The Ediacaran (607–593 Ma) Ferani volcanic rocks are exposed in South Sinai, at the extreme northern tip of the Arabian-Nubian Shield (ANS). The studied volcanics constitute a cogenetic continuous ...intermediate (andesite to dacite) to acid (rhyodacite to rhyolite) lava sequence with a high-K calc-alkaline metaluminous to slightly peraluminous nature. They contain a high concentration of large-ion lithophile elements (i.e., Ba, Rb, Pb, and Th), but lower contents of Nb, P, Ti, and Sr. They also have a general enrichment in light rare earth elements ((La/Sm)N=2.66–4.92), compared to heavy rare earth elements ((Gd/Yb)N=1.10–2.29), with a slightly negative Eu anomaly (Eu/Eu*=0.35–0.94). The cooling of the Ferani magma began at ∼1000°–1100°C and went to ∼700°C at low pressure (<5.1 kbar) and shallow crustal levels (<17 km), according to thermobarometric modeling. The low degree of partial melting of the mafic lower-crustal rocks could have produced the andesitic-dacitic magmas that ascended through the crust and fractionated, leading to the production of the early intermediate Ferani lavas. Progressive fractional crystallization of the intermediate melts could consequently have formed the rhyodacite and rhyolite melts, which were later erupted to form the upper acidic Ferani volcanic sequence. Petrological and geochemical features support a postcollisional setting of the Ferani volcanics. Lithospheric delamination is the main geodynamic process responsible for the formation of the Ferani volcanics during the postcollisional extensional stage in the northern ANS crust.
Alkaline ring complexes are widely distributed in the south Eastern Desert (SED) of Egypt, but their petrogenesis and geodynamic settings are a matter of many discussions. In this contribution, ...mineral chemistry, and whole-rock geochemical data of the Maladob intrusive rocks were used to investigate their petrogenesis. The Maladob ring complex is a small alkaline intrusion in the SED of Egypt, composed of oversaturated syenite, quartz syenites and peralkaline granite. The rocks consist of K-feldspar (Or
94–97
) and albite (An
0-1
), alkali amphiboles (arfvedsonite and ferro-katophorite), sodic pyroxene (aegirine), with accessory aenigmatite, zircon, apatite, ilmenite, magnetite and titanite. Geochemically, the rocks are peralkaline, show distinctive geochemical characteristics such as low contents of CaO, MgO, Sr and high contents of alkalis, Rb, Nb, Y, and REE, typical of A-type granites. The rocks are weakly to moderately fractionated with a general enrichment in LREE (La/Sm)
N
= 2.96–3.64. Typically, the Maladob rocks are classified as within plate granites and exhibit A1 subtype characteristics. We suggest that the Maladob rocks were formed from a similar OIB-like mafic magma by fractional crystallization. The fractionation of feldspars and mafic minerals play a significant role during magma evolution. During the Mesozoic intraplate magmatism, the upwelling of asthenosphere causes underplating of lithospheric OIB-like magma which was subjected to prolonged fractional crystallization to produce the Maladob syenites and peralkaline granite.
Mineral chemistry, whole-rock geochemical and Sr–Nd isotopic data are reported for the Abu-Diab granitoids in the northern Arabian-Nubian Shield (ANS) of Egypt, to investigate their petrogenesis and ...geodynamic significance. Gabal Abu-Diab constitute a multiphase pluton, consisting largely of two-mica granites (TMGs) enclosing microgranular enclaves and intruded by garnet bearing muscovite granites (GMGs) and muscovite granites (MGs). The granitoids are weakly peraluminous (A/CNK = 1.01–1.12) and show high SiO2 (>72.9 wt%) and alkali (K2O + Na2O = 8.60–9.13) contents. The geochemical features show that they are post-collisional and highly fractionated A-type granitoids. Compared to their host TMGs, the microgranular enclaves are strongly peraluminous (A/CNK = 1.18–1.24) with lower SiO2 and higher abundances of trace elements. The TMGs are depleted in Ba, Nb, P and Ti and are enriched in LREEs relative to HREEs with weakly negative Eu anomalies (Eu/Eu* = 0.45–0.64). In contrast, the GMGs and MGs are extremely depleted in Ba, Sr and Ti and have tetrad-type REE patterns (TE1–3 = 1.1–1.3) with strongly pronounced negative Eu anomalies (Eu/Eu* = 0.03–0.26), similar to rare metals bearing granites. The Ediacaran (585 ± 24 Ma) TMGs, are characterized by restricted and relatively low initial 87Sr/86Sr ratios (0.70337–0.70382) that suggests their derivation from a depleted mantle source, with little contamination from the older continental crust. In contrast, the GMGs and MGs have extremely high 87Rb/86Sr and 87Sr/86Sr ratios that reflect the disturbance of the Rb-Sr isotopic system and may give an indication for magmatic-fluid interaction. However, all the granitoids display positive εNd(t) (4.41–6.57) and depleted mantle model ages TDM2 between 777 and 956 Ma, which indicate their derivation from a Neoproterozoic juvenile magma sources and preclude the occurrence of pre-Neoproterozoic crustal rocks in the ANS. The microgranular enclaves represent globules of hot mafic magma that have injected and partly mixed with the colder and more felsic TMGs magma. Geochemical and isotopic data along with petrogenetic modelling, suggest that the TMGs were formed by low degrees of partial melting of the pre-existing I-type granodiorites, followed by extensive fractional crystallization and fluid fractionation to produce the geochemically specialized rare metals GMGs and MGs in the margin of Abu-Diab pluton. During the post-collisional stage of ANS and due to lithospheric delamination processes, the underplated fluid/volatile rich mantle magma had interplated and migrated upward to shallow crustal levels, through extensional faults/shear zones, and enhanced the partial melting and fractionation of granodiorites to eventually form Abu-Diab A-type granitoids.
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•The Abu-Diab pluton contains three highly fractionated A-type granitoids.•The Ediacaran age (585 ± 24 Ma) was confirmed using Rb-Sr method.•The young TDM2 model ages reflect the juvenile crustal nature of the granitoids.•The granitoids were formed by both partial melting and fractional crystallization.•Tectono-magmatic evolution model of the Abu-Diab granitoids was proposed.
The central Eastern Desert (CED) of Egypt is well-known for its granite-related Nb–Ta mineralization. The garnet-bearing muscovite granite (GMG) of the Abu-Diab composite pluton in the CED consists ...mainly of quartz, K-feldspar (Or88–98), albite (An0-4) and muscovite, with accessory minerals including garnet, zircon, columbite, ilmenite, Ti-rich hematite, rutile, ilmenorutile, thorite, apatite, xenotime and chlorite. The GMG is weakly peraluminous and has low Nb/Ta (9.6–15.4) and Zr/Hf (16–31) with discernible REEs tetrad effect (TE1-3 = 1.11–1.35), typical of highly evolved granites. Zircon contains high concentrations of U and Th typical of late-magmatic zircon and similar to zircon type from highly evolved granite. The homogenous and weak zoned columbites are classified as manganocolumbite. The formation of Ta-rich rim in the columbite may indicate that later fluids were from the GMG granite itself at advanced fractionation into exsolving fluids, and not from an external source. Ilmenite is greatly enriched in MnO, which indicates the significant pyrophanite (up to 29 mol %) molecules in ilmenite through simple substitution of Mn for Fe2+ with increasing oxygen fugacity under magmatic-hydrothermal conditions. Xenotimes show low analytical totals, suggesting probably hydration during their post-magmatic alteration, while apatite is small-grained associated with tiny zircons, suggesting late-crystalized phases. During late magmatic differentiation stage, the interaction of granitic melt with F-rich late magmatic fluids could be resulted in the formation of Ti–Nb–Ta–Zr minerals. Overall, the Abu Diab GMG possesses mineralogical and geochemical features that make it a potential target for Ti–Nb–Ta–Zr minerals.
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•The highly evolved granitic phase in the Abu-Diab composite pluton contains significant Ti-Nb-Ta-Zr bearing minerals.•Zircon shows a feature of late-magmatic type with high U and Th contents.•The columbite-Mn is homogenous to weakly zoned of magmatic origin.•The F-rich late magmatic fluids play a vital role in the formation of the Abu-Diab Ti–Nb–Ta–Zr minerals.
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.
Granitic pegmatites of Wadi Al-Baroud area in the Central Eastern Desert of Egypt have appreciated amounts of radioactive (U, Th) and rare metal- (Nb, Ta, Y, Zr, Hf, and rare earth elements—REEs) ...bearing minerals. A combination of both geochemical and physical methods has been used for investigation of Wadi Al-Baroud granitic pegmatites. The identification, imaging, and chemistry of rare metal-bearing minerals were conducted using the optical microscope, X-ray diffraction (XRD), scanning electron microscope (SEM), and electron microprobe analyzer (EMPA). The pegmatites host Nb-Ta oxides (euxenite-Y, fergusonite-Y, and yttrocolumbite-Y), REE minerals (xenotime-Y, monazite-Ce and allanite-Ce), U-Th minerals (thorite and uranothorite), and Hf-rich zircon. In addition, muscovite, quartz, feldspars, and some iron oxide minerals such as magnetite, goethite, and lepidocrocite represent the essential, gangue, and associated minerals. Physical upgrading of Wadi Al-Baroud-mineralized pegmatites was carried out using gravity and magnetic separation techniques. Applying the optimum conditions for both separation techniques, it is possible to attain a good concentrate with an acceptable recovery. Accordingly, the final concentrate contains ~ 0.25% U, 0.46% Th, and 0.31% REE with recovery of 91.17% U, 96.56% Th, and 86.19% REE in a weight of 6.58% out of the original sample assays 0.02% U, 0.04% Th, and 0.03% REE. Therefore, it is well-recommended that the final concentrate should subject to proper hydrometallurgical treatment to extract their valuable metal contents.
The utilization of phosphorite deposits as an industrial resource is of paramount importance, and its sustainability largely depends on ensuring safe and responsible practices. This study aims to ...evaluate the suitability of phosphorite deposits for industrial applications such as the production of phosphoric acid and phosphatic fertilizers. To achieve this goal, the study meticulously examines the geochemical characteristics of the deposits, investigates the distribution of natural Radioactivity within them, and assesses the potential radiological risk associated with their use. The phosphorites are massive and collected from different beds within the Duwi Formation at the Hamadat mining area. They are grain-supported and composed of phosphatic pellets, bioclasts (bones), non-phosphatic minerals, and cement. Geochemically, phosphorites contain high concentrations of P2O5 (23.59-28.36 wt.%) and CaO (40.85-44.35 wt.%), with low amounts of Al2O3 (0.23-0.51 wt.%), TiO2 (0.01-0.03 wt.%), Fe2O3 (1.14-2.28 wt.%), Na2O (0.37-1.19 wt.%), K2O (0.03-0.12 wt.%), and MnO (0.08-0.18 wt.%), suggesting the low contribution of the detrital material during their deposition. Moreover, they belong to contain enhanced U concentration (55-128 ppm). They are also enriched with Sr, Ba, Cr, V, and Zn and depleted in Th, Zr, and Rb, which strongly supports the low detrital input during the formation of the Hamadat phosphorites. The high Radioactivity of the studied phosphorites is probably due to the widespread occurrence of phosphatic components (e.g., apatite) that accommodate U in high concentrations. Gamma spectrometry based on NaI (Tl) crystal 3×3 has been used to measure occurring radionuclides in the phosphorite samples. The results indicate that the radioactive concentrations' average values of 226Ra, 232Th, and 40K are 184.18±9.19, 125.82±6.29, and 63.82±3.19 Bq Kg-1, respectively. Additionally, evaluations have been made of the radiological hazards. The calculated risk indicators exceeded the recommended national and world averages. The data obtained will serve as a reference for follow-up studies to evaluate the effectiveness of the Radioactivity of phosphatic materials collected from the Hamdat mine area.
The aim of this paper is to generalise the construction of
n
-ary Hom-Lie bracket by means of an
(
n
-
2
)
-cochain of given Hom-Lie algebra to super case inducing
n
-Hom-Lie superalgebras. We study ...the notion of generalized derivations and Rota-Baxter operators of
n
-ary Hom-Nambu and
n
-Hom-Lie superalgebras and their relation with generalized derivations and Rota-Baxter operators of Hom-Lie superalgebras. We also introduce the notion of 3-Hom-pre-Lie superalgebras which is the generalization of 3-Hom-pre-Lie algebras.
This study primarily investigates the natural radioactivity level in alkaline rocks collected from the Wadi El-Dib ring complex (WDRC) in North Eastern Desert of Egypt, and assesses potential health ...risks associated with their use as decorative building materials. The work was accomplished using a high-purity germanium detector as well as ICP-MS and ICP-AES techniques. The WDRC composed essentially of trachyte, quartz syenite, granite and syenite. Geochemically, these rocks contain high SiO
and alkalis with metaluminous to slightly peraluminous features. All rocks contain high concentrations of rare earth elements (∑REEs = 109-1075 ppm), with clear enrichment in light REEs compared to heavy REEs (La/Yb)
= 8.3-25.3. Radiometrically, the concentrations of the natural radioisotopes (
U,
Th, and
K) in the studied rock types surpassed the worldwide average values assigned for building materials by UNSCEAR. This elevation of the radioisotope concentration values is due to the presence of supplement minerals such as monazite, zircon, allanite, and rutile. Granites exhibit the highest mean concentrations of
U (av. 164.24 ± 14.76 Bq/kg) and
Th (av. 214.37 ± 23.33 Bq/kg), while trachytes demonstrate the highest
K (av. 1352.56 ± 65.56 Bq/kg) concentrations. In contrast, syenites exhibite the lowest mean concentrations for
U (av. 54.51 ± 6.81 Bq/kg) and
Th (av. 56.76 ± 6.25 Bq/kg), while quartz syenites display the lowest mean concentration of
K (av. 1144.78 ± 96.19 Bq/kg). The radiogenic heat production (RHP) associated with U, Th, and K range between 1.41 to 9.33 μW/m
, exceeding the typical crustal mean value of 0.8 to 1.2 μW/m
. The radiological parameters and indices evaluating risks of the outdoor and indoor radiation doses due to the investigated rocks were assessed. The results indicated that these rocks meet globally accepted values and safety standards (approved by UNSCEAR, ICRP, and EC) for surface building materials, as well as they underscore the importance of adhering to safety protocols to safeguard workers from radiation exposure within the WDRC area. Ultimately, the data herein provide a valuable database for assessing the compatibility of geochemical data and natural radioactivity level in WDRC rocks. Additionally, it reveals that from the radiological perspective, the investigated rocks are considered safe for use as decorative construction materials.
Climatic variability and silicate weathering are remarkable features throughout the Late Cretaceous period. Late Campanian black shale is considered the most significant silicate source rock in the ...southern Tethys. Here, we used mineralogical and geochemical data to evaluate the continental weathering intensity and climatic changes as well as their impact on the deposition of the Late Campanian black shale in the Western Desert of Egypt. The studied black shale has a relatively high concentration of Al, Fe, Mg, Ca, Sr, Ga, Co, Cr, and V when compared to the average Post-Archean Australian Shales (PAAS). The studied samples have elevated values of Ga/Rb, and low values of Rb/Sr, Sr/Cu, and K2O/Al2O3, supporting the deposition of Late Campanian shale under warm/humid conditions. Furthermore, the average chemical index of alteration (CIA, 78.6%), chemical index of weathering (CIW; 83.8%), C-value (1.26), Fe/Mn (408), and Mg/Ca (1.54) reveal the predominance of warm/humid climate. The chemical weathering proxies (CIA, CIW, PIA, LnAl2O3/Na2O) and ACNK diagram imply that the Late Campanian samples were exposed to a moderate grade of chemical alteration. The deposition of black shale occurred under high seawater salinity conditions based on Sr/Ba (Avg = 3.6). Additionally, the weathering indices are well correlated with paleoclimatic proxies, suggesting that weathering intensity is strongly affected by paleoclimate. However, chemical weathering during the Late Campanian has a weak influence on oceanic nutrient fluxes. No substantial impact of the paleoclimate during the deposition of Late Campanian black shale on water salinity was reported.
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