the first factor. The second factor expresses the reducing conditions that prevailed during the deposition of the organic-rich marine environments. The euxinity of the basin is recognized by the third factor where sulfide and vanadium seem to be mutual. The fourth factor expresses the role of dolomitization while the fifth factor points to the humble role of oxidation. Considering the metric core samples, the highest TOC content recorded in the borehole drilled in Abu Tartur plateau is 3.6%, but it is about 14% for Quseir area. Regarding the spot samples in Quseir area, the highest TOC measured about 24%. It is not only the low TOC in Abu Tartur but also the kerogen type that is of type II + III, mostly of terrestrial origin (gas-prone) and lithology dominated by argillites. Organic richness is remarkable in Quseir-Safaga area, where the average TOC of 160-m-thick sequence is about 5%, with kerogen of type I or mixed I + II, mostly of marine origin (oil prone). The Dakhla Formation (Maastrichtian-Danian) is the richest in organic matter while Quseir Formation (Campanian) has the least organic richness and lowest kerogen quality. Detailed investigation on biomarkers confirms the relations among transgression, organic richness, kerogen type, and anoxic conditions. The organic matter is immature as witnessed by the low S1 values (<5%, in average), the low T max (<430 °C), the low vitrinite reflectance (<0.4%), and biomarker signature. The variation in the S1 values between 1 and 9% is attributed to the influence of tectonics associating the Red Sea rift. In Quseir-Safaga area, there are particular prolific horizons of oil shale that seem to be visible for utilization by different technologies of combustion and retorting. The content of the heavy metals and uranium, as well as the spent, is a significant benefit. The faulting, dragging, and steep tilting of beds in the Quseir-Safaga area shall remain a serious challenge for extensive utilization of the estimated in-place geological reserves.

Dakhla–Kharga iron-rich paleosols, Western Desert, Egypt: geology, geochemistry, and mineralization

The purpose of the present paper is to identify the source of iron oxides as well as the paleo-oxygenation conditions by using major oxide and trace element geochemistry of the Quseir and Sabaya formations exposed at the Dakhla–Kharga basin, Western Desert, Egypt. The iron-rich paleosol occurs chiefly overlying different Upper Cretaceous rocks, particularly the red clay of the Campanian Quseir Formation at the Dakhla Oasis or the Cenomanian Sabaya Formation at the Kharga Oasis. The iron-rich paleosols consist mainly of massive yellow goethite-rich beds with high concentrations of Fe(OH). The presence of high Fe/Mn ratio with a wide range of variation indicates that the sources of the iron-rich paleosols are from the discharge of iron-rich Nubian Aquifer water controlled largely by localized fractures which formed spring mounds deposited of Pleistocene age. These mounds were exposed to subaerial weathering that resulted in the formation of lateritic goethite ore during tropical climatic periods. There is evidence of hydrothermal vents (hot spring) such as found native Au, magnetite. and high concentrations of zirconium, cobalt. and vanadium. In the depositional history of Mut and Zayat ironstones, four main processes will be clarified as follows: (1) the syn-depositional, (2) diagenetic, (3) hot spring processes, and (4) post-diagenetic (soil formation). At the end, the high Fe2O3 concentrations and replacement of lithic fragments by microcrystalline goethite indicate that the Dakhla–Kharga sedimentary rocks were subjected to ferrugination. These alterations thought to be result of either post-depositional hydrothermal alteration or syn-depositional interaction with seawater at low temperatures or some combination of the two processes.