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The Nuweibi albite granite (NAG) is a postcollisional intrusion emplaced as a high-level magmatic cupola into metamorphic and syntectonic calc-alkaline country rocks. It consists of two cogenetic intrusive bodies: the western, nonporphyritic, albite granite was emplaced deeper than the eastern, fine-grained, porphyritic, albite granite. In places the nonporphyritic phase crosscuts the earlier porphyritic phase, but the occurrence of gradational contacts between the phases implies a near coincidence in time, with the nonporphyritic phase emplaced before crystallization of the porphyritic phase was complete. The steeply dipping slope of the western contact of the Nuweibi pluton against country rocks, in contrast to the gently dipping contacts above the eastern and northeastern parts, indicates the probable location of the cupola apex in the eastern part of the pluton. The NAG intrusion is highly evolved meta- to peraluminous leucocratic rare-metal albite granite. The NAG intrusion is chemically zoned, with upward increases of Al2O3, Na2O, Sr, Ga, and Ta concentrations, alongside upward decreases in SiO2, K2O, Rb, Nb, Zn, Zr, Th, Sn, and rare earth element concentrations. These trends are interrupted by a compositional gap with discontinuities in evolutionary trends of both compatible and incompatible elements, suggesting multiple pulses of intrusion. The NAG was generated via partial melting of a juvenile crust that had undergone extensive fractional crystallization combined with late-magmatic fluid overprint. Accumulation of residual volatile-rich melt and exsolved fluids in the apical part of the magmatic cupola produced stockscheider pegmatite, greisen, and quartz veins that cut the peripheries of the NAG pluton. Metasomatic activity by late- to postmagmatic fluids drove changes in the bulk composition of the cupola, removing K and driving the alkali feldspars toward pure albite.

The Wadi Muweilha muscovite pegmatite in the Central Eastern Desert (CED) of Egypt is strongly influenced by a strike-slip shearing and fault system related to the final stage of the East African Orogen (EAO) in the Arabian Nubian Shield (ANS). It intrudes the volcano-sedimentary succession, occurs in large pegmatitic plugs, and is comprised of K-feldspar, quartz, plagioclase, and muscovite as rock-forming minerals, while abundant garnet, monazite-(Ce), Nb-depleted rutile, ilmenite, zircon, xenotime-(Y), and Y–thorite represent the rare metal minerals. Most minerals show several signatures of ductile/brittle deformations. Garnets form almandine–spessartine solid solutions and exhibit Mn bell-shaped type zoning, due to temperature decrease and fractionation of Fe–Mn during crystallization. The monazite occurs in three phases: pristine (Mnz1), recrystallized (Mnz2), and hydrothermal (Mnz3). The Y–Th-enriched Mn1 was altered into Y–Th-depleted Mnz3 associated with xenotime–thorite solid solutions (Y–thorite) via dissolution–reprecipitation mechanism. The mineral reaction happened along the preexisting microfractures (resulting from the former brittle deformation) that were used as pathways for interfacial fluids. The chemical and textural characteristics of monazite, garnet, and other minerals enhance the igneous origin of pegmatite and the relation to syn-tectonic I-type granitic magma source. The 641 ± 5 Ma (2σ) age of Mnz1 indicates that the post-collisional stage began after ~ 640 Ma in the north of the ANS. The date range (584–590 Ma) of Mnz2 is simultaneous with the rare metal-bearing post-collisional A-type granite in the CED, while the 538 to 563 Ma date range of Mnz3 may suggest a prolonged period (100 Ma) of the tectonic rejuvenation in the Mubarak–Barramiya Shear Belt at ca. 640–540 Ma.

The rare metals of Abu Dabbab area in the Central Eastern Desert of Egypt have been investigated for their mineralogy and conditions of precipitation using combination of EMPA and fluid inclusions studies, in order to delineate the source, mechanism of formation and evolutionary model for these economic metals. The (Ta-Nb-Sn) -bearing minerals at the Abu Dabbab area include columbite group minerals (CGMs), wodginite and cassiterite. In both granitic intrusion and its enclosed quartz veins, most of zoned CGMs and cassiterite grains are commonly characterized by a well-developed two-stage texture. Hence, columbite-(Mn) (CGM-I) represents the early formed phase of CGMs that is characterized by high Mn # values (0.64–0.92) with quite low Ta # values (0.13–0.49). It was invaded by Ta-rich phases including tantalite-(Mn) (CGM-II; Ta # = 0.13–0.49) and wodginite, which contain high Ta 2 O 5 and SnO 2 (17.91 wt.%). In regard to cassiterite, there are distinct compositional differences between the early-phase cassiterite (Cst-I) and the late-phase one (Cst-II), where the latter is enriched in Ta 2 O 5 , Nb 2 O 5 and FeO. The chemistry and textural criteria of the early stage CGM-I and Cst-I, all are indicative of magmatic origin. While, the latter CGM-II, wodginite and Cst-II were influenced by the late magmatic Ta-rich fluids. Fluid inclusions microthermometry shows criteria of phase separation represented by both boiling and fluid immiscibility. The initial fluid was supposed to be of magmatic origin (magmatic CH 4 ), that was consequently influenced by fluid mixing/dilution with post-hydrothermal/meteoric water with respect to the decompression process during uplift. Isochore construction gave rise to an estimate P-T conditions ( T = 330–370 °C, P = 22–50 MPa). The fluid inclusions’ microthermometry supports a transition between magmatic and late to post-hydrothermal activities in addition to surface-derived fluid (meteoric fluid?) in a part as main source for the polymetallic deposits.

Studies of early syn-rift successions in the Duwi Basin have revealed repetitive lacustrine carbonate deposits exhibiting regressive sequences and early diagenetic processes. Two main informal stratigraphic units (Units 1 and 2), spanning the Late Oligocene to Early Miocene, have been identified in the area. Unit 1 primarily consists of lacustrine limestone and calcrete deposits that formed in a palustrine environment, whereas Unit 2 is composed of dolomites and cherts, which developed during times of lake evaporation and desiccation under arid climatic conditions. A wide variety of pedogenic features, including brecciation, nodulization, rhizocretions, fissuring, microkarsts, and circumgranular cracks, dominate the carbonate sequence, indicating deposition in a marginal lacustrine setting. Integrated petrographic, mineralogical, geochemical, and isotopic studies of carbonate facies reveal two distinct evolutionary stages in the Duwi Basin, with dolomitization and silicification characterizing the late stage. Their isotopic compositions show a wide range of δ13C and δ18O values, ranging from −9.00‰ to −7.98‰ and from −10.03‰ to −0.68‰, respectively. Dolomite beds exhibit more negative δ13C and δ18O values, whereas palustrine limestones display higher (less negative) values. The upward trend of δ18O enrichment in carbonates suggests that the lake became hydrologically closed. Trace element concentrations serve as potential markers for distinguishing carbonate facies, aiding with paleoenvironmental and diagenetic interpretations. Our findings indicate that the studied dolomites and cherts formed under both biogenic and abiogenic conditions in an evaporative, alkaline-saline lake system. Biogenic dolomite and silica likely resulted from microbial activity, whereas abiogenic formation was driven by physicochemical conditions, including decreasing pH values and the presence of smectite clays. Tectonics, local climate, and provenance played crucial roles in controlling the overall diagenetic patterns and evolutionary history of the lake basin system during the Late Oligocene to Early Miocene.

The effects of different regional tectonic events on the Neoproterozoic basement rocks of the Arabian–Nubian Shield in Sinai, as well as the Egyptian unstable and stable shelves, remain uncertain. Coupling fission-track thermochronometry findings with the modeling of the time–temperature history has proved to be an effective method for tackling these issues. The obtained zircon fission-track ages were differentiated into two groups from the Ediacaran–Cambrian and the Ordovician–Carboniferous periods, while the apatite fission-track data revealed two separate groups of cooling ages of the Carboniferous–Triassic and Late Cretaceous ages. The integration of these cooling ages and modeling of the time–temperature history revealed four discrete cooling pulses during the Neoproterozoic, Devonian–Carboniferous, Cretaceous, and Oligocene–Miocene eras. After integrating our findings with the regional tectonic historical and sedimentological records, these could be identified as cooling/exhumation pulses activated in response to the post-accretional event of erosion, Variscan tectonism, the disintegration of Gondwana, and the Gulf of Suez rifting, respectively. Furthermore, the southern border of the Egyptian unstable shelf was found to extend southward to South Sinai and south of the Bahariya depression.

Serpentinites make up one of the most significant rock units associated with primary suture zones throughout the ophiolite sequence of the Arabian–Nubian Shield. Wadi Sodmein serpentinites (WSSs) represent dismembered parts of the oceanic supra-subduction system in the central Eastern Desert of Egypt. In this context, we present whole-rock major, trace, and rare earth elements (REE) analyses, as well as mineral chemical data, to constrain the petrogenesis and geotectonic setting of WSS. Antigorite represents the main serpentine mineral with minor amounts of chrysotile. The predominance of antigorite implies the formation of WSS under prograde metamorphism, similar to typical metamorphic peridotites of harzburgitic protolith compositions. The chemistry of serpentinites points to their refractory composition with notably low Al2O3, CaO contents, and high Mg# (90–92), indicating their origin from depleted supra-subduction zone harzburgites that likely formed in a forearc mantle wedge setting due to high degrees of hydrous partial melting and emplaced owing to the collision of the intra–oceanic arc with Meatiq Gneisses. Spinels of WSS generally exhibit pristine compositions that resemble those of residual mantle peridotites and their Cr# (0.625–0.71) and TiO2 contents (<0.05 wt%) similar to forearc peridotite spinels. Moreover, WSS demonstrates a significant excess of fluid mobile elements (e.g., Th, U, Pb), compared to high-field strength elements (e.g., Ti, Zr, Nb, Ta), implying an interaction between mantle peridotites and fluids derived from the oceanic subducted-slab. The distinct U-shaped REE patterns coupled with high Cr# of spinel from WSS reflect their evolution from mantle wedge harzburgite protolith that underwent extensive melt extraction and re-fertilized locally.

The Abu Farayed Granite (AFG), located in the southeastern desert of Egypt, was intruded during the early to late stages of Pan-African orogeny that prevailed within the Arabian–Nubian Shield. The AFG intrudes an association of gneisses, island arc volcano–sedimentary rocks, and serpentinite masses. Field observations, supported by remote sensing and geochemical data, reveal a composite granitic intrusion that is differentiated into two magmatic phases. The early granitic phase comprises weakly deformed subduction-related calc–alkaline rocks ranging from diorite to tonalite, while the later encloses undeformed granodiorite and granite. Landsat-8 (OLI) remote sensing data have shown to be highly effective in discriminating among the different varieties of granites present in the area. Furthermore, the data have provided important insights into the structural characteristics of the AFG region. Specifically, the data indicate the presence of major tectonic trends with ENE–WSW and NW–SE directions transecting the AFG area. Geochemically, the AFG generally has a calc–alkaline metaluminous affinity with relatively high values of Cs, Rb, K, Sr, Nd, and Hf but low contents of Nb, Ta, P, and Y. The early magmatic phase has lower alkalis and REEs, while the later phases have higher alkalis and REEs with distinctly negative Eu anomalies. The AFG is structurally controlled, forming a N–S arch, which may be due to the influence of the wadi Hodein major shear zone. The diorite and tonalite are believed to have been originally derived from subduction-related magmatism during regional compression. This began with the dehydration of the descending oceanic crust with differential melting of the metasomatized mantle wedge. Magma ascent was long enough to react with the thickened crust and therefore suffered fractional crystallization and assimilation (AFC) to produce the calc–alkaline diorite–tonalite association. The granodiorite and granites were produced due to partial melting, assimilation, and fractionation of lower crustal rocks (mainly diorite–tonalite of the early stage) after subduction and arc volcanism during a late orogenic relaxation–rebound event associated with uplift transitioning to extension.

Understanding pollution levels, ecological health risks, and sources of potentially toxic metals (PTMs) in the soil from university campuses is critical for assessing environmental safety. Soil samples were collected from 12 locations across urban parks and green areas at Sohag University in Egypt. The samples were processed and analysed for heavy metals, including iron (Fe), manganese (Mn), cobalt (Co), nickel (Ni), chromium (Cr), lead (Pb), zinc (Zn), copper (Cu), and cadmium (Cd). Pollution levels were evaluated using indices such as the pollution index (PI), pollution load index (PLI), geo-accumulation index (Igeo), and enrichment factors (EFs). Among the pollution indices, the EFs showed the highest sensitivity in detecting anthropogenic contributions, particularly for Cd, Pb, and Cr. Spatial distribution maps and multivariate statistical analyses, including correlation matrix (CM), principal component analysis (PCA), and cluster analysis (CA), were applied to identify the relationships between PTMs and soil properties, and source apportionment was performed using positive matrix factorisation (PMF). The results indicated that Mn, Ni, and Co were primarily geogenic, whereas Pb, Zn, Cr, and Cd showed higher concentrations, suggesting moderate-to-significant anthropogenic pollution. Pb and Cd pose considerable ecological risks, whereas other metals such as Cr and Cu exhibit moderate ecological threats. The non-carcinogenic and carcinogenic risks to the students were within safe limits, as defined by United States Environmental Protection Agency (USEPA) threshold values. Source apportionment using PMF identified five main sources of PTMs: industrial and anthropogenic activities (30.0%), traffic emissions (25.0%), natural soil processes (20.0%), agricultural practices (15.0%), and mixed industrial traffic sources (10.0%). These findings emphasise the importance of controlling anthropogenic activities to ensure a safer campus environment.

The El Bola mafic–ultramafic intrusion (EBMU) in Egypt’s Northern Eastern Desert represents an example of Neoproterozoic post-collisional layered mafic–ultramafic magmatism in the Arabian–Nubian Shield (ANS). The intrusion is composed of pyroxenite, olivine gabbro, pyroxene gabbro, pyroxene–hornblende gabbro, and hornblende-gabbro, exhibiting adcumulate to heter-adcumulate textures. Mineralogical and geochemical analyses reveal a coherent trend of fractional crystallization. Compositions of whole rock and minerals indicate a parental magma of ferropicritic affinity, derived from partial melting of a hydrous, metasomatized spinel-bearing mantle source, likely modified by subduction-related fluids. Geothermobarometric calculations yield crystallization temperatures from ~1120 °C to ~800 °C and pressures from ~5.2 to ~3.1 kbar, while oxygen fugacity estimates suggest progressive oxidation (log fO2 from −17.3 to −15.7) during differentiation. The EBMU displays Light Rare Earth element (LREE) enrichment, trace element patterns marked by Large Ion Lithophile Element (LILE) enrichment, Nb-Ta depletion and high LILE/HFSE (High Field Strength Elements) ratios, suggesting a mantle-derived source that remained largely unaffected by crustal contribution and was metasomatized by slab-derived fluids. Tectonic discrimination modeling suggests that EBMU magmatism was triggered by asthenospheric upwelling and slab break-off. Considering these findings alongside regional geologic features, we propose that the mafic–ultramafic intrusion from the ANS originated in a tectonic transition between subduction and collision (slab break-off) following the assembly of Gondwana.

Beryl mineralization in the Nugrus-Sikait domain in the South Eastern Desert (SED) of Egypt occurs as disseminated crystals in granitic pegmatite and quartz, as well as pegmatite veins crosscutting mélange schist and ophiolitic rocks. When granitic pegmatite comes into contact with the ophiolitic rocks, phlogopite and amphibole schists are formed due to K metasomatism. The ophiolitic mélange is intruded by leucogranite and related pegmatite along the NNW to NW Nugrus shear zone. Beryl samples have been collected from Um Sleimat, Madinat Nugrus, Wadi Abu Rusheid, and Wadi Sikait. Major oxides and in situ trace and rare earth elements (REEs) of beryl and associated minerals were analyzed through EPMA and LA-ICP-MS, respectively. The investigated beryl, based on its color and chemical compositions, can be classified into the two following types: pegmatitic beryl (type I) and schist-related beryl (type II). The former is colorless to pale green, and is mainly restricted in pegmatite veins; it is poor in Cr2O3 (up to 0.03 wt%) and MgO (Nil). The latter, deep green in color, is rich in Cr2O3 (up to 0.27 wt%) and MgO (up to 2.71 wt%), and occurs within quartz veins, phlogopite schists, and tremolite schists. The abundant beryl mineralization in phlogopite schists and their related quartz veins suggests that granite and associated pegmatite are the source rocks for the Be-bearing fluids that migrate along the NW-SE trending deep-seated tectonic zone, such as the Nugrus shear zone. Therefore, the formation of beryl in schists is attributed to the interaction of granitic/pegmatitic-derived Be-bearing fluids with serpentinite and gabbro interlayered with mélange schists. Variations in the trace and REE contents of both beryl types (I and II) indicate their two-stage formation from different compositions of Be-rich fluids, where light REEs, Zr, Nb, Ba, and Th decrease from type I beryl to type II. These two phases of beryl could be attributed to the magmatic/hydrothermal fluids associated with the pegmatite emplacement. The early phase of the late-stage magmatic-derived fluids was closely related to magma evolution and pegmatite formation, forming euhedral type I beryl. The late phase of pegmatite-derived fluids was mixed with serpentinite/schist-derived fluids that cause high V and Cr content in type II beryl. The composition of parent magmas of felsic rocks, the high degree of magma fractionation or the late stage melts, fluid compositions (rich in Be, Li, Cs, Rb, K), and alkali metasomatism, as well as the linear NW-SE trending deep-seated shear zone, are all factors possibly influencing beryl mineralization in the SED of Egypt.