Search Results (46)

Between approximately 725 and 518 Ma, a suite of specialized felsic plutons and granitic stocks were emplaced across the Arabian Shield, many of which are now recognized as highly mineralized prospects enriched in rare earth elements (REEs), rare metals, and radioactive elements bearing mineralizations. The current investigation focused on the radiological and geochemical characterization of naturally occurring radionuclides, specifically ²³⁸U, ²²⁶Ra, ²³²Th, and ⁴⁰K, within three strategically selected granitic prospects, namely, J. Tawlah albite granite (TW), J. Hamra (HM), and J. Abu Al Dod alkali feldspar syenite and granites (AD). Concerning the radioactivity levels of the investigated granitic stocks, specifically the activity concentrations of ²³⁸U, ²²⁶Ra, ²³²Th, and ⁴⁰K, the measured average values demonstrate significant variability across the TW, HM, and AD stocks. The average ²³⁸U concentrations are 195 (SD = 38.7), 88.66 (SD = 25.6), and 214.3 (SD = 140.8) Bq/kg for TW, HM, and AD granitic stocks, respectively. Corresponding ²²⁶Ra levels are recorded at 172.4 (SD = 34.6), 75.62 (SD = 25.9), and 198.4 (SD = 139.5) Bq/kg. For ²³²Th, the concentrations are markedly elevated in TW at 5453.8 (SD = 2182.9) Bq/kg, compared to 77.16 (SD = 27.02) and 160.2 (SD = 103.8) Bq/kg in HM and AD granitic stocks, respectively. Meanwhile, ⁴⁰K levels are reported at 1670 (SD = 535.9), 2846.2 (SD = 249.9), and 3225 (SD = 222.3) Bq/kg for TW, HM, and AD granitic plutons, respectively. Notably, these values exceed the global average background levels, indicating an anomalous enrichment of the studied granitic occurrences. The mean radiological hazard indices for each granitic unit generally exceed global benchmarks, except for AEDE_out in the HM and AD stocks, which remain below international limits. The geochemical disparities observed are indicative of post-magmatic alteration processes, as substantiated by the interpretation of remote sensing datasets. In light of the significant radiological burden presented by these granitic stocks, it is essential to implement a rigorous precautionary framework for any future mining. These materials must be categorically excluded from uses that entail direct human exposure, especially in residential construction or infrastructure projects. Full article

The article provides a comprehensive analysis of the Magal Gebreel granitic suites (MGGs) using petrological (fieldwork, petrography, mineral chemistry, and bulk rock analysis) aspects to infer their petrogenesis and emplacement setting. Our understanding of the development of the northern portion of the Arabian Nubian Shield is significantly improved by the Neoproterozoic granitic rocks of the seldom studied MGGs in Egypt’s south Eastern Desert. According to detailed field, mineralogical, and geochemical assessments, they comprise syn-collision (granodiorites) and post-collision (monzogranites, syenogranites, and alkali feldspar rocks). Granodiorite has strong positive Pb, notable negative P, Ti, and Nb anomalies, and is magnesian in composition. They have high content of LREEs (light rare-earth elements) compared to HREEs (heavy rare-earth elements) and clear elevation of LFSEs (low-field strength elements; K Rb, and Ba) compared to HFSEs (high-field strength elements; Zr and Nb), which are in accord with the contents of I-type granites from the Eastern Desert. In this context, the granodiorites are indicative of an early magmatic phase that probably resulted from the partial melting of high K-mafic sources in the subduction zone. Conversely, the post-collision rocks have low contents of Mg#, CaO, P₂O₅, MgO, Fe₂O₃, Sr, and Ti, and high SiO₂, Fe₂O₃/MgO, Nb, Ce, and Ga/Al, suggesting A-type features with ferroan affinity. Their P, Nb, Sr, Ba, and Ti negative anomalies are in accord with the findings for Eastern Desert granites of the A2-type. Furthermore, they exhibit a prominent negative anomaly in Eu and a small elevation of LREEs in relation to HREEs. The oxygen fugacity (fO₂) for the rocks under investigation can be calculated using the biotite chemistry. The narrow Fe/(Fe + Mg) ratio range (0.6–0.75) indicates that they crystallized under moderately oxidizing conditions between ~QFM +0.1 and QFM +1. The A-type rocks were formed by the partial melting of a tonalite source (underplating rocks) in a post-collisional environment during the late period of extension via slab delamination. The lithosphere became somewhat impregnated with particular elements as a result of the interaction between the deeper crust and the upwelling mantle. Full article

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. Full article

Continental rifts represent one of the most important settings geologically and economically. The Suez Rift represents more than 74% of the Egyptian crude oil. It represents the northern end of the Red Sea, which understanding is vital to reconstructing the tectonics, dynamics, and time–temperature history of the whole region. An effective method to reveal rift-related history is by studying its flanks, which are represented here by the Arabian-Nubian Shield Neoproterozoic basement rocks. We applied an approach integrating new fission-track thermochronology data, new time–temperature modeling, stratigraphic information, and geological knowledge, which has proven its effectiveness in such geological settings. The collected samples from the Wadi Hebran area on the eastern flank of the Suez rift showed two differentiated cooling histories: The first has a Carboniferous zircon fission-track and a Cretaceous apatite fission-track age, and the second has a Triassic zircon fission-track and an Oligocene–Miocene apatite fission-track age. The time–temperature history modeling supported four distinct cooling events activated through the Neoproterozoic post-accretion erosional event, Variscan tectonic event, Gondwana disintegration, and the Suez Rift initiation. The rock uplift that accompanied the Suez Rift reaches up to 4 km, explaining the extraordinary elevations of the Catherina region, and supports an active rift component in the southern segment of the Suez Rift eastern flank. Full article

The granitic rocks and the Dokhan Volcanics at the transect between Safaga and Qena, the Egyptian Northern Eastern Desert represent the northern termination of the Arabian–Nubian Shield (ANS), which, in turn, represents the northern part of the East African Orogeny (EAO). The geochronological development of the magmatic activities that constructed the ANS is critical in understanding these orogenies. The ANS was constructed through pre-collisional, syn-collisional, and post-collisional magmatic phases. The transition between these magmatic phases marks tectonic shifting from subduction to compressional and extensional tectonic settings, respectively. The chronological constraints of these tectonic–magmatic phases are still questionable. Our study aims to refine these chronological constraints through the dating of four calc-alkaline granitic rocks (722 ± 5 Ma–561 ± 4 Ma), five alkaline granitic rocks (758 ± 5 Ma–555 ± 4 Ma), and three Dokhan Volcanic rocks (618 ± 5 Ma–606 ± 5 Ma). Our results suggest the absence of any pre-collisional rocks. The syn-collisional magmatism extended here from 758 ± 5 Ma to 653 ± 7 Ma, demonstrating the chronological domination of the syn-orogenic compressional regime in the NED. The Dokhan Volcanic activity marked the shifting of the tectonic setting from a compressional to an extensional regime at 618 ± 5 Ma. Post-collisional plutonism dominated between 583 ± 5 Ma and 555 ± 4 Ma in the studied region, suggesting that ANS magmatic activity was extended to the Phanerozoic edge. These findings refute the classical interpretations of older magmatism as calc-alkaline granitoids and younger magmatism as alkaline granitoids. Pre-Neoproterozoic (pre-ANS) xenocrysts with ages of 1879 ± 22, 1401 ± 25, 1385 ± 12, 1232 ± 27, 1210 ± 18, and 1130 ± 15 Ma were yielded, which might support a local reworked ancient magmatic source. Full article

The transition zone between a shallow-water delta and tidal flat is characterized by a high degree of mixed siliciclastic–carbonate sedimentation. There are frequent lateral and vertical variations in sandstone, dolostone, limestone, and mixed siliciclastic–carbonate rock (MSR); however, their influence on reservoir quality remains uncertain. Member B of the Asmari Formation (Asmari B) in Iraq’s C Oilfield was deposited in a remnant ocean basin formed by the closure of the Neo-Tethys Ocean. During the Oligocene–Miocene, frequent exposure of the Arabian Shield provided intermittent sediment sources to the study area. Under shallow water and relatively arid conditions, widespread mixed sedimentation of siliciclastic sand and dolomitic components occurred. Taking Asmari B as a case study, this research employs core and thin-section observations, trace element analyses, and quantitative mineralogical interpretations of logging data to investigate the characteristics of mixed sedimentation and to evaluate its impact on reservoir quality. Four key aspects were identified: (1) Four main types of mixed lithofacies developed in Member B of the Asmari Formation, namely sandstone-bearing dolomite, dolomitic sandstone, dolostone-bearing sand, and sandy dolostone. These lithofacies were deposited in the transition zone between distributary channels and intertidal zone with different water depths. As the terrigenous input decreased, the water depth for sand-bearing facies increased. In particular, sandy dolostone was predominantly formed in subtidal settings under the influence of storm events. (2) MSRs are categorized based on the proportion of the minor component into high and low mixing degrees. Based on mineral compositions interpreted from well logging data, the mixing degree of MSRs was characterized by the thickness ratio, using the thickness of high- and low-mixing-degree MSRs relative to the total thickness of the formation. The MSRs mainly developed in the B1, B2, B3-1, B3-2, and B4 sublayers, where moderate provenance supply facilitated the high mixing of terrigenous clastic and carbonate components. (3) The pore and throat patterns of MSR reservoirs change with the mixing degree index. When the dolomite content in sandstone exceeds 25%, the pore–throat structure changes significantly. A small amount of sand in dolostone has little effect on the pore and throat. Sandy dolostone exhibits the poorest reservoir quality. (4) Mixed sandstone reservoirs are distributed on both sides of the distributary channels and mouth bar. The dolostone-bearing sand reservoirs are distributed in the transition zone between the sandy flat and dolomite flat. Sandy dolostone is mainly thin and isolated due to the influence of storm events. This study provides guidance for understanding the development patterns of MSR reservoirs under similar geological settings, facilitating the next step of oil and gas exploration in these special reservoirs. Full article

Groundwater availability in semi-arid regions like the Widyan Basin, the Kingdom of Saudi Arabia (KSA), is a critical challenge due to climatic, topographic, and hydrological variations. The accurate identification of groundwater zones is essential for sustainable development. Therefore, this study combines remote-sensing datasets (Sentinel-2 and ASTER-DEM) with conventional data using Geographic Information System (GIS) and analytical hierarchy process (AHP) techniques to delineate groundwater potential zones (GWPZs). The basin’s geology includes Pre-Cambrian rock units of the Arabian Shield in the southwest and Cambrian–Ordovician units in the northeast, with the Saq Formation serving as the main groundwater aquifer. Six soil types were identified: Haplic and Calcic Yermosols, Calcaric Regosols, Cambic Arenosols, Orthic Solonchaks, and Lithosols. The topography varies from steep areas in the southwest and northwest to nearly flat terrain in the northeast. Hydrologically, the basin is divided into 28 sub-basins with four stream orders. Using GIS-based AHP and weighted overlay methods, the GWPZs were mapped, achieving a model consistency ratio of 0.0956. The zones were categorized as excellent (15.21%), good (40.85%), fair (43.94%), and poor (0%). The GWPZ model was validated by analyzing data from 48 water wells distributed in the study area. These wells range from fresh water to primary saline water, with water depths varying between 13.98 and 130 m. Nine wells—with an average total dissolved solids (TDS) value of 597.2 mg/L—fall within the excellent zone, twenty-one wells are categorized in the good zone, fifteen wells are classified in the fair zone, and the remaining wells fall into the poor zone, with TDS values reaching up to 2177 mg/L. The results indicate that the central zone of the study area is suitable for drilling new water wells. Full article

The Muteh–Golpaygan metamorphic complex, situated within the Sanandaj–Sirjan zone of Iran, represents a pivotal site for investigating the late Neoproterozoic Cadomian orogeny and its implications for crustal evolution along the northern margin of Gondwana. This study integrates geochemical, isotopic, and geochronological data to elucidate the petrogenesis, magma sources, and geodynamic significance of granitic (ortho-) gneisses from this region. The granitic gneisses are predominantly peraluminous and calc-alkaline, with A/CNK [molar Al₂O₃/(CaO + Na₂O + K₂O)] values ranging from 1.05 to 1.43. They exhibit enrichment in light rare earth elements (LREEs), flat heavy REE (HREE) patterns, and pronounced negative Eu anomalies, suggesting that the magma was derived from subduction-related melts that interacted with metasedimentary materials in the upper crust. Zircon U-Pb geochronology reveals crystallization ages of ~570–560 Ma, with inherited zircons dating back to the Neoarchean and Paleoproterozoic. Isotopic signatures, including εHf(t) values (−7.2 to +6.2) and δ¹⁸O values (+7.07‰ to +9.88‰), indicate a complex interplay between juvenile mantle-derived components and reworked crustal materials. Geodynamically, the magmatic characteristics align with an active continental margin setting driven by the subduction of the Proto-Tethys Ocean. Comparisons with coeval magmatism in the Arabian–Nubian Shield and Anatolia indicate a unified tectonic framework along the northern margin of Gondwana. This study provides critical insights into the tectono-magmatic processes of the Cadomian orogeny, emphasizing the roles of subduction dynamics, crustal recycling, and juvenile contributions in shaping the early continental lithosphere. Full article

The Arabian–Nubian Shield (ANS) hosts numerous volcanogenic massive sulphide (VMS) deposits formed in submarine volcanic settings and enriched by hydrothermal processes, making it a critical region for mineral exploration due to the types of deposits it hosts and its geological complexity. The Wadi Bidah Mineral Belt (WBMB), located within the Arabian Shield, contains over 30 polymetallic VMS occurrences associated with an island arc system active between 950 and 800 million years ago. Despite its mineral potential, the WBMB still needs to be explored, with limited geophysical studies to support resource evaluation. This study focuses on the Hawiah area, a prominent VMS site within the WBMB, to delineate subsurface mineralization using transient electromagnetic (TEM) methods. TEM surveys were conducted to characterize the conductivity structure and identify potential zones of sulphide mineralization. Data were processed and inverted to generate 1D, 2D, and 3D resistivity models, providing critical insights into the depth, geometry, and continuity of the mineralized zones based on the final 3D resistivity distribution. The results revealed distinct conductive (very low resistivity) anomalies, correlating with known surface gossans and inferred sulphide-rich layers, and extended these features into the subsurface. The integration of TEM results with geological and geochemical data highlights the effectiveness of this approach in detecting and mapping concealed mineral deposits in complex geological environments. This study advances the understanding of VMS systems in the WBMB and demonstrates the potential of TEM surveys as a key tool for mineral exploration in the Arabian Shield. Full article

Heavy metal soil contamination is a global environmental issue that poses serious threats to human health, agricultural advancement, and ecosystem systems. Thirty-five soil samples from various parts of Jazan, Southwest Saudi Arabia, were collected. To create spatial pattern maps for nine potentially toxic elements (PTEs) (As, Co, Cr, Cu, Fe, Ni, Pb, V, and Zn), Ordinary Kriging (OK) was utilized. The variability of the soil metal concentration was estimated using multivariate analysis, including principal component analysis (PCA) and cluster analysis. In addition, the levels of soil contamination in the research area were assessed using contaminations indices, namely, Enrichment Factor (EF), Contamination Factor (CF), and geoaccumulation index (Igeo), and modified contamination degree (mC_d). Normalized Difference Vegetation Index (NDVI) and land use/land cover (LULC) were assessed to evaluate vegetation density and identify different forms of land cover and land use. The results showed that the Gaussian model fitted As well, whereas the spherical model fitted Co, Cr, Cu, Ni, and Zn. An exponential model was fitted to Fe and V. Pb also suited the Stable model. In each of the selected metals, the root mean square standardized error (RMSSE) values were close to one, and the mean standardized error (MSE) values were almost zero for each fitted model. Moreover, the findings showed that there was a tendency for the concentration of heavy metals in the research area to rise from west to east. The cluster analysis divided the data in this investigation into two clusters. Significant alterations in Co, Cr, Cu, Fe, Ni, V, and Zn were revealed by the acquired data. However, the total As and Pb concentrations in the two clusters did not differ significantly. The mC_d value of the research region often fell into one of three classes, with areas of 148.20 km² (nil to very low degree of contamination), 26.16 km² (low degree of contamination), and 0.495 km² (moderate degree of contamination). The findings indicated that the minerals connected to the Arabian Shield’s basement rocks are the main source of these PTEs. It is crucial to monitor PTEs contamination because the research region is highly cultivated, as shown by the NDVI and LULC status. Given the potential for future pollution due to human activity, PTEsPTEs decision-makers may use the findings of the spatial distribution maps of pollutants and their concentrations as a basis for future monitoring of PTEs concentrations in the study area. Full article

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. Full article

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. Full article

To assess the contamination levels, sources, and ecological health risks of potentially toxic elements (PTEs) in the sediments of Al Lith on the Saudi Red Sea coast, 25 samples were collected and analyzed for Zn, V, Cr, Cu, Ni, As, Pb, and Fe using inductively coupled plasma-atomic emission spectrometry. The average concentrations of PTEs (μg/g) were obtained in the following order: Fe (14,259) > V (28.30) > Zn (22.74) > Cr (16.81) > Cu (12.41) > Ni (10.63) > As (2.66) > Pb (2.46). The average values of enrichment factor were in the following order: As (1.12) > Zn (0.75) > V (0.70) > Cr (0.69) > Cu (0.69) > Pb (0.67) > Ni (0.46). This indicated that the Al Lith sediments exhibited either no or minimal enrichment of PTEs, with concentrations below the low effect range. This suggests that the primary source of these PTEs is the minerals associated with the basement rocks of the Arabian Shield (sphalerite, vanadiferous magnetite, chromite, pentlandite, arsenopyrite, and galena) and that they are unlikely to pose a substantial risk to benthic communities. The hazard index (HI) values for the PTEs in both adults and children were below 1.0, indicating no significant non-carcinogenic risk. The lifetime cancer risk (LCR) values for Pb, As, and Cr in both adults and children were within acceptable or tolerable levels, posing no significant health threats. However, a few samples showed LCR values exceeding 1 × 10⁻⁴, which may indicate potential risks. Full article

The Deki Amhare complex is located in central Eritrea, within the Arabian–Nubian Shield (ANS). It consists of an inner core of monzogranite porphyry and diorite enclaves (MMEs), surrounded outwardly by granodiorite and quartz diorite. The zircon U–Pb ages, whole-rock geochemistry, and Sr–Nd–Hf isotopic compositions of the Deki Amhare complex granitoids were used to discuss the Neoproterozoic tectonics of the ANS. The Late Tonian granodiorite and quartz diorite are metaluminous and calc-alkaline to slightly high-K calc-alkaline I-type plutons, with ages of 811.2 ± 4.8 Ma and 811.6 ± 5.7 Ma, respectively. They exhibit positive ε_Hf(t) (7.6–9.5) and ε_Nd(t) (3.9–4.7) values and relatively low (⁸⁷Sr/⁸⁶Sr)_i ratios (0.70374–0.70463), indicating that they derived from the partial melting of a metasomatized mantle wedge during intra-oceanic subduction. The Ediacaran monzogranite porphyry and MMEs are subalkaline to alkaline A₂-type granitoids with ages of 620.0 ± 4.3 Ma and 614.8 ± 3.9 Ma. These display positive ε_Hf(t) (5.3–8.7) and ε_Nd(t) (4.2–4.7) values, as well as low (⁸⁷Sr/⁸⁶Sr)_i ratios (0.70310–0.70480), implying that they formed through crust–mantle magma mixing related to post-collisional slab break-off. Based on these data, three stages of regional tectonic evolution can be described: (1) from ~1200 Ma to ~875 Ma, the mafic oceanic crust was derived from depleted mantle during the opening of the Mozambique Ocean; (2) from ~875 Ma to ~630 Ma, intra-oceanic subduction and arc formation occurred with the development of I-type batholiths; and (3) from ~630 Ma to ~600 Ma, crustal and lithospheric reworking took place post-collision, leading to the formation of A₂-type granitoids. Full article

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. Full article