Egyptian Desert Research Articles

From the Nile to the Red Sea: On roads, quarries, and mines - S. E. Sidebotham, and J. E. Gates-Foster, eds., with J.-L. Rivard, figures ed. 2019. The Archaeological Survey of the Desert Roads between Berenike and the Nile Valley: Expeditions by the University of Michigan and the University of Delaware to the Eastern Desert of Egypt, 1987–2015. American Schools

From the Nile to the Red Sea: On roads, quarries, and mines - S. E. Sidebotham, and J. E. Gates-Foster, eds., with J.-L. Rivard, figures ed. 2019. The Archaeological Survey of the Desert Roads between Berenike and the Nile Valley: Expeditions by the University of Michigan and the University of Delaware to the Eastern Desert of Egypt, 1987–2015. American Schools of Oriental Research Archeological Reports 26. Boston: American Schools of Oriental Research. - Volume 35 Issue 1

Petrogenesis of arc-related serpentinized peridotites (Egypt): Insights into Neoproterozoic mantle evolution beneath the Arabian-Nubian Shield

• Two ophiolitic peridotites in the SE Desert of Egypt provide a window into the Neoproterzoic mantle. • Geochemistry of peridotite and its mineral chemistry suggest an origin in the arc-related setting. • SED peridotites are refractory mantle residues (25–40% melting), like modern fore-arc peridotites. • Geochemical aspects of peridotite indicate changing from extension during subduction initiation. Korab Kansi and Abu Dahr Neoproterozoic ophiolitic peridotites in the Southern Eastern Desert (SED) of Egypt, are parts of the largest ophiolitic nappes in the Arabian-Nubian Shield. They mainly comprise refractory harzburgites with minor dunites that are commonly altered to serpentinites and talc carbonates. Olivine relics in serpentinized peridotites of the two complexes have olivines with high forsterite (Fo 90.6-92.2 ) and NiO (0.39 wt%) and low MnO (0. 13 wt%) contents, similar to those of mantle olivines. High Mg# (0.91–0.95) of orthopyroxene is consistent with that of depleted harzburgites. Primary spinel Cr# (0.55–0.75) and TiO 2 contents (<0.04 wt%) of the two peridotite complexes are similar to forearc peridotite spinels. The estimated degree of partial melting of Korab Kansi peridotites (25–40% melting) is slightly lower than that of Abu Dahr (30–40% melting), consistent with modern forearc peridotites. Korab Kansi peridotites exhibit lower oxygen fugacity (Δlog ƒO 2 , FMQ + 0.7 on average) and equilibrium temperature (610–710 °C) than those of Abu Dahr ( T , 750–900 °C at Δlog ƒO 2 , FMQ + 2.1), both suggesting subduction-modified peridotites. The low concentrations of incompatible elements, U-shaped REE patterns and high spinel Cr# of both peridotites indicate highly depleted mantle protoliths, reflecting multiple metasomatic and melting episodes in the mantle wedge. Enrichment of fluid mobile elements (e.g. B, Li, Th, U, Pb) relative to high-field strength elements (e.g. Nb, Ta, Ti, Zr) may reflect interaction between slab-derived fluids and peridotites. Calculated parental melts in equilibrium with Korab Kansi and Abu Dahr peridotite spinels have tholeiitic (MORB-like) and boninitic affinities, which were generated during proto-forearc spreading to a mature arc stage. Variations in melt compositions suggest a transitional setting from early proto-forearc spreading of mantle beneath Korab Kansi to the mature arc stage of Abu Dahr peridotites. Subduction initiation possibly started in the W and/or SW with proto-forearc spreading, and progressed to the E and/or NE where a mature arc stage with boninitic melts above an E- and/or SE-dipping subduction zone.

Hydrothermal alteration of Ni-rich sulfides in peridotites of Abu Dahr, Eastern Desert, Egypt: Relationships among minerals in the Fe-Ni-Co-O-S system,fO2 andfS2

AbstractThe Neoproterozoic peridotites of Abu Dahr, Eastern Desert of Egypt, consist mainly of highly depleted harzburgites that have experienced multiple stages of serpentinization (lizarditization and antigoritization) and carbonation/listvenitization in a forearc environment. The Abu Dahr forearc harzburgites are more oxidized than oceanic mantle, with the oxygen fugacity (fO2) values ranging from FMQ+0.41 to FMQ+1.20 (average = +0.60 FMQ), and were equilibrated at temperatures of 910–1217 °C and pressures of 4.1–7.8 kbar. This study has documented for the first time the presence of various Ni-rich Ni-Fe (-Co) sulfide and metal phases along with Fe-oxides/oxyhydroxides in serpentinized-carbonated peridotites of the Abu Dahr forearc. Here I concentrate on the relationship between redox state and Fe-Ni-Co-O-S minerals with emphasis on the role of hydrothermal processes in upgrading magmatic sulfide tenors, desulfurization (sulfur-loss) of magmatic pentlandite and hydrothermal upgrading of the sulfide phases in Abu Dahr forearc environment. The minerals involved are high-Ni pentlandite (Fe4Ni5S8), cobaltian pentlandite (Fe3.47Ni4.78Co0.75S8), heazlewoodite (Fe0.07Ni2.93S2), godlevskite (Fe0.26Ni8.73Co0.01S8), millerite (Fe0.01Ni0.98Cu0.01S), awaruite (Ni75Fe21) and native Ni (Ni93Fe5), and nickeliferous magnetite and goethite. Chalcopyrite is a rare mineral; other Cu-phases, Fe-sulfides and Ni-arsenides/phosphides are not present. Texturally, Ni-sulfide and alloy minerals occur as interstitial disseminated blebs of either solitary phases or composite intergrowths with characteristic replacement textures, documenting strong variations in oxygen and sulfur fugacities (fO2-fS2). Sulfide assemblages are divided into three main facies: (1) pentlandite-rich; (2) godlevskite-rich; and (3) millerite-rich. Textural relationships imply the following sequence: (a) primary pentlandite → cobaltian pentlandite, with partial replacement of the latter by awaruite and/or heazlewoodite along with magnetite; (b) heazlewoodite is replaced by godlevskite, which in turns is replaced by millerite; (c) Ni-rich awaruite breaks down to millerite; and finally, (d) magnetite is completely replaced by goethite. The sulfide mineralogy reflects the magmatic and post-magmatic evolution of the complex. The primary magmatic processes gave rise to pentlandite, whereas the secondary Ni-sulfides together with the metallic alloys formed in response to changing fO2 and fS2 conditions associated with post-magmatic serpentinization and carbonation. Serpentinization-related Ni-Fe-Co remobilization from magmatic olivines resulted in; (1) upgrading the Ni-Co tenors of pre-existing primary pentlandite, and desulfidation to form low-sulfur sulfides (mainly heazlewoodite) and awaruite under extremely low fO2 and fS2 conditions; (2) in situ precipitation of secondary Ni-sulfides in the presence of extra sulfur as aqueous H2S derived from the desulfurization of magmatic pentlandite or native Ni when fS2 approaches 0; (3) transformation from low-sulfur pentlandite- and godlevskite-rich assemblages to the high-sulfur millerite-rich assemblages related to later carbonation with increasing fO2; and (4) partial dehydration of antigorite serpentinites under high-pressure conditions (&amp;gt;1 GPa) generated Ni-rich awaruite in equilibrium with the prograde assemblage antigorite-metamorphic olivine at higher fO2 and fS2 within subduction channel. The mineralogical, chemical, and thermal similarities with other serpentinite-related Ni-sulfides worldwide suggest that Ni minerals in the Fe-Ni-Co-O-S system record changing fO2 and fS2 during progressive serpentinization and carbonation.

Geochemical Characterizations and Spectrometric Prospecting of the Arabian-Nubian Shield: A Сase Study from Abu Rusheid Area, South Eastern Desert of Egypt

Geochemical Characterizations and Spectrometric Prospecting of the Arabian-Nubian Shield: A Сase Study from Abu Rusheid Area, South Eastern Desert of Egypt

Exploring mineralization zones using remote sensing and aeromagnetic data, West Allaqi Area, Eastern-Desert, Egypt

Wadi-Allaqi district, in the southern part of the Eastern Desert of Egypt, is a historic well-known gold resource that has been exploited since the Pharaonic era. The study area represents the western segment of Wadi-Allaqi, about 220 km southeast Aswan city, Upper Egypt. It covers approximately 4702 km2. Exploring new potential mineralization zones was conducted by integrating the Landsat-8 and aeromagnetic data to map different surfaces of alteration zones and trace shallow and deep mineralized bodies. The corrected Landsat-Operational Land Imager (OLI) bands were processed using the Band Ratio (BR), Crosta, selective for the Minimum Noise Fraction (MNF) transformation, and False-Color Composition (FCC) techniques were used to detect the hydrothermal alteration zones and recognize the different geological units. The enhanced eigenimage (MNF1) was processed to delineate the fractures and weakness zones over the west Allaqi-Heini Suture (AHS). The shallow residual mineralized sources have been detected and mapped using the Tilt Derivative (TDR), First Derivative (FVD) and high pass filter techniques of aeromagnetic data. The depths to the mineralized magnetic sources, and hence the roots of gold and other minerals, were obtained using the power spectrum and Euler techniques. Accordingly, new gold and mineralization potential zones were successfully delineated over the study area's ophiolitic, metavolcanics, and granitic rocks. Lineaments deduced from aeromagnetic and remote sensing data represent the pathways of the ascending hydrothermal fluids. The main trends of the dominant structural systems were detected through the statistical analyses of these lineaments.

Facies analysis and sequence stratigraphy of the Middle Miocene Marmarica Formation at Siwa area, north Western Desert, Egypt

The Middle Miocene rocks in the northern part of the Western Desert of Egypt are dominated by carbonate rocks that constitute the Marmarica Formation. To determine the depositional environments and sequence architecture of the Marmarica Formation, three sections were described and sampled in detail. These sections from west to east are; Girba, Naqb El‐Migahhiz, and Gabal Umm Hiyus. The Marmarica Formation in the Siwa area includes three members, from bottom to top: the Oasis, Siwa Escarpment, and El Diffa Plateau members. The microfacies of the Marmarica Formation comprise abundant mud‐supported microfacies with minor grain‐supported microfacies. Sedimentation during the Middle Miocene took place on a homoclinal ramp. Dolomitization is the most prevalent diagenetic process that affected carbonate sediments of the Marmarica Formation. The Marmarica Formation comprises two sequence boundaries. The first sequence boundary (SB1) is demarcated by the presence of Thalassinoides ichnofacies at the boundary between the Oasis and Siwa Escarpment members in all the studied sections. It is considered a type 1 sequence boundary. The second sequence boundary (SB2) is represented by an erosional surface, which is recorded only in Girba section. The SB2 was traced at both Naqb El‐Migahhiz and Umm Hiyus sections by the occurrence of burrows that relate to the Glossifungites ichnofacies. The latter boundary is considered type 2. Three third‐order depositional sequences have been recognized in the Middle Miocene Marmarica Formation. Therefore, the Marmarica Formation at Siwa Oasis exhibits relative sea‐level oscillation. During the Middle Miocene, the prevailing warm climate caused transgression and deposition of carbonates along the marine shelf surrounding western and northern Africa.

Disempowering Minority Communities: Tourism Development in the Siwa Oasis, Egypt

ABSTRACT Tourism planning and development is a complex, multifaceted, and highly politicised phenomenon, particularly in the context of economic development for rural minority communities. This paper discusses such a case in the context of a remote rural community, Siwa Oasis in the western desert of Egypt, which was one of the destinations identified in the development policy termed Infitāḥ, or “openness” in the early 1970s. As part of a long-term project, this article examines how community members perceive tourism development and its effects on their livelihoods, specifically from gender perspective. Findings show that the government development policy in effect resulted resulted in Siwan seeking to protect their identity, including values associated with traditional gender relations, where women are considered to be the safeguards of domestic duties, child-raising, and minority languages, providing empirical evidence on how development can be “closing” rather than “opening” opportunities, disempowering rather than empowering.

Differential rRNA gene metabarcoding of prokaryotic consortia in desert athalassohaline and thalassohaline brines

Culture-independent molecular study presented the first exploring and evaluation of prokaryotic communities in two desert brines; the athalassohaline Lake “Aghormy”, Siwa Oasis, Western Desert of Egypt, and the thalassohaline saltern “Sebeaka Sabkha”, Bardawil Lagoon, north coast of the Sinai. 16S rRNA gene metabarcoding generated a total of 488,828 reads from both sites, grouped into 17,741 operational taxonomic units (OTUs). 3030 OTUs were shared in both sites, while 2255 and 9426 OTUs were unique to Aghormy Lake and Sebeaka Sabkha, respectively. Both sites showed an abundance of Bacteroidetes, particularly the genera Salisaeta and Salinibacter in Aghormy and Sebeaka Sabkha, respectively. Aghormy brine was characterized by phylotypes belonging to Deinococcus-Thermus, Spirochaetes, Rhodovibrio, Piscirickettsiaceae and GMD14H09 (Deltaproteobacteria). While phylotypes assigned to AT12OctB3 (Bacteroidetes), Rhodobacteriaceae, Ectothiorhodospiraceae, and Xanthomonadaceae formed Sebeaka Sabkha bacterial community. A Cyanobacteria-like phylotype was assigned to genus Dactylococcopsis in both brines. The archaeal family, Halobacteriaceae, represented 4.8% of Sebeaka brine reads. Although some of the recorded phylotypes in both brines belonged to the same phyla, they differed in lower taxonomic ranks, implicating distant brine environments' impact on shaping halophilic communities. The metabolic prediction analyses showed a dominance of TCA cycle, branched amino acid biosynthesis and heme biosynthesis, common metabolic features for salt tolerance.

High precision structural mapping using edge filters of potential field and remote sensing data: A case study from Wadi Umm Ghalqa area, South Eastern Desert, Egypt

Recently, detecting the edges and geologic structures (deep and shallow) from potential field sources provides a fundamental tool for interpreting geological structures. Therefore, the high precision computation of the edges of potential sources is becoming an essential requirement for studying subsurface structures. In this study, nine common detectors like tilte angle (TA), Theta-map (TM), Horizontal tilt angle (TDX), hyperbolic tilt angle (HTA), Improved tilt angle (ITA), Tilt angle of the total horizontal gradient (TTHG), Tilt angle of the total gradient (TTG), improved Theta-map (ITM), and improved logistic (IL) were applied. These filters have been tested on theoretical models and real data (aeromagnetic) from the Wadi Umm Ghalqa area, South Eastern Desert of Egypt. The obtained results have shown that the improved logistic (IL) filter could detect edges more successfully than the other eight filters. The results of the IL method were used to generate new accurate structural maps for local and deep components of the investigated area. Moreover, surface structures obtained from remote sensing data were considered to control the interpretation of the mapped subsurface lineaments. Hence, the IL method can be utilized as a sharp tool for the high precision structural imaging of the potential data.

Primary dispersion patterns of gold and associated elements in Um Arka area, Allaqi Region, South Eastern Desert of Egypt.

Primary dispersion patterns of gold and associated elements in Um Arka area, Allaqi Region, South Eastern Desert of Egypt.

Natural Radionuclide Concentrations by γ-Ray Spectrometry in Granitic Rocks of the Sol Hamed Area, Southeastern Desert of Egypt, and Their Radiological Implications

The occurrence of heavy radioactive minerals in construction supplies such as granite has drawn attention to the extraction of heavy radioactive minerals. Granitic rocks were identified to serve an essential economic role in the study area’s surrounding locations. As a result, the current study attempted to detect the activity concentrations of 238U, 232Th, and 40K in the granitic rock samples tested and estimate the radiological dangers associated with these rocks. The obtained data on activity concentrations for 238U (610 ± 1730 Bq kg−1), 232Th (110 ± 69 Bq kg−1) and 40K (1157 ± 467 Bq kg−1) in the granitic samples (GR) were higher than the recommended worldwide average. The radioactive levels found in the samples were caused by radioactive materials being altered and trapped inside granite faults. The exposure to gamma radiation from the granitic rocks were assessed via various radiological parameters, such as radium equivalent content (856 Bq kg−1), absorbed dose rate (Dair) in the air (396 nGy/h), and annual effective dose for either outdoor (0.48 mSv y−1) or indoor (1.9 mSv y−1). Statistical analysis was performed to detect the correlations between radioactive concentrations and radiological parameters. The radioactive effects contributed by the uranium minerals were associated with the granitic rocks. Based on the analysis, the radioactive levels in the examined granitic surpassed the acceptable limits; therefore, they are not safe to use in building and infrastructure applications and may cause adverse health effects.

Cryogenian accretion of the Northern Arabian-Nubian shield: Integrated evidence from central Eastern Desert Egypt

Accretionary geology of the Arabian-Nubian shield (ANS) is critical in deciphering the Neoproterozoic global tectonics. Multidiscipline investigation of ophiolites, sediments, and igneous units of central Eastern Desert Egypt results in a revisited tectono-magmatic scenario. The first baddeleyite U-Pb age (ca. 687 Ma) of the ANS ophiolites is obtained from the layered gabbro of the Wadi Ghadir ophiolite, which limits the back-arc spreading age. Significant Archean-Paleoproterozoic detrital zircon age spectrum, similar to those of the Saharan-Congo craton, is identified from a conglomerate of the Atud turbidites, indicating the existence of craton basement in the shield. Significant ca. 840 Ma and ca. 750 Ma detrital zircon ages with a mixing of juvenile and ancient Hf isotope features approve the provenances to be arc(s) with craton basement. Two episodes of calc-alkaline units represented by the Umm Rus complex (URC) and the El Sibai complex (ESC) are dated at ca. 680 Ma and ca. 660 Ma, respectively. They were both originated from juvenile sources (in situ zircon ɛHft = +6.1 ∼ +12.2) with depleted high-strengthen field elements (e.g., Nb, Ta, Zr, Hf) but enriched large ion lithophile (e.g., Ba, Sr) and radiogenic elements (e.g., Th, U). The Ti-in-zircon temperature of the ESC granitoids (696 ± 16 °C) is lower than that of the older URC (749 ± 21 °C), as well as the inferred ca. 840 Ma and ca. 750 Ma arcs; and this reconciles an increased hydrous melting during the final Gondwana assembly. The older plutons represented by the URC show an E-W elongated distribution consistent with the alignment of the regional imbricated thrusting; whereas the elongation of the younger generation represented by the ESC is N-NE to S-SW and is coherent with the axis of the core complexes and the major strike-slip faults of the region. This possibly coincides a direction-change of paleo-subduction. In summary, the Northern ANS likely represents a superimposed arc accreted at 680–660 Ma during the closure of the Mozambique ocean.

Trace Element Geochemistry and Genesis of Beryl from Wadi Nugrus, South Eastern Desert, Egypt

Beryl occurs in the ancient Roman mines at Wadi Nugrus, South Eastern Desert of Egypt. It ranges from small crystals to 10 mm in size, and it varies in color, appearing as bright green, pale green, dark green and brown-green with biotite inclusions. The trace and minor elements were analyzed by the SIMS method. The two rims are richer in Cs, Na, Mg, Fe, Sc, V, Rb and H2O than cores but are poor in Mn, Ca, Co, Sr and Li. The bright-green rim is richer than the pale-green one in Na, P, K, Ca, Fe, Rb, Cs and F, but poorer in Mg and Li. The alkaline elements (Cs, Na, Rb) and Fe correlate with the color zoning, and where beryl crystals have a maximum of these elements, the green color is strong and bright. The emerald of Wadi Nugrus has similarities with the geological setting of the Canadian emeralds. Emeralds occur along the contact zone between biotite schists, pegmatites and quartz veins. A large-scale interaction between Be-bearing magmatic fluids from granites and related pegmatites took place with hydrothermal fluids enriched in Cr, V, Sc, Mg and Ca after percolation through pre-existing serpentinite and talc carbonates, metagabbros and biotite schists and additional fluids bearing H2O, NaCl and CO2.

An integrated assessment approach for fossil groundwater quality and crop water requirements in the El-Kharga Oasis, Western Desert, Egypt

Study regionThe El-Kharga Oasis in the Western Desert of Egypt is selected as the study area due to its hyberarid climate condition and water scarcity. In this region, the fossil groundwater is the main water source; therefore, preserving groundwater quality and quantity is mandatory. Study focusThis study evaluated groundwater suitability for irrigation purposes and assessed the water requirements of cultivated crops to optimize the water supply in hyperarid climate regions. In total, 79 deep groundwater samples were hydrochemically tested to determine the suitability for irrigation by assessing the key water quality parameters. Spatial distribution maps of all chemical parameters, such as pH, EC, SAR, RSC, SSP, TDS, total hardness, Na+, K+, Ca++, Mg++, Fe, Mn, Cl-, and SO4—, were developed. The FAO CROPWAT 8.0 model, based on the Penman–Monteith equation, was used to forecast agricultural water requirements for three years, 2010, 2011, and 2012. New hydrological insights for the regionThe groundwater had medium salinity and low sodium in 84% of the cases. In comparison, high salinity was found in 16% of the samples, indicating that groundwater can be used for many soil types with a low risk of exchangeable sodium. Except for 15 of the 79 wells, all groundwater samples had chloride concentrations less than 100 mg/l. The sulfate ion distribution map showed a low sulfate ion content in the extreme western south. The total annual irrigation water requirements of all crops for 2010, 2011 and 2012 were 199.4, 215.1, and 231.7 million m3/year, respectively, reflecting a gradual increase of approximately 16.57 million m3/total area/year due to the expansion of the cultivated area. The analysis showed that modern irrigation systems reduced the amount of irrigation water by 32% and increased the cultivated area by 45% compared to conventional irrigation methods. Severe groundwater depletion occurred during the dry season from March to July, which exacerbated the water stress in the study region. The results confirmed that the region is under water stress. Accordingly, water conservation is urgently recommended.

Implementation of lithofacies and microfacies types on reservoir quality and heterogeneity of the Late Cretaceous Upper Bahariya Member in the Shurouk Field, Shoushan Basin, North Western Desert, Egypt

The Late Cretaceous Upper Bahariya Member is one of the most prolific reservoir sequences in the North Western Desert of Egypt. In this paper, we describe core samples of the Upper Bahariya Member, including core photos, conventional core analysis, petrographical description, scanning electron microscope images, and XRD analysis. Samples for this study are from the reservoir sequence in four wells selected from the Shurouk Field in the Shoushan Basin to delineate the impact of the constraint mineral composition on the reservoir quality. The objective of this study is to get an accurate reservoir characterization of this reservoir by applying the rock typing technique to the studied sequence where four Lithofacies Associations (LFA1, LFA2, LFA3, and LFA4) and four corresponding Reservoir Rock Types (RRT1, RRT2, RRT3, and RRT4) were assigned. These are defined as 1) very fine massive sandstone (LFA1, RRT1), 2) laminated, cross-bedded and bioturbated sandstone (LFA2, RRT2), 3) laminated, highly argillaceous and ferruginated sandstone and siltstone (LFA3, RRT3), and 4) laminated and ferruginated siltstone and well cemented bioturbated limestone (LFA4, RRT4). Petrographically, these lithofacies were categorized into five microfacies; 1) glauconitic quartz arenite, 2) subfeldspathic arenite, 3) glauconitic sublithic arenite, 4) ferruginated subfeldspathic wackes, and 5) sandy fossiliferous packstone microfacies. Conventional core samples include bulk and grain densities (ρb and ρg, respectively), helium porosity (∅He), and horizontal and vertical permeabilities (kH and kV, respectively). The application of the Dykstra-Parsons technique to the available permeability data indicates that the studied sequence is extremely heterogeneous (heterogeneity factor (V) = 0.90). Based on the available samples, the normalized porosity index (∅z), reservoir quality index (RQI), flow zone indicator (FZI), and the discrete rock type values (DRT) were estimated to determine the reservoir quality. The RRT1 samples are characterized by the best reservoir properties (av. ∅He = 14.7%, av. kH 42.0 = md, av. RQI = 0.47 µm, av. FZI = 2.87 µm, and av. DRT = 13), whereas the lowest reservoir quality is assigned to the RRT4 samples (av. ∅He = 18.8%, av. kH 0.30 = md, av. FZI = 0.15 µm, av. RQI = 0.04 µm, and av. DRT = 7). The low reservoir quality of the RRT4 is primarily attributed to the predominance of lower quality features (compaction effect, cementation, and presence of glauconite and authigenic minerals). Following the Improved Stratigraphic Modified Lorenz (ISML plot), the Upper Bahariya reservoir is subdivided into five Hydraulic Flow Units (HFUs) such as the HFU-2, and the HFU-4 that are considered superconductive flow units that alternate with three poorly hydraulic conductive HFUs (HFU-1, HFU-3, and HFU-5). The present integrated sedimentological and petrophysical workflow is considered a significant study of the Shoushan basin which can improve exploration activities as well as production optimization. In addition, dividing the studied clastic sequence into five microfacies association and four reservoir rock types can be extended to other equivalent subsurface Late Cretaceous clastic sedimentary rocks in the vicinity and other basins.

Granitoids and trachytes of Um Shager-Hamadat area, Central Eastern Desert, Egypt: Remote sensing characterization and petrology

The late Neoproterozoic granitoids of Gebel Um Shager and Gebel Hamadat, Central Eastern Desert of Egypt, in addition to Paleozoic trachytes of both areas were discriminated using Landsat-8, and Sentinel-2 dataset. Band rationing and Principal Component Analysis techniques were applied. The studied granitoids represent the extreme end-members of the subduction-related I-type calc-alkaline granitic magmas (primitive to more evolved varieties) that developed over a long period of time. These granites were extruded by Paleozoic intra-plate trachytes. Petrography and petrogenesis of these rocks were dealt with and discussed. The Um Shager Older Granitoids (calcic tonalite to quartz monzodiorite) represent poorly differentiated metaluminous magma characterized by very low Rb/Sr ratio ∼0.07. Evolutionary, they follow the calc-alkaline subtype trend and most probably were originated from parent gabbroic magma by fractional crystallization in a volcanic arc setting. On contrary, the Hamadat Younger Granites represent alkali calcic magma which was developed in post-collision setting. They comprise evolved subsolvus metaluminous syenogranite and alkali feldspar granite. Evolutionary, they follow the subalkaline subtype trend. Crystallization courses of both syenogranite and alkali feldspar granite were started by alkali feldspar, followed by cotectic crystallization of alkali feldspar and quartz and ended by eutectic crystallization of all quartzofeldspathic minerals. The trachytes represent intra-plate continental alkaline magmatism. The Um Shager trachytes were developed at local extension zones, while the Hamadat trachytes were originated during global continental rifting system. Syenogranite, alkali feldspar granite and trachytes are important sources of alkali feldspar, which has wide spectrum applications in industry and agriculture.

Mineral chemistry and monazite chemical Th–U–total Pb dating of the Wadi Muweilha muscovite pegmatite, Central Eastern Desert of Egypt: constraints on its origin and geodynamic evolution relative to the Arabian Nubian Shield

Mineral chemistry and monazite chemical Th–U–total Pb dating of the Wadi Muweilha muscovite pegmatite, Central Eastern Desert of Egypt: constraints on its origin and geodynamic evolution relative to the Arabian Nubian Shield

Chemical and spectroscopic characterization of tourmaline from the ancient Roman mines in the Eastern Desert of Egypt

Chemical and spectroscopic characterization of tourmaline from the ancient Roman mines in the Eastern Desert of Egypt

Eco-friendly bioremediation approach for crude oil-polluted soils using a novel and biostimulated Enterobacter hormaechei ODB H32 strain

Petroleum oil contaminants have become severe ecological problems and negatively impact human health. It is, therefore, imperative to identify environmentally friendly approaches to remediate oil-polluted environments. Therefore, bacterial oil degradation stimulated with a nitrogen source under optimum conditions was assessed in this study. Based on the 16S rRNA analysis, strain ODB H32 recovered from oil-based mud of some petroleum drilling sites in the western desert, Egypt, was identified as Enterobacter hormaechei. The metabolic fingerprint of E. hormaechei, achieved using BIOLOG GEN III, revealed that the strain could utilize diverse carbon and chemical sources. Also, E. hormaechei could biodegrade 0.6% of oil under optimized pH (7.0) and temperature (30 °C) conditions. Analyzing different nitrogen stimulants revealed that peptone ˃ yeast extract ˃ ammonium nitrate ˃ urea enhanced the growth of E. hormaechei on mineral salts medium (MSM). Analysis by capillary gas chromatography revealed maximum (70.7%) degradation of peptone by E. hormaechei, indicating that peptone was a good biostimulant for oil degradation. These findings recommend using biostimulated E. hormaechei as an eco-friendly approach for remediating oil-polluted environments, under optimized conditions, especially in arid regions like the western desert of Egypt.

Mineral Chemistry and Genesis of Emerald and Beryl Mineralization in the south Eastern Desert of Egypt

Mineral Chemistry and Genesis of Emerald and Beryl Mineralization in the south Eastern Desert of Egypt