North Eastern Desert Research Articles

Low-temperature alteration of uranium–thorium bearing minerals and its significance in neoformation of radioactive minerals in stream sediments of Wadi El-Reddah, North Eastern Desert, Egypt

The stream sediments of Wadi El Reddah (North Eastern Desert, Egypt) are geochemically and mineralogically investigated. Their content of radioactive and other heavy minerals is mainly represented by thorite, uranothorite, zircon, monazite, xenotime, columbite, fergusonite, and unknown rare earth elements (REEs) bearing minerals as well as cassiterite. Special emphasis on REE content of thorite, uranothorite, zircon and xenotime has been done to correlate them with the increase of uranium contents in these sediments. The key evidence for the presence low-temperature alteration processes includes the presence of some zircon crystals as remnants after complete dissolution of the overgrowth zircon in severe acidic environment, the sulphur content, biogenic minerals, occurrence of unusual minerals as cassiterite pore filling in zircon, variation in the REEs content from the surrounding granites to the stream sediments and the abundance of monazite in the surrounding granites. Most minerals are partially and/or completely altered, which indicated by the pseudomorphism of zircon by xenotime, thorite, and uranothorite.

Aeromagnetic data for mapping geologic contacts at Samr El-Qaa area, North Eastern Desert, Egypt

Delineating the edges of different magnetized sources represents a fundamental tool for interpreting and mapping rock boundaries of magnetic data. The present study deals with the enhancement of reduced to the pole map (RTP) of Samr El-Qaa area, North Eastern Desert, Egypt, to map deep and surface geologic contacts. The edge detection of geologic contacts is ensured by the upward continuation of reduced to the pole data at an altitude of 3 km, followed by the calculation of theta derivative and horizontal tilt angle derivative (HTAD) for RTP and upward continuation (3 km). The results obtained from the application of these techniques showed that the theta derivative delineates RTP source edges well, but the response of deeper sources is diffused. While HTAD presented well, responds to shallow and deep sources and also the edges of the sources were delineated well. HTAD showed a much sharper gradient over the edges of the magnetized sources at Samr El-Qaa area. The interpreted structural trends derived from shallow and deep Theta and HTAD maps of Samr El-Qaa territory illustrated that the most shallow dominant trends are NNE, NE, N-S, NNW, WNW, E-W and NW directions. While the deep structural ones are the ENE, NW, N-S, and E-W directions. This approach for edge detection used in this study is comprehensively applicable to other portions of the Egyptian Eastern Desert and other areas with alike geologic conditions around the world to give much sharper gradient over the edges of the magnetized sources which can be used for mineral and oil/gas exploration.

Benthic foraminiferal communities of the Eocene platform, north Eastern Desert, Egypt

The Eocene successions on Beni Suef – El Zaafarana road at north Eastern Desert of Egypt have been examined for their benthic foraminiferal contents from three rock units: El Fashn, Beni Suef and Maadi formations. The studied material of this work allowed us to identify 153 benthic foraminiferal species. The Eocene age of the studied successions is defined by the co-occurrence of the planktonic and benthic foraminiferal species. The studied succession could be subdivided into five benthic foraminifera biozones from the late Middle to Late Eocene age. These zones are Palmula ansaryi Range Zone (late Middle Eocene), Bulimina jacksonensis - Uvigerina mediterranea Concurrent-Range Zone, Cancris auricula Lowest Occurrence Zone, Pararotalia audouini Concurrent-Range Zone and Pyrgo elongata Concurrent-Range Zone (Late Eocene). The identified benthic foraminiferal species were analyzed using R- and Q-mode cluster analysis in order to better understand the linkage between the benthic foraminiferal assemblages and paleoenvironmental conditions. The cluster analysis revealed that the benthic foraminifera could be grouped into 7 assemblages and 7 biofacies in the measured sections. The recorded benthic foraminiferal biofacies suggest that the environments are deep outer ramp setting with meso-to moderately eutrophic conditions, and minimum to moderate oxygenation level on El Fashn Formation. The environment of Beni Suef and Maadi formations is inner to middle ramp with high oxygen level and oligotrophic conditions.

Uranium potentiality mapping of G-V occurrence at Gabal Gattar area, North Eastern Desert, Egypt, using GIS approach

Delineation and evaluation of mineral resources are major exploration parameters required for investment decisions. Identifying the best probable sites for uranium mineralization in terrains of lack subsurface penetrations is a challenging task. In northern part of Egyptian Eastern Desert, the uranium occurrences of Gabal Gattar area are among the most important source of uranium mineralization. Gattar-V (G-V) uranium occurrence considered as the most important uranium locality in the northern parts of Gabal Gattar area. The well-known uranium mineralization in this occurrence is restricted to the geological contact zone between the Hammamat sedimentary rocks and the G. Gattar Alkali feldspar granite. The lithological units and their alteration zones that are associated with the uranium mineralization and the ground spectrometric measurements data are identified and delineated throughout the field work of the geological investigation. In addition to the delineation of visible uranium mineralized zones, useful aid for the location of uranium promising zones is provided. Uranium potential (UP) mapping is a systematic tools that considers the main controlling factors which influence the localization of uranium mineralization within their host rocks. The present study aims to highlight, identify, model and map uranium promising zones in G-V uranium occurrence by using Geographic Information System (GIS) to construct multiple geological thematic maps such as different kind of alteration, contact zone, radiometric measurement and secondary zones of uranium mineralization. The constructed thematic maps of the different controlling factors of U-mineralization are assigned with a fixed score, weight, and calculated using a linear equation approach. Each weighted thematic map is statistically calculated to produce a uranium potential levels map of the investigated area. The uranium potential areas thus obtained were classified into four classes of potentiality (very high, high, moderate and low). The obtained an integrated uranium potential map of the investigated area will be a useful guide in the mining planning activity and create a good decision for better planning and management of uranium resource.

Resolution enhancement of foraminiferal biostratigraphy of the Campanian-Maastrichtian interval: A case study from the Eastern Desert, Egypt

The Campanian-Maastrichtian (C-M) rocks exposed at the Southern Galala Plateau, North Eastern Desert of Egypt are represented by Sudr Formation, which consists of snow white chalky limestone, rich in planktonic and benthonic foraminifera. The major C-M transgression resulted in a deposition of Sudr Formation in outer neritic environment with high diversity and abundance of species, which led to defining nine planktonic foraminiferal zones and establishing the stage boundaries. In comparison with the foraminiferal zones of the GSSP of the C/M boundary, the lowest occurrence of Rugoglobigerina scotti is here considered to be the only marker for this boundary. In contrast, the other species (e.g. Contusotruncana contusa) that used to define this boundary at the GSSP is a diachronous and not save to depend on it in definition of the C/M boundary. Therefore, the present study helps in refinement of the C/M boundary definition not only in the study area, but also elsewhere.

Hydrothermal alteration and evolution of Zr-Th-U-REE mineralization in the microgranite of Wadi Ras Abda, North Eastern Desert, Egypt

Ras Abda plutonic suite, North Eastern Desert of Egypt, consists predominantly of Neoproterozoic calc-alkaline older granites. Minor exposures of pink microgranite are occurring along Wadi Ras Abda within the older granites. Previous studies on this area demonstrated that the microgranite is altered in some parts and contains anomalous concentrations of rare metal elements (Zr, Th, and U). These altered and mineralized zones are re-assessed using field observations, chemical analysis, and by the application of various transmitted light and electron microscopic techniques. The rare metals exist as mineral segregation grew freely into open cavities of the microgranite and concordant with the NNE strike-slip fault movement. The mineralized zones contain an assemblage of secondary magnetite, zircon, uranothorite, columbite-(Mn), fergusonite-(Y), and allanite-(Ce). The extreme abundance of zircon in the mineralized zone, along with other evidence, indicates a hydrothermal origin of this zircon together with associated rare metals. The geochemical investigation and mass balance calculations revealed extreme enrichment of Zr, Th, U, Y, Nb, Ta, and REE. Post-magmatic hydrothermal alterations resulted in such pronounced chemical and mineralogical heterogeneity. The hydrothermal fluids are thought to be oxidizing, alkaline and of medium temperature (> 250 °C). The average contents of the elements Zr (1606 ppm), Th (1639 ppm), U (306 ppm), Nb (955 ppm), and REE (1710 ppm) in the mineralized microgranite reach sub-economic levels and could be a potential source of these elements.

The Ediacaran volcanosedimentary succession of Gabal Abu Had, North Eastern Desert, Egypt: geological study, facies analyses, and depositional setting

Gabal Abu Had is an exposure of a volcanosedimentary succession in the North Eastern Desert Basement Complex. This succession includes intercalation of two major rock units, which are Dokhan Volcanics and Hammamat Group with different styles of formation, deposition environments, and genesis. Gabal Abu Had succession (GHS) is a northward dipping, c. 700-m-thick volcanosedimentary succession that rests on metavolcanic and old granitoid rocks with erosion unconformity. The lower part of GHS is dominated by volcaniclastic mass flow deposits and andesitic lava with interbedded gravely sandstone, whereas the upper sequence is composed of pyroclastic flow deposits including welded to no welded ignimbrite intercalated with gravely sandstone and massive clast-support conglomerate toward the top. Facies analysis study of GHS presented eight lithofacies types, which grouped into five lithofacies associations. The GHS basin started with effusive eruption of silica-poor volcanic center, which produced andesitic lava. A part of lava underwent hyaloclastic fragmentation due to the presence of fluvial water in places producing the volcaniclastic mass flow deposits. Later, an explosive silica-rich volcanic center affected the GHS basin and created the pyroclastic plain deposits (ignimbrite and bedded tuff). The fluvial braided river is still in action since the first eruption, producing gravely sandstone, which is intercalated with the volcanic sequence. The upper GHS is characterized by thick, massive, and clast-supported conglomerate (well rounded clasts up to 100 cm) of alluvial fan facies. Several silica-rich and silica-poor subvolcanic intrusions were emplaced in the GHS. The GHS development displays a cycle from low- to high-energy sedimentation under humid climatic conditions, in addition to extension and down faulting of basin shoulders. In comparison with Gabal El Urf, located to the north of GHS and was studied by El-Gameel (2010), the GHS is a lava-rich succession rather than Gabal El Urf succession which is mainly pyroclastic rich.

Fluid evolution of Au-Cu zones in Um Balad area, North Eastern Desert of Egypt: Implications from mineral chemistry and fluid inclusions

Scanning electron microscope (SEM), Electron microprobe (EMPA) and fluid inclusion studies of the ore body, as well as geochemical analyses of country rocks were performed to determine the nature and characteristics of the mineralizing fluid responsible for Au-Cu deposits in Um Balad area, Northern Eastern Desert of Egypt. The Um Balad Au-Cu deposits are confined to well developed-quartz veins and veinlets cutting through the hosting country rocks. Petrographic and geochemical investigations of the hosting rocks distinguished between two main rock units; 1) metagabbro-diorite rocks with tholeiitic nature derived in island arc/continental margin tectonic regime, and 2) granodiorite rocks formed from calc-alkaline magma in continental margin regime. Wallrock alterations are represented by propylitic and argillic types. The mineralized quartz veins are striking in NE-SW direction and dipping between (35°–45°) in SE direction, other mineralized mafic dykes enriched with auriferous quartz veinlets are trending NE-SW and dipping 70°/SE. The main ore minerals are represented by gold, chalcopyrite, pyrite, sphalerite, malachite, covellite and goethite. While, geffroyite, cuprite, chrysocolla, pseudomalachite, britholite, wolframite, scheelite, hematite and rutile are detected as minor constituents. Fluid inclusions microthermometry and isochore calculations combined with chlorite geothermometry revealed that the Um Balad deposits were formed at temperature ranging from 305 °C to 325 °C and pressure between (100–500 bar). The mineralization had been developed in the shallow levels, beneath the water table at depth of 350–1760 m, rather than common mesothermal vein-type deposits in Egypt. Magmatic water have been suggested as the main source for the mineralized fluid. The transportation of the gold metal seems to be happen as bisulfide complexes in moderately acidic environment. The deposition was resulted from combination of changes in physico-chemical parameters, temperature and pressure plus the instability of the reduced sulfur complexes. A contamination with metamorphic and/or meteoric water was also proposed that has strong influence during the depositional process.

Mid-Cretaceous echinoids from the Dhalqut Formation of Dhofar, southern Oman – Taxonomy and biostratigraphical implications

Several small echinoid faunules are recorded from the Umbaraaf and Khadrafi members of the Dhalqut Formation, the upper unit of the Albian–Turonian Qamar Group in the eastern part of the Jeza-Qamar Basin of Dhofar (southern Oman). In all, 11 species, in nine (sub)genera, are described: Arabicodiadema dhofarense (Roman), Arabicodiadema romani Smith and Jagt n. sp., Heterodiadema libycum (Desor, in Agassiz and Desor), Emiratia raskhaimahensis Ali, Orthopsis miliaris (d’Archiac), Pedinopsis (P.) sphaerica Smith, Simmons and Racey, Pedinopsis (Sinaiopsis) sinaica (Desor, in Agassiz and Desor), Goniopygus dhalqutensis Smith and Jagt n. sp., Coenholectypus excisus (Desor, in Agassiz and Desor), Coenholectypus larteti (Cotteau) and Pliotoxaster dieneri (de Loriol). These novel echinoid data suggest that the Umbaraaf Member extends into the Cenomanian, thus supplementing previous biostratigraphical dating based on foraminifera. The echinoid fauna also suggests correlation of the Umbaraaf and Khadrafi members with strata such as the Natih Formation in north-central Oman, the Mauddud Formation of the northeastern United Arab Emirates, the Galala Formation of the North-Eastern Desert of Egypt and the Wasia Formation of central Saudi Arabia.

Genetic link between uranium mineralization and the emplacement of limited intrusion adjacent to alkaline granites, Abu Hamr area, north Eastern Desert, Egypt

The recorded uranium mineralization is genetically related to the U content and structural setting of syenogranitic dyke that occurs near alkaline granites, Abu Hamr area, north Eastern Desert of Egypt. The associated abnormal level of radioactivity exhibits maximum equivalent uranium (eU) of 155.6 parts per million (ppm) with an average of 54 ppm while the maximum of eTh reaches up to 235 ppm with average content of 120 ppm. The nearby alkaline granites of Gabal Abu Hamr show a normal distribution of eU and eTh resembling that of normal granites (4 ppm eU and 8 ppm eTh). Radioactive anomalies can be interpreted as successive concentrations of U-Th, which are related to magmatic processes of syn-shearing syenogranite dyke formation followed by hydrothermal redistribution during the emplacement, and then supergene enrichment. Testing of uranium equilibrium has revealed major chemical U addition to both the syenogranitic dyke and, to less extent, the alkaline granites. The rare-earth element (REE) patterns display pronounced enrichment of light REEs and heavy REEs of the syenogranitic dyke in contrast to the alkaline granites, which might have attributed to the subsequent hydrothermal circulation. The studied dyke is also characterized by well-developed U, Th, and Pb enrichments. Post-magmatic hydrothermal activity is evident from the presence of dark violet fluorite with inclusion of U and Th minerals, in addition to the presence of zircon crystals with overgrowth, xenocrystic cores, REE replacements, and spatially inclusions of allanite-(Ce) with irregularly distributed patchy overgrowths of U and Th.

Petrographical and mineralogical studies of Hammamat sediments and Gattarian granite along Wadi Belih, north Eastern Desert, Egypt.

The Hammamat sediments at Wadi Belih area are represented by greywacke and siltstones. The greywackes are immature and are fine to coarse grained and composed of quartz, feldspar and rock fragments. The siltstones consist of quartz, feldspar and hematite. The younger granites (The Gattar granites) are composed mainly of quartz and feldspars as essential minerals and biotite, hornblende, zircon, and apatite as accessory minerals. Some secondary minerals as epidote, chlorite and sericite are found. The radioactive minerals are identified by using the Quanta FEG-250 ESEM instrument which is an environmental Scanning Electron Microscope (ESEM) attached by Energy Dispersive X-ray(EDX) in the national central research (NCR). The younger granites and Hammamat rocks at Wadi Belih area contain primary uranium mineral as Coffinite, secondary minerals as Uranophane, Kasolite, Schroeckingerite and uranium bearing minerals like Columbite.

Tectonostratigraphic and sedimentary evolution of the Ubur–Orabi sub-basin, southeast Nile Delta, Egypt

Core study of two wells drilled in the southeastern part of the Nile Delta reveals a sub-basin in northern Egypt from the Carboniferous–Permian up to the post-Miocene. The drilled sections are approximately 2600 m thick in the Ubur well in the east and about 3238 m thick in the Orabi well to the west. Basement rocks are recorded in the eastern side of the sub-basin, whereas drilling reached only Lower Cretaceous rocks in the west. The faulting movements played the most important factor determining the distribution, lateral facies changes and unconformities between the different rock units across the sub-basin. The reversal of the faulted blocks over time led to different thicknesses of the drilled units. During the Paleogene, the downfaulted western Orabi part of the sub-basin received up to 1163 m of Paleocene–Eocene sediments, whereas only 203 m were deposited in the eastern uplifted Ubur part. During the Miocene, reversal of the sub-basin taphonomy took place leading to deposition of a thick Miocene section (898 m) in the downfaulted Ubur eastern part, whereas minor thickness (387 m) of the Miocene sediments were laid down in the high Orabi western part of the sub-basin. The stratigraphy of sections drilled is more related to the north Eastern Desert and Sinai rather than to the Western Desert facies. During the Miocene, stratigraphy of the rock units and their facies are a continuation of the Mediterranean subsurface in northern Sinai and eastern Nile Delta facies.

Intrusive rocks of the Wadi Hamad Area, North Eastern Desert, Egypt: Change of magma composition with maturity of Neoproterozoic continental island arc and the role of collisional plutonism in the differentiation of arc crust

The igneous rocks of the Wadi Hamad area are exposed in the northernmost segment of the Arabian–Nubian Shield (ANS). These rocks represent part of crustal section of Neoproterozoic continental island arc which is intruded by late to post-collisional alkali feldspar granites. The subduction-related intrusives comprise earlier gabbro–diorites and later granodiorites–granites. Subduction setting of these intrusives is indicated by medium- to high-K calc-alkaline affinity, Ta–Nb troughs on the spider diagrams and pyroxene and biotite compositions similar to those crystallized from arc magmas. The collisional alkali feldspar granites have high-K highly fractionated calc-alkaline nature and their spider diagrams almost devoid of Ta–Nb troughs. The earlier subduction gabbro–diorites have lower alkalis, LREE, Nb, Zr and Hf values compared with the later subduction granodiorites–granites, which display more LILE-enriched spider diagrams with shallower Ta–Nb troughs, reflecting variation of magma composition with arc evolution. The later subduction granitoids were generated by lower degree of partial melting of mantle wedge and contain higher arc crustal component compared with the earlier subduction gabbro–diorites. The highly silicic alkali feldspar granites represent extensively evolved melts derived from partial melting of intermediate arc crustal sources during the collisional stage. Re-melting of arc crustal sources during the collisional stage results in geochemical differentiation of the continental arc crust and the silicic collisional plutonism drives the composition of its upper part towards that of mature continental crust.

Structural imaging of the East Beni Sueif Basin, north eastern Desert, Egypt

The East Beni Sueif Basin is the only tested hydrocarbon-bearing basin on the eastern side of the Nile in Egypt. The basin is located around 150 km to the south of Cairo. This work introduces the first attempt of seismic interpretation and structural patterns of this basin, for which subsurface published works are lacking. Structural imaging of the area is achieved through interpretation of pre-stack time migration (PSTM) seismic cube and data sets of seven wells. The penetrated sedimentary section is represented by Albian-Middle Eocene sediments.The East Beni Sueif Basin is a type of the whole graben-system and is bounded by two NW-SE bounding faults. These faults had continued activity in an extensional regime associated with fault-propagating folds. The basin is traversed by a N75°E-trending fault system at basement level. This fault system separates the basin into two structural provinces. The Northwestern Province is deeper and shows more subsidence with a predominance of NW-trending longitudinal faults and N60·W oblique faults to the basin trend. The Southeastern Province is shallow and crossed by N14·W-trending faults which are slightly oblique to the basin axis.Albian time had witnessed the main extensional tectonic phase and resulted in major subsidence along basin-bounding faults associated with growth thickening of basal deposits. During Senonian time, the basin experienced a mild phase of transtensional tectonics, which formed negative-flower structures entrapping different folds along the N75°E and N60·W faults. The timing and style of these structures are similar to the Syrian-Arc structures in several Western Desert oil fields. The basin emerged during the Paleocene with scoured and eroded top Cretaceous sediments. Subsidence was resumed during the Early Eocene and resulted in 1500 m-thick carbonate sediments. Lastly, a mild extensional activity possibly occurred during the Oligocene-Miocene time.Despite the possible restricted potentiality of the source rock, the main hydrocarbon accumulation risk is attributed to retention in traps of long-span tectonic history. Reaching of main faults to surface through brittle carbonate cap rocks and limited thickness of the shale in the reservoir section risk hydrocarbon sealing. Buried structures of passive setting during the Tertiary show a minor trapping risk.

Facies and architecture of a coarse-grained alluvial-dominated incised valley fill: a case study from the Oligocene Gebel Ahmar Formation, Southern Tethyan-shelf (northern Egypt)

Exposures of multistorey, alluvial deposits from the Oligocene Gebel Ahmar Formation in the Cairo-Suez province (north Eastern Desert, Egypt) show the architecture of an up to 35m thick continuously prograding fluvial/alluvial filling of an incised valley. The Oligocene base level fall resulted in cannibalization of the Eocene bedrock. Subsequent baselevel rise created accommodation space that was filled by deposition of four stacked storeys: lower storeys (1-2) of low sinuosity sandy braid plains and upper storeys (3-4) of gravelly braid plain. These braid plains were sourced from exposed Upper Cretaceous-Eocene and Paleozoic-Lower Cretaceous siliciclastic successions to the south. These successions dominate the Galala-Araba inverted structures. The sandy braid plain channel belts mainly downstream accretion (DA), downstream oblique accretion(DLA), lateral accretion (LA), sandy bedforms (SB), channel (CH), and Hollow (HO) elements, while the gravelly braid plain consists mainly of gravel bars and sheets (GB), gravel-sandstone foresets (GSF), gravel-sand couplets (GSC), and scour pool filling (SPF) architectures. Incised valley incision is potentially linked to a global drop of sea level caused by glaciation, although hinterland tectonism (i.e. Late Cretaceous-Paleogene tectonic inversion and Late Eocene-Oligocene crustal updoming in the source terrains) as well as Late Oligocene-Miocene rifting play a significant role in the subsequent filling. The hinterland tectonism as well as the climate controls the sediment supply. The understanding of the nature of the Oligocene incised valley fill helps in the constrain potential down depositional dip hydrocarbon reservoirs in Nile Delta, East Mediterranean basins, and similar settings in passive continental margins.

Desert truffles from northeastern Algerian coasal dunes: Ecology, identification and symbiosis

For several years, greater attention has been focused on desert truffles of Southern and Western Algeria. The present work is the first to be concerned on desert truffles from northeastern Algerian littoral dunes. The aim of this work is to describe northeastern Algerian truffle fields, identify collected truffle species and their symbiotic plant partner. We required two years field prospections, soil analysis, ascocarps morpho-anatomical and molecular analysis. We concluded that truffle fields share an acid sandy-loam soil and a notable abundance of many subspecies of Tuberaria gutatta (L.) Fourr. 1868, proved as desert truffles symbiotic partner. Two sandy truffle species are recorded: Terfezia arenaria (Moris) Trappe (1971) and Tuber gennadii (Chatin) Patouillard 1903. This data is the first to review knowledge on northeastern desert truffles and to report Tuber gennadii in Algeria.

Late Carboniferous Macroflora from Rod El-Hamal Formation Wadi Araba, North Eastern Desert, Egypt

The Late Carboniferous of Rod El-Hamal Formation, Wadi Araba has some fossil plant remains content. The systematic description of these remains reveals the identification of twelve species representing Lycophyta, Sphenophyta, Pteridospermatophyta, and Cordaitophyta. All are recorded for the first time from this formation.

The geochemical evaluation and biological effect of Aspergillus niger on the kerogen-bearing limestone of El Galala El Qebbliay plateau, Wadi Araba area, North Eastern Desert, Egypt

The dark grey limestone in El Galala El Qebbliay plateau, in North Eastern Desert, Egypt contains TOC (Total Organic Carbon) that ranges from 0.24 to 1.84wt.% and reaches good organic richness, geochemical analysis made for the collected samples indicated that the samples have from poor to good organic richness, with poor hydrocarbon potentiality. The kerogen type is mainly type III, or III/IV with immature thermal maturation. The presence of uranium is useful as an acceleration mineral for hydrocarbon maturation.Recovery of metal sorbet into the biomass is one of the important aspects of any successful biosorbation process. Bioleaching is a new trend for leaching and processing operation of ground ore. Aspergillus niger is one of the most widely used fungi in the bioleaching applications and has many advantages over bacterial leaching. Uranium can be easily recovered by solvent extraction unit.This study shed the light to geochemical evaluation for the study area, important clean and environmental friendly source to collect the organic material. The action of A. niger resulted in devenish the uranium content of the limestone, and recollect it as a valuable ore.

Microfacies Analysis and Cyclostratigraphy of the Upper Cretaceous-Lower Paleogene Succession of Bir Dakhl Section, North Eastern Desert, Egypt

Abstract: The Bir Dakhl section which is located in the southern Galala plateau, north eastern desert was sampled for microfacies analysis of the upper Cretaceous–lower Paleogene succession. Microfacies analysis led to the recognition of eight mixed clastic-carbonate facies types (black shale lithofacies MF-1, pure shale lithofacies MF-2, sandy shale lithofacies MF-3, marly shale lithofacies MF-4, mudstone microfacies MF-5, foraminiferal wackestone microfacies MF-6, bioclastic wackestone microfacies MF-7, and bioclastic packstone microfacies MF-8) of the studied interval. These microfacies can be grouped into three depositional environments: inner, middle and outer ramp. The interpreted depositional environments have been suggested to range from neritic to middle bathyal (∼ 700 m). Based on cyclostratigraphy, five deepening upward cycles and three shallowing upward cycles have been differentiated in Bir Dakhl section.

Architecture and evolution of a tectonically-induced Middle Eocene clastic wedge on the southern Tethyan carbonate shelf, North Eastern Desert, Egypt

The North Eastern Desert Basin is a series of interconnected basins located within the internal zone of the Syrian arc inversion belts. Throughout the Middle Eocene the basin was subject to pulses of transpression tectonics which led to development of a Middle Eocene clastic wedge. It is well exposed in the Shabraweet area, North Eastern Desert (Egypt). Detailed sedimentological study including facies analysis, and identification paleo-drainage directions were carried out in order to evaluate the development stages and architecture of the Middle Eocene clastic wedge and response to basin inversion. This was achieved through detailed description and measurement of eight surface profiles in the Shabraweet area. Twelve facies have been identified and can be arranged into nine facies associations. The overall architecture can be differentiated into 5 discontinuity-based sequences, described from oldest to youngest. Sequence 1 shows variation from a stream-dominated delta in the north to lagoonal deposits through the delta fringes. Sequence 2 shows downstream variation from alluvial channels, to alluvial fringes, and to distal floodbasin. Sequence 3 shows downstream variation from amalgamated fluvial channels to alluvial plain deposits. Sequence 4 shows downstream variation from deltaic to lagoon margin deposits. Sequence 5 shows variation from estuarine to offshore lagoonal environments. Tectonic inversion is interpreted as the primary control of the development of Middle Eocene clastic wedge. The sequences 1–3 reflect a progressive inversion with complete emergence and establishment of an alluvial plain, while the upper sequences 4 and 5 reflect a tectonic quiescence and gradual return to marine conditions.