Genetic Variability and Phenotypic Correlations Study among Grain Quality Traits and Mineral Elements Concentrations in Colored and Non-Colored Rice (Oryza sativa L.)

Twenty-four rice genotypes were examined to assess genetic variability,heritability,and correlations for seven-grain quality traits,eight nutritional elements,and protein.ANOVA revealed significant differences for the quality traits studied.For every trait under study,the phenotypic coefficient of variation was higher than the correspon-dence genotypic coefficient of variation.Heritability in a broad sense varied from 29.75%for grain length to 98.31%for the elongation trait.Hulling percentage recovery had a highly significant positive correlation with milling and head rice percentage.Consequently,milling percentage had a highly positive correlation with head rice percentage.In amylose percentage,all the genotypes belonged to low amylose except the Hassawi-1 variety,which had intermediate amylose content.Mineral nutrition contents of magnesium(Mg),sodium(Na),potas-sium(K),calcium(Ca),copper(Cu),manganese(Mn),zinc(Zn),iron(Fe),or protein percentage gave different variations for 24 rice genotypes under all the nutritional elements.Among the 24 genotypes,ten rice genotypes–HighNutrient-1,HighNutrient-2,HighNutrient-9,HighNutrient-8,HighNutrient-3,Hassawi-2,HighNutrient-7,HighNutrient-6,Hassawi-1,and HighNutrient-4–had the highest heist value for all nutritional and protein con-tents,and could be used as a donor to improving new varieties.There was a positive and significant correlation between magnesium Mg,K,Zn and Fe.Consequently,K had a positive correlation with zinc Zn,Fe,and protein percentage.Clustering analysis was divided into two groups:thefirst group included all genotypes rich in nutri-ents,while the remaining genotypes with low nutritional content were included in the second group.

Metabolites Composition of Bacillus subtilis HussainT-AMU Determined by LC-MS and Their Effect on Fusarium Dry Rot of Potato Seed Tuber

Fusarium dry rot is considered to be the most critical soilborne and postharvest disease that damages potato tubers worldwide when they are stored for a long time.This study was performed to demonstrate the effect of crude extract,culture filtrate,and cell suspension obtained from the bacterium Bacillus subtilis Hussain T-AMU,on the net house and field.From oil-contaminated soil,through the serial dilution method,biosurfactant bacteria were isolated on nutrient agar medium.To isolate and screen the prospective biosurfactant strain,various biosurfactant screening methods were used.Standard protocols were carried out for morphological,molecular,and chemical characterization.The disease incidences were significantly decreased under net house and field conditions after treatment with biosurfactant extract(20%,70%),culture filtrate(23%,49%),and bacterial cell suspension(46%,27%),respectively.These results indicate a significant effect of B.subtilis HussainT-AMU against Fusarium oxysporum.The characterization of the partially purified extract by gas-chromatography indicated the existence of a high amount of methyl ester fatty acids.The quantitative analysis determined the presence of lipopeptide-surfactin,fengycin,and iturin in the biosurfactant extract.Scanning electron microscopy revealed that morphological variation was revealed in the structure of stomata size in leaves and in the mycelia of the pathogen that was investigated.This promising biocontrol agent can be a plausible option for further research and can also be used for the production of green biomolecules at an additional industrial level.

The Impact of Inoculum Preparation Media on Pollutant Removal through Phycoremediation of Agricultural Drainage Water by Desmodesmus sp.

Water is the most essential natural resource for the future development.Agriculture production is extensively water-dependent and a significant polluter of water resources.So,this work investigated the effect of two different preparation media[Bold’s Basal Medium(BBM)and Domiati cheese whey(DCW)]for agricultural drainage water(ADW)remediation.All treatments were incubated for 6 days.According to the results of biomass productivity,specific growth rate,photosynthetic pigments,and biochemical composition,Desmodesmus sp.can grow in drainage water without dilution.The two treatments significantly reduced the concentration of nitrate,phosphate,chemical oxygen demand,and sodium in ADW.Finally,using cheese whey with BBM as inoculum preparation media enhanced the lipid accumulation in the algal biomass(25.4%w/w)and gave the best biodiesel properties among treatments.Therefore,combining remediation of drainage water with microalgae mass production can achieve the sustainability of agriculture.

埃及Burullus潟湖沉积生源要素变化:百年来人类活动影响

Burullus是尼罗河河口高封闭性潟湖,其生源要素主要来源于尼罗河,是研究Aswan大坝建成以来流域变化如何影响河口湖泊环境的最佳区域。研究通过对Burullus潟湖B1岩芯的210Pb测年、粒度、以及TOC、TN、TP、BSi生源要素的测试分析,结合历史资料,试图揭示Aswan建坝前后河口湖泊营养盐的差异变化,以及这些变化对生态环境的影响。结果表明:1)沉积物中TOC、TN和TP含量自下而上总体增加,表明尽管Aswan大坝导致营养盐通量急剧减少,但由于下游人类排放N、P通量大大增加,导致下游湖泊N、P浓度并没减少;且沉积TN/TP均小于16,表明湖泊仍为P限制。2)但BSi和BSi/TOC自下而上总体呈减少趋势,表明Aswan大坝引起的水沙减少导致湖泊中硅藻的生物量及其总初级生产力占比都在减少,潟湖水体生态环境将趋于恶化。

Sedimentary records of eutrophication in the Changjiang Estuary upwelling area over last 100 a

The upwelling area in the Changjiang Estuary was selected to collect the core, where the red tide occurred frequently and hypoxic existed. The total organic carbon （TOC）, total nitrogen （TN）, biogenic silica （BSi） and stable organic carbon isotopic ratios（δ13 Corg） were determined on the 210pb-dated sediment core. The concentrations of TOC, TN, BSi as well as their sedimentation fluxes have in- creased to some extent since the 1970s. TOC and TN fluxes increased about 45%, 36% respectively. The average δ13 Coorg value in the core was -23.67 ×10^-3 which remained nearly constant before the 20 century. The δ13 Corg values increased after the 1900s, two marked increases were observed from the 1950s and the 1970s. A simple δ13 Cors model was used to estimate the contribution of terrigenous and marine organic matter inputs for the sediment, which indicated the increase in accumulation since the 1970s has been almost exclusively marine. The increasing of marine organic matter accumulation （TOC, TN and BSi） was corresponding with the increasing of fertilizer consumption and the NO3-N budgets from the Changjiang River. The riverine runoff of fertilizers and nutrients stimulated the algae blooming. Enhanced primary production resulted in an enrichment of organic matter in the sediment. These data support the hypothesis that anthropogenic nutrient loading has been a significant factor on the eutrophication in the Changjiang Estuary.

Serpentinized Peridotites at the North Part of the Wadi Allaqi District(Egypt): Implications for the Tectono-Magmatic Evolution of Fore-arc Crust

The Neoproterozoic Allaqi-Heiani suture （800-700 Ma） in the south Eastern Desert of Egypt is the northernmost linear ophiolitic belt that defines an arc-arc suture in the Arabian- Nubian shield （ANS）. The Neoproterozoic serpentinized peridotites represent a distinct lithology of dismembered ophiolites along the Allaqi-Heiani suture zone. The alteration of peridotites varies, some contain relicts of primary minerals （Cr-spinel and olivine） and others are extremely altered, especially along thrusts and shear zones, with development of talc, talc-carbonate and quartz-carbonate. The fresh cores of the chromian spinels are rimmed by ferritchromite and Cr- magnetite. The fresh chromian spinels have high Cr# （0.62 to 0.79）, while Mg# shows wider variation （0.35-0.59）. High Cr# in the relict chromian spinels and Fo content in the primary olivines indicate that they are residual peridotites after extensive partial melting. The studied ophiolitic upper mantle peridotites are highly depleted and most probably underwent high degrees of partial melting at a supra-subduction zone setting. They can be produced by up to -20%-22% dynamic melting of a primitive mantle source. The mineralogical and geochemical features of the studied rocks reflect that the mantle peridotites of the north part of the Wadi Allaqi district are similar to the fore-arc peridotites of a supra-subduction zone.

Geochemical Constraints of the Ediacaran Volcano-Sedimentary Succession of the Sa'al Metamorphic Complex at Wadi Zaghra, South Sinai, Egypt

The volcano-sedimentary succession around Wadi Zaghra in Sinai, at the northernmost segment of the Arabian Nubian Shield, comprises volcanic rocks interbedded with rather immature sediments. The succession is dominated by intermediate to silicic volcanics of medium-to high-K calc-alkaline affinity. It is divided into two units, the lower unit includes intermediate rocks and dacites interbedded with graywackes, semi-pelites and pelites and topped by polymict conglomerates. This unit is subjected to folding and regional metamorphism(up to garnet zone) and is intruded by quartz diorite-granodiorite inducing, locally, low-pressure contact thermal metamorphism. The unmetamorphosed upper unit encompasses acid volcanics intercalated with litharenite, sublitharenite and minor arenite. The rhyolites of this unit pertain to the highly fractionated granites and are characterized by an agpaitic index(NK/A) ranging from 0.87 to 0.96. They may reflect either extensive interaction of subduction-related magmas with the continental crust or a change in the tectonic regime. The present lithological and geochemical characteristics of the studied sediments together with available zircon ages indicate rather distal provenance of their detritus. This detritus comprises fluvial-alluvial sediments accumulated in the intermontane basins, which are half-grabens or tilted fault blocks. The tectonic setting of the depositional basins is active continental margin and continental island arcs. Geochemical patterns of the Zaghra volcano-sedimentary succession indicate their correlation with the Dokhan Volcanics-Hammamat Clastics sequence of the Eastern Desert of Egypt. Also, the Zaghra volcanics display geochemical similarities with those exposed in Sinai, at the Rutig, Ferani and Iqna Shar'a areas. The Zaghra succession is dated as Ediacaran but is not related either to the ensimatic island arc assemblage or to the rift-related assemblage formed during the early stages of the break-up of Rodinia as previously thought.

Geochemistry and Petrogenesis of Late Ediacaran Rare-metal Albite Granites of the Arabian-Nubian Shield

The Abu Dabbab albite granite(ADAG),in the central Eastern Desert of Egypt,hosts the most significant rare metal ore deposit in the northern part of the Neoproterozoic Arabian-Nubian Shield.Here,we report detailed field,petrographic,mineralogical and geochemical investigation of the ADAG,an isolated stock-like granitic body with sharp intrusive contacts against metamorphic country rocks,probably emplaced at about 600 Ma.The fine-grained porphyritic upper unit is a preserved remnant of the shallowly-emplaced apex of the magma chamber,whereas the medium-grained lower unit crystallized at deeper levels under subvolcanic conditions.The peraluminous leucocratic ADAG shares common geochemical characteristics with post-collisional intraplate A-type magmas.In addition to the conspicuous enrichment in Na2O,the ADAG is remarkable for its anomalous concentrations of Ta,Nb,Li,Hf,Ga,Sn,Zn and heavy rare-earth elements.Nb-Ta minerals in the ADAG are mixed with Fe-Mn oxides,forming black patches that increase in abundance toward of the base of the intrusion.Columbite-tantalite,cassiterite and wolframite are the most important ore minerals.Pronounced negative Eu anomalies(Eu/Eu*=0.10–0.24)reflect extreme magmatic fractionation and perhaps the effects of late fluid-rock interaction.The ADAG was most likely generated by partial melting of the juvenile middle crust of the ANS as the geotherm was elevated by erosional uplift following lithospheric delamination and it was emplaced at the intersection of lineations of structural weakness.Although formation of the ADAG and its primary enrichment in rare metals are essentially due to magmatic processes,late-stage metasomatism caused limited redistribution of rare metals.Fluid-driven subsolidus modification was limited to the apex of the magma chamber and drove development of greisen,amazonite,and quartz veins along fracture systems.

The Petrological and Geochemical Evolution of Ediacaran Rare-Metal Bearing A-type Granites from the Jabal Aja Complex, Northern Arabian Shield, Saudi Arabia

New fieldwork, mineralogical and geochemical data and interpretations are presented for the rare-metal bearing A-type granites of the Aja intrusive complex(AIC) in the northern segment of the Arabian Shield. This complex is characterized by discontinuous ring-shaped outcrops cut by later faulting. The A-type rocks of the AIC are late Neoproterozoic post-collisional granites, including alkali feldspar granite, alkaline granite and peralkaline granite. They represent the outer zones of the AIC, surrounding a core of older rocks including monzogranite, syenogranite and granophyre granite. The sharp contacts between A-type granites of the outer zone and the different granitic rocks of the inner zone suggest that the AIC was emplaced as different phases over a time interval, following complete crystallization of earlier batches. The A-type granites represent the late intrusive phases of the AIC, which were emplaced during tectonic extension, as shown by the emplacement of dykes synchronous with the granite emplacement and the presence of cataclastic features. The A-type granites consist of K-feldspars, quartz, albite, amphiboles and sodic pyroxene with a wide variety of accessory minerals, including Fe-Ti oxides, zircon, allanite, fluorite, monazite, titanite, apatite, columbite, xenotime and epidote. They are highly evolved(71.3–75.8 wt% SiO2) and display the typical geochemical characteristics of post-collisional, within-plate granites. They are rare-metal granites enriched in total alkalis, Nb, Zr, Y, Ga, Ta, REE with low CaO, MgO, Ba, and Sr. Eu-negative anomalies(Eu/Eu* = 0.17–0.37) of the A-type granites reflect extreme magmatic fractionation and perhaps the effects of late fluid-rock interactions. The chemical characteristics indicate that the A-type granites of the AIC represent products of extreme fractional crystallization involving alkali feldspar, quartz and, to a lesser extent, ferromagnesian minerals. The parent magma was derived from the partial melting of a juvenile crustal protolith with a mantle contribution. Accumulation of residual volatile-rich melt and exsolved fluids in the late stage of the magma evolution produced pegmatite and quartz veins that cut the peripheries of the AIC. Post-magmatic alteration related to the final stages of the evolution of the A-type granitic magma, indicated by alterations of sodic amphibole and sodic pyroxene, hematitization and partial albitization.

Water-use efficiency in response to simulated increasing precipitation in a temperate desert ecosystem of Xinjiang, China

Water-use efficiency（WUE） is a key plant functional trait that plays a central role in the global cycles of water and carbon. Although increasing precipitation may cause vegetation changes, few studies have explored the linkage between alteration in vegetation and WUE. Here, we analyzed the responses of leaf WUE, ecosystem carbon and water exchanges, ecosystem WUE, and plant community composition changes under normal conditions and also under extra 15% or 30% increases in annual precipitation in a temperate desert ecosystem of Xinjiang, China. We found that leaf WUE and ecosystem WUE showed inconsistent responses to increasing precipitation. Leaf WUE consistently decreased as precipitation increased. By contrast, the responses of the ecosystem WUE to increasing precipitation are different in different precipitation regimes： increasing by 33.9% in the wet year（i.e., the normal precipitation years）and decreasing by 4.1% in the dry year when the precipitation was about 30% less than that in the wet year.We systematically assessed the herbaceous community dynamics, community composition, and vegetation coverage to explain the responses of ecosystem WUE, and found that the between-year discrepancy in ecosystem WUE was consistent with the extent to which plant biomass was stimulated by the increase in precipitation. Although there was no change in the relative significance of ephemerals in the plant community, its greater overall plant biomass drove an increased ecosystem WUE under the conditions of increasing precipitation in 2011. However, the slight increase in plant biomass exerted no significant effect on ecosystem WUE in 2012. Our findings suggest that an alteration in the dominant species in this plant community can induce a shift in the carbon-and water-based economics of desert ecosystems.

Chemical and Geological Control on Surface Water within the Shade River Watershed in Southeastern Ohio

The under-sampled middle and western branches of Shade River Watershed (SRW) in SE Ohio were investigated as part of the Ohio University—U.S. Environmental Protection Agency (EPA) STAR grant. This project was for monitoring the quality of watersheds in Ohio and classifying them according to their physical, chemical, and biological conditions. Water samples, as well as field parameters, were taken at twenty-two sites for chemical analyses. The ions analyzed included Ca, Mg, Na, Fe, Mn, Al, NO3, SO4, HCO3, and total PO4, while the field parameters measured included pH, dissolved oxygen (DO), total dissolved solids (TDS), electrical conductivity (EC), and alkalinity. To assess the water quality within the SRW, the analyzed ions and field parameters were compared to the USEPA criteria for the survival of aquatic life. Analytical results showed that the watershed is dominated by Ca-HCO3waters with DO, Fe, Mn, and PO4being the main causes of impairment within the streams. The relatively elevated concentrations of manganese and less extent iron may be associated with the local geology and the acidic nature of the soils. The high alkalinity and calcium concentrations are due to the limestone geology. The elevated phosphate concentration may be due to anthropogenic sources, fertilizers, or contributions from phosphorus-rich bedrock that differs geochemically from other areas.

Sorghum:Nutritional Factors,Bioactive Compounds,Pharmaceutical and Application in Food Systems:A Review

After wheat,rice,maize,and barley,sorghum is the fifth most widely grown cereal on the planet.Due to its high production,drought resistance,and heat tolerance,this crop is replacing maize in some areas.Sorghum is available in a variety of colors,including cream,lemon-yellow,red,and even black.The principal grain anatomical components are pericarp,germ or embryo and endosperm.This review provides an overview of key sorghum grain components,including starches,fiber,proteins,lipids,and vitamins.Also,we summarized phenolic compounds,flavonoids,tannins,carotenoids,vitamin E,amines,Policosanols and Phytosterols in sorghum grains.Sorghum is used to manufacture bread and porridge,and it provides a significant source of energy and nutrition for humans;sorghum is extensively farmed for animal feed.However,because the natural components in sorghum are useful in the development of healthy and functional foods,sorghum farming for both biofuel production and human consumption is gaining popularity.Pigmented sorghum grain is high in antioxidants such as polyphenols,primarily tannins,which have a variety of health benefits,including antiproliferative properties linked to the prevention of certain cancers,antioxidant activities linked to the prevention of diseases linked to oxidative stress,and anti-inflammatory effects,as well as improving glucose metabolism.Because these chemicals cannot be assimilated,their application in the food business has been limited,as sorghum is regarded as a lownutritional grain due to the presence of anti-nutritional components such as strong tannins,which form complexes with proteins and iron,limiting their digestibility.This review aims to show the utilization of sorghum as a source of bioactive chemicals and the value they bestow on human health due to the general biological potential it possesses.

Petrology and Geochemistry of Some Ophiolitic Metaperidotites from the Eastern Desert of Egypt:Insights into Geodynamic Evolution and Metasomatic Processes

Ophiolitic peridotites exposed in the Eastern Desert(ED)of Egypt record multiple stages of evolution,including different degrees of partial melting and melt extraction,serpentinization,carbonatization and metamorphism.The present study deals with metaperidotites at two selected localities in the central and southern ED,namely Wadi El-Nabáand Wadi Ghadir,respectively.They represent residual mantle sections of a Neoproterozoic dismembered ophiolite that tectonically emplaced over a volcano-sedimentary succession that represents island–arc assemblages.The studied metaperidotites are serpentinized,with the development of talc-carbonate and quartz-carbonate rocks,especially along shear and fault planes.Fresh relics of primary minerals(olivine,orthopyroxene and Cr-spinel)are preserved in a few samples of partiallyserpentinized peridotite.Most of the Cr-spinel crystals have fresh cores followed by outer zones of ferritchromite and Crmagnetite,which indicates that melt extraction from the mantle protolith took place under oxidizing conditions.The protoliths of the studied metaperidotites were dominated by harzburgites,which is supported by the abundance of mesh and bastite textures in addition to some evidence from mineral and whole-rock chemical compositions.The high Cr#(0.62–0.69;Av.0.66)and low TiO_(2)(<0.3 wt%)contents of the fresh Cr-spinels,the higher Fo(89–92;Av.91)and NiO(0.24–0.54 wt%,Av.0.40)contents of the primary olivine relics,together with the high Mg#(0.91–0.93;Av.91)and low CaO,Al2 O3 and TiO_(2)of the orthopyroxene relics,are all comparable with depleted to highly depleted forearc harzburgite from a suprasubduction zone setting.The investigated peridotites have suffered subsequent phases of metasomatism,from oceanfloor hydrothermal alteration(serpentinization)to magmatic hydrothermal alteration.The enrichment of the studied samples in light rare earth elements(LREEs)relative to the heavy ones(HREEs)is attributed to most probably be due to the contamination of their mantle source with granitic source hydrothermal fluids after the obduction of the ophiolite assemblage onto the continental crust.The examined rocks represent mantle residue that experienced different degrees of partial melting(~10%to 25%for W.El-Nabárocks and~5%to 23%for W.Ghadir rocks).Variable degrees of partial melting among the two investigated areas suggest mantle heterogeneity beneath the Arabian-Nubian Shield(ANS).

Tonian–Ediacaran Tectonometamorphic History of the Sa'al Complex,Sinai(Egypt):Implications for the Tectonostratigraphic Framework of the Northern Arabian–Nubian Shield

The Sa'al Metamorphic Complex(SMC;southern Sinai)encompasses the oldest arc rocks in the Arabian–Nubian Shield,comprising two non-consanguineous metavolcanic successions(the Agramiya Group and the Post-Ra'ayan Formation)separated by the metasediments of the Ra'ayan Formation.It experienced three distinct deformational events(D_(1)–D_(3))and two low-medium grade regional metamorphic events(M_1–M_(2)).The Agramiya Group and the Ra'ayan Formation experienced all tectonometamorphic events(D_1–D_(3)and M_(1)–M_(2)),whereas the Post-Ra'ayan volcanic rocks were only affected by the D_(3)and M_(2)events.D_(1)is an extensional event and is connected to the late Rodinia break-up(~Tonian;900–870 Ma).The M_(1)metamorphism variably affected the older Agramiya Group,the rhyolitic tuffs experiencing lower to upper greenschist facies conditions and the basic and intermediate volcanic rocks undergoing amphibolite facies metamorphism.The Ra'ayan Formation metasediments experienced upper greenschist to amphibolite facies metamorphism.The upper greenschist facies M_(2)affected the youngest Post-Ra'ayan volcanic rocks and other stratigraphic successions.The compressive D_(2)and D_(3)events were coeval with the accretion of dismembered terranes in the assembly of Gondwana.D_(2)can be linked to the Tonian–Cryogenian arc-arc assembly(~880–760 Ma;in Elat and Sinai),whereas D_(3)and the accompanying M_(2)is constrained to 622–600 Ma(Ediacaran).

Genetic Variation among Fragmented Populations of Atriplex halimus L. Using Start Codon Targeted (SCoT) and ITS1-5.8S-ITS2 Region Markers

Two forms of A. halimus shrubs: erect habit (A. halimus) and bushy habit shrub (A. schweinfurthii) are used naturally isolated by a considerable distance from each other and occupy the same area. To explore the effect of natural isolation on the genetic basis of the two forms, Start Codon Targeted (SCoT) and the phylogenetic relationships of A. halimus by sequencing ITS1-5.8S-ITS2 regions of the ribosomal DNA are used. Significant isolation-by-distance relationship was found (r = 0.62, P = 0.001). Soil factors did not influence molecular variations. The natural isolation of A. halimus habitats restricts gene flow among the populations and the observed high within-population genetic diversity (74.19%) in this species is best explained by its outcrossing behaviour, long-lived individuals and overlapping generations. The UPGMA analysis of the SCoT results showed that all the studied populations were divided into two discrete genetic groups with significant separation of the two forms in Burg El-Arab area (Populations 1 and 2) and insignificant separation between two forms in El-Hammam area (population 5 and 6). The sequencing of the ITS1-5.8S-ITS2 rDNA regions also showed the insignificant separation of the two A. halimus forms. We conclude that gene flow depending on habitat fragmentation was the main factor affecting the population genetic differentiation. We suggest that the two forms do not merit specific rank in presence of interference between the two forms and absence of a breeding barrier fail to separate the different populations when they become sympatric.

Origin and geochemical characteristics of beryllium mineralization in the Zabara-Wadi El Gemal region,South Eastern Desert,Egypt

Beryl is the commercial source of beryllium and several varieties of it are valued as a gemstone.To contribute to understanding the mechanism of beryl formation,we carried out detailed geological,petrographical,and geochemical investigations on beryl mineralization occurrences in the Zabara-Wadi El Gemal(Z-WG)region.This region is an NW-SE trending tract that includes six berylhosting areas.The green gem variety of beryl(emerald)is restricted to phlogopite schist,pegmatite,and quartz veins.Prismatic hexagonal emerald crystals are well-developed in phlogopite schist and pegmatite.The gem variety emerald examined is sodic and Cr-dominant.It contains high concentrations of chromophore transition elements ordering Cr(up to 1511 ppm)>V(up to 242 ppm)>Sc(up to 245 ppm),giving rise to its vivid green color,refl ecting mafic-ultramafic source contribution.Among the investigated emeralds,the Sikait area contains the highest BeO(av.10.76wt.%)concentration.The compositional variability of emeralds is most likely attributed to the contribution from the host rocks.This is revealed by the examined emerald mineralization,for instance;the Abu Rusheid area(one of the best areas exposing rare metal-bearing granitoids)possesses the highest average of trace and REEs concentrations.In contrast,Um Kabu emerald has the highest contents of Co(av.20 ppm),Ni(av.299 ppm),MgO(av.8.2wt.%),Fe_(2)O_(3)(av.3.12wt.%),and CaO(avg.3.4wt.%)relative to other areas,which may be linked to contribution of ultramafic rocks exposed there.The proposed mechanism we suggest for emerald genesis is metasomatic interaction between felsic intrusions,that are enriched with K,Na,Be,Li,and B,with mafic-ultramafic rocks that are enriched in Cr,V,Mg,Fe,and Ca.This interaction is marked by the formation of phlogopite schist,the growth of emerald crystals,and desilicated pegmatite.

Geochemistry,Petrogenesis and Alteration of Rare-Metal-Bearing Granitoids and Mineralized Silexite of the Al-Ghurayyah Stock,Arabian Shield,Saudi Arabia

New data are presented for the rare-metal bearing A-type granitoids of the AlGhurayyah stock in the northwestern segment of the Arabian Shield, a composite pluton intruding metamorphosed volcano-sedimentary successions of the Silasia Formation. Metals in the granitoids are variably enriched, with up to 1 990 μg/g Zn, 7 680 μg/g Zr, 2 316 μg/g Nb, 232 μg/g Ta, 485 μg/g Hf, 670 μg/g Th, 137 μg/g U and 1 647 μg/g total rare earth elements(REE). The silexite is highly mineralized and yields higher maximum concentrations of several metals than the granitoids, including up to 1 860 μg/g Y, 9 400 μg/g Zr, 878 μg/g Hf, 1 000 μg/g Th, and 2 029 μg/g total REE. The Al-Ghurayyah stock has been assigned to an intraplate setting. Lithospheric delamination led to generation of mantle melts that supplied heat to melt the juvenile crust of the ANS. The fluorine and rare-metal enriched parental magma evolved by fractional crystallization. The quartz-rich silexite, distinct in character from ordinary hydrothermal vein quartz, is inferred to be co-genetic with the granitoids on the basis of their similar REE patterns;it is interpreted as a small volume of residual magma enriched in SiO2, volatiles, and trace metals. Mineralization took place both at the magmatic stage and later during a hydrothermal stage that concentrated these elements to economic grades.