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Ore Controls and Metallogenesis of Au-ag Deposits at Atalla Mine,Central Eastern Desert of Egypt

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Acta Geologica Sinica(English Edition) 2020年第5期94卷 1451-1470页

作者： mohamed ABD EL MONSEF Geology Department Faculty of ScienceTanta UniversityTanta 31527Egypt Institute of Geological Sciences Faculty of ScienceMasaryk UniversityBrnoCzech Republic

Gold-silver deposits in the Atalla area occur as hydrothermal quartz veins in NE–SW pre-existing fractures within the Atalla granitic *** orientation of such quartz veins has been attributed to extensional behavior related to the Atalla Shear Zone(ASZ).The Atalla area is covered by a variety of lithologies that are(from oldest to youngest):metasedimentary rocks,metavolcanic rocks,ophiolite assemblage(serpentinites/talc-carbonates),Atalla granite and Dokhan volcanic ***,Atalla granite ranges in composition from granodiorite to *** geochemistry constrains the calc-alkaine affinity of the Atalla granite that was intruded within an orogenic(syncollision)tectonic *** ore minerals are represented by gold/silver(electrum),pyrite(Py1&Py2),arsenopyrite,pyrrhotite,sphalerite,chalcopyrite,galena,covellite and *** temperature of ore formation ranges from 240 to 285℃and the estimated fluid pressure is in the range of 20–100 *** on the geological setting,ore textures and fluid characteristics;the Atalla Au-ag deposits are considered to be orogenic in nature,formed from a continental collision(~653-590 Ma),synchronous with the emplacement of calc-alkaline magmatism during the evolutionary history of the Arabian Nubian Shield(ANS).The initial ore-forming fluid was primarily derived from a metamorphic source related to ophiolitic-serpentinite rocks under deep regional conditions of greenschist-amphibolite facies,where the Atalla granitic eruption provided the required temperature conditions for the metamorphic process to take *** such conditions,the transportation of ore metals as bisulfide complexes is *** deposition of ore minerals was triggered by fluidwallrock interaction through fracture pathways in conjunction with a temperature-pressure drop that is likely to have been related to uplift into the crustal levels.

关键词： Gold-silver arsenopyrite geothermometry fluid inclusions orogenic deposits Atalla Shear Zone(ASZ)

Geochemical Stream Sediment Survey in the Wadi Umm Rilan Area,South Eastern Desert,Egypt:A New Occurrence for Gold Mineralization

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Acta Geologica Sinica(English Edition) 2017年第3期91卷 1041-1062页

作者： mohamed Abdallah Gad DARWISH Geology Department Faculty of ScienceAswan University

The present paper investigates the stream sediment geochemistry, behavior of gold and associated elements, delineates Au-anomalous sites and defines related sources in the Wadi Umm Rilan area. Fifty three major and trace elements were analyzed using ICP-MS and treated applying various statistical and mapping techniques. The results showed a significant difference of mean and median Au and most chemical elements in the three portions of the area, and higher values were recorded in the western portion. Furthermore, Au-anomalous sites appeared in upper and lower parts of the Wadi Umm Rilan, along the tributaries of metavolcanic unit and near granitoid contacts. This indicates the main source of Au mineralization is related to emplacement of granitoid plutons and accompanying hydrothermal solutions. There are significant indications for the presence of more than one mineralization event forming a probable single major episode of mineralization in the area, involving Au, Pb and U mineralizations. Geology, geomorphologic aspects and weathering processes could control stream sediment geochemistry, anomalies of Au and associated elements, elemental association and their dispersion patterns. Therefore, the area is fruitful and regarded as a promising target for Au exploration, using ag, As, Sb, Cd, Cs, and TI as pathfinder elements.

关键词： geochemical survey stream sediments Au mineralization Wadi Umm Rilan area southEastern Desert Egypt

Geochemical and Environmental Evaluation of Um Shashoba Gold Mine Area,Southeastern Desert,Egypt

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Acta Geologica Sinica(English Edition) 2011年第4期85卷 881-898页

作者： mohamed Abdallah Gad DARWISH Geology Department Aswan Faculty of ScienceSouth Valley UniversityPost No.81528 AswanEgypt

A suite of elements（ag,Au,Ba,Bi,Cd,Co,Cr,Cu,Ga,Hf,Hg,Mn,Mo,Ni,Pb,Rb,Sb,Se, Sr,Te and Zn）,total organic carbon（TOC）and pH were analyzed in stream sediment and tailing samples from Um Shashoba area,in order to evaluate Au placer and the sediments being impacted by old mining *** results were examined using statistical,graphical and mapping *** spite of the results revealing that Au and most of the elements in sediments were in general significantly lower than those in tailing,Au was concentrated in the NE and SW parts forming Au *** is remarkably a close association of Au with Hg and Sb;both are useful as pathfinder elements for Au *** of pH could not control a fate of analyzed elements,whereas TOC and Mn oxides and hydroxides could uptake some elements Au,Ba,Co,Cr,Hg,Ni,and *** results also indicated that the sediments were contaminated by anthropogenic factors causing moderate,strong to very strong pollution with respect to Bi,Se and Te,***,geogenic factors could also contribute elemental enrichment to the drainage system and cause significant toxicity level.

关键词： geochemical exploration environmental evaluation Um Shashoba gold mine Egypt

Microchemical Characterization of Natural Gold and Copper Alloys from the Ancient Um Shashoba Gold Mine, South Egypt

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Acta Geologica Sinica(English Edition) 2014年第1期88卷 196-212页

作者： mohamed Abdallah Gad DARWISH Geology Department Faculty of Science Aswan University

The SEM-EDX technique was applied to investigate Au, and Cu＋Sn alloyed grains in the mineralization of the Um Shashoba mine for achieving further understanding of occurrences, internal structures and microchemistry of Au and Cu alloys and associated minerals, and mineralization type. This study is aiming at the genetic history of ore-bearing fluid events, geochemical evaluation and exploration significance. The results showed that the mineralization could be considered as a single major episode generated by metamorphic mesothermal solution rich in sulfides and unsaturated respect to Au. It was differentiated into many stages; started with formation of auriferous pyrite that was pseudomorphed by secondary hematite, limonite and goethite. Three phases of Au alloy were precipitated, and Cu＋Sn and ag-rich alloys were produced respectively and followed by deposition of two generations of barren pyrite. Calcite and ankerite were crystalized, surrounded and partially replaced some of early formed minerals. Finally, barren muscovite recrystallized around and inside both later formed carbonate minerals that were free of any sign of Au in their structures. The processes of deformation, recrystallization, annealing, dissolution, remobilization and re-precipitation played the most important roles in the genetic history of the mineralization.

关键词： SEM–EDX analyses Au and Cu alloy grains Um Shashoba gold mine Egypt

Geochemistry of the High Dam Lake sediments,south Egypt:implications for environmental significance

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International Journal of Sediment Research 2013年第4期28卷 544-559页

作者： mohamed Abdallah Gad DARWISH Geology department Faculty of ScienceAswan University

The goal of the present work is to perform a geochemical assessment of High Dam Lake bottom sediments for determining the fate,dispersion and levels of trace elements causing environmental pollution,and provided an access to their probable *** sediment samples were analyzed using ICP-MS for 20 elements;ag,Ba,Cr,Cu,Ga,Hf,Mn,Pb,Rb,Sc,Sc,Sn,Sr,Ta Th Ti,T1,U,V and Zr,and their obtained data were treated using statistical,graphical and mapping *** results showed the data set of all analyzed elements affected by outliers and extreme values that caused deviation away from *** Wallis test revealed that median of some trace clement levels in Lake sediments,was not significantly different and other elements rejected the Null *** analyzed elements had high values of median and mean in sediments of Lake Nubia rather than Lake Nasser and their normalization gave the same results of calculated environment ***,Lake Nubia sediments possessed high combined EF levels of Th,Sc,Sn,ag,Zr,Hf,Ta,Sr,U,Ti,V,Cr,and Mn,causing significant contamination,which was great potentially related to industrial,agricultural,urbanization and mining ***,combined EF of Se,Cu,Ga,Pb,Ba,Rb,and Tl,which are highly elevated in southern Lake Nasser sediments owing to their source are great possibly derived from Lake Nubia and geogenic *** decreasing distance towards the High Dam body,the contaminant elements were diminished due to reduction in the environmental factors and Sudanese pollution sources leading to the northern Lake Nasser considered to be less ***,the present study is an environmental alert for contaminated sediments that carried contaminants and considered the secondary source of pollution impact on ecosystem,and subsequently,their environmental risk on Human health.

关键词： Geochemistry High Dam Lake sediments Environmental significance South Egypt

Geology and Mineral Chemistry of Uranium-and Thorium-bearing Minerals in Rare-Metal(NYF)Pegmatites of Um Solimate,South Eastern Desert,Egypt

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Acta Geologica Sinica(English Edition) 2021年第5期95卷 1568-1582页

作者： mohamed A.ALI Ahmed E.ABDEL GAWAD mohamed M.GHONEIM Nuclear Materials Authority 530 El-MaadiCairoEgypt

The garnet muscovite granitic pegmatite of Um Solimate,in southern Egypt,represents a promising asset for strategic and economic metals,especially Bi-Ni-ag-Nb-Ta as well as U and *** ore bodies occur as large masses,pockets and/or veins of very coarse-grained pegmatites,which consist mainly of K-feldspar,quartz and albite with subordinate muscovite,garnet,and *** data revealed that e U-and e Th-contents of the pegmatites reach up to 39 ppm and 82 ppm,*** studied pegmatites are enriched in primary U and Th minerals(uraninite,coffinite,thorianite and uranothorite)as well as Hf-rich zircon and monazite,which give rise to anomalous radioactive ***-tantalium-bearing minerals(***,microlite and uranopyrochlore),xenotime,barite,galena,fluorite,and apatite are ubiquitous,and,consequently,the studied pegmatites belong tothe Niobium-Yttrium-Fluorine-type(NYF)*** noble metal mineralization includes argentite(ag_(2)S),native Ni and Bi as well as bismite and *** addition,beryl and tourmaline are observed in pegmatites near the contact with metasediments and ultramafic *** observed compositional variations of Ta/(Ta+Nb)and Mn/(Mn+Fe)ratios in columbite(0.08-0.45 and 0.11-0.57,respectively)and Hf contents in zircon(3.54-6.46 wt%)may reflectan extreme degree of magmatic fractionation leading to formation of the pegmatite orebody.

关键词： radioactivity rare-metal mineralization pegmatites U/Th-bearing minerals Um Solimate Egypt

Childhood anemia in Rural Haiti:the potential role of community health workers

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Global Health Research and Policy 2017年第1期2卷 349-356页

作者： Marie N.Séraphin Chen Xinguang mohamed ag Ayoya Ismael Ngnie-Teta Ellen Boldon Aissa Mamadoultaibou Jean Ernst Saint-Fleur Inobert Pierre Department of Medicine Division of Infectious Diseases and Global MedicineUniversity of Florida2055 Mowry RoadSuite 250PO Box 103600GainesvilleFL 32610-3600USA Department of Epidemiology College of Public Health and Health Professions and the College of MedicineUniversity of FloridaGainesvilleFLUSA UNICEF Country Office 125 Rue FaubertPetionvillePort-au-PrinceHaiti St.Boniface Haïti Foundation 12 Rue E.GuelloFond des BlancsHaiti

Background:Childhood iron deficiency anemia(IDA)is an important contributor to under-five mortality in the developing *** is evidence that Community Health Worker(CHW)delivered programs to increase maternal knowledge of child health practices may decrease childhood *** study reports findings on the association between a long standing CHW intervention and childhood anemia status in rural ***:Using structural equations and mediation analyses on data from a household-based survey of 621 mother/child dyads,we tested the hypothesis that CHW would have a direct positive effect on maternal knowledge and an indirect effect on childhood anemia in rural ***:CHW contact was significantly associated with maternal knowledge of key child health practices(β=0.193,SE=0.058,p=0.001).However,knowledge was not associated with childhood anemia(β=-0.008,SE=0.009,p=0.382).Maternal knowledge categories significantly affected by CHW contact included diarrheal prevention knowledge(β=0.111,SE=0.045,p=0.013)and signs of malnutrition(β=0.217,SE=0.071,p=0.002).There was no significant association with knowledge of vitamin A and iron rich foods(β=0.057,SE=0.032,p=0.074),which is the intervention most likely to impact childhood *** all path models tested,we identified the control variables low household socio-economic status,mothers’anemia status,and child’s age less than 24 months as significant predictors of childhood ***:CHWs delivered interventions are associated with improved maternal knowledge of child health practices in rural Haiti;however,this knowledge is not associated with improved childhood *** with CHW-delivered programs,interventions household poverty are implied to impact childhood health outcomes in resource poor settings.

关键词： anemia mother prevention

Phase-junction ag/TiO_(2)nanocomposite as photocathode for H_(2)generation

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Journal of Materials Science & Technology 2021年第24期83卷 179-187页

作者： Hemdan S.H.mohamed mohamed Rabia Xian-Gang Zhou Xu-Sen Qin Gomaa Khabiri mohamed Shaban Hussein A.Younus S.Taha Zhi-Yi Hu Jing Liu Yu Li Bao-Lian Su State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan430070China Physics Department Faculty of ScienceFayoum UniversityFayoum63514Egypt Nanophotonics and Applications Lab Physics DepartmentFaculty of ScienceBeni-Suef UniversityBeni-Suef62514Egypt Chemistry Department Faculty of ScienceFayoum UniversityFayoum63514Egypt Nanostructure Research Centre(NRC) Wuhan University of TechnologyWuhan430070China Laboratory of Inorganic Materials Chemistry(CMI) University of Namur61 rue de Bruxelles5000NamurBelgium

Developing anatase/rutile phase-junction in Ti O_(2)to construct Z-scheme system is quite effective to improve its photoelectrochemical *** this work,the anatase/rutile phase-junction ag/Ti O_(2)nanocomposites are developed as photocathodes for hydrogen *** optimized ag/Ti O_(2)nanocomposite achieves a high current density of 1.28 m A cm-2,an incident photon-to-current conversion efficiency(IPCE)of 10.8%,an applied bias photon-to-current efficiency(ABPE)of 0.32 at 390 nm and a charge carriers’lifetime up to 2000 *** enhancement on photoelectrochemical activity can be attributed to:(ⅰ)the generated Z-scheme system in the anatase/rutile phase-junction ag/Ti O_(2)photocathode enhances the separation,diffusion and transformation of electron/hole pairs inside the structure,(ⅱ)ag nanodots modification in the anatase/rutile phases leading to the tuned band gap with enhanced light absorption and(ⅲ)the formed Schottky barrier after ag nanodots surface modification provides enough electron traps to avoid the recombination of photogenerated electrons and *** results here suggest that developing phase-junction nanocomposite as photocathode will provide a new vision for their enhanced photoelectrochemical generation of hydrogen.

关键词： ag/TiO_(2)nanocomposites Anatase/rutile phase-junction Z-scheme Photocathode H2 generation

Advantages and disadvantages of nuclear reactions used in reactors or cyclotrons,in addition to a theoretical study based on photodisintegration on natural indium for^(111)ag production

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Nuclear Science and Techniques 2022年第2期33卷 1-13页

作者： Khaled M.El-Azony Nader M.A.mohamed Dalal A.Aloraini Radioactive Isotopes and Generators Department Hot Labs.CenterEgyptian Atomic Energy AuthorityP.O.Box 13759CairoEgypt Reactors Department Egyptian Atomic Energy AuthorityP.O.Box 13759CairoEgypt Physics Department College of SciencePrincess Nourah Bint Abdulrahman UniversityRiyadhKingdom of Saudi Arabia

Production routes were recorded on available reactions for^(111)ag production from nuclear reactors or cyclotrons using a natural palladium target based on^(110)Pd(n,γ)and^(110)pd(d,n)reactions,respectively.^(nat)Cd(γ,x)based on^(110)Cd(γ,p)has also been studied as a prospective reaction for the production of^(111)***,these nuclear reactions are difficult to utilize because,in some cases,they reduce the specific activity of^(111)*** is a consequence of the stable silver isotopes produced in high *** isotopes include^(107,109)ag and,in other cases,the high impurity of silver radioisotopes,such as^(110)m,^(106)m,^(105)ag,that are produced during parallel nuclear *** to a scarcity of data regarding the(γ,α)reaction,the gamma reaction on natural indium for^(111)ag production based on the^(115)In(γ,α)reaction was *** ^(nat)In(γ,α)reaction satisfies the criteria as a possible reaction to produce^(111)ag with a sufficient yield and purity as consequence of the high^(115)In(95.7%)abundance as an enriched form and a relatively soft background caused by the parallel nuclear reactions.

关键词： Silver-111 Nuclear data Natural cadmium Natural palladium Natural indium