Eastern Desert Of Egypt Research Articles

Rodingitization of Neoproterozoic Al-Barramiya ophiolite metagabbro in the Eastern Desert of Egypt, Arabian-Nubian Shield

ABSTRACT The present work studies the rodingite that is recorded for the first time as being associated to Al-Barramiya Neoproterozoic ophiolite at Eastern Desert of Egypt, Arabian-Nubian Shield (ANS). Al-Barramiya ophiolite is one of the most important ophiolitic sequences exposed in the ANS. It is affected by different styles of alterations included carbonatization, listvenitization, chloritization and rodingitization. The Neoproterozoic ophiolitic rocks of Al-Barramiya district consists of serpentinized peridotite and metagabbros. Serpentinized peridotites are highly altered to assemblages of talc-carbonate rocks, listvenite and magnesite, while metagabbro is partly converted into rodingite. The field studies indicate that serpentinite and rodingite in Al-Barramiya area display high-strain cataclastic deformation. Rodingite consists of garnet, diopside, vesuvianite and chlorite with minor epidote, prehnite, actinolite and opaque minerals. The garnets and vesuvianite are mostly concentrated near the peripheries of the studied rodingite masses, while clinopyroxene, chlorite, epidote and prehnite gradually increase inwards due to progressive decreasing water/rock ratio as fluids originally buffered by serpentinite move towards equilibrium with gabbroic bulk chemistry. Some rodingite samples preserve a few relics of igneous textures of ophiolitic metagabbros. Garnets are distinguished into andradite, hydroandradite and grossular. Pyroxene is represented mainly by secondary clinopyroxene beside primary fresh relics of diopside; the latter has high Mg# (0.92–0.97) similar to ophiolitic clinopyroxene in the ANS. Rodingite is enriched in CaO, Fe2O3 and MgO but depleted in SiO2, Al2O3 and Na2O compared to associated metagabbro. The association of rodingite with serpentinites and metagabbros suggests that Al-Barramiya rodingite is genetically related to serpentinization of ultramafic rocks. The rodingitization occurred during ocean floor alteration contemporaneous with the serpentinization process. The superposition of cataclastic deformation on the altered rocks indicates that alteration preceded obduction and occurred on the seafloor of the suprasubduction zone where Al-Barramiya ophiolite was originally emplaced. During serpentinization the olivine in the peridotite broke down and released Mg2+ in the metasomatic fluids and clinopyroxene broke down producing Ca-rich fluids. These fluids react with the mafic protoliths and enrich them in MgO and CaO. Also, serpentinization fluids react with the plagioclase of the metagabbro, releasing Ca from the mafic source and concentrated it in the rodingitized samples. The positive Eu anomalies beside high Sr contents of the rodingite can be inherited from a plagioclase-rich protolith such as ophiolitic metagabbro. The enrichment of rodingite in Th and U indicates two distinct solutions affected the gabbroic protolith because the alteration of depleted peridotite to serpentinite cannot be an efficient source to enrich these elements. The present study indicates that the rodingitization process underwent lower greenschist facies conditions associating metamorphism that caused serpentinization and released Ca-rich metasomatic fluids.

Magnesite hosted by the Neoarchean ultramafic rocks in Attappadi, southern India: Insights from spectral and stable isotope investigation

Magnesite is an economically important mineral commonly found in ultramafic complexes worldwide, primarily in Archean to Proterozoic ultramafic complexes. This study focuses on the chemical and spectral characterization of magnesite found in the Neoarchean ultramafic rocks in the Attappadi region in the Southern Granulite Terrane of southern India. The research utilizes x‐ray diffraction analysis, hyperspectral, laser Raman, Fourier Transform Infrared, and Isotope Ratio Mass Spectrometry. The studied ultramafic rocks are part of a well‐exposed ophiolitic suite known as the Agali ophiolitic complex. Magnesite primarily occurs as veins, veinlets, and lenses within weathered ultramafic rocks. The hyperspectral analysis of the magnesite samples shows absorption bands in the shortwave infrared region, particularly around 2.3 and 2.5 μm, which correspond to the stretching and bending of the CO bond in the (CO3)2− ion in MgCO3. The laser Raman spectra show intensity peaks at 1095, 738, and 330 cm−1, which may be attributed to the translational and librational vibrations. The Fourier transform infrared data reveal transmittance at 1434, 880, and 747 cm−1, corresponding to MgO bond stretching and asymmetrical CO stretching. The x‐ray powder diffraction spectra exhibit diffraction peaks at 32°, 35°, 42°, 46° and 53°, characteristic of pure magnesite. The spectroscopic parameters derived from various analyses indicate that the magnesite is high quality and free from gangue minerals. Stable isotope analysis of the magnesite samples yielded δ13C values ranging from −5‰ to −9‰ and δ18O values in the range of 21‰–25‰. The estimated water temperature from which the magnesite has been precipitated is ~59 ± 3.9°C. Based on the field relations, mode of occurrence and isotopic signatures, the mineralization is considered to have been formed by the low‐temperature alteration of ultramafic rocks facilitated by CO2‐rich fluids in the near‐surface environment. This study compares the characteristics of magnesite from the study area with a few Neoproterozoic serpentinite‐hosted magnesite veins in the ophiolitic sequence of the Egyptian Eastern Desert, which is part of the Arabian Nubian shield. The research aims to contribute to understanding magnesite formation in Archaean to Proterozoic mafic–ultramafic rocks on the Earth's crust. It also provides insights into the geological processes that govern the genesis of ultramafic‐hosted magnesite globally, particularly in East Gondwana fragments. This information can enhance mineral exploration and resource evaluation in these regions, helping to identify economic prospects and assess the feasibility of magnesite resource extraction and utilization in East Gondwana fragments.

Remote sensing and magnetic characterization of the Au mineralization and its structural implications: Meatiq dome, Eastern Desert, Egypt

This article examines hydrothermally altered ophiolitic ultramafic rocks (HAOU), specifically Listvenite, which are thrust over the Meatiq dome in the context of gold mineralization. These rocks represent gneissic complexes located in Egypt's eastern desert. The analyses presented herein are essential for understanding the distribution of sheared serpentinite on and beneath the surface and the underlying domal structure. This study offers critical insights into the distribution of serpentinite at Meatiq. It combines remote sensing, aerial and ground magnetic data with petrological, geochemical, and geological analyses to create precise geological maps of potential subsurface igneous structures commonly linked to gold mineralization. Remote sensing is used to test for rock differentiation; intensive field geological investigations were conducted along several traverses. Petrographic and geochemical analysis of selected samples confirmed Au content in some localities. Additionally, tomographic inversion of the collected magnetic land profiles has unveiled previously unidentified subsurface distributions of magnetic susceptibilities, which are essential for explaining the observed surface magnetic anomalies and for understanding the subsurface arrangement of various rock units. Results show that the HAOU rocks have a lower magnetic susceptibility signature relative to the adjacent serpentinites, the serpentinite from South Meatiq shows relatively high gold content, and the gold content decreases with carbonation and alteration of the serpentinite into talc-carbonate, as detected geochemically. The procedure followed in the present study can be regionally applied to studying HAOU rocks of similar geologic conditions. The novelty of this study, beyond the introduction of a novel workflow, lies in the revelation that the rocks forming the Meatiq dome are in thrust contact with steeply dipping suprastructure units.

Hydrothermal alteration processes in monzogranite: a case study from the Eastern Desert of Egypt: implications from remote sensing, geochemistry and mineralogy

The South Eastern Desert (SED) of Egypt is one of the most promising areas in Egypt; it is widely explored for exploring the rare earth elements (REEs) and uranium-bearing ores. It is a main part of the Arabian-Nubian Shield (ANS). Therefore, the present study concerns with Sikait-Nugrus area as one of the most prolific sites in this region. The study provides a detailed geological, structural, and mineralogical investigation of the monzogranites to describe and characterize the various alteration types and sequence. For this purpose, remote sensing, geochemical and petrographical techniques were applied. The remote sensing technique helped in constructing a detailed geologic map of the study area to follow up strictly the alteration zone of the Sikait-Nugrus area. Petrographically, the granites predominates in the study area, they are described as slightly and highly altered monzogranites. The slightly altered one is composed mainly of quartz (~ 20–35%), alkali feldspar (~ 25–30%), plagioclase (~ 25–30%), and mica (~ 5–15%), while accessory minerals are represented by zircon and monazite. On the other hand, the portion of this granite close to the shearing zone is intensively altered and characterized by sericitization as the main alteration processes. This sheared portion is characterized by accessory minerals as, uranothorite, allanite, fluorite and Nb-minerals (ishikawaite). Minerlogically, the altered monzogranites are predominated by the following mineral groups: (1) radioactive minerals as uranyl silicates (soddyite, uranophane and kasolite), and thorium minerals (thorite and uranothorite), (2) Nb–Ta minerals (betafite, plumbobetafite, columbite, fergusonite, and aeschynite), (3) REE minerals (monazite, cheralite and xenotime), and (4) zircon and fluorite as accessory minerals. Geochemically, the recorded pattern of the REEs tetrad effect (M-type) for the highly altered samples indicate that these granites are highly evolved and affected by late stage of hydrothermal alteration and the effective water-rich alteration processes that connected to intensive physico-chemical changes. The total REE concentrations equal 241.8 and 249.75 ppm for the highly and slightly altered samples. A significant mass change (MC) was analyzed by the isocon technique (22.95 & 11.11) and volume change (VC) (1.8 &-7.99) for the highly and slightly altered samples, respectively. The mass balance calculations and the isocon diagrams revealed that some major oxides were removed from the slightly altered monzogranites and transformed later into highly altered monzogranites with increasing the alteration intensity due to the impacts of hydrothermal alteration processes. The studied area is virgin, where no detailed studies have been applied to this region. It is extendable to other parts of the Arabian-Nubian Shield in around the Red Sea in Egypt, Sudan, Saudi Arabia and Yemen. The applied technical workflow is also extendible to other surface analogues everywhere.

Precious and Base Metal Minerals in Black Sands of the Egyptian Mediterranean Coast: Mineralogical and Geochemical Attributes

This paper investigates the mineralogical and geochemical characteristics, as well as the possible sources, of gold, silver, platinum group elements (PGE), copper, and lead found in the beach sands along Egypt’s Mediterranean coast. Using scanning electron microscopy and electron probe micro-analysis, this study determines the morphology and micro-chemistry of separated grains to assess their economic potential and how various minerals respond to different transport distances. The analysis reveals that gold grains are of high purity (94.11 to 98.55 wt.%; average 96 wt.% Au) and are alloyed with Ag (1.28–2.32 wt.%) and Cu (0.16–3.15 wt.%). Two types of gold grains were identified, indicating differences in transport distances. Variations in morphology, surface features, inclusion types, rims, and chemistry of the native metals, including gold grains, suggest differences in composition, weathering degree, transport distance, deposit types, and host rocks. The average Ag concentration in gold grains (1.86 wt.%) suggests a link to mesothermal or supergene deposits. Most silver, copper, and lead grains are spherical, with some variations in shape. Silver grains have 71.66–95.34 wt.% Ag (avg. 82.67 wt.%). Copper grains have 92.54–98.42 wt.% Cu (avg. 94.22 wt.%). Lead grains contain 74.22–84.45 wt.% Pb (avg. 79.26 wt.%). The identified platinum group minerals (PGM) belong to the Pt–Fe alloys and sperrylite, both of which are PPGE-bearing minerals. These metals likely originate from the weathering of upstream Nile tributaries surrounded by igneous and metamorphic rocks from Ethiopian and Central African regions, with a minor contribution from the Egyptian Eastern Desert Mountains.

Geological controls of mineralization occurrences in the Egyptian Eastern Desert using advanced integration of remote sensing and magnetic data

This study presents a comprehensive analysis of mineralization exploration in the Egyptian Eastern Desert (ED), one of the most sought-after areas for those interested in mining industry, by integrating Landsat-9 images and geophysical magnetic data. Employing advanced techniques like Principal Component (PC) analysis, Minimum Noise Fraction (MNf) transform, and Band-Ratio (B-Ratio), the research focuses on mapping lithological units, hydrothermal alteration regions, and structural elements. Composite images derived from specific PC, and MNf bands, and B-Ratio exhibit superior lithological unit identification. The findings emphasize that there are significant variations in the types of rocks extend from the southern to the northern parts of the ED. Hydrothermal alteration mapping, guided by B-Ratio results, aids qualitative lithological discrimination. A novel false color composite image optimizes Landsat-9 B-Ratios, enhancing rock unit discrimination. Correlation analyses reveal associations between mineralization types and major lithological units, while exploration of the magnetic anomaly map highlights its role in correlating mineralization sites. Structural features, analyzed through Center for Exploration-Targeting Grid-Analysis (CET-GA) and Center for Exploration-Targeting Porphyry-Analysis (CET-GA) with Tilt Derivative of RTP (TDR) techniques, contribute to a robust association between regions with medium to high structural density and porphyry intrusions and mineralization. The study significantly supports the advanced exploration geoscience, providing insights into the geological structures and dynamics governing mineralization in the Egyptian ED.

Potassium isotopes trace the formation of juvenile continental crust

Constraining the processes associated with the formation of new (juvenile) continental crust from mantle-derived (basaltic) sources is key to understanding the origin and evolution of Earth’s landmasses. Here we present high-precision measurements of stable isotopes of potassium (K) from Earth’s most voluminous plagiogranites, exposed near El-Shadli in the Eastern Desert of Egypt. These plagiogranites exhibit a wide range of δ41K values (–0.31‰ ± 0.06‰ to 0.36‰ ± 0.05‰; 2 SE, standard error) that are significantly higher (isotopically heavier) than mantle values (–0.42‰ ± 0.08‰). Isotopic (87Sr/86Sr and 143Nd/144Nd) and trace element data indicate that the large variation in δ41K was inherited from the basaltic source rocks of the El-Shadli plagiogranites, consistent with an origin through partial melting of hydrothermally-altered mid-to-lower oceanic crust. These data demonstrate that K isotopes have the potential to better constrain the source of granitoid rocks and thus the secular evolution of the continental crust.

Analyzing recent deformation in Wadi Hagul, Eastern Desert, Egypt, via advanced remote sensing and geodetic data processing

Abstract The Wadi Hagul region in the eastern desert of Egypt is facing seismic hazards and increased human activity. This study uses remote sensing and geodetic methods to monitor and analyze recent deformation in the area. Interferometric Synthetic Aperture Radar (InSAR) data from the Sentinel-1A satellite and Global Navigation Satellite System (GNSS) data were combined to track surface movements and deformations accurately. The study analyzed InSAR data from February 4, 2020, to February 07, 2024, and GNSS data from the Wadi Hagul geodetic network established in July 2022 and monitored until January 2024. Despite the relatively short GNSS monitoring period, it provided valuable insights into recent deformation trends. By integrating data from ten GNSS stations, including International Geodetic stations (IGS), and InSAR scenes from the Sentinel-1A mission, the study estimated recent ground deformation in the region. The main objectives were to analyze recent crustal movements by identifying spatial and temporal patterns of deformation and assess implications for geological processes. In Key Findings, horizontal movement fluctuates between 0.5 and 2.5 ± 0.1 mm annually across the geodetic network. The estimated velocity of the area was 1.5–2 ± 0.5 mm per year. Integrating GNSS and InSAR data helped calculate movement rates along fault lines and create a fault map. In conclusion, the results suggest that while current deformation rates are moderate, they could increase significantly due to human activity, leading to higher seismic activity and potential earthquakes. Limiting human activity in the region is advisable to prevent negative impacts on nearby populated areas.

Delineating the uranium anomalous zones using remote sensing and radiometric data: a case study from Gabal Umm Tinassib area, North Eastern Desert, Egypt

AbstractRemote sensing (RS) and airborne gamma-ray spectrometric (AGS) methods are utilized to delineate significant uranium zones and altered mineralization areas in Gabal Umm Tinassib and its surrounding region, situated in the northern section of the Egyptian Eastern Desert. AGS serves as a valuable tool for mapping surface geology and conducting mineral exploration. It assesses the concentrations of radioactive elements such as potassium (K), equivalent uranium (eU), and equivalent thorium (eTh). The concentration of radioelements exhibits measurable and significant variation according to lithology. On the other hand, several processing steps are employed for the RS data to generate high-quality images for geological mapping and to identify the mineralized alteration zones. The analysis of RS and AGS data in this study led to insightful conclusions. The utilization of False Color Composite (FCC) with the three best bands derived from the Optimum Index Factor (OIF), Principal Component Analysis (PCA) to extract two highly informative datasets, and the application of two band ratios contributed to accurate geological mapping. These band ratios notably identified identical alteration locations on both younger and older granite basement rocks. Additionally, the constrained energy minimization (CEM) technique effectively pinpointed alterations across these strata. The statistical analysis of AGS data revealed that radioactivity levels in the region range from 1.3 to 19.3 Ur for the total-count (TC), 0.2–3.6% for K, 0.09–11.6 ppm for eU, and 1.1–30.0 ppm for eTh. The estimated coefficient of variability (CoV) demonstrated that the three radio-elements exhibited normal distribution patterns across different rock units, with CoV values of less than 100%, except for K in the Malha Formation. High radiometric readings are observed in the outcroppings of younger and older granites. However, the lowest readings are recorded over undifferentiated Upper-Cretaceous sediments, Abu Rimth Formation, Galala Formation, and some parts of Quaternary sediments. The derived ternary radio-elements map highlights significant radiometric and related uranium anomalous zones as bright white regions. A strong correlation was found between high radiometric anomalous zones and the presumed occurrence of alteration zones in the study area.

The use of Egyptian volcanic glass powder as a potential source for improving the properties of alkali-activated fly ash cement

In this article, for the first time, the potential use of Egyptian volcanic glass powder (VGP) has emerged as an intriguing option. The intriguing potential advantages of incorporating VGP into alkali-activated fly ash (AAFA) cement were explored. The volcanic glass (VG) was brought from the Egyptian eastern desert quarry in the form of lumps and fragments. To utilize it effectively, the VG was crushed and ground before being mixed with fly ash (FA). Various proportions of VGP ranging from 10% to 70% were blended with FA as a partial substitution. Both plain FA and those blended with VGP were then activated using an alkaline activator, resulting in the creation of alkali-activated cement. An investigation was conducted to assess the effect of various ratios of VGP on the flowability, compressive strength up to 90 days, resistance of drying/wetting cycles, crystalline phases, hydration products, and microstructures of AAFA cement. The results confirmed a positive effect of AAFA properties with including VGP. The obtained blended cement can be used in several potential applications such as in roadways, bridges and tunnels, facades and cladding, indoor and outdoor floorings, as well as aerospace and defense industries due to its high durability to resist the degradation caused by wetting/drying cycles.

Unravelling the genesis and depositional setting of Neoproterozoic banded iron formation from central Eastern Desert, Egypt

The Neoproterozoic banded iron formations (BIFs) are widely occurred in the Egyptian Eastern Desert. This study integrates field observations, petrographic studies, geochemical data, and lead isotopes to construct the genesis and depositional environment of Wadi El-Mis hama BIF deposits. The iron layers, primarily of oxide facies within a volcano-sedimentary sequence, comprise magnetite-rich beds alternating with jaspilite or silicate laminae. The studied BIFs exhibit a dominant composition of SiO2 and Fe2O3t with relatively low contents of TiO2 and Al2O3. The positive correlation of REEs (La, Sm, Yb) with Zr and low concentrations of HFSEs (Ta, Nb, Th, Hf) indicate a primary formation mechanism of chemical precipitation, maintaining original geochemical signatures. Geochemical patterns show depletion in LREEs, enrichment in HREEs (La/YbPAAS = 0.08–0.12), and positive La anomalies (La/LaPAAS = 1.15–8.57), consistent with seawater influence. Additionally, various geochemical discrimination diagrams supported by elevated super-chondritic Y/Ho values (29.6–38.7), weak positive Eu anomalies, and low contents of transition metals (Cu and Zn), point to the interaction of low-temperature (<200°C) hydrothermal fluids (bearing Fe and Si) with seawater during the deposition of the BIFs. The lack of significant negative Ce anomalies along with low Ni/Co, U/Th, and Cu/Zn ratios, imply that the iron mineralization was precipitated from dysoxic to oxic conditions. The geochemical and Pb isotopic data suggest that the iron deposits formed in an extensional geodynamic setting (intra-oceanic arc basin environment) due to the subduction of the Mozambique Plate, with signatures closely matching other Precambrian Algoma-type BIFs.

Raw-material exploitation in the Earlier and Middle Stone Age in the Eastern Desert of Egypt: evidence from Wadi Abu Subeira

AbstractDespite its key role in out-of-Africa hominin dispersals, little is known about Pleistocene human occupation of north-eastern Africa outside the Nile Valley and desert oases. A survey in Wadi Abu Subeira aims to help fill this gap and attests to the repeated occupation of the Eastern Desert during the Pleistocene.

Case study of fluorite mineralization using traditional and laser spectroscopic techniques, homret akarem area south eastern desert, Egypt

Green fluorite samples from Homret Akarem, eastern desert Egypt, were investigated by laser-based Raman spectroscopy to study the effect of rare earth elements (REEs) and natural radiation from the surrounding environment on their physico-chemical properties, taking into consideration the geological setting. Geochemical data of trace elements display fluorite enrichment with Y, Pb, Sr, Sn, and other REEs. XRD showed lattice parameters with values higher than those for synthetic fluorite due to the substitution of Ca by Sr and less likely by radiation from U. A considerable shift in the binding energy (BE) for Ca and F obtained from the XPS spectrum indicates that U carried by the hydrothermal solutions formed a discontinuous thin film on the surface of fluorite. Laser-Raman spectroscopy showed strong peaks below 500 cm−1 and both shallow and weak peaks above 500 cm−1. The strong peaks indicate that the substitution of Ca by Sr, point defects, and natural radiation caused by U have a stronger effect on the crystal structure than REEs. Raman spectroscopy supported the initial reports of uranium minerals like Rutherfordine, Kasolite, Soddyite, and Uranophane-alpha.

Geochemistry of island arc assemblage in the Eastern Desert of Egypt and the role of Pan-African magmatism in crustal growth of the Arabian–Nubian Shield: A review

Geochemistry of island arc assemblage in the Eastern Desert of Egypt and the role of Pan-African magmatism in crustal growth of the Arabian–Nubian Shield: A review

Depositional mechanism of Duwi Formation organic-rich rocks in anoxic Campanian-early Maastrichtian condensed sections in the Qusseir–Safaga region in Eastern Desert of Egypt and their economic importance

The organic-rich rocks of the Duwi Formation have gained much attention in recent years because of the growing demand for their utilization as energy and metal sources. A depositional model for these important rocks is delineated in the present study based on multiple analytical approaches. Samples from these organic-rich rocks were collected from eight mines in the Qusseir-Safaga region along the Red Sea coast in the Eastern Desert of Egypt. These mines are located at El Nakheil, Younis, El Beida, Atshan, Hamadat, Tundub Bahri, Tundub Qubli, and Zog EL Bahr. The depositional model is based firstly on organic geochemical and petrographical analyses of the organic matter to identify its enrichment, composition, hydrocarbon potential, types and origin, and their relationship to rock minerals. Secondly, the inorganic geochemical analysis, including mineralogy and trace elements, is integrated to explore the lithological characteristics and to confirm the results obtained from other analyses. Only the El Nakheil, Atshan, Tundub Bahri, and Tundub Qubli mines are found to have total organic carbon content above 10 wt%. These mines contain hydrogen-rich organic matter that reached a maximum in the El Nakheil Mine as reflected in the Rock-Eval parameters of S2 (137.95 mg HC/g rock) and hydrogen index (HI of 707 mg HC/g TOC). The organic matter is composed mainly of large sheet-like alginite particles and prasinophytes that are finely laminated with minerals, planktonic debris of fish bones, and foraminifera without any sign of the presence of benthic organisms or bioturbation. This lamination is attributed to the occurrence of condensed sections in the studied mines. In addition, the high organic enrichment in terms of quantity and quality is accompanied by enriched metal composition including trace elements that signify anoxic conditions and low sedimentation rates. This composition points to the occurrence of prominent anoxic conditions that are stabilized by a slow sea level rise, which inhibits water circulation and water column stagnation in a restricted basin. The depositional model emphasizes the optimal balance between anoxia, sedimentation rate, and paleoproductivity that resulted in enhanced organic matter preservation in a condensed section. The deposition of the organic-rich rocks is situated in the deep parts of the basin or depocenters that reached their present-day distribution by topographic inversion. The organic and metalliferous reserves in these organic-rich sediments are calculated in the studied mines. The estimation of these reserves is found to be economic for many trace metals in an ore reserve that reached 151742 tons in one bed alone within the Duwi Formation.

Subduction-related mafic-silicic magmatism in the Nubian Shield: Tectono-magmatic implications of ensialic island arc association at Central Eastern Desert, Egypt.

For the Wadi El Mayet, the metagabbro-granodiorite-tonalite intrusive complex (MIC) occupies the eastern sector of famous wadi Mubarak–Dabr complex which considered as the largest intrusion in the Egyptian Eastern Desert. The basement associations in the area include volcano-sedimentary rocks, metavolcanics, and ultramafics. The whole successions were intruded by MIC, and granites. The (MIC) comprises multifarious gabbroic varieties namely: olivine, pyroxene, hornblende, uralitized gabbros and rare amphibolites, while silicic portion includes tonalite and granodiorite. Microprobe analytical chemistry of gabbros and granites refers that: the amphiboles are calcic magnesio hornblende formed at low pressure conditions. Chlorites have corundophillite composition. Plagioclase range between labradorite, andesine and oligoclase. Biotite is mainly siderophylite. Muscovite minerals are mainly cheladonite. Geothermo-barometers calculations reveal crystallization temperatures of 550 °C and 860 °C for granites and metagabbros respectively. The (MIC) cover a wide silica range (44.5–74.5 wt %). It has transitional tholeiitic to calc-alkaline magmas. The gabbroic rocks show distinct fecundity with LILE (e.g. Rb, Ba, U and Th), but show observed shortage in most HFSE (e.g. Zr, Nb, Ta). The REE patterns show enrichment in light REE and posse variably positive Eu. It is suggested that, the gabbroic units were likely generated by fractional crystallization of mafic magmas produced through partial melting of metasomatized mantle within island-arc environments. Tonalite - granodiorite (TG) suite show calc-alkaline magmas of I-type settings. They also exhibit enrichment in Ba, Zr, Hf, Rb, U and Th, while P, Nb, Ta and Sr are depleted. Such reductions are harmonious with fractionation of K-feldspar phases. The (TG) show enrichment of (LREE) compare to (HREE) this proposes either the existence of persistent garnet or LREE fertile magma sources. The (TG) is believed to be formed through dehydration melting processes at lower crust settings. Based on the field, geochemistry and structure elements, the investigated mafic and silicic suites are not linked to a single magma origin. The (MIC) can be comparable with intrusions formed in ensialic island-arcs settings. At subduction zone integration between mantle (basaltic suites) and silicic magmas from lower crust forming the early stages of (MIC) crystallization. The whole association was suffered by insignificant fractionation processes and addition of crustal materials during the final stages of (MIC) emplacement.

Late Cryogenian and early Ediacaran rare-metal rich granites in the Eastern Desert of Egypt: constraints from zircon ages and whole-rock Sr- and Nd- and feldspar Pb-isotopic compositions

Rare metals (Nb, Ta, Y, Zr, Sn, U, W and REE) are economically important and new supplies need to be found. In order to understand Neoproterozoic rare metal granites of the Arabian–Nubian Shield (ANS), six samples from five rare-metal mineralized alkali feldspar granites, syenogranites and granodiorite from the Central and SE Desert of Egypt were studied for zircon U–Pb ages and O-isotopic compositions as well as whole-rock Sr- and Nd- and alkali feldspar Pb-isotopic compositions. These are transitional between I-type and A-type granites, mostly high-K calc-alkaline, peraluminous granites with gullwing-shaped REE patterns and strongly negative Eu anomalies. Four granites gave mantle-like zircon δ 18 O V-SMOW between 4.2 and 5.96‰ and yielded ages of 628–633 Ma. This is about when subduction-related magmatism began to be replaced by collision-related magmatism. Igla Ahmr granites are older, formed at 691.7–678.9 Ma with δ 18 O V-SMOW c . 5.95‰. All have positive initial ε Nd values (+3.3 to +6.9) typical for mantle and juvenile crust. Pb isotopic compositions are unusually radiogenic compared with unmineralized ANS granitic rocks. The data indicate similar magmatic sources for ANS mineralized and unmineralized granites. Exploration for other rare-metal mineralized granites in the ANS should focus on bodies with similar characteristics. Supplementary material : Details of analytical details and supplementary tables and figures are available at https://doi.org/10.6084/m9.figshare.c.6949402

Groundwater Recharge Potentiality Mapping in Wadi Qena, Eastern Desert Basins of Egypt for Sustainable Agriculture Base Using Geomatics Approaches

In arid and hyper-arid areas, groundwater is a precious and rare resource. The need for water supply has grown over the past few decades as a result of population growth, urbanization, and agricultural endeavors. This research aims to locate groundwater recharge potential zones (GWPZs) using multi-criteria evaluation (MCE) in the Wadi Qena Basin, Eastern Desert of Egypt, which represents one of the most promising valleys on which the government depends for land reclamations and developments. These approaches have been used to integrate and delineate the locations of high groundwater recharge and the potential of the Quaternary aquifer in the Wadi Qena basin. After allocating weight factors to identify features in each case based on infiltration, land use/land cover, slope, geology, topology, soil, drainage density, lineament density, rainfall, flow accumulation, and flow direction, these thematic maps were combined. The results of the GIS modeling led to the division of the area’s groundwater recharge potential into five groups, ranging from very high (in the western part) to very low (in the eastern part of the basin). The zones with the best prospects for groundwater exploration turned out to be the alluvial and flood plains, with their thick strata of sand and gravel. The groundwater recharge potential map was validated using data from the field and earlier investigations. The promising recharging areas show high suitability for soil cultivation. The results overall reveal that RS and GIS methodologies offer insightful instruments for more precise assessment, planning, and monitoring of water resources in arid regions and anywhere with similar setups for groundwater prospecting and management.

The role of the Red Sea rift and the inherited geological structures in the seismo-volcanic activity along the rift flanks

The role of the Red Sea rift on the development and the discrepancy of the seismo-volcanic activity along its flanks is still a debate. Here we tried to resolve this debate by a high-resolution tomographic imaging of the northern Red Sea subsurface structures. For the first time, a large number of arrival time data from the Saudi and Egyptian seismic networks were used. The area comprises the Lunayyir volcanic field in the Saudi Arabia, the Abu-Dabbab seismogenic zone in the Egyptian Red Sea coast, and the Zabargad Shear Zone in the Red Sea. This study revealed clear images of the Red Sea rift-related structures along its flanks. The subsurface extension of the different shear and suture zones existing in the Arabian Nubian shield are well imaged. It is found that the Lunayyir seismo-volcanic activity is possibly controlled by the reactivation of the Yanbu suture zone that is associated with steeply northwestward dipping structure. The suture detachments were observed and identified across the Red Sea as low-V channels. The Egyptian Eastern Desert is found to be highly deformed with crustal-scaled low-V structures which were inherited from the early period of Gondwana collision. The NE-SW strike slip faults along the Red Sea were found to be a part of this deformation that are extended deeply in the crust. The Abu-Dabbab and Marsa-Alam areas were strongly influenced by this deformation with possible magma intrusions. This study provides new insights on the role of the Red Sea in the seismo-volcanic activity along its flanks.

Quarrymen in the Roman quarries of the Egyptian eastern desert (types and social life)

Quarrymen in the Roman quarries of the Egyptian eastern desert (types and social life)