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Rare metal-bearing pegmatites from the southeastern Desert of Egypt:Geology,geochemical characteristics,and petrogenesis

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Chinese Journal Of Geochemistry 2007年第1期26卷 8-22页

作者： gehad.m.s.leh Nuclear materials Authority P.O.Box:530 El-MaadiCairoEgypt

The pegmatite province of the southeastern Desert (sED) is part of a pegmatite district that extends from Egypt (extends to 1200 km2). Rare metal pegmatites are divided into (1) unzoned, sn-mineralized; (2) zoned Li, Nb, Ta and Be-bearing; and (3) pegmatites and pegmatites containing colored, gem-quality tourmaline. The Rb/sr data reflect a crustal origin for the rare metal pegmatites and indicate that the original sED magma was generated during the peak of regional metamorphism and predates the intrusion of post-tectonic leucogranites. These bodies developed an early border zone consisting of coarse to very coarse muscovite+quartz+alkali feldspar, followed by an intermediate zone of dominant quartz+feldspar+muscovite rock. Garnet, tourmaline, beryl, galena, pyrite, amblygonite, apatite and monazite are rare accessories in both zones. Cassiterite tends to concentrate in replacement zones and along fractures in albite+quartz+muscovite-rich portions. The highest concentrations of cassiterite occur in irregular greisenized zones which consist dominantly of micaceous aggregates of green Li-rich muscovite, quartz, albite and coarse-grained cassiterite. The different metasomatic post-solidification alterations include sodic and potassic metasomatism, greisenization and tourmalinization. Geochemically, the pegmatite-generating granites have a metaluminous composition, showing a differentiation trend from coarse-grained, unfractionated plagioclase-rich granite towards highly fractionated fine- to medium-grained, local albite-rich rock. Economically important ore minerals introduced by volatile-rich, rare metal-bearing fluids, either primarily or during the breakdown of the primary mineral assemblages, are niobium-tantalum oxides, sn-oxides (cassiterite), Li-silicates (petalite, spodumene, euctyptite, and pollucite), Li-phosphates (amblygonite, montebrasite and lithopilite) and minor REE-minerals (Hf-zircon, monazite, xenotime, thorian, loparite and yttrio-fluorite). The pol

关键词：埃及东南部沙漠稀有金属伟晶岩地质地球化学特征岩石成因

Geology and rare-earth element geochemistry of highly evolved, molybdenite-bearing granitic plutons, southeastern Desert, Egypt

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Chinese Journal Of Geochemistry 2007年第4期26卷 333-344页

作者： gehad m. saleh Nuclear materials Authority P.O.Box: 530 El Maadi Egypt

The field relations, mineralogy, and major and trace elements (including REE analyses of whole-rock samples and minerals) of granites and their associated molybdenite + uranium mineralized aplites in southeastern Desert, Egypt, have been studied. The granites are leucocratic and mostly peraluminous in nature with muscovite increasing at the expense of biotite. The chemical and mineralogical characteristics of the granitic rocks indicate that their melts originated from the LILE-enriched mantle wedge by partial melting and are contaminated by crustal melts, followed by thermogravitational processes. Leucogranites with higher Na2O/K2O ratios from Um Dargag and Um maiat crystallized under H2O-saturated equilibrium conditions in which the exsolved vapor continuously migrated away. The REE patterns of the granites studied are characterized by LREE enrichments and negative Eu anomalies. In comparison, the potassic aplites and the more sodic leucogranites are depleted in LREE, enriched in HREE and show more remarkable negative Eu anomalies. Allanite and monazite are the most important REE carriers in the granites. These minerals are strongly enriched in LREE, whereas fluorite and xenotime, which are more abundant in the aplites, are enriched in HREE. The average Lu/Ce ratio represents the fractionation trend with respect to HREE. It is 0.71 for radioactive fluorite, and it increases to 1.22 for non-radioactive fluorite. The high REE contents of molybdenite represent re-deposition of the mobilized mo and REE. Due to the strong control of accessory minerals, the REEs are of limited use in petrogenetic modelling of highly evolved granitic systems.

关键词：辉钼矿稀土资源褐帘石独居石西南地区沙漠地带埃及

URANIUm mINERALIZATION IN THE mUsCOVITE-RICH GRANITEs OF THE sHALATIN REGION, sOUTHEAsTERN DEsERT, EGYPT

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Chinese Journal Of Geochemistry 2006年第1期25卷 1-15页

作者： gehad m. sAleh NUCLEAR mATERIALs AUTHORITY P.O.BOX: 530 EL MAADI CAIRO EGYPT

The younger granitoids of the shalatin district in the southeastern Desert of Egypt, are of biotite and two-mica granite compositions. The geochemistry of rare-earth elements (REE), yttrium, thorium and uranium forms the basis for many important methods to reconstruct igneous petrogenesis. since the recognition that REE, Y, Th, U-rich accessories may play an important role in controlling the geochemistry of crustal melts, a considerable amount of work has been done in an attempt to understand their effects. However, this effort has been almost exclusively focused on three minerals: zircon, monazite and apatite. Nevertheless, the variety of REE-Th-U-rich accessories in granite rocks are neither limited to these three minerals nor are they always the main REE, Y, Th carriers. The geochemistry of REE, Y, Th and U reflects the behavior of accessories and some key major minerals such as garnet and feldspars, and may therefore give valuable information about the conditions of partial melting, melt segregation and crystallization of granite magmas in different crustal regimes. The geochemistry of U and Th during magmatic differentiation has been studied in many granites from different areas and it has been known that the U and Th contents of granitic rocks generally increase during differentiation, although in some cases they decrease. The Th/U ratio can either increase or decrease, depending on redox conditions, the volatile content or alteration by endogene or supergene solutions. The accessory assemblage of muscovite-rich granites and high-grade rocks is composed of monazite, xenotime, apatite, Th-orthosilicate, secondary U-mineralization and betafite-pyrochlore. REE, Y, Th and U are not suitable for geochemical modeling of granitoids by means of equilibrium-based trace element fractionation equations, but are still useful petrogenetic tools.

关键词：铀矿化作用稀土元素花岗岩沙漠埃及

Geologic relationships and mineralization of peralkaline/alkaline granite-syenite of the Zargat Na’am ring complex, southeastern Desert, Egypt

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Chinese Journal Of Geochemistry 2006年第2期25卷 97-111页

作者： gehad m. saleh Nuclear materials Authority P.O. Box: 530 EL Maadi Cairo Egypt

The Zargat Na’am ring complex crops out 90 km NW of shalatin City in the southeastern Desert of Egypt. The ring complex forms a prominent ridge standing high above the surrounding mafic-ultramafic hills. It is cut by two sets of joints and faults which strike predominantly NNW-ssE and E-W, and is injected by dikes, porphyritic alkaline syenites, and felsite porphyries. It consists of alkali syenites, alkali quartz syenites, and peralkaline arfvedsonite-bearing granitic and pegmatitic dikes and sills. The complex is characterized locally by extreme enrichments in REEs, wolframite and rare, high field strength metals (HFsm), such as Zr and Nb. The highest concentrations ({1.5} wt% Zr, {0.25} wt% Nb, {0.6} wt% ∑REEs) occur in aegirine-albite aplites that formed around arfvedsonite pegmatites. Quartz-hosted melt inclusions in arfvedsonite granite and pegmatite provide unequivocal evidence that the peralkaline compositions and rare metal enrichments are primary magmatic features. Glass inclusions in quartz crystals also have high concentrations of incompatible trace elements including Nb (750×10+{-6}), Zr (2500×10+{-6}) and REEs (1450×10+{-6}). The REEs, Nb and Zr compositions of the aegirine-albite aplites plot along the same linear enrichment trends as the melt inclusions, and Y/Ho ratios mostly display unfractionated, near-chondritic values. The chemical and textural features of the aegirine-albite aplites are apparently resultant from rapid crystallization after volatile loss from a residual peralkaline granitic melt similar in composition to the melt inclusions.

关键词：花岗岩埃及矿化作用地质条件

The chromite deposits associated with ophiolite complexes, southeastern Desert, Egypt: Petrological and geochemical characteristics and mineralization

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Chinese Journal Of Geochemistry 2006年第4期25卷 307-317页

作者： gehad m. saleh Nuclear materials Authority P.O.Box: 530 El Maadi Cairo Egypt

The podiform chromitites occur in a well-preserved mantle sequence consisting of lherzolite-harzburgite with abundant lenses of olivine dunite. The podiform chromitite deposits are common as small and irregularly shaped masses in the southeastern Desert (sED) of Egypt. The podiform chromitites exhibit a wide range of compositions from high Cr to high Al varieties. The Cr of chrome spinel ranges from 0.67 to 0.88 in olivine-dunite, quite similar to that of the high-Cr chromitite, whereas it is around 0.62 in lherzolite-harzburgite. Primary hydrous mineral inclusions, amphibole and phlogopite, in chrome spinel have been reported for the first time from the Pan-African Proterozoic podiform chromitites. On the other hand, petrographic and geochemical evidence suggests that podiform chromitites in the sED of Egypt were formed as a result of crystallization of mafic melts, probably of boninitic composition, the boninitic parental magmas were probably produced by a second stage of melting above a subduction zone. Three types of chromite ores can be distinguished within the sED of Egypt: (a) sulphide-poor podiform ores; (b) brecciated ores; and (c) sulphide-rich ores. Two textural types of inclusions in chromite are distinguished: (1) primary silicate inclusions generally have high mg-number (>96), Cr and Ni, and are dominated by pargasitic amphibole, forsterite, diopside, enstatite and Na-phlogopite. A diversity of primary and secondary platinum group minerals (PGm) is described from the chromitites, including alloys, sulphides, sulpharsenides and arsenides of Ru, Os, Ir, Rh, Ni, Cu, Fe and Co; (2) in addition to primary PGm and hydrous silicates, the fluids are of low to moderate salinity, sodium-dominated aqueous solutions with complex gas contents. Variable amounts of water, hydrogen, hydrocarbons, carbon dioxides and nitrogen have been determined in inclusion-rich samples. The chondrite-normalized PGE patterns of lherzolite-harzburgite and olivine-dunite have negative

关键词：铬铁矿沉淀蛇绿岩复合物东南沙漠埃及岩石学

Impact of Zika virus non-structural protein mutations on hippocampal damage

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Neural Regeneration Research 2025年第8期20卷 2307-2308页

作者： Larissa m.G.Cassiano Roney s.Coimbra Neurogenômica/Imunopatologia Instituto RenéRachouFiocruzBelo HorizonteBrazil Departamento de Bioquímica e Imunologia Instituto de Ciências BiológicasUniversidade Federal de Minas GeraisBelo HorizonteBrazil

The Zika virus(ZIKV),a member of the Flaviviridae family,attracted worldwide attention for its connection to severe neurological effects,notably microcephaly in newborns,first reported during the 2015 epidemic in ***,its impact goes beyond fetal and neonatal abnormalities,also affecting the central nervous system(CNs)in both children and adults,leading to enduring cognitive and behavioral impairments.

关键词： damage fetal neonatal

spectrophotometric Determination of Albendazole Drug in Tablets： spectroscopic Characterization of the Chargetransfer solid Complexes

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Chinese Journal of Chemistry 2011年第2期29卷 324-332页

作者： Refat moamen s mohamed gehad G. Fathi Ahmed Department of Chemistry Faculty of Science Port Said University Port Said Egypt Department of Chemistry Faculty of Science Taif University 888 Taif Kingdom Saudi Arabia Chemistry Department Faculty of Science Cairo University Egypt

simple, rapid and reliable method for the determination of albendazole （ABZ） was described. This includes the utility of some π-acceptors such as 2,3-dichloro-5,6-dicyano-p-benzoquinone （DDQ） and 3,6-dichloro-2,5-dihydroxy-p-benzoquinone （p-CLA） for estimation of ABZ drug （act as donor）. The experimental conditions were optimized and the system obeys Beer＇s law for 7.50-80 and 10.00-85.00 ug·mL-1 of ABZ using DDQ and p-CLA, respectively. The molar absorptivity and sandell sensitivity were calculated to be 1.83× 10^3 and 1.12× 10^3 L·mol ·cm -1 and 2.60 and 3.40 ng·cm -2 using DDQ and p-CLA, respectively. The limits of detection and quantification were calculated to be （7.42 and 6.73） and （9.94 and 4.13） ug·mL-1 using DDQ and p-CLA, respectively. The proposed methods were successfully applied to the determination of ABZ in commercially available dosage forms. The reliability of the assays was established by parallel determination by the official method and recovery studies. The chemical structures of the solid charge-transfer （CT） complexes formed via reaction between ABZ under study and π-acceptors, have been elucidated using elemental analyses （C, H and N）, IR, 1H NmR and mass spectra.

关键词： albendazole DDQ p-CLA spectrophotometry charge-transfer complexes

Petrogenesis,Geodynamics and Radioactivity of the Granitic Rocks of the Nugrus Weakness Zone,south Eastern Desert,Egypt

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Acta Geologica sinica(English Edition) 2021年第4期95卷 1183-1198页

作者： soliman ABU ELATTA Abdallah mahmoud gehad m.R.mANsOUR Nuclear materials Authority CairoEgypt.P.O.Box 530 El Maadi

The studied granitic bodies belong to the south Eastern Desert of *** extend in a NNW–ssE trend along the same strike of the Nugrus weakness zone by which they are structurally *** rocks are composed of biotite and biotite-muscovite monzogranites to ***,a higher abundance of Ba and Rb in biotite granites with a relatively low abundance in biotite-muscovite granites as well as the diversity of Th,U,Nb,Ta,Zr,and REE reflects their origin from different sources and geodynamic *** biotite granites are predominantly metaluminous to low peraluminous whereas the biotite-muscovite granites have a peraluminous *** enrichment at the expense of calcium in these rocks reflects a derivation from crustal sources by partial melting in the presence of a volatile *** investigation showed high abundances of U(up to 38 ppm)and Th(up to 26 ppm)in biotite-muscovite granites relative to biotite granites(up to 5 ppm U and 18 ppm Th).Radioactive anomalies furthermore have been recorded in parts of biotite-muscovite granites that were affected by the faults(up to 116 ppm eU and 97 ppm eTh).Consequently,biotite-muscovite granites form a potentially fertile source for uranium mineralization.

关键词： partial melting biotite-muscovite granites peraluminous geodynamic radioactivity Nugrus

Geochemistry and spectrometric prospection of younger granites and granitic pegmatites bearing uranium mineralization at *** El Rakeb area, Central Eastern Desert, Egypt

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Acta Geochimica 2021年第4期40卷 575-601页

作者： gehad.m.s.leh Bahaa m.Emad Ibrahim B.Abdel Kader Nuclear materials Authority El MaadiP.O.Box 530CairoEgypt

The present study deals with the detailed field geology,mineralogy,geochemistry,and spectrometric prospection of rare metals and radioactive minerals associated with granitic pegmatites in the Gabal Um LassafAbu Dob-Um Atelia-Kadabora-Kab El Rakeb area(LDAKK),which are situated in the central Eastern Desert of *** study area is composed of granodiorites and *** latter is dissected by granitic pegmatites with a discriminatory distribution of economically important mineralization(rare-metals and U-Th minerals).The granitic pegmatites display a zoning structure composed of feldspar-rich zones enveloping pockets of mica(mostly muscovite) and all zoning internal quartz ***,the monzogranite and granitic pegmatites are composed of potash-feldspar,albite,and quartz with a small amount of biotite and *** mineralogical investigation of the highly radioactive zones in the granitic pegmatite shows enrichment in kasolite,uranothorite,thorite,xenotime,columbite,zircon,bismuth,and ***,the granitic pegmatites are enriched with high field strength elements(HFsE;Zr,Nb,Th,and U) and ion lithophilic elements(LILE;Rb,and Pb) and depleted in Ba,sr,and *** are strongly peralkaline to metalumainous except for two samples,which are *** are formed by partial melting of metagreywackes at *** studied granitic pegmatites could belong to the NYF family(Niobium-Yttrium-Fluorine family) according to the geochemistry of the trace *** studied granitic pegmatites show deep negative Eu anomaly and display a strong m-type tetrad effect of rare earth *** field spectroscopy measurements showed the localization of the radiometric anomalous associated with the granitic pegmatites,which are intruded in the granitic host *** eU and eTh contents reached up to 316 and 1367 ppm,*** and thorium occurrences in the investigated granitic pegmatites are related to magmatic(syngenetic)ori

关键词： Geochemistry Gabal Um Lassaf-Abu Dob-Um Atelia-Kadabora-Kab El Rakeb area(LDAKK) Uranium REE Egypt