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The Wadi Ranga sulfidic jasperoids in the Southern Eastern Desert (SED) of Egypt are hosted within the Neoproterozoic Shadli metavolcanics as an important juvenile crustal section of the Arabian Nubian Shield (ANS). This study deals with remote sensing and geochemical data to understand the mechanism and source of pyritization, silicification, and hematization in the host metavolcanics and to shed light on the genesis of their jasperoids. The host rocks are mainly dacitic to rhyolitic metatuffs, which are proximal to volcanic vents. They show peraluminous calc-alkaline affinity. These felsic metatuffs also exhibit a nearly flat REE pattern with slight LREE enrichment (La/Yb = 1.19–1.25) that has a nearly negative Eu anomaly (Eu/Eu* = 0.708–0.776), while their spider patterns display enrichment in Ba, K, and Pb and depletion in Nb, Ta, P, and Ti, reflecting the role of slab-derived fluid metasomatism during their formation in the island arc setting. The ratios of La/Yb (1.19–1.25) and La/Gd (1.0–1.17) of the studied felsic metatuffs are similar to those of the primitive mantle, suggesting their generation from fractionated melts that were derived from a depleted mantle source. Their Nb and Ti negative anomalies, along with the positive anomalies at Pb, K, Rb, and Ba, are attributed to the influence of fluids/melt derived from the subducted slab. The Wadi Ranga jasperoids are mainly composed of SiO2 (89.73–90.35 wt.%) and show wide ranges of Fe2O3t (2.73–6.63 wt.%) attributed to the significant amount of pyrite (up to 10 vol.%), hematite, goethite, and magnetite. They are also rich in some base metals (Cu + Pb + Zn = 58.32–240.68 ppm), leading to sulfidic jasperoids. Pyrite crystals with a minor concentration of Ag (up to 0.32 wt.%) are partially to completely converted to secondary hematite and goethite, giving the red ochre and forming hematization. Euhedral cubic pyrite is of magmatic origin and was formed in the early stages and accumulated in jasperoid by epigenetic Si-rich magmatic-derived hydrothermal fluids; pyritization is considered a magmatic–hydrothermal stage, followed by silicification and then hematization as post-magmatic stages. The euhedral apatite crystals in jasperoid are used to estimate the saturation temperature of their crystallization from the melt at about 850 °C. The chondrite (C1)-normalized REE pattern of the jasperoids shows slightly U–shaped patterns with a slightly negative Eu anomaly (Eu/Eu* = 0.43–0.98) due to slab-derived fluid metasomatism during their origin; these jasperoids are also rich in LILEs (e.g., K, Pb, and Sr) and depleted in HFSEs (e.g., Nb and Ta), reflecting their hydrothermal origin in the island arc tectonic setting. The source of silica in the studied jasperoids is likely derived from the felsic dyke and a nearby volcanic vent, where the resultant Si-rich fluids may circulate along the NW–SE, NE–SW, and E–W major faults and shear zones in the surrounding metavolcanics to leach Fe, S, and Si to form hydrothermal jasperoid lenses and veins. [ABSTRACT FROM AUTHOR]

The Igla Ahmr region in the Central Eastern Desert (CED) of Egypt comprises mainly syenogranites and alkali feldspar granites, with a few tonalite xenoliths. The mineral potential maps were presented in order to convert the concentrations of total rare earth elements (REEs) and associated elements such as Zr, Nb, Ga, Y, Sc, Ta, Mo, U, and Th into mappable exploration criteria based on the line density, five alteration indices, random forest (RF) machine learning, and the weighted sum model (WSM). According to petrography and geochemical analysis, random forest (RF) gives the best result and represents new locations for rare metal mineralization compared with the WSM. The studied tonalites resemble I-type granites and were crystallized from mantle-derived magmas that were contaminated by crustal materials via assimilation, while the alkali feldspar granites and syenogranites are peraluminous A-type granites. The tonalites are the old phase and are considered a transitional stage from I-type to A-type, whereas the A-type granites have evolved from the I-type ones. Their calculated zircon saturation temperature TZr ranges from 717 °C to 820 °C at pressure < 4 kbar and depth < 14 km in relatively oxidized conditions. The A-type granites have high SiO2 (71.46–77.22 wt.%), high total alkali (up to 9 wt.%), Zr (up to 482 ppm), FeOt/(FeOt + MgO) ratios > 0.86, A/CNK ratios > 1, Al2O3 + CaO < 15 wt.%, and high ΣREEs (230 ppm), but low CaO and MgO and negative Eu anomalies (Eu/Eu* = 0.24–0.43). These chemical features resemble those of post-collisional rare metal A-type granites in the Arabian-Nubian Shield (ANS). The parent magma of these A-type granites was possibly derived from the partial melting of the I-type tonalitic protolith during lithospheric delamination, followed by severe fractional crystallization in the upper crust in the post-collisional setting. Their rare metal-bearing minerals, including zircon, apatite, titanite, and rutile, are of magmatic origin, while allanite, xenotime, parisite, and betafite are hydrothermal in origin. The rare metal mineralization in the Igla Ahmr granites is possibly attributed to: (1) essential components of both parental peraluminous melts and magmatic-emanated fluids that have caused metasomatism, leading to rare metal enrichment in the Igla Ahmr granites during the interaction between rocks and fluids, and (2) structural control of rare metals by the major NW–SE structures (Najd trend) and conjugate N–S and NE–SW faults, which all are channels for hydrothermal fluids that in turn have led to hydrothermal alteration. This explains why rare metal mineralization in granites is affected by hydrothermal alteration, including silicification, phyllic alteration, sericitization, kaolinitization, and chloritization. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Neoproterozoic mineralized granites from the Umm Naggat and Homrit Waggat areas in the Central Eastern Desert (CED) of Egypt, are parts of the Neoproterozoic Nubian Shield. On the basis of textural and chemical characteristics, they resemble highly fractionated ferroan peraluminous A-type granites. Decorrelation stretch (DS) and band ratio (BR) techniques of Sentinel-2 and Landsat-9 data were used for the spectral identification of lithological units, alteration and mineralized zones in A-type granites. Spatial and spectral extent of the hydrothermal mineralized alteration zones (e.g., sericitization, carbonatization, kaolinitization, ferrous silicates and hydroxyl) related to the rare metal-bearing granitic plutons can be discriminated by processed ASTER data. Some structural features have been identified by Sentinel-1enhanced Soble directional filter images. The NW–SE Najd fault system is conjugated with N–S and NE–SW faults, which structurally control the distribution of both mineralized alteration zones and rare metal-bearing granites in the CED of Egypt. The studied mineralized granites comprise syenogranite and alkali feldspar granite. Essential minerals are quartz, K-feldspar (Or94-99), plagioclase (An0-7) and biotite, with subordinate amounts of chlorite, muscovite and fluorite. Zircon, Fe-Ti oxides, rutile, apatite, epidote, titanite, columbite and thorite are main accessory phases. Average zircon saturation temperature (TZr) of the studied granites ranges from 780 °C to 880 °C at pressures of 0.7–3.0 kbars and depth < 8 km. These granites are highly evolved (SiO2 = 73–78 wt. %), and show characteristics of high-K calc-alkaline peraluminous rocks (A/CNK = 1–1.13). They are enriched in Rb, Nb, Y, Ta, Hf, Ga, Zr and rare-earth elements (ΣREEs: up to 558 ppm) and show pronounced negative Eu anomalies (Eu/Eu* = 0.01–0.29), similar to post-collisional rare metal-bearing A-type granites either in Egypt or elsewhere in the world. These A-type granites more likely crystallized from highly fractionated I-type tonalite-granodiorite magmas, followed by extensive fractional crystallization in the upper crust during and just after lithospheric delamination. Rare-metal minerals such as zircon, rutile, xenotime, thorite, cerite-(Ce), apatite, parisite, uranothorite, columbite, ishikawaite and bastnaesite crystallized under both magmatic and hydrothermal conditions. Remote sensing and geochemical data enabled us to characterize mineralized zones in A-type granites and indicated that albitization is accompanied by higher concentrations of REEs (544 ppm), Zr (up to 378 ppm), Y (142 ppm), Nb (127 ppm) and Th (26 ppm) than other alteration types, suggesting stabilization of these elements by Na-, F- and Cl-rich fluids during Na-metasomatism. [ABSTRACT FROM AUTHOR]

The Wadi El-Hima Neoproterozoic I- and A-type granites in the Southern Eastern Desert of Egypt are rich in garnets (up to 30 vol%) and are cut by NW–SE strike-slip faults, as confirmed from structure lineament extraction maps. These mineralized granites and garnet mineralization zones can be successfully discriminated using remote sensing techniques. Spectral angle mapper and matched filtering techniques are highly effective for mapping garnet-rich zones and show that the highest garnet concentrations occur along the intrusive contact zone of NW–SE striking faults. El-Hima granites have high SiO2 (73.5–75.1 wt%), Al2O3 (13.4–15.3 wt%) and total alkali (6.7–8.7 wt%) contents, suggesting that they were sourced from peraluminous (A/CNK > 1) parental magmas. Garnet-bearing trondhjemites are metasomatic in origin and formed after I-type tonalite-granodiorites, which originated in a volcanic arc tectonic setting. Garnet-rich syenogranites and alkali-feldspar granites are both post-collisional A-type granites: the syenogranites formed from peraluminous magmas generated by partial melting of lower crustal tonalite and metasedimentary protoliths during lithospheric delamination, and the alkali-feldspar granites crystallized from highly fractionated, felsic and alkali-rich peraluminous magmas in the upper crust. Garnets in El-Hima mineralized granites occur in three forms: (1) subhedral disseminated crystals, (2) vein-type crystals, and (3) aggregated subhedral crystals, reflecting different mechanisms of accumulation. All are dominantly almandine in composition (Alm76Sps10 Prp7Grs6Adr1) and have high average concentrations of heavy rare earth elements (HREE) (ΣHREE = 1636 ppm), Y = (3394 ppm), Zn (325 ppm), Li (39.17 ppm) and Ga (34.94 ppm). Garnet REE patterns show strong negative Eu anomalies with HREE enriched relative to LREE, indicating a magmatic origin. These magmatic garnets are late-stage crystallization products of Al-rich hydrous magmas, and formed at low temperature (680–730 °C) and pressure (2.1–2.93 kbar) conditions in the upper continental crust. Peculiar garnet concentrations in syenogranites near and along contact zones with alkali feldspar granites are related to peraluminous parent hydrous magma compositions. These garnets formed by in situ crystallization from A-type granite melts, alongside accumulation of residual garnets left behind after partial melting of the host garnet-rich granites along the intrusive contact. Magmatic-fluid flow along the NW–SE striking fault of Najd system enhanced garnet accumulation in melts, which formed clots and veins of garnet. [ABSTRACT FROM AUTHOR]

Black sands in the southern Eastern Desert (SED) of Egypt contain substantial reserves of heavy minerals (up to 5 %), and are found mainly in three basins namely: Hodein, Ibib and Diit between Shalateen and Halayeeb cities. The heavy minerals in these black sands include ilmenite-leucoxene (31 %–44 %), magnetite (15–18 %), zircon (11–21 %), garnet and green silicates (11–15 %), rutile (6–12 %) and monazite (2–4 %). Cassiterite, thorite, uranothorite, gold, xenotime and chromian spinel are minor quantities (<1 %). Magnetite (FeO: 75–93.5 wt%) and ilmenite (TiO 2 : 42.7–56.9 wt%), hosting high Mn, V, Zr, Zn, Cr, Nb and Co, were probably derived from gabbroic rocks. The detrital chromian spinel composition (Cr#, 0.51–0.61; Mg#, 0.5–0.63; TiO 2 < 1.0 wt%) and its morphology are similar to those of spinels in fore-arc peridotites from the SED of Egypt, suggesting dominance of fore-arc basins for peridotite emplacement. These basins were formed during arc-arc or arc-oceanic crust collision and encolsed ophiolites, gabbroic rocks and I-type granites as sources of the SED black sands. The studied garnets are mostly almandine in composition with few grossularite and spessartine; they might have been derived from I-type granites and gneisses sources. The rutile and monazite show enriched LREE relative to HREE, and display marked defeciency in Eu, suggesting highly fractionated granitic rocks as a main source. Two distinct types of zircon are recorded: radioactive (Hf: 1578–8770, Y: 319–1335, U: 36–114 and Th: 40–64 ppm) and non radioactive (Hf: 427, Y: 44, U: 2 and Th: 2 ppm); they were probably derived from different granitic sources. Compositions and P-T conditions (T : 655–970 °C, P: 1.18–9.53 kbar) of magmatic amphiboles are similar to those derived from I-type granitoids. Bulk analyses of the economic heavy mineral assemblages show significant concentrations of Fe (393 kg/ton) , Zr (183 kg/ton) and Ti (129 kg/ton) with minor Cr (14 kg/ton), Ba (7 kg/ton), Hf (4.9 kg/ton), Th (up to 3.34 kg/ton) and U (0.29 kg/ton). The elevated contents of Th and U could be related to the occurrence of monazite and zircon with subordinate thorite, uranothorite and xenotime. The total REE contents of these bulk analyses range from 1 to 4 kg/ton, where LREEs form 80–90 % of total REEs. Monazite (ΣREEs: 443604 ppm on average), garnet, zicon (ΣREEs: 421 ppm) and rutile (ΣREEs: 309 ppm) are the main host of REEs in the investigated black sands. Tonnages of raw sands, to a depth of one meter, are estimated per 10 km2 in each basin, giving 18 million tons for Ibib basin and 19 million tons for both Diit and Hodein basins. Economic heavy minerals constitute 6–26 % of the total heavy minerals and around 1.0 % of total raw sands. Calculated reserves of these economic minerals, per 10 km2 of black sands, range from 0.1 million ton in Ibib and Hodein basins to 0.2 million ton in the Diit basin. [Display omitted] • Mapping of source rocks and determine transportation paths of black sands • Mineralogical and chemical data of heavy minerals separated from the southern Eastern Desert black sands • Genesis of heavy minerals and evaluation of black-sand concentrations and distributions • Geodynamic evolution and petrogenesis of source rocks of black sands based on compositions of detrital Cr-spinels [ABSTRACT FROM AUTHOR]

The Korab Kansi and Abu Ghalaga Neoproterozoic mafic-ultramafic intrusions in the South Eastern Desert (SED) of Egypt host economic Fe–Ti–V oxide deposits, ∼41 million tons for Abu Ghalaga ores. The Korab Kansi deposits are composed of titanomagnetite with subordinate ilmenite layers in dunites, gabbros and troctolites. The Abu Ghalaga ores consist of hemo-ilmenite and ilmenite with subordinate magnetite and titanomagnetite lenses in norites, gabbros and anorthosites. The difference in calculated oxygen fugacity (f O2 : ∼ ΔFMQ–1.24 to −3.28 for Korab Kansi ores and +0.21 to −0.3 for Abu Ghalaga ores) during subsolidus re-equilibration is consistent with different dominant iron and titanium oxides, magnetite and hematite, respectively. Ilmenite in both deposits is enriched in Nb, Ta, Zr, Hf and V, but is poor in Cr and Ni relative to coexisting magnetite, which belongs to magmatic Fe–Ti–V deposits. The Korab Kansi and Abu Ghalaga ore deposits are rich in Ti, Fe, V, Nb, Ta and Hf with subordinate S, Cu, Ga and Zn at high f O2. The Abu Ghalaga gabbroic intrusion crystallized from ferrobasaltic magmas of tholeiitic affinity at lower temperature (∼1082 °C) and pressure (5.1 kbar) than the Korab Kansi intrusion (∼1180 °C, 8.3 kbar). The Korab Kansi ore deposits mainly formed by fractional crystallization of olivine followed by in situ crystallization of Fe–Ti oxides from ferropicritic/ferrobasaltic parent melts at the floor of the magma chamber. The Abu Ghalaga ores formed as a result of more advanced fractional crystallization of ferrobasaltic parent melts. The Abu Ghalaga Fe–Ti oxides in massive ores at the base of the intrusion grew in situ, whereas most ore lenses in the middle to the top of the intrusion precipitated from immiscible oxide melts that separated from the parental magma in association with floatation of plagioclase and sulfide crystals at a late magmatic stage. Both Fe–Ti ore deposits formed from similar mantle-derived magmas but Korab Kansi ores formed as early fractionates, whereas Abu Ghalaga ores formed late. The Korab Kansi ilmenite is rich in vanadium (up to 3.8 wt% V 2 O 5) relative to that of other magmatic deposits. Its parental melt may have formed from locally Fe–Ti–V enriched part of the Neoproterozoic mantle due to interaction with upwelling asthenosphere or a mantle plume. Controlling factors for formation of economic SED Fe–Ti–V deposits were the V-rich ferropicritic/ferrobasaltic compositions of the parental magmas, and addition of H 2 O to cause high magma ƒ O2. [Display omitted] • Microtexture, mineralogy and chemistry of Fe–Ti–V ore deposits in mafic-ultramafic intrusions. • Evidence for fractional crystallization of V-rich melts and formation of Fe–Ti oxide deposits. • Role of in situ crystallization and immiscible separation for genesis of Fe–Ti–V ore deposits. • Controlling factors for economic Fe–Ti–V deposits in Egypt, and explaining high V in deposits. [ABSTRACT FROM AUTHOR]

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

[Display omitted] • Gabbro alteration zones delineated by Landsat 8 OLI/TIRS, Sentinel 2-B and ASTER1T. • Whole-rock and in-situ trace elements characterized magma of sulfide-bearing gabbros. • Analyzed Au (g/t) by fire assay method, where its high content at intrusive contact. • Genesis and distribution of sulfides and gold in gabbros and their alteration zones. The whole–rock chemistry, mineral chemistry, and remote sensing data of the Atud–Um Khasila Neoproterozoic mafic intrusions in the Eastern Desert of Egypt show two different mafic plutons: (1) the metagabbro–diorite complex; and (2) the G. Atud gabbros. Both of these contain two types of Cu–Ni–Fe–sulfide mineralizations. Multispectral remotely sensed images of Landsat 8 OLI/TIRS, Sentinel 2–B, and ASTER1T were used to give an overview of hydrothermal alteration signatures and distinguish different lithological units. The G. Atud gabbros are intruded into the metagabbro–diorite complex and consist mainly of olivine gabbros, while the metagabbro–diorite complex comprises metagabbros, diorites, and quartz diorites. They were formed under high fO 2 (ΔFMQ= +1.43 to + 0.33) with a higher crystallization temperature (∼ 900–1100 °C) and pressure (∼ 6.0 kbar on average) at 18 km depth relative to associated metagabbros. Like magmatic sulfides in mafic intrusions, the G. Atud gabbros contain disseminated grains of pyrrhotite, pentlandite, chalcopyrite, and pyrite, up to 5 vol%. On the other hand, sulfide deposits (up to 30 vol%) such as pyrite, As–bearing pyrite, arsenopyrite, and gold with minor sphalerite and galena at the Atud gold mine, are related to the metagabbro–diorite intrusion. They are found as disseminations, patches, microveinlets, and bands. The sulfide deposits and economic gold are spatially concentrated in smoky quartz veins (up to 25 g/t) and metasomatic alteration zones, i.e., silicification and hematization of metagabbros (0.32 g/t), phyllic, argillic, and propylitic alteration, and carbonate–silicified zones, along gabbroic intrusive contacts, which all follow the Najd NW–SE shear zone. They are possibly of hydrothermal origin (epigenetic). They are also precipitated by mineralized fluids (rich in Si, K, Fe, Pb, Ag, Au, As, S, Ni, Zn, Cu, CO 2 , and H 2 O) that have been derived from a mixed magmatic–metamorphic source. The high Au contents with As–bearing pyrite and arsenopyrite in both Fe–rich and smoky quartz veins are related to the interaction between Fe from metagabbro–diorites and the Au(HS)-2 compound as well as the crystallization of pyrite, which reduced the sulfur contents in the mineralized fluids and hence led to gold precipitation. The late intrusion of G. Atud gabbros into metagabbro–diorite rocks enhanced the circulation of sulfide-gold-bearing hydrothermal fluids towards the contacts of the latter ones. These fluids along the shear zones cause metasomatic alteration in addition to leaching and the collection of sulfides and gold in the metagabbros. The protoliths of metagabbro–diorite rocks have a calc–alkaline nature and were formed in a volcanic arc setting, while the G. Atud gabbros were crystallized from Mg-rich tholeiitic melts in the extensional rift (e.g., rifted arc) setting as a result of asthenospheric upwelling due to the slab detachment and/or lithospheric delamination. The Atud gold–sulfide mineralization was related to the thermal uplifting–extensional tectonism. The enrichment of the G. Atud gabbros in LILE, alongside LREE over HFSE, reflects their derivation from a metasomatized mantle source during a rifted arc following the subduction processes. [ABSTRACT FROM AUTHOR]

The Gabal Al-Ijlah Al-Hamra granites in the Central Eastern Desert of Egypt are rich in rare metal-bearing minerals. The enhanced Senetinal-2-Planet fused image with 3 m spatial resolution using Gram–Schmidt fused technique was successfully used in detailed discrimination of the rock units in the study area. Various enhanced remote sensing data of Sentinel-2, Landsat-9, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), and fused ASTER-Sentinel-2 datasets were used in the mapping process and verified by field investigation and petrographic analysis. The hydrothermal mineralized alteration zones related to rare metal-bearing granites were identified using ASTER and Sentinel-2 fused images. According to petrographic and ASTER mineral indices, various types of alteration zones, including sericitization, chloritization, carbonatization, kaolinitization and silicification were detected. The surface structural features were well detected using Soble directional filtering of Sentinel-1 enhanced image. The major structural directions that have been detected in Al-Ijlah Al-Hamra granitic pluton are NW-SE and NE-SW. These major trends were used to detect potential pathways for migration and concentration of rare-metals. The hyperspectral TerraSpec Halo mineral identifier (ASD) as well as petrographical investigation successfully identified the rock-forming minerals (i.e. quartz, K-feldspar, plagioclase, biotites, muscovite, chlorite, kaolinite, sericite) of syenogranites and alkali feldspar granites in the Gabal Al-Ijlah Al-Hamra area. Rare metal-bearing minerals including zircon, rutile, allanite, parisite and xenotime were identified using Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-Ray Spectroscopy (EDS). The results of remote sensing data, field observations and petrographic investigation are successfully used in exploration for rare metal-bearing minerals in the Central Eastern Desert of Egypt and similar areas worldwide. [Display omitted] • Integrated remote sensing data, field observation and petrography for discrimination different rock units. • The ASD TerraSpec Halo Mineral for identifying the spectral signature characteristics of rare metal-bearing granites. • Alteration zones detection by ASTER and Sentinel-2 fused image. • Rare metal-bearing minerals detection by SEM coupled with EDS analyses. [ABSTRACT FROM AUTHOR]