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Sample records for pan-african alkali granites

  1. Pan-African alkali granites and syenites of Kerala as imprints of taphrogenic magmatism in the South Indian shield

    Science.gov (United States)

    Santosh, M.; Drury, S. A.; Iyer, S. S.

    1988-01-01

    Granite and syenite plutons with alkaline affinities ranging in age from 550 to 750 Ma sporadically puncture the Precambrian granulites of the Kerala region. All the bodies are small (20 to 60 sq km), E-W to NW-SE elongated elliptical intrusives with sharp contacts and lie on or close to major late Proterozoic lineaments. Geochemical plots of A-F-M and An-Ab-Or relations show an apparent alkali enrichment trend on the former, but the plutons define relatively distinct fields on the latter. Most of the plutons are adamellitic to granitic by chemistry. The variations of SiO2 with log sub 10 K2O/MgO (1) brings out the distinct alkaline nature of the plutons. Some of the granites are extremely potassic, like the Peralimala pluton, which shows up to 11.8 percent K2O. On a SiO2-Al2O3-Na2O+K2O (mol percent) plot, the plutons vary from peraluminous to peralkaline, but none are nepheline normative. Low MgO, low to moderate CaO and high Fe2O3/FeO values are other common characteristics. Among trace elements, depletion of Ba, Sr and Rb with high K/Ba and K/Rb values are typical. Overall, the plutons show a trend of decreasing K/Rb ratio with increasing K content. Individual plutons show more clearly defined trends similar to those from granitic masses characterized by plagioclase fractionation.

  2. Transpressional granite-emplacement model: Structural and magnetic study of the Pan-African Bandja granitic pluton (West Cameroon)

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    Sandjo, A. F. Yakeu; Njanko, T.; Njonfang, E.; Errami, E.; Rochette, P.; Fozing, E.

    2016-02-01

    The Pan-African NE-SW elongated Bandja granitic pluton, located at the western part of the Pan-African belt in Cameroon, is a K-feldspar megacryst granite. It is emplaced in banded gneiss and its NW border underwent mylonitization. The magmatic foliation shows NE-SW and NNE-SSW strike directions with moderate to strong dip respectively in its northern and central parts. This mostly, ferromagnetic granite displays magnetic fabrics carried by magnetite and characterized by (i) magnetic foliation with best poles at 295/34, 283/33 and 35/59 respectively in its northern, central and southern parts and (ii) a subhorizontal magnetic lineation with best line at 37/8, 191/9 and 267/22 respectively in the northern, central and southern parts. Magnetic lineation shows an `S' shape trend that allows to (1) consider the complete emplacement and deformation of the pluton during the Pan-African D 2 and D 3 events which occurred in the Pan-African belt in Cameroon and (2) reorganize Pan-African ages from Nguiessi Tchakam et al. (1997) compared with those of the other granitic plutons in the belt as: 686 ±17 Ma (Rb/Sr) for D 1 age of metamorphism recorded in gneiss; and the period between 604-557 Ma for D 2-D 3 emplacement and deformation age of the granitic pluton in a dextral ENE-WSW shear movement.

  3. Age and Isotopic Studies of Some Pan-African Granite from North-Central Nigeria

    International Nuclear Information System (INIS)

    Breemen, O. van; Pidgeon, R.T.; Bowden, P.

    1977-01-01

    Twenty-nine Rb-Sr whole-rock isotopic analyses and three U-Pb zircon analyses on foliated granites and largely unfoliated charnockitic rocks indicate that the central part of the Pan-African belt in west Africa was characterised by intense orogenic plutonism. These data and Rb-Sr analyses on muscovite books from late cross-cutting pegmatites indicate that the peak of magmatic activity occurred 610 +- 10 m.y.ago. Initial 87 Sr/ 86 Sr ratios for the granitic and charnockitic rocks are in the range 0.7065-0.7125, and indicate a significantly older crustal component in the magmas

  4. Characteristics and significance of uranium bearing pan african younger granite in the eastern desert, Egypt

    International Nuclear Information System (INIS)

    Hassan, M.A.; Dabbour, G.A.; Mohammden, T.F.

    1998-01-01

    Surficial uranium mineralization was discovered in four pan african younger granite plutons in the eastern desert of egypt. The present study revealed great similarity between these plutons both in petrography and geochemistry. They are two-feldspar, two-mica peraluminous granites which have been formed by melting of crustal materials and emplaced during the late stage stage of a late proterozoic orogenic cycle. Radiometric and geochemical investigations indicate that these granites are fertile with respect to U and form a potential target for primary uranium deposits. Four models are suggested to explain the source and mechanism of the surficial uranium mineralization in these granites. The most applicable model is the oxidation of U +4 found in minute disseminated uraninite grains and its subsequent mobilization. This is supported by petrographic and autoradiographic studies. The bearings of the present study on further exploration for uranium deposits in granites of the arabian- Nubian shield in general are discussed

  5. The alkaline peralkaline granitic post-collisional Tin Zebane dyke swarm (Pan-African Tuareg shield, Algeria): prevalent mantle signature and late agpaitic differentiation

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    Hadj-Kaddour, Zakia; Liégeois, Jean-Paul; Demaiffe, Daniel; Caby, Renaud

    1998-12-01

    The Tin Zebane dyke swarm was emplaced at the end of the Pan-African orogeny along a mega-shear zone separating two contrasting terranes of the Tuareg shield. It is located along the western boundary of the Archaean In Ouzzal rigid terrane, but inside the adjacent Tassendjanet terrane, strongly remobilized at the end of the Precambrian. The Tin Zebane swarm was emplaced during post-collisional sinistral movements along the shear zone at 592.2±5.8 Ma (19WR Rb-Sr isochron). It is a dyke-on-dyke system consisting of dykes and stocks of gabbros and dykes of metaluminous and peralkaline granites. All rock types have Sr and Nd isotopic initial ratios (Sr i=0.7028 and ɛNd=+6.2) typical of a depleted mantle source, similar to the prevalent mantle (PREMA) at that period. No crustal contamination occurred in the genesis of the Tin Zebane swarm. Even the samples showing evidence of fluid interaction (essentially alkali mobility) have the same isotopic signature. The peralkaline granites have peculiar geochemical characteristics that mimic subduction-related granites: this geochemical signature is interpreted in terms of extensive differentiation effects due to late cumulates comprising aegirine, zircon, titanite, allanite and possibly fergusonite, separated from the liquid in the swarm itself due to magmatic flow turbulence. The Tin Zebane dyke swarm is thus of paramount importance for constraining the differentiation of mantle products to generate highly evolved alkaline granites without continental crust participation, in a post-collisional setting.

  6. Miocene metamorphism of pan-African granites in the Edough Massif (NE Algeria)

    International Nuclear Information System (INIS)

    Hammor, D.; Lancelot, J.

    1998-01-01

    The Edough Massif is the eastern most crystalline core of the Maghrebides that represents the African segment of the west Mediterranean Alpine belt. U-Pb zircon dating provides upper intercept ages of 595± My and 606±55 My and orthogneiss of the lower unit and a deformed leucogranite of the upper pelitic unit, respectively. These ages suggest emplacement of the two granitoids during the Pan-African orogeny. Monazites from a paragneiss sample gave a 18± My U-Pb age that points to a Miocene age of the high-temperature metamorphism. (authors)

  7. Microstructures and magnetic fabrics of the Ngaoundéré granite pluton (Cameroon): Implications to the late-Pan-African evolution of Central Cameroon Shear Zone

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    Dawaï, Daouda; Tchameni, Rigobert; Bascou, Jérome; Awe Wangmene, Salomon; Fosso Tchunte, Périclex Martial; Bouchez, Jean-Luc

    2017-05-01

    The Ngaoundéré granite pluton, in Central-North Cameroon, located near the Central Cameroon Shear zone (CCSZ), and previously studied for its petrography and geochemistry, is characterized by the absence of macroscopic markers of deformation. In this study, we report microstructures and magnetic fabrics (AMS) of this pluton and discuss the relationship with the Pan-African evolution of the CCSZ. The pluton consists of a porphyritic Hbl-Bt-monzogranite at its rim and a porphyritic biotite-granite at its core, a petrographic distribution denoting a normal zoning pattern, i.e. more silicic toward the centre. As expected, magnetic susceptibilities values also exhibit a zoning pattern in agreement with petrographic zonation. Thermomagnetic data indicate that this pluton is dominantly ferromagnetic in behaviour. As indicated by its microstructures, the pluton has suffered a continuum of deformation from the magmatic state to the high temperature solid-state during magma crystallization and solidification. The magnetic foliations dominantly strike NE-SW and dip moderately to steeply and the lineations mostly plunge shallowly to the NE or SW, roughly parallel to NE-to ENE-trending Central Cameroun Shear Zone (CCSZ). The foliation poles define a girdle pattern with a zone axis (52°/11°) rather close to the best line of the lineations (44°/21°). These fabrics correlate with the structures of the country rocks ascribed by several workers to a regional transpression. Toward the margins of the pluton, particularly the northern one, the lineations tend to rotate from NE to N in azimuth. This change is interpreted as due to strain partitioning, simple shearing with NE-SW extension being relayed by compression toward the northern pluton border. This new magnetic fabric study suggests that the Ngaoundéré pluton (poorly dated at c. 575 Ma) was emplaced during the late stages of the CCSZ dextral transpressive movement. It also provides some more constraints on the correlation

  8. Geochemistry and geochronology Rb-Sr, K-Ar and 40Ar/39Ar of the Pan-African granitic complexes of the Tamanrasset area (Algeria): relationships with the associated Sn-W mineralizations and tectonic evolution of Central Hoggar

    International Nuclear Information System (INIS)

    Bertrand, J.M.; Zimmermann, J.L.; Dautel, D.; Boullier, A.M.; Bouabsa, L.; Farrar, E.; Archibald, D.A.; Moulahoum, O.

    1992-01-01

    New field mapping, petrographic and mineralogic, geochemical and geochronological data allow us to distinguish two successive magmatic suites with contrasting geochemistry: (1) granites with subalkaline affinity between 615 Ma (Anfeg) and 576 Ma (Tifferkit); (2) peraluminous magmatism and Li-F specialized leucogranites with associated Sn-W mineralization between 539 and 525 Ma. Such a magmatic evolution is interpreted as resulting from thickening of the continental crust during the Pan-African collision. Earliest magmas show mantle contribution and were formed close to the crust-mantle boundary where synchronous crustal stacking developed in amphibolite facies conditions. Latest peraluminous magmatism of crustal derivation and albite-topaz leucogranites appear to be controlled by localized extensional structures, 80 Ma after the main tectono-metamorphic event

  9. Archives: Pan African Medical Journal

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    Items 1 - 28 of 28 ... Archives: Pan African Medical Journal. Journal Home > Archives: Pan African Medical Journal. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives. 1 - 28 of 28 Items ...

  10. Alkali control of high-grade metamorphism and granitization

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    Oleg G. Safonov

    2014-09-01

    Full Text Available We review petrologic observations of reaction textures from high-grade rocks that suggest the passage of fluids with variable alkali activities. Development of these reaction textures is accompanied by regular compositional variations in plagioclase, pyroxenes, biotite, amphibole and garnet. The textures are interpreted in terms of exchange and net-transfer reactions controlled by the K and Na activities in the fluids. On the regional scale, these reactions operate in granitized, charnockitized, syenitized etc. shear zones within high-grade complexes. Thermodynamic calculations in simple chemical systems show that changes in mineral assemblages, including the transition from the hydrous to the anhydrous ones, may occur at constant pressure and temperature due only to variations in the H2O and the alkali activities. A simple procedure for estimating the activity of the two major alkali oxides, K2O and Na2O, is implemented in the TWQ software. Examples of calculations are presented for well-documented dehydration zones from South Africa, southern India, and Sri Lanka. The calculations have revealed two end-member regimes of alkalis during specific metamorphic processes: rock buffered, which is characteristic for the precursor rocks containing two feldspars, and fluid-buffered for the precursor rocks without K-feldspar. The observed reaction textures and the results of thermodynamic modeling are compared with the results of available experimental studies on the interaction of the alkali chloride and carbonate-bearing fluids with metamorphic rocks at mid-crustal conditions. The experiments show the complex effect of alkali activities in the fluid phase on the mineral assemblages. Both thermodynamic calculations and experiments closely reproduce paragenetic relations theoretically predicted by D.S. Korzhinskii in the 1940s.

  11. U-Pb and origen of the Uruana quartz syenite and Itapuranga alkali granite in Goias, central Brazil: Late Braziliano alkali-rich magmatism in the Anapolis-Itaucu complex

    International Nuclear Information System (INIS)

    Pimentel, Marcio Martins; Dantas, Elton Luis; Fuck, Reinhardt Adolfo

    2001-01-01

    The Brasilia Belt is part of a Brasiliano/Pan African orogen developed between the Amazon and Sao Francisco cratons (for a review see Pimentel et al. 2000 and Dardenne 2000). The stabilization of the belt occurred after the last metamorphic event at ca. 620±20 Ma. Until recently, important late- to post-orogenic Neoproterozoic granitic magmatism was recognized mostly within the limits of the Goias Magmatic Arc, in the western part of the orogen. Recent studies by Pimentel et al. (1999) and Fischel et al (1999), as well as some unpublished U-Pb SHRIMP geochronological data, have also shown that Neoproterozoic granites represent an important component of the Anapolis- Itaucu Complex, a high grade terrain exposed in the central part of the Brasilia Belt, in between metasediments (Araxa Group) of the internal part of the belt. In the northern part of this granulitic complex, two alkali rich intrusions, the Uruana quartz syenite and the Itapuranga alkali suite (Lacerda Filho and Oliveira 1995) form large bodies elongated in the E-W direction. Their age and tectonic significance has been the matter of continuous debate. In this study we present new conventional and SHRIMP U-Pb results as well as whole-rock Sm-Nd data for samples of these intrusions (au)

  12. Metasomatic alkali-feldspar syenites (episyenites) of the Proterozoic Suomenniemi rapakivi granite complex, southeastern Finland

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    Suikkanen, E.; Rämö, O. T.

    2017-12-01

    Peralkaline to marginally metaluminous alkali-feldspar syenites and quartz alkali-feldspar syenites are hosted by subalkaline, ferroan rapakivi granites in the 1644 Ma Suomenniemi complex of southeastern Finland. These alkali syenites form NW-oriented dikes and small (fingerprints are, within error, identical to those of the subalkaline granites of the complex. We propose that the Suomenniemi alkali-feldspar syenites are episyenites, formed as the result of pervasive local metasomatism of the subalkaline granites caused by high-temperature oxidizing peralkaline fluids. The process led to major geochemical changes, e.g., addition of Na, Al and Fe3 +, depletion of Si and Fe2 +, and partial to complete recrystallization of the granites along fluid pathways.

  13. Re-Os dating of molybdenites from Southern India: implication for Pan-African metallogeny

    International Nuclear Information System (INIS)

    Santosh, M.; Suzuki, Katsuhiko; Masuda, Akimasa

    1994-01-01

    Rhenium-osmium (Re-Os) dating of two molybdenite samples from the alkali granite and pegmatite of Ambalavayal in northern Kerala (S. India) yielded ages of 567 ±28 Ma and 566±77 Ma, respectively. These ages closely compare with the previously determined Rb-Sr whole rock age of 595±20 Ma Rb-Sr for granite, and K-Ar biotite age of 560±30 Ma for the pegmatite. Our study provides the first direct determination of the timing of ore mineralization associated with felsic magmatism in southern India, and reveals the fingerprints of a prominent Pan-African metallogenic event. This timing coincides with the formation of rare metal and gemstone-bearing pegmatites in different parts of southern India, Sri Lanka, Madagascar and East Antarctica. In most cases, the mineralizations are genetically related to felsic magmas emplaced along structural conduits, suggesting that the magmatism and metallogeny are related to deep-seated extension in the cratonized crustal segments of the Gondwana assembly. (author). 20 refs., 3 figs., 1 tab

  14. Assessment of the Alteration of Granitic Rocks and its Influence on Alkalis Release

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    Ferraz, Ana Rita; Fernandes, Isabel; Soares, Dora; Santos Silva, António; Quinta-Ferreira, Mário

    2017-12-01

    Several concrete structures had shown signs of degradation some years after construction due to internal expansive reactions. Among these reactions there are the alkali-aggregate reactions (AAR) that occur between the aggregates and the concrete interstitial fluids which can be divided in two types: the alkali-silica reaction (ASR) and alkali-carbonate reaction (ACR). The more common is the ASR which occurs when certain types of reactive silica are present in the aggregates. In consequence, an expansive alkali-silica gel is formed leading to the concrete cracking and degradation. Granites are rocks composed essentially of quartz, micas and feldspars, the latter being the minerals which contain more alkalis in their structure and thus, able to release them in conditions of high alkalinity. Although these aggregates are of slow reaction, some structures where they were applied show evidence of deterioration due to ASR some years or decades after the construction. In the present work, the possible contribution of granitic aggregates to the interstitial fluids of concrete by alkalis release was studied by performing chemical attack with NaOH and KOH solutions. Due to the heterogeneity of the quarries in what concerns the degree of alteration and/or fracturing, rock samples with different alteration were analysed. The alteration degree was characterized both under optical microscope and image analysis and compared with the results obtained from the chemical tests. It was concluded that natural alteration reduces dramatically the releasable alkalis available in the rocks.

  15. Student-Centered Designs of Pan-African Literature Courses

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    M'Baye, Babacar

    2010-01-01

    A student-centered teaching methodology is an essential ingredient of a successful Pan-African literary course. In this article, the author defines Pan-Africanism and how to go about designing a Pan-African literature course. The author combines reading assignments with journals, film presentations, and lectures in a productive learning…

  16. Bronchiectasis: a bacteriological profile | Bopaka | Pan African ...

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    Pan African Medical Journal. Journal Home · ABOUT · Advanced Search · Current Issue · Archives · Journal Home > Vol 22, No 1 (2015) >. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Download this PDF file. The PDF file you selected should load here if your ...

  17. Influence of granitic aggregates from Northeast Brazil on the alkali-aggregate reaction

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    Gomes Neto, David de Paiva; Santana, Rodrigo Soares de; Barreto, Ledjane Silva, E-mail: pvgomes@uol.com.br [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Dept. de Ciencias dos Materiais e Engenharia; Conceicao, Herbert; Lisboa, Vinicios Anselmo Carvalho [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Dept. de Geologia

    2014-08-15

    The alkali-aggregate reaction (AAR) in concrete structures is a problem that has concerned engineers and researchers for decades. This reaction occurs when silicates in the aggregates react with the alkalis, forming an expanded gel that can cause cracks in the concrete and reduce its lifespan. The aim of this study was to characterize three coarse granitic aggregates employed in concrete production in northeastern Brazil, correlating petrographic analysis with the kinetics of silica dissolution and the evolution of expansions in mortar bars, assisted by SEM/EDS, XRD, and EDX. The presence of grains showing recrystallization into individual microcrystalline quartz subgrains was associated with faster dissolution of silica and greater expansion in mortar bars. Aggregates showing substantial deformation, such as stretched grains of quartz with strong undulatory extinction, experienced slower dissolution, with reaction and expansion occurring over longer periods that could not be detected using accelerated tests with mortar bars. (author)

  18. The Serra do Carambei Granite - PR and the uraniferous anomalism

    International Nuclear Information System (INIS)

    Pinto-Coelho, C.V.

    1986-01-01

    The Serra do Carambei Granite forms a pluton relatively homogeneous, covering about 33 km 2 , cropping out as an elongate retangular body trending NE-SW, being emplaced in the Cunhaporanga Granitoid Complex. Its characteristics indicates a kind of hololeucocratic granite, equigranular, medium to coarse-grained, consisting predominantly of microperthitic alkali-feldspar, quartz and a small amount of biotite (less than 1%), thus being classified as an alaskite. Chemical data allows a classification in the group of granite with high contents of silica (74-76% Wt. SiO 2 ), dominantly alkaline chemism and hypersolvus character, derived from a parental magma under saturated in water with distinguished features of granitoids from the magnetite series and types I and A granites. The pluton shows important chemical variations due to weathering processes. However detailed chemical studies reveal the presence of anomalous concentrations of trace elements such as U, Sn, Nb, Y, Zr, the Serra do Carambei Granite lacks economically important mineralizations because of the absence of well-developed tardi/pos-magmatic processes that could concentrate them. The SW side of the granite is cut by leucocratic rhyolite dykes that show some radiometric anomalies. These rocks, which are highly diferentiated, were emplaced contemporaneously to the Serra do Carambei Granite. Although petrographic and chronological similarities are found between the uraniferous alaskite of Roessing (Namibia) and the Serra do Carambei Granite anyhow it was not possible to establish any lateral continuity with the uranifeous Pan-African Province. (Author) [pt

  19. Source constraints on the genesis of Danubian granites in the South Carpathians Alpine Belt (Romania)

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    Duchesne, Jean-Clair; Laurent, Oscar; Gerdes, Axel; Bonin, Bernard; Liégeois, Jean-Paul; Tatu, Mihai; Berza, Tudor

    2017-12-01

    The pre-Alpine basement of the Lower Danubian nappes in the South Carpathians is made up of two Precambrian terranes (Drăgşan and Lainici-Păiuş) that were intruded by Pan-African/Cadomian and Variscan granitoid massifs. We focus on the major and trace element geochemistry (1) in the Drăgşan terrane, of the Variscan Retezat and Parâng intrusions; (2) in the Lainici-Păiuş terrane, of the Variscan Furcǎtura, Petreanu and Frumosu intrusions and of the Pan-African Vârful Pietrii, Şuşiţa and Olteţ granites and granitic leucosomes of migmatites; and (3) in the Upper Danubian nappes basement, of the Variscan Muntele Mic, Sfârdin, Cherbelezu and Ogradena intrusions. For each intrusion, in which a range of composition is observed, we decipher the differentiation mechanisms (fractional crystallization, hybridization, melt laden with restite minerals, etc.) in order to define the parental liquid compositions. The latter are calc-alkaline to alkali-calcic (except Olteţ that is calcic) and medium to high-K in composition. With [La/Yb]N > 10 and Sr/Y > 15, most melts display the so-called "continental adakite" affinities. The parental melt compositions are compared with experimental data to determine the melting conditions and the nature of the source rock. When the P-T conditions can be estimated, the temperatures range between 850 °C and 875 °C and the pressure between 5 and 15 kbar regardless of the ages of the granites and the terrane in which they have intruded. The source rock composition is dominated by a variety of mafic igneous compositions or metasediments rich in volcanic components. Clay-rich (pelitic) protoliths have not been identified. We confirm a Variscan age (c. 300 Ma) for the Frumosu intrusion granite and inherited Precambrian ages (c. 1.7-1.9 and 2.6-2.9 Ga) for the Motru dyke swarm. Thus, both Drăgşan and Lainici-Păiuş together with the Upper Danubian basement terranes were affected by Variscan post-collisional granitic plutonism. In

  20. Afro-Americans and Early Pan-Africanism

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    Contee, Clarence G.

    1970-01-01

    History of the Pan-African movement, the roles of W.E.B.Du Bois and Marcus Garvey in the movement activities, and the shift to African based leadership of the movement in the 1940's are discussed. (KG)

  1. Pan African Medical Journal - Vol 16, No 1 (2014)

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    Pan African Medical Journal - Vol 16, No 1 (2014) .... Cancer incidence in Morocco: report from Casablanca registry 2005-2007 · EMAIL FREE FULL .... Maladie de Leo-Buerger faisant suite à une intoxication au cannabis · EMAIL FREE FULL ...

  2. Characterization and application of municipal solid waste incineration (MSWI) bottom ash and waste granite powder in alkali activated slag

    NARCIS (Netherlands)

    Gao, X.; Yuan, B.; Yu, Q. L.; Brouwers, H. J.H.

    2017-01-01

    In this paper, the feasibility of using two solid wastes in alkali activated slag composites as construction and building materials is evaluated. One waste is the municipal solid waste incineration (MSWI) bottom ash, and the other one is fine granite powder from aggregate manufacturing. These two

  3. Neoliberal Imperialism and Pan-African Resistance

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    Niels S.C. Hahn

    2015-08-01

    Full Text Available Neoliberalism has in the past three decades had a tremendous impact on both thought and practice throughout most of the world, and has dominated international development since the early 1980s. Although neoliberalism presents itself as modern and progressive, it is argued that the underlying ideologies and power agendas have their origins in the political debates of the eighteenth century and earlier. Through an analysis of neoliberalism from a world-historical and global perspective, indications are seen that the international development agenda has more to do with political and economic interests than with benevolent pro-poor development. This leads to the debate about redistribution of resources and State-led Development versus Free-market Development, which is inextricable from the discussion of Liberal Democratic Peace Theory versus Realism. From this perspective it is argued that the notion of democratic peace is used as a popular seductive rhetoric, to legitimize western military interventions and the imposition of economic policies in the name of democracy, human rights and free market economy. In this context, it is argued that neoliberalism cannot be analysed without also considering inherent links to imperialism and neo-colonialism, which is being resisted by pan-African movements.

  4. Thrusting and transpressional shearing in the Pan-African nappe southwest El-Sibai core complex, Central Eastern Desert, Egypt

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    El-Wahed, Mohamed A. Abd.

    2008-01-01

    The Wadi El-Shush area in the Central Eastern Desert (CED) of Egypt is occupied by the Sibai core complex and its surrounding Pan-African nappe complex. The sequence of metamorphic and structural events in the Sibai core complex and the enveloping Pan-African nappe can be summarized as follows: (1) high temperature metamorphism associated with partial melting of amphibolites and development of gneissic and migmatitic rocks, (2) between 740 and 660 Ma, oblique island arc accretion resulted in Pan-African nappe emplacement and the intrusion of syn-tectonic gneissic tonalite at about 680 ± 10 Ma. The NNW-SSE shortening associated with oblique island arc accretion produced low angle NNW-directed thrusts and open folds in volcaniclastic metasediments, schists and isolated serpentinite masses (Pan-African nappe) and created NNE-trending recumbent folds in syn-tectonic granites. The NNW-SSE shortening has produced imbricate structures and thrust duplexes in the Pan-African nappe, (3) NE-ward thrusting which deformed the Pan-African nappe into SW-dipping imbricate slices. The ENE-WSW compression event has created NE-directed thrusts, folded the NNW-directed thrusts and produced NW-trending major and minor folds in the Pan-African nappe. Prograde metamorphism (480-525 °C at 2-4.5 kbar) was synchronous with thrusting events, (4) retrograde metamorphism during sinistral shearing along NNW- to NW-striking strike-slip shear zones (660-580 Ma), marking the external boundaries of the Sibai core complex and related to the Najd Fault System. Sinistral shearing has produced steeply dipping mylonitic foliation and open plunging folds in the NNW- and NE-ward thrust planes. Presence of retrograde metamorphism supports the slow exhumation of Sibai core complex under brittle-ductile low temperature conditions. Arc-accretion caused thrusting, imbrication and crustal thickening, whereas gravitational collapse of a compressed and thickened lithosphere initiated the sinistral movement

  5. Towards a holistic review of Pan-Africanism: linking the idea and the movement.

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    Young, Kurt B

    2010-01-01

    This article explores two general approaches to defining Pan-Africanism. Traditional Pan-Africanism reflects definitions of Pan-Africanism that begin with the assumption that distinctions must be made between early "ideas" of group identification with Africa versus modern organizational activities. However, holistic approaches emphasize the interconnectivity of Pan-African ideas and concrete activities. This discussion explores these approaches and their implications for contemporary analyses of Pan-Africanism. The essay concludes that the holistic line is best suited for developing a new model in Pan-Africanism.

  6. Geochemistry, Mineralogy and Economic Potential of a Pan-African Pegmatite from Wadi Huwar, Southwest Jordan

    International Nuclear Information System (INIS)

    Saffarini, G.; Jarrar, G.

    2002-01-01

    The Wadi Huwar pegmatite (WHP) is hosted in a two-mice monzogranite (TMG). The host rock is a post-tectonic granitoid intrusion, belongs to the Rahma suite of the Aqaba complex and represents a late stage of the Pan-African orogeny. The emplacement of the pegmatite was controlled by the late Pan-African tectonics. The pegmatites and their host are mainly composed of quartz, alkali feldspar, Na-plagioclase, muscovite and biotite. Garnet and zircon are accessories in the monzogranite, whereas in the hosted pegmatites both minerals are abundant. Major, minor and trace element geochemistries indicate that the pegmatites and their host are peraluminous in nature and were intruded under a syn-collision tectonic regime. The mineralogical simplicity, decrease in abundance of ferromagnesian minerals in pegmatite and the sharp contacts with the host, as well as phase equilibria calculations using muscovite chemistry imply that the studied pegmatites might have crystallized during magma ascent to low crustal levels (2 Kbar and 550 deg C). Based on pegtrographic, geochemical and economic evaluation, the studied pegmatites were found to be unprofitable. (authors) 32., 9 figs., 6 tabs

  7. Harlequin color change in preterm infant | Hamida | Pan African ...

    African Journals Online (AJOL)

    Pan African Medical Journal. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 22, No 1 (2015) >. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Download this PDF file. The PDF file you selected should ...

  8. Femi Osofisan's discourse on Pan-Africanism and reconciliation in ...

    African Journals Online (AJOL)

    The paper is a critical appraisal of Femi Osofisan's ideological perspectives of Pan-Africanism, imperialism and reconciliation as exemplified in his plays especially in Nkrumah-Ni… Africa-Ni and Reel, Rwanda. The paper also explores the playwright's views on the dynamics of the problems confronting the African continent ...

  9. Prostatic fossa calculus | El Abiad | Pan African Medical Journal

    African Journals Online (AJOL)

    Pan African Medical Journal. Journal Home · ABOUT · Advanced Search · Current Issue · Archives · Journal Home > Vol 21, No 1 (2015) >. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Download this PDF file. The PDF file you selected should load here if your ...

  10. Sexuality in Nigerian older adults | Olatayo | Pan African Medical ...

    African Journals Online (AJOL)

    Pan African Medical Journal. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 22, No 1 (2015) >. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Download this PDF file. The PDF file you selected should ...

  11. Cannabis body packing : a case report | Ngatchou | Pan African ...

    African Journals Online (AJOL)

    Cannabis body packing : a case report. ... a diffuse abdominal plain to the emergency department. Abdominal X-ray demonstrated multiple foreign bodies along the intestinal tract, which were found to be cannabis packets. The patient was treated conservatively with a good result. The Pan African Medical Journal 2016;24.

  12. Extreme alkali bicarbonate- and carbonate-rich fluid inclusions in granite pegmatite from the Precambrian Rønne granite, Bornholm Island, Denmark

    Science.gov (United States)

    Thomas, Rainer; Davidson, Paul; Schmidt, Christian

    2011-02-01

    Our study of fluid and melt inclusions in quartz and feldspar from granite pegmatite from the Precambrian Rønne granite, Bornholm Island, Denmark revealed extremely alkali bicarbonate- and carbonate-rich inclusions. The solid phases (daughter crystals) are mainly nahcolite [NaHCO3], zabuyelite [Li2CO3], and in rare cases potash [K2CO3] in addition to the volatile phases CO2 and aqueous carbonate/bicarbonate solution. Rare melt inclusions contain nahcolite, dawsonite [NaAl(CO3)(OH)2], and muscovite. In addition to fluid and melt inclusions, there are primary CO2-rich vapor inclusions, which mostly contain small nahcolite crystals. The identification of potash as a naturally occurring mineral would appear to be the first recorded instance. From the appearance of high concentrations of these carbonates and bicarbonates, we suggest that the mineral-forming media were water- and alkali carbonate-rich silicate melts or highly concentrated fluids. The coexistence of silicate melt inclusions with carbonate-rich fluid and nahcolite-rich vapor inclusions indicates a melt-melt-vapor equilibrium during the crystallization of the pegmatite. These results are supported by the results of hydrothermal diamond anvil cell experiments in the pseudoternary system H2O-NaHCO3-SiO2. Additionally, we show that boundary layer effects were insignificant in the Bornholm pegmatites and are not required for the origin of primary textures in compositionally simple pegmatites at least.

  13. Field, geochemistry and Sr-Nd isotopes of the Pan-African granitoids from the Tifnoute Valley (Sirwa, Anti-Atlas, Morocco): a post-collisional event in a metacratonic setting

    Science.gov (United States)

    Toummite, A.; Liegeois, J. P.; Gasquet, D.; Bruguier, O.; Beraaouz, E. H.; Ikenne, M.

    2013-10-01

    In the Tifnoute Valley, three plutonic units have been defined: the Askaoun intrusion, the Imourkhssen intrusion and the Ougougane group of small intrusions. They are made of quartz diorite, granodiorite and granite and all contain abundant mafic microgranular enclaves (MME). The Askaoun granodiorite and the Imourkhssen granite have been dated by LA-ICP-MS on zircon at 558 ± 2 Ma and 561 ± 3 Ma, respectively. These granitic intrusions are subcontemporaneous to the widespread volcanic and volcano-detrital rocks from the Ouarzazate Group (580-545 Ma), marking the post-collisional transtensional period in the Anti-Atlas and which evolved towards alkaline and tholeiitic lavas in minor volume at the beginning of the Cambrian anorogenic intraplate extensional period. Geochemically, the Tifnoute Valley granitoids belong to an alkali-calcic series (high-K calc-alkaline) with typical Nb-Ta negative anomalies and no alkaline affinities. Granitoids and enclaves display positive ɛNd-560Ma (+0.8 to +3.5) with young Nd-TDM between 800 and 1200 Ma and relatively low 87Sr/86Sr initial ratios (Sri: 0.7034 and 0.7065). These values indicate a mainly juvenile source corresponding to a Pan-African metasomatized lithospheric mantle partly mixed with an old crustal component from the underlying West African Craton (WAC). Preservation in the Anti-Atlas of pre-Pan-African lithologies (c. 2.03 Ga basement, c. 800 Ma passive margin greenschist-facies sediments, allochthonous 750-700 Ma ophiolitic sequences) indicates that the Anti-Atlas lithosphere has not been thickened and was never an active margin during the Neoproterozoic. After a transpressive period, the late Ediacaran period (580-545 Ma) is marked by movement on near vertical transtensional faults, synchronous with the emplacement of the huge Ouarzazate Group and the Tifnoute Valley granitoids. We propose here a geodynamical model where the Tifnoute Valley granitoids as well as the Ouarzazate Group were generated during the post

  14. Avalonian (Pan-African) mylonitic deformation west of Boston, U.S.A.

    Science.gov (United States)

    Rast, N.; Skehan, J. W.

    1995-07-01

    West of Boston, Mass., Castle and others (1976) recognized an up to 5km wide, possibly folded, NE-SW trending Burlington Mylonite Zone. We have extended mapping south into Natick and Framington quadrangles, and supplemented it by fixing local directions of tectonic motion, which are more variable than reported by Goldstein (1989). In Natick the mylonite zone is partly migmatized and converted into blastomylonites, forming the lithodemic Rice Gneiss and is intersected by the Dedham Granite dated ca 630 Ma. The granite also invades deformed, folded, and commonly mylonitized Westboro Quartzite. Thus mylonitization, folding, and formation of migmatitic blastomylonites are all earlier than ca 630 Ma, and can collectively be attributed to the main phase of the Avalonian orogeny that in Africa is referred to as the Pan-African I. The sense of movements in the Rice Gneiss is generally sinistral strike-slip with a NE-SW trend of foliation. Other local mylonites have more variable directions of motion. A narrower E-W zone of mylonitization has been recognized by Grimes (M.S. thesis 1993, Boston College) and named the Nobscot Shear Zone. It affects the Milford Granite, also about 630 Ma in age, while similar but narrow shear zones affect other local granites including the Dedham. These zones, dipping steeply north and including the Nobscot, are less intensely mylonitized and are not associated with migmatites. Their age is not known, but since they affect only Precambrian rocks, they are assumed to be late Proterozoic. We attribute these zones to the second stage of the Avalonian or the Pan-African II. The older rocks west of Boston are widely affected by numerous brittle faults. These are all of unknown age, but probably Phanerozoic. The most significant brittle fault in the Burlington area is the mid to late Paleozoic Bloody Bluff Fault. We do not associate large scale mylonitization with that fault, because the mylonites are commonly cut by undeformed or little deformed

  15. New U Pb SHRIMP zircon age for the Schurwedraai alkali granite: Implications for pre-impact development of the Vredefort Dome and extent of Bushveld magmatism, South Africa

    Science.gov (United States)

    Graham, I. T.; De Waal, S. A.; Armstrong, R. A.

    2005-12-01

    The Schurwedraai alkali granite is one of a number of prominent ultramafic-mafic and felsic intrusions in the Neoarchaean to Palaeoproterozoic sub-vertical supracrustal collar rocks of the Vredefort Dome, South Africa. The alkali granite intruded the Neoarchaean Witwatersrand Supergroup and has a peralkaline to peraluminous composition. A new zircon SHRIMP crystallization age of 2052 ± 14 Ma for the Schurwedraai alkali granite places it statistically before the Vredefort impact event at 2023 ± 4 Ma and within the accepted emplacement interval of 2050-2060 Ma of the Bushveld magmatic event. The presence of the alkali granite and associated small ultramafic-mafic intrusions in the Vredefort collar rocks extends the southern extremity of Bushveld-related intrusions to some 120 km south of Johannesburg and about 150 km south of the current outcrop area of the Bushveld Complex. The combined effect of these ultramafic-mafic and felsic bodies may have contributed to a pronouncedly steep pre-impact geothermal gradient in the Vredefort area, and to the amphibolite-grade metamorphism observed in the supracrustal collar rocks of the Vredefort Dome.

  16. Old model Nd ages in Namibian Pan-African rocks

    International Nuclear Information System (INIS)

    Hawkesworth, C.J.; Kramers, J.D.

    1981-01-01

    The Nd-isotope analytical technique has been used to study the Damara high-temperature belt of Namibia formed during the widespread orogenic event categorized as Pan African. The results are presented of an investigation by Nd and Sr isotopes of the range in age and geochemical characteristics of rock sequences and provinces within both the upper mantle and the pre-existing crust which were sampled during the orogeny, and hence provided the major components of what is now a stable segment of continental crust. (U.K.)

  17. Proceedings: Onderstepoort Centenary Pan-African Veterinary Conference : foreword

    Directory of Open Access Journals (Sweden)

    Editorial Office

    2009-09-01

    Full Text Available In 1908 a Pan-African Veterinary Conference formed part of the inauguration ceremony of the Onderstepoort Veterinary Laboratory. Attended by 18 delegates from 12 countries in southern Africa, including the four colonies and three protectorates forming British South Africa, Rhodesia, German South West Africa, Portuguese East Africa, Madagascar and the Belgian Congo, discussions focussed on the animal diseases of the region with the emphasis on trypanosomosis (nagana and East Coast fever. The successful meeting was followed by a series of similar conferences held in different African countries during the first half of the 20th Century.

  18. Rn-222 release to the environment: comparison between different granite sources

    International Nuclear Information System (INIS)

    Mamoon, M.; Kamal, S.M.

    2005-01-01

    In this work three different types of granites were studied, namely: pure granite, alkali granite and altered (hydrated) alkali granite. General radioactivity of the granites was studied along with the potential for 222 Rn emanation. The study indicated that altered alkali granite releases, relatively, the highest 222 Rn emanation to the surrounding air while alkali granite emits the more intense gamma radiation of the three granites. Hence, altered alkali granite can be used as a laboratory source for 222 Rn.

  19. Paleomagnetism and tectonic evolution of the Pan-African Damara Belt, southern Africa

    Science.gov (United States)

    McWilliams, M. O.; KröNer, A.

    1981-06-01

    Paleomagnetic results are reported from the Nosib, Otavi, and Mulden groups of the Damara Supergroup, a late Precambrian shelf sequence on the southern margin of the Congo craton in Namibia. Three magnetizations were isolated in the Nosib group samples. In order of decreasing blocking temperature they are NQ1 (n = 6 sites, λ = 28°N, ϕ = 323°E, α95 = 15°), NQ2 (n = 7 sites, λ = 51°S, ϕ = 213°E, α95 = 12°), and NQ3 (n = 13 samples, λ = 09°N, ϕ = 295°E, α95 = 13°). Overall precision of all three magnetizations upon tectonic correction suggests that they predate Pan-African (650-450 Ma) folding. Two magnetizations were isolated in the Otavi group samples, above the Nosib in stratigraphic sequence. The DC1 component of possible prefolding age (n = 4 sites, λ = 52°S, ϕ = 186°E, α95 = 35°) has been over-printed by the DC2 magnetization (n = 10 sites, λ = 55°S, ϕ = 044°E, α95 = 15°) of probable postfolding age. A single magnetization of probable pre-folding age was isolated in the overlying Mulden Group samples (n = 6 sites, λ = 12°S, ϕ = 090°E, α95 = 16°). Together with previously published paleomagnetic data from Africa, the new data showed that no great relative movements have occurred between the Congo and Kalahari cratons during the interval of Pan-African tectonism in the Damara belt (McElhinny and McWilliams, 1977). Continental collision preceded by large relative displacements and closure of a wide ocean (e.g., a Himalayan analog) is effectively ruled out for the Damara belt. We develop an alternative model consistent with the available paleomagnetic and geologic data, which invokes rifting, heating, and stretching of the lithosphere underneath the Damara belt, followed by delamination of the subcrustal lithosphere. Hot asthenospheric material rises to take the place of the detached and sinking lithospheric base, inducing subduction and interstacking of continental crust. The much thickened continental crust is partially melted

  20. Indirect dating of deformation: a geochronological study from the Pan African Ajaj shear zone, Saudi Arabia.

    Science.gov (United States)

    Hassan, Mahmoud; Abu-Alam, Tamer; Stüwe, Kurt; Klötzli, Urs

    2013-04-01

    The metamorphic complexes of the Arabian-Nubian Shield were exhumed by different exhumation mechanisms (i.e. in extension or oblique transpression regime) during the Pan African activity of Najd Fault System - the largest pre-Mesozoic shear zone on Earth. The different exhumation mechanisms could be the consequence of (i) orientation of the complexes at slightly different angles with respect to the overall orientation of the principal stresses of the Najd Fault System, (ii) exhumation from different depths, or (iii) change of the stress regime through time. In order to test the third hypothesis, geochronological work will be applied on a representative suite of complexes across the Najd Fault System. In particular we focus on three complexes in the Arabian part of the shield named Qazaz, Hamadat and Wajh. In general, the metamorphic complexes of the Arabian part of the shield exhibit left-lateral transcurrent tectonism along the NW-SE Najd faults and right-lateral movement along conjugate NE-SW striking structures. The whole unit forms an anastomosing network of planar structures that demarcate large fish-shaped bodies of high grade metamorphics. The Hamadat complex is surrounded by a left-lateral greenshist facies WNW-ESE Ajaj shear zone. The complex consists of folds that are strongly pinched to the north and more open to the south marked by a well-developed parallel stretching sub-horizontal lineation. Granite intrusions along and across the Ajaj shear zone may allow testing the timing of the deformation. Deformed and non-deformed samples of these granites will be examined by age dating to determine the absolute timing of the metamorphism and the deformation for the complex. Some 20 samples are currently being prepared for zircon dating. Whilst no results are available at the time of writing of this abstract, they will be presented at EGU 2013.

  1. Wadi Ladid Al-JI,Dan Alkali Feldspar Granites and Associated Pegmatites, North Eastern Eser, Egypt:Geology,Mineralogy and Radioactivity

    International Nuclear Information System (INIS)

    Abu Steet, A.A.; Ayoub, R.R.; Bakhit, A.F.

    2013-01-01

    This article deals with the geology, structure, mineralogy and radioactivity of the alkali feldspar granites at wadi Ladid al-Ji,dan, north Eastern Desert of Egypt. Geologically, the area consists mainly of alkali feldspar granites. These granites are medium to coarse grained, pink to red in colour and form numbers of moderate to relatively high elevated outcrops. These rocks are altered in some parts due to secondary processes especially along the fault zones and contacts. The area displays primary and secondary structures. Primary structures comprise layering, volcanic flows, vesicular tops of lavas and volcanic bombs. The secondary structures are represented by exfoliation, joints and faults. The granites are dissected by several sets of joints predominating in the N-S direction, dipping 84°-88° mainly to west; E-W direction, dipping 70°-75° mainly to south and NW-SE direction, dipping 80°-82° to SW direction. The majority of joints are tension ones. These tension joints are commonly filled with quartz, feldspars, epidote, iron oxides, manganese oxides and aplite. The studied area is dissected by major regional faults. Along the fault zones; the granites are marked by fault breccia and alteration features, especially silicification, hematitization, kaolinitization and chloritization. The area is cutting by faults trending mainly in N-S, NE-SW and NNW-SSE directions. The average uranium and thorium contents of the alkali feldspar granites are 12 and 23 ppm and reaches up to 36 and 37 ppm in the normal pegmatites. In the anomalous pegmatites the maximum values recorded are 91 and 72 ppm. Generally, the averages of uranium and thorium contents in the studied pegmatites are higher than that of the world and Egyptian uraniferous pegmatites. The high uranium content in alkali feldspar granites is related to the presence of some accessory minerals such as zircon, fluorite and apatite but the high uranium content in the pegmatites is related to the presence of

  2. Geochemical characteristics of Proterozoic granite magmatism from Southern Granulite Terrain, India: Implications for Gondwana

    Science.gov (United States)

    Yellappa, T.; Rao, J. Mallikharjuna

    2018-03-01

    Granitoid intrusions occur widely in the Southern Granulite Terrain (SGT) of India, particularly within the Cauvery Suture Zone (CSZ), which is considered as the trace of the Neoproterozoic Mozambique ocean closure. Here we present the petrological and geochemical features of 19 granite plutons across the three major tectonic blocks of the terrain. Our data show a wide variation in the compositions of these intrusions from alkali feldspathic syenite to granite. The whole rock geochemistry of these intrusions displays higher concentrations of SiO2, FeO*, K2O, Ba, Zr, Th, LREE and low MgO, Na2O, Ti, P, Nb, Y and HREE's. The granitoids are metaluminous to slightly peraluminous in nature revealing both I-type and A-type origin. In tectonic discrimination plots, the plutons dominantly show volcanic arc and syn-collisional as well as post-collisional affinity. Based on the available age data together with geochemical constrains, we demonstrate that the granitic magmatism in the centre and south of the terrain is mostly associated with the Neoproterozoic subduction-collision-accretion-orogeny, followed by extensional mechanism of Gondwana tectonics events. Similar widespread granitic activity has also been documented in the Arabian Nubian shield, Madagascar, Sri Lanka and Antarctica, providing similarities for the reconstruction of the crustal fragments of Gondwana supercontinent followed by Pan-African orogeny.

  3. Pan-africanism and its impact on the sierra leonean elite up to 1945

    OpenAIRE

    faiza, meberbeche

    2014-01-01

    Pan-africanism is a protest movement besed of the belief that all the blacks of african descent inside africa and throughout the diaspora must unite under a major and effective global force tp achieve the lost dignity.

  4. Pan-Africanism Caught in the Crossfire of Identity and Globalization

    African Journals Online (AJOL)

    Pan-Africanism Caught in the Crossfire of Identity and Globalization. ... the extent that 'globalization' is as much a subject of media interest as of academic enquiry. ... over time, across space, and within and between cultures and social classes.

  5. Tracing the HIMU component within Pan-African lithosphere beneath northeast Africa: Evidence from Late Cretaceous Natash alkaline volcanics, Egypt

    Science.gov (United States)

    Abu El-Rus, M. A.; Chazot, G.; Vannucci, R.; Paquette, J.-L.

    2018-02-01

    A large late Cretaceous ( 90 Ma) volcanic field (the Natash volcanic province) crops out in southeast Egypt at the northwestern boundary of the Arabian-Nubian shield. The lavas are mainly of alkaline affinity and exhibit a continuous compositional range from alkali olivine basalt (AOB) to trachyte and rhyolite. All basaltic lavas in the province record various extents of fractional crystallization of olivine, clinopyroxene, plagioclase and spinel. The basaltic lavas show variations in Sr-Nd-Pb-Hf isotopic ratios [(87Sr/86Sr)i = 0.7030-0.70286; (143Nd/144Nd)i = 0.512653-0.512761; (206Pb/204Pb)i = 19.28-19.94; (177Hf-176Hf)i = 0.28274-0.28285], that correlate markedly with the major and trace element ratios and abundances. Assimilation of crustal material cannot explain these correlations, and we invoke instead melting of a multicomponent mantle source. We infer the existence of High-μ (HIMU), Enriched mantle type-I (EM-I) and Depleted mantle (DM) domains in the melting source, with a predominant contribution from the HIMU-type. We suggests further that the basaltic lavas originate from low degrees of partial melting (F negative K-anomalies in the primitive mantle-normalized patterns of the fractionation-corrected melts. The presence of amphibole within the lithosphere is a strong evidence that the lithospheric mantle underwent metasomatic enrichment prior to melting in Late Cretaceous. This metasomatic event affected on the Pb isotopic compositions of the Natash volcanics by adding Th and U to the melting source. Time-integrated calculations to remove the decoupling between 206Pb and 207Pb isotopes that most probably resulted from the metasomatic event indicate a tentative link between the metasomatism occurring in the Pan-African lithospheric mantle and the formation of juvenile crust during the Pan-African Orogeny. A two stage evolution model is therefore proposed for volcanism in the Natash area: fluxing of the lithosphere by hydrous fluids during Pan-African

  6. Tibet- Himalayan Analogs of Pan-African Shear Zones : Implications for Neoproterozoic Tectonics

    Science.gov (United States)

    Attoh, K.; Brown, L. D.

    2009-12-01

    Large-scale shear zones are distinct features of Tibet-Himalayan orogen and the Pan-African Trans-Saharan belt. Prominent examples in the Pan-African-belt extend for ~2500 km from the Sahara to the Gulf of Guinea and are characterized by right-slip movements. The NS shear zones, such as 4°50’-Kandi shear zone (KSZ) are complemented by NE-SW shear zones that preserve a record of sinistral movements and are represented by the Central Cameroon shear zone (CCSZ) in the eastern part of the Pan-African domain. The West African shear zones project into similar structures in the Borborema Province of northeast Brazil. In addition, the Pan-African belt preserves structures and rock assemblages that indicate subduction-collision tectonics We propose that structures of Tibet-Himalayan collisional orogen are instructive analogs of the Pan-African structures where: (i) the Pan-African front corresponds to the Main Himalayan thrust and it’s splays; (ii) the main Pan-African suture zone is analogous to the Indus-Tsangpo suture in the Tibet-Himalayan belt; (iii) the 4°50’-KSZ corresponds to Karakoram and it’s linkages with Jiali fault system and (iv) left-slip CCSZ and related shear zones are analogs of Altyn Tagh and Kumlun faults and their splays. This suggests the operation of escape-type tectonics in the Neoproterozoic belt of West-Africa and predicts the nature of the deep structures in the Cenozoic Tibet-Himalayan orogen.

  7. The LATEA metacraton (Central Hoggar, Tuareg shield, Algeria): behaviour of an old passive margin during the Pan-African orogeny

    Science.gov (United States)

    Liégeois, Jean Paul; Latouche, Louis; Boughrara, Mustapha; Navez, Jacques; Guiraud, Michel

    2003-10-01

    850 Ma to the west of LATEA, the Serouenout terrane in the 700-620 Ma age range to the east. No subduction-related magmas have intruded LATEA during this epoch, which behaved as a passive margin. During the main Pan-African phase (625-580 Ma), LATEA was dissected by mega-shear zones that induced several hundreds km of relative displacement and allowed the emplacement of high-K calc-alkaline batholiths. Smaller movements continued till 525 Ma, accompanied by the emplacement of subcircular plutons with alkaline affinity. Here is dated the Ounane granodiorite (624 ± 15 Ma; 87Sr/ 86Sr i=0.70839 ± 0.00016; 6WR, MSWD=0.87) and the Tisselliline granite (552 ± 15 Ma; 87Sr/ 86Sr i=0.7074 ± 0.0001; 5WR, MSWD=1.4). Nd isotopes indicate a preponderant Palaeoproterozoic crustal source for these two plutons: ɛNd=-14 to -21 at 624 Ma and TDM=1650-2320 Ma for Ounane and ɛNd=-13 to -15 at 555 Ma and TDM=1550-1720 Ma for Tisselliline. Our model links these intrusions to a linear lithospheric delamination along mega-shear zones, allowing the hot asthenosphere to rise, melt by adiabatic pressure release and inducing the melting of the Palaeoproterozoic and Archaean lower crust. The LATEA cratonic microcontinent remained however sufficiently rigid to preserve Archaean and Palaeoproterozoic lithologies as well as Middle Neoproterozoic oceanic thrust sheets. This corresponds to the notion of metacraton [J. African Earth Sci. 34 (2002) 119], i.e. a craton that has been remobilized during an orogenic event but is still recognizable dominantly through its rheological, geochronological, isotopic and sometimes petrological characteristics.

  8. Mueilha rare metals granite, Eastern Desert of Egypt: An example of a magmatic-hydrothermal system in the Arabian-Nubian Shield

    Science.gov (United States)

    Abu El-Rus, Mohamed A.; Mohamed, Mohamed A.; Lindh, Anders

    2017-12-01

    The Mueilha granite pluton is one of the rare-metals bearing peraluminous granitic plutons in the Arabian-Nubian Shield. It represents the apical part of a highly evolved magma chamber emplaced at a shallow level subsequent to the post Pan-African orogeny. The pluton can be seen as a highly leucocratic medium-grained albite/oligoclase framework infilled with quartz, K-feldspar and muscovite that are variably overgrown by K-feldspar, muscovite, quartz and topaz megacrysts. The increasing number and size of the K-feldspar megacrysts at the expense of the whitened albite/oligoclase framework imparts variably red color to the Mueilha granite. Contacts between the milky white and red granites are usually gradational, but may be locally sharp or may form narrow transition zones resulting from abrupt variations in texture and lithology. Textural relations indicate an initial stage of hydrothermal albitization of magmatic plagioclase and crystallization of topaz megacrysts resulting from infiltration of Na-rich fluorine bearing fluids. A subsequent stage of metasomatic enrichment is characterized by extensive growth of large K-feldspar, quartz and muscovite megacrysts at the expense of the albite/oligoclase crystals as a result of infiltration of K-Si rich hydrous fluids. Post-magmatic infiltration of hydrous fluids along the fault planes is shown by the intense replacement of alkali feldspar megacrysts by quartz, development of myrmekitic intergrowth pockets along the K-feldspar megacrysts and sealing of the micro-fractures by cryptocrystalline mixtures of clay minerals, iron oxides, sericite and chlorite. Compositionally, the red granitic rocks have higher SiO2, Fe2O3total, K2O/Na2O, Σ REE, Y, Th, U, Zr and Zn and lower Al2O3, Ga, Ta, Nb and Mo compared to the milky white granites. LILE and Sn do not show clear variation trends throughout the Mueilha granite pluton, suggesting their immobility during hydrothermal alteration. Microthermometric measurements indicate that

  9. Superposition de la tectonique éburnéenne et panafricaine dans les granitoïdes de la bordure nord du craton ouest africain, boutonniére de Zenaga, Anti-Atlas central, Maroc(Pan-african overprint on Eburnian granitoids at the northern boundary of the West African Craton, Zenaga Inlier, central Anti-Atlas, Morocco)

    Science.gov (United States)

    Ennih, N.; Laduron, D.; Greiling, R. O.; Errami, E.; de Wall, H.; Boutaleb, M.

    2001-05-01

    The Zenaga Inlier shows a comprehensive record of the Eburnian and Pan-African Orogenies. The Eburnian is characterised by high-temperature regional metamorphism and complex magmatism. The early (Azguemerzi) granodiorite has an isotopic mantle signature and was emplaced diapirically during the Eburnian Orogeny causing local thermal metamorphism. The foliation observed in this granitoid is a result of the interference between its primary syn-emplacement foliation and the regional foliation under amphibolite-facies conditions. The northern part of Zenaga has been intruded by the leucocratic granites of Tazenakht. These granites are cut by mylonites and phyllonites, corresponding to the Pan-African shear zones and accompanied with sub-greenschist-facies metamorphism during the Pan-African Orogeny. The deformation was the result of a regional sinistral transpressive event. This study in the northern part of the West African Craton shows the superposition of the Pan-African on the Eburnian Orogeny and the presence of a major fault in the Anti-Atlas.

  10. Kinematic evolution of the Mbakop Pan-African granitoids (western Cameroon domain): An integrated AMS and EBSD approach

    Science.gov (United States)

    Bella Nké, B. E.; Njanko, T.; Mamtani, M. A.; Njonfang, E.; Rochette, P.

    2018-06-01

    This study integrates anisotropy of magnetic susceptibility, microstructural and crystallographic preferred orientation (CPO) data from the Mbakop granitic pluton (MGP; Pan-African age) in order to decipher its kinematic evolution. The MGP lies close to NE-SW branch of Central Cameroon Shear Zone (CCSZ) and is emplaced in gneissic basement. High mean magnetic susceptibility and presence of multi-domain magnetite are recorded. Quartz CPO measured using Electron Backscatter diffraction reveals dominance of rhomb , prism and prism slip in different samples, which is consistent with microstructures developed under upper greenschist/amphibolite facies conditions. Quartz CPO along with other kinematic indicators (feldspar porphyroclasts/mineral fish) indicate non-coaxial deformation was important during tectonic evolution of the MGP. Contrasting sense of shear is recorded implying multi-stage mylonitization in the Western Cameroon Domain. Top-towards-south sense of shear is related to regional D2 deformation (613-585 Ma), while top-towards-north is related to D3 (585-540 Ma). The magnetic fabric in MGP records D3. The obliquity between mean orientation of magnetic foliation (N12°E) and the NE-SW CCSZ branch (N48°E) gives kinematic vorticity number of 0.95. This indicates dominantly simple shear with a minor pure shear component. It is concluded that regional transpression was important during MGP emplacement.

  11. The rhetoric of Pan-Africanism and the debate on African identity in ...

    African Journals Online (AJOL)

    apartheid South Africa within the context of former President Mbeki's Pan-African reflections on the African Renaissance in his quest to include South Africa in two power games. Firstly, President Mbeki aims to insert South Africa into the politics of ...

  12. Black Americans, Africa and History: A Reassessment of the Pan-African and Identity Paradigms.

    Science.gov (United States)

    Adeleke, Tunde

    1998-01-01

    Examines the paradigm of Pan-Africanism and the identity construct in the historic and cultural contexts of blacks outside of Africa, critiquing theories on the African identity construct. Suggests that black American identity is too complex for this simplification and must be considered within the context of world acculturation. Contains 34…

  13. A purple swelling on the tongue | Panta | Pan African Medical Journal

    African Journals Online (AJOL)

    Hemangiomas are benign hamartomatous lesions that are slow growing, sessile or pedunculated, smooth or lobulated, red swellings which sometimes exhibit a bluish hue. Hemangiomas of the tongue need special attention due to their susceptability to trauma from masticatory forces. Pan African Medical Journal 2015; 21 ...

  14. Sarcome d'Ewing de localisation pétreuse | Lahiani | Pan African ...

    African Journals Online (AJOL)

    Pan African Medical Journal. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 22, No 1 (2015) >. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Download this PDF file. The PDF file you selected should ...

  15. Geology of the Pan-African basement Complex in Ube-Wulko area ...

    African Journals Online (AJOL)

    The Ube-Wulko area of southeast Akwanga falls within the Pan-African remobilized Basement Complex of northcentral Nigeria. It consists of intensely multi-deformed high grade polymetamorphic basement rocks, predominantly composed of migmatitic gneisses and schists and subordinate quartzites, marbles, and ...

  16. Sepsis in Africa: practical steps to stem the tide | Otu | Pan African ...

    African Journals Online (AJOL)

    Pan African Medical Journal. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 21, No 1 (2015) >. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Download this PDF file. The PDF file you selected should ...

  17. Report of the 10th Biennial conference of Pan African Pediatric ...

    African Journals Online (AJOL)

    Keywords: congress, Egyptian Pediatric Surgical Association, Pan African. Pediatric Surgical Association, report. Department of Surgery, Pediatric surgery unit, Faculty of Medicine, Tanta. University, Tanta, Egypt. Correspondence to Essam Elhalaby, MD, Division of Pediatric Surgery,. Faculty of Medicine, Tanta University, ...

  18. Bullose diabétique | El Makrini | Pan African Medical Journal

    African Journals Online (AJOL)

    Therapeutically, no particular treatment seems necessary except local antiseptic care after the recess bubbles. Bullosis diabeticorum is a characteristic skin complication of diabetes. Its etiology is still unknown. Its evolution is benign and its management is essentially preventive. Pan African Medical Journal 2016; 23 ...

  19. Snake bite on scrotum – a case report | Arshad | Pan African Medical ...

    African Journals Online (AJOL)

    Pan African Medical Journal. Journal Home · ABOUT · Advanced Search · Current Issue · Archives · Journal Home > Vol 10 (2011) >. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Download this PDF file. The PDF file you selected should load here if your Web ...

  20. Syndrome de moelle bas attachée | Badaoui | Pan African Medical ...

    African Journals Online (AJOL)

    Pan African Medical Journal. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 22, No 1 (2015) >. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Download this PDF file. The PDF file you selected should ...

  1. Cervical hibernoma in a two year old boy | Khattala | Pan African ...

    African Journals Online (AJOL)

    Pan African Medical Journal. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 16, No 1 (2014) >. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Download this PDF file. The PDF file you selected should ...

  2. Sepsis in Africa: practical steps to stem the tide | Otu | Pan African ...

    African Journals Online (AJOL)

    Sepsis in Africa: practical steps to stem the tide. Akaninyene Otu, James Elston, Emmanuel Nsutebu. Abstract. Pan African Medical Journal 2015; 21. Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT · AJOL African Journals Online. HOW TO USE AJOL.

  3. Exploring Pan-Africanism's theories: from race-based solidarity to political unity and beyond

    Czech Academy of Sciences Publication Activity Database

    Kasanda, Albert

    2016-01-01

    Roč. 28, č. 2 (2016), s. 179-195 ISSN 1369-6815 Institutional support: RVO:67985955 Keywords : solidarity * unity * sovereignty * race * Africa * Afropolitanism * Pan-Africanism * colonization Subject RIV: AA - Philosophy ; Religion Impact factor: 0.917, year: 2016

  4. Tectonometamorphic evolution of Ghana, Togo and Benin in the light of the Pan-African/Brasiliano orogeny

    Science.gov (United States)

    Castaing, C.; Triboulet, C.; Feybesse, J. L.; Chèvremont, P.

    1993-02-01

    The South Pan-African belt of West Africa (Ghana, Togo and Benin province) can be divided into three domains: (1) the external nappes thrust over the West African craton, derived from passive-margin sedimentary deposits (Middle to Late Proterozoic) and displaying middle- to high-pressure metamorphism, such as the Kanté and Atacora nappes; (2) the intermediate nappes including the suture-zone rocks with eclogitic assemblages (protoliths ca. 800 Ma), and mainly monocyclic metasedimentary rock and orthogneiss, that are found in central Togo and northwest Benin; (3) the internal nappes composed of high-grade commonly anatectic gneiss (anatexis ca. 600 Ma), including orthogneiss (Eburnian plutons), elongated granulite belts, reworked Archean basement, and an intrusive granite and charnockite association (ca. 600 Ma), which are exposed in Benin and Nigeria. The P- T- t- d paths calculated from rocks in these three domains show a prograde-retrograde evolution: (1) an initial clockwise evolution related to an early burial stage ( HP- HT in the intermediate nappes) followed by oblique thrusting in a SW direction, that caused nappe stacking and subsequent uplift; (2) a second anti-clockwise evolution with late temperature and pressure increases, only recorded in the more internal units. This temperature increase was a consequence of the previous crustal thickening with subsequent doming, extension and anatexis. The pressure increase was related to movement along the Kandi fault, working as a dextral strike-slip fault with a transpressional component under late E-W shortening. The retrograde trend corresponds to the final uplift. The evolution of the belt can thus be divided into three successive stages: (1) a first stage was characterized by an oblique collision inducing SW oblique thrusting with associated syn-foliation reverse metamorphism; (2) during a second stage anatectic doming took place; followed by (3) a third stage at still high temperature with dextral wrench

  5. Geology and mineralization of the Jabalat alkali-feldspar granite, northern Asir region, Kingdom of Saudi Arabia

    Science.gov (United States)

    Al Tayyar, Jaffar; Jackson, Norman J.; Al-Yazidi, Saeed

    The Jabalat post-tectonic granite pluton is composed of albite- and oligoclase-bearing, low-calcium, F-, Sn- and Rb-rich subsolvus granites. These granites display evidence of late-magmatic, granitophile- and metallic-element specialization, resulting ultimately in the development of post-magmatic, metalliferous hydrothermal systems characterized by a Mo sbnd Sn sbnd Cu sbnd Pb sbnd Zn sbnd Bi sbnd Ag sbnd F signature. Two main types of mineralization are present within the pluton and its environs: (1) weakly mineralized felsic and aplitic dikes and veins enhanced in Mo, Bi, Ag, Pb and Cu; and (2) pyrite—molybdenite—chalcopyrite-bearing quartz and quartz—feldspar veins rich in Mo, Sn, Bi, Cu, Zn and Ag. A satellite stock, 3 km north of the main intrusion, is composed of fine-grained, miarolitic, muscovite—albite—microcline (microperthite) granite. The flanks of this intrusion and adjacent dioritic rocks are greisenized and highly enriched in Sn, Bi and Ag. Quartz veins which transect the satellite stock contain molybdenite and stannite.

  6. Seismic signatures of the Pan-African orogeny: implications for southern Indian high-grade terranes

    Science.gov (United States)

    Rai, Abhishek; Gaur, V. K.; Rai, S. S.; Priestley, K.

    2009-02-01

    We present the results of a study designed to investigate and compare the seismic characteristics of the once contiguous terranes of eastern Gondwanaland, now incorporated in five separated continental masses, which, during the Neoproterozoic (~600Ma) Pan-African orogeny, suffered a high degree of thermal stress and deformation. Receiver functions and surface wave data from stations located in East Antarctica, Sri Lanka, the southern-Indian high-grade terranes, Madagascar and the Tanzania-Mozambique belt, were used to determine the shear-wave velocity structure, Moho depth and VP/VS values of the respective crustal segments. This study provides an additional dimension to the otherwise well-documented characteristic petrology of their surface exposures and other geological signatures such as their extensive granulitization and gem formation during the Pan-African event. Analysis of the receiver functions and surface wave data for these seismic stations located on their present day widely distributed continental fragments have been made. It is observed that with the exception of KOD (at Kodaikanal hill), situated on the southern Indian granulites having the thickest crust (~43.5 km), most of the Pan-African granulitic terranes have a crustal thicknesses of ~37 +/- 0.8km, with a transition to higher velocity at mid-crustal depths, and that their bulk composition is felsic. Average crustal VP/VS values (1.704 +/- 0.03) and thicknesses (37.8 +/- 0.8km), for four stations (SYO, PALK, TRV and ABPO), now located in East Antarctica, Sri Lanka, India and Madagascar, respectively, show remarkable similarity, indicating that the Pan-African orogeny was extensive enough to reorder the crustal structure of a wide region with a broadly similar stamp.

  7. Questionnaire survey of the pan-African trade in lion body parts

    OpenAIRE

    Williams, Vivienne L.; Loveridge, Andrew J.; Newton, David J.; Macdonald, David W.

    2017-01-01

    The African lion is in decline across its range, and consumptive utilisation and trade of their body parts and skins has been postulated as a cause for concern. We undertook a pan-African questionnaire and literature survey to document informed opinion and evidence for the occurrence of domestic and international trade and consumption in African lion body parts across current and former range states. Sixty-five people from 18 countries participated in the online questionnaire survey (run from...

  8. The Pan-African continental margin in northeastern Africa: Evidence from a geochronological study of granulites at Sabaloka, Sudan

    International Nuclear Information System (INIS)

    Kroener, A.

    1987-01-01

    Ion microprobe zircon ages, a Nd model age and Rb-Sr whole-rock dates are reported from the high-grade gneiss terrain at Sabaloka on the River Nile north of Khartoum, formally considered to be part of the Archaean/early Proterozoic Nile craton. The granulites, which are of both sedimentary and igneous derivation, occur as remnants in migmatites. Detrital zircon ages range from ≅ 1000 to ≅ 2650 Ma and prove the existence of Archaean to late Proterozoic continental crust in the sedimentary source region. The Nd model age for one sedimentary granulite is between 1.26 (T CHUR ) and 1.70 (T DM ) Ga and provides a mean crustal residence age for the sedimentary precursor. Igneous zircons in enderbitic gneiss crystallized at 719±81 Ma ago, an age that also corresponds to severe Pb loss in the detrital zircons and whic probably reflects the granulite event at Sabaloka. The Rb-Sr data indicate isotropic homogenization at about 700 Ma ago in the granulites and severe post-granulite disturbance at ≅ 570 Ma in the migmatites. We associate this disturbance with hydration, retrograde metamorphism and anatexis that produced undeformed granites ≅ 540 Ma ago. The ≅ 700 Ma granulite event at Sabaloka suggests that this part of the Sudan belongs to the Pan-African Mozambique belt while the ancient Nile craton lay farther west. The gneisses studied here may represent the infrastructure of the ancient African continental margin onto which the juvenile arc assemblage of the Arabian-Nubian shield was accreted during intense horizontal shortening and crustal interstacking of a major collision event. (orig.)

  9. Radiometric, magnetic, and gravity study of the Quixadá batholith, central Ceará domain (NE Brazil): evidence for Pan-African/Brasiliano extension-controlled emplacement

    Science.gov (United States)

    Lopes de Castro, David; Mariano Gomes Castelo Branco, Raimundo; Martins, Guttenberg; Araújo de Castro, Neivaldo

    2002-10-01

    A geophysical survey was conducted in the central Ceará domain of the Borborema Province (NE Brazil). The aim of this investigation was to find geophysical evidence for the emplacement of the Quixadá batholith, which is a granitic body probably situated in the local extensional site in the oblique collisional regime of the Pan-African/Brasiliano collage. Remote sensing and airborne geophysical data provided information on the regional deformation that affected the intrusion and surrounding country rocks. In addition, a gravity study was used to determine the three-dimensional geometry and constrain the emplacement model of the Quixadá granite at depth. The trajectories of structural and magnetic lineaments suggest that the regional deformation is strongly influenced by dextral transcurrent movements of the major shear zones. The batholith, which shows an unusual positive gravity anomaly and a low U counts, displays a subhorizontal floor with several gently dipping areas, which are interpreted as magma feeder channels. The 2300 m thick root zones are roughly aligned with NE-SW-trending shear zones. Finally, the internal architecture of the pluton suggests that the Quixadá batholith was emplaced in a dilational shear zone tip area at the north end of Quixeramobim shear zone.

  10. Thermochronology and geochemistry of the Pan-African basement below the Sab'atayn Basin, Yemen

    Science.gov (United States)

    Veeningen, Resi; Rice, A. Hugh N.; Schneider, David A.; Grasemann, Bernhard

    2015-02-01

    Three important lithologies occur in two drill wells from the Pan-African basement underlying the Mesozoic Sab'atayn Basin, in a previously undocumented area of the Pan-African, 83 and 90 km NE of known exposures in Yemen. Cores from well 1 include amphibolite, with basaltic to andesitic compositions, affected by crustal contamination during emplacement into a thickened crust. Deeper in the well, an unfoliated dark red monzogranite has a U-Pb zircon age of 628.8 ± 3.1 Ma and a Rb-Sr biotite cooling age of 591.6 ± 5.8 Ma (∼300 °C). Regional constraints suggest emplacement in a transitional tectonic setting with compressional terrane amalgamation followed by extensional collapse. Sm-Nd isotope analysis yields a TDM model age of 1.24 Ga with negative εNd values, suggesting the monzogranite is part of the Al Bayda island arc terrane. Cores from well 2 contains a weakly deformed, massive (unbedded) medium grey meta-arkose exhibiting essentially no geochemical signature of weathering and with an almost pure dacitic composition. This rock may have been directly derived from an (extrusive) granitoid that was emplaced prior to, or during terrane amalgamation. A (U-Th-Sm)/He zircon age of 156 ± 14 Ma constrains the time of basement cooling to ∼180 °C, synchronous with basin formation. These lithologies provide new insights in the development of the Pan-African basement of Yemen, extending our knowledge of the nearby surface geology to the subsurface.

  11. Uranium cycle and tectono-metamorphic evolution of the Lufilian Pan-African orogenic belt (Zambia)

    International Nuclear Information System (INIS)

    Eglinger, Aurelien

    2013-01-01

    Uranium is an incompatible and lithophile element, and thus more concentrated in silicate melt produced by the partial melting of the mantle related to continental crust formation. Uranium can be used as a geochemical tracer to discuss the generation and the evolution of continental crust. This thesis, focused on the Pan-African Lufilian belt in Zambia, combines structural geology, metamorphic petrology and thermos-barometry, fluid inclusions, geochemistry and geochronology in order to characterize the uranium cycle for this crustal segment. Silici-clastic and evaporitic sediments have been deposited within an intra-continental rift during the dislocation of the Rodinia super-continent during the early Neo-proterozoic. U-Pb ages on detrital zircon grains in these units indicate a dominant Paleo-proterozoic provenance. The same zircon grains show sub-chondritic εHf (between 0 and -15) and yield Hf model ages between ∼2.9 and 2.5 Ga. These data suggest that the continental crust was generated before the end of the Archean (< 2.5 Ga) associated with uranium extraction from the mantle. This old crust has been reworked by deformation and metamorphism during the Proterozoic. Uranium has been re-mobilized and reconcentrated during several orogenic cycles until the Pan-African orogeny. During this Pan-African cycle, U-Pb and REY (REE and Yttrium) signatures of uranium oxides indicate a first mineralizing event at ca. 650 Ma during the continental rifting. This event is related to late diagenesis hydrothermal processes at the basement/cover interface with the circulation of basinal brines linked to evaporites of the Roan. The second stage, dated at 530 Ma, is connected to metamorphic highly saline fluid circulations, synchronous to the metamorphic peak of the Lufilian orogeny (P=9±3 kbar; T=610±30 deg. C). These fluids are derived from the Roan evaporite dissolution. Some late uranium re-mobilizations are described during exhumation of metamorphic rocks and their

  12. Pan-African U-Pb zircon age from apatite-magnetite veins of eastern ghats granulite belt, India

    International Nuclear Information System (INIS)

    Kovach, V.P.; Salnikova, E.B.; Kotov, A.B.; Yakovleva, S.Z.; Rao, A.T.

    1997-01-01

    206 Pb/ 238 U ages of zircon correspond to 502±3 Ma and 207 Pb/ 206 Pb ages are equal to 508±14 Ma. U-Pb isotopic study of the Kasipatnam zircon has led to the recognition of pan-African thermal event in the eastern ghats granulite belt, India. (author)

  13. Pan-Africanism, the Mystique of World Black Unity: An Afro-American Scholar's Sojourn in Africa.

    Science.gov (United States)

    Staples, Robert

    1977-01-01

    The author explores the ideology of Pan-Africanism in terms of the social and economic position of Blacks in the United States. He briefly describes his visit to Africa (Senegal and Nigeria) and the effects that this experience has had in forming his political viewpoint. (MC)

  14. The development of pan-African food forecasting and the exploration of satellite-based precipitation estimates

    NARCIS (Netherlands)

    Thiemig, Vera

    2014-01-01

    The main objective of this PhD is to contribute to the development of a pan-African flood forecasting system in order to enhance flood forecasting for the whole of Africa. In view of the dimension and complexity of this goal, this research focused on particular aspects of flood forecasting,

  15. Grenvillian vs Pan-African tectonic evolution in the Gamburtsev Province of East Antarctica

    Science.gov (United States)

    Ferraccioli, F.; Guochao, W.; Finn, C.; Bell, R. E.

    2017-12-01

    The Gamburtsev Subglacial Mountains in interior East Antarctica are underlain by 50-60 km thick crust. In contrast, the Archean to Mesoproterozoic Mawson craton that occupies the Wilkes and Terre Adelie region features only 40-45 km thick crust. The Gamburtsev Province is underlain by 200 km thick lithoshere, as typically observed over Precambrian lithosphere that has not been substantially reworked during Phanerozoic subduction or collision. Ferraccioli et al., (2011) proposed that a segment of a stalled orogen (i.e. an orogen where widespread orogenic collapse and root delamination has not occurred) is preserved in the Gamburtsev Province and hypothesised that its origin relates to accretionary and subsequent collisional events at ca 1 Ga, linked to the assembly of Rodinia. However, passive seismic interpretations indicate that crustal thickening may relate instead to Pan-African age assembly of Gondwana (at ca 550 Ma). Here we interpret a set of enhanced magnetic and gravity images, depth to magnetic and gravity sources and 2D and forward and inverse models to characterise the crustal architecture of the Gamburtsev Province. Enhanced aeromagnetic images reveal a system of subglacial faults that segment the Gamburtsev Province into three distinct geophysical domains, the northern, central and southern domains. Apparent offsets in high-frequency magnetic anomalies within the central domain are interpreted as revealing a transpressional fault system parallel to the previously proposed Gamburtsev Suture. Our magnetic and gravity model, combined with independent constraints from sediment provenance ages, is interpreted as revealing arc and back arc terranes of inferred Grenvillian age in the northern and Central domains of the Gambrurtsev Province. Distinct magnetic anomalies correspond to inferred Paleoproterozoic crust that may have affinities with the Lambert Terrane and the South Pole Province, an inferred Mesoproterozoic (1.6-1.4 Ga?) igneous province. We

  16. Fossil imprints of the Pan-African collision process revealed by seismic anisotropy in southern Madagasca

    Science.gov (United States)

    Tilmann, F. J.; Rindraharisaona, E. J.; Reiss, M. C.; Dreiling, J.; Rumpker, G.; Yuan, X.; Giese, J.; Priestley, K. F.; Wysession, M. E.; Barruol, G.; Rambolamanana, G.

    2017-12-01

    In the assembly of Pangaea during the Proterozoic Pan-African Orogeny and later rifting and break-up of Gondwanaland, Madagascar occupied a central position, sandwiched between East Africa and India-Seychelles. Today, its metamorphic terranes still bear witness to the collision process. In the SELASOMA project we have deployed a seismic array in southern Madagascar in order to determine the imprint of these events onto the present day-crustal structure. 25 broadband and 23 SP stations were deployed for a period of 1-2 years. We present an overview of the results of several studies (receiver functions, ambient noise surface wave analysis, SKS splitting) constraining the isotropic and anisotropic crustal structure of southern Madagascar based on this deployment, supplemented by permanent stations and the contemporaneous MACOMO and RHUM-RUM deployments. The upper and middle crust of the Archean and Proterozoic provinces is overall quite similar, but a remarkable difference is that the Archean crust shows clear signs of underplating; we surmise that the Proterozoic crust was lost in the Pan-African collision. Both horizontal (from shear-wave splitting) and radial (SH/SV from Love and Rayleigh discrepancy) anisotropy shows evidence of collisional processes. A 150 km-wide zone of anomalous splitting measurements (deviating from the APM-parallel fast directions in most of Madagascar) in the region, where several major fossil shear zones have been mapped, can be explained as a zone of extensive coherent deformation within the crust; fast directions here align with the dominant strike of the major fossil shear zones. Negative radial anisotropy (i.e., SV faster than SH) in the mid-crust, likewise interpreted to have been formed by the collision, highlights the likely role of vertical shearing, presumably caused by extensive folding. In the lower crust, however, positive radial anisotropy is found in most of the Proterozoic and Archean terranes, which, analogous to the

  17. Pan-African reactivation of the Lurio segment of the Kibaran Belt system: a reappraisal from recent age determinations in northern Mozambique

    Science.gov (United States)

    Sacchi, R.; Cadoppi, P.; Costa, M.

    2000-04-01

    The role of the Lurio Belt in northern Mozambique, and the geological evolution of its foreland in the Proterozoic are discussed in the light of recent, single zircon age determinations showing Pan-African age for the granulite-facies metamorphism. The following tentative conclusions are reached, and evidence for and against them is reviewed. The Lurio Belt had a two-fold history, as a crust-forming orogen during the Kibaran and as a transpressive suture in Pan-African times. Together with the Zambezi Belt and the Schlesien-Mwembeshi Lineament, it formed a 3000 km discontinuity which underwent an embryonic oceanic development before being sutured during the Pan-African collisional event. The Lurio Belt foreland had a tectonic-metamorphic evolution at ca 1000 Ma, prior to major, Pan-African overprinting and was probably continuous with the basement of Queen Maud Land (Antarctica) and Natal. In Pan-African times, clockwise transpressive movements along the Lurio Belt brought about emplacement of granulite klippen in its foreland. If there is a southward continuation of the Pan-African Mozambique Belt beyond Mozambique, it is probably to be found in Antarctica.

  18. THE PAN AFRICAN E-NETWORK PROJECT: A New Learning Culture

    Directory of Open Access Journals (Sweden)

    Nundoo-Ghoorah SUNITI

    2012-07-01

    Full Text Available This paper sets out to explore the paradigm shift in learning culture brought about by the advent of online learning in the mostly print-based ODL system at the Mauritius College of the Air (MCA. It delves into the perceptions of learners and MCA staff involved in a range of undergraduate to Master’s programmes forming part of the Pan African e- Network Project that wires 23 African countries with top-ranking Indian universities through synchronous and interactive state of the art technology. Learners across five of the disciplines offered through tele-learning and a team of MCA staff participating in programme delivery were surveyed through questionnaires and interviews to collect both quantitative and qualitative data. For most of the respondents this new learning ethos has induced an acculturation process requiring radical reconceptualisation of prior notions about teaching/learning. MCA staff, too, have had to learn conducive behavior patterns to consolidate existing support services. Survival in this new learning environment where the tutor is a remote on-screen entity, where e-books replace printed material, where connectivity can be a daily struggle, demands another mindset, another set of values enabling learning and fine-tuned ICT skills. Socialisation with tutors and fellow learners is possible through links in Facebook and Twitter. However, learners still tend to feel somewhat isolated. It is proposed that an e-platform be set up to link up learners as a mutually supportive learning community engaged in the construction of knowledge.

  19. Nature, geochemistry and petrogenesis of the syn-tectonic Amspoort suite (Pan-African Boundary Igneous Complex, Kaoko Belt, NW Namibia)

    Science.gov (United States)

    Janousek, Vojtech; Konopasek, Jiri; Ulrich, Stanislav

    2010-05-01

    Crucial information on the Neoproterozoic-Cambrian amalgamation of Western Gondwana is provided by studies of the large Pan-African collisional belt in central-northern Namibia. This so-called Damara Orogen (Miller, 1983) can be subdivided into two branches, the SW-NE trending Damara Belt and a roughly perpendicular, NNW-SSE trending Kaoko Belt further north. The Kaoko Belt consists of two principal crustal units. The easterly part has a Congo Craton affinity (a basement built mostly by ≥ 1.5 Ga granitic gneisses with Neoproterozoic metasedimentary cover), whereas the westerly Coastal Terrane consists of Neoproterozoic (c.850-650 Ma) metapsammites and minor metabasic bodies; no exposures of the basement were found. The at least 180 km long, NNW-SSE trending suture between both units was intruded by numerous syn-tectonic magmatic bodies with ages spanning the interval 580-550 Ma (Seth et al., 1998; Kröner et al., 2004) designated as the Boundary Igneous Complex by Konopásek et al. (2008). The most typical representatives of this syn-collision igneous association are c.550 Ma old K-feldspar-phyric, Bt ± Cam granites-granodiorites of the Amspoort suite, with minor Cpx gabbro and rare two-pyroxene dolerite bodies. The petrological character, whole-rock geochemistry and Sr-Nd isotopic signatures of the scarce Opx-Cpx-Bt dolerites indicate an origin from a CHUR-like mantle-derived melts (87Sr/86Sr550 ~ 0.7045, ɛNd550 ~ 0) modified by extensive (?Ol-) Cpx fractionation. The rest of the suite is interpreted as a product of a high-temperature anatexis of a heterogeneous lower crust, built mainly by immature metapsammites - rich in arc-derived detritus - with minor metabasite and intermediate metaigneous bodies. The most likely source appears to be the anatectic Coastal Terrane gneisses. Yet, partial melting of the so far little constrained Congo Craton cover, if formed by immature and youthful detritus unrelated to the basement, cannot be discounted. In any case, the

  20. A-type granites from the Guéra Massif, Central Chad: Petrology, geochemistry, geochronology, and petrogenesis.

    Science.gov (United States)

    Pham, Ngoc Ha T.; Shellnutt, J. Gregory; Yeh, Meng-Wan; Lee, Tung-Yi

    2017-04-01

    The poorly studied Saharan Metacraton of North-Central Africa is located between the Arabian-Nubian Shield in the east, the Tuareg Shield in the west and the Central African Orogenic Belt in the south. The Saharan Metacraton is composed of Neoproterozoic juvenile crust and the relics of pre-Neoproterozoic components reactivated during the Pan-African Orogeny. The Republic of Chad, constrained within the Saharan Metacraton, comprises a Phanerozoic cover overlying Precambrian basement outcroppings in four distinct massifs: the Mayo Kebbi, Tibesti, Ouaddaï, and the Guéra. The Guéra massif is the least studied of the four massifs but it likely preserves structures that were formed during the collision between Congo Craton and Saharan Metacraton. The Guéra Massif is composed of mostly granitic rocks. The granitoids have petrologic features that are consistent with A-type granite, such as micrographic intergrowth of sodic and potassic feldspar, the presence of sodic- and iron-rich amphibole, and iron-rich biotite. Compositionally, the granitic rocks of the Guéra Massif have high silica (SiO2 ≥ 68.9 wt.%) content and are metaluminous to marginally peraluminous. The rocks are classified as ferroan calc-alkalic to alkali-calcic with moderately high to very high Fe* ratios. The first zircon U/Pb geochronology of the silicic rocks from the Guéra Massif yielded three main age groups: 590 Ma, 570 Ma, 560 Ma, while a single gabbro yielded an intermediate age ( 580 Ma). A weakly foliated biotite granite yielded two populations, in which the emplacement age is interpreted to be 590 ± 10 Ma, whereas the younger age (550 ± 11 Ma) is considered to be a deformation age. Furthermore, inherited Meso- to Paleoproterozoic zircons are found in this sample. The geochemical and geochronology data indicate that there is a temporal evolution in the composition of rocks with the old, high Mg# granitoids shifting to young, low Mg# granitoids. This reveals that the A-type granites in

  1. Triple junction orogeny: tectonic evolution of the Pan-African Northern Damara Belt, Namibia

    Science.gov (United States)

    Lehmann, Jérémie; Saalmann, Kerstin; Naydenov, Kalin V.; Milani, Lorenzo; Charlesworth, Eugene G.; Kinnaird, Judith A.; Frei, Dirk; Kramers, Jan D.; Zwingmann, Horst

    2014-05-01

    Trench-trench-trench triple junctions are generally geometrically and kinematically unstable and therefore can result at the latest stages in complicated collisional orogenic belts. In such geodynamic sites, mechanism and timescale of deformations that accommodate convergence and final assembly of the three colliding continental plates are poorly studied. In western Namibia, Pan-African convergence of three cratonic blocks led to pene-contemporaneous closure of two highly oblique oceanic domains and formation of the triple junction Damara Orogen where the NE-striking Damara Belt abuts to the west against the NNW-striking Kaoko-Gariep Belt. Detailed description of structures and microstructures associated with remote sensing analysis, and dating of individual deformation events by means of K-Ar, Ar-Ar (micas) and U-Pb (zircon) isotopic studies from the Northern Damara Belt provide robust constraints on the tectonic evolution of this palaeo-triple junction orogeny. There, passive margin sequences of the Neoproterozoic ocean were polydeformed and polymetamorphosed to the biotite zone of the greenschist facies to up to granulite facies and anatexis towards the southern migmatitic core of the Central Damara Belt. Subtle relict structures and fold pattern analyses reveal the existence of an early D1 N-S shortening event, tentatively dated between ~635 Ma and ~580 Ma using published data. D1 structures were almost obliterated by pervasive and major D2 E-W coaxial shortening, related to the closure of the Kaoko-Gariep oceanic domain and subsequent formation of the NNW-striking Kaoko-Gariep Belt to the west of the study area. Early, km-scale D1 E-W trending steep folds were refolded during this D2 event, producing either Type I or Type II fold interference patterns visible from space. The D2 E-W convergence could have lasted until ~533 Ma based on published and new U-Pb ages. The final D3 NW-SE convergence in the northernmost Damara Belt produced a NE-striking deformation

  2. Groundwater recharge in the tropics: a pan-African analysis of observations

    Science.gov (United States)

    Taylor, R. G.

    2015-12-01

    Groundwater is a vital source of freshwater in sub-Saharan Africa where rainfall and river discharge are unreliable and per-capita reservoir storage is among the lowest in the world. Groundwater is widely considered a distributed, low-cost and climate-resilient option to meet rapidly growing freshwater demand and alleviate endemic poverty by expanding access to safe water and improving food security through irrigation. Recent research indicates that groundwater storage in Africa is about 100 times greater than annual river discharge yet major uncertainties remain in the magnitude and nature of replenishment through recharge as well as the impacts of land-use and climate change. Here, we present newly compiled, multi-decadal observations of groundwater levels from 5 countries (Benin, Burkina Faso, Niger, Tanzania, Uganda) and paired measurements of stable isotope ratios of O and H in precipitation and groundwater at 11 locations. These data reveal both a distinct bias in groundwater recharge to intensive rainfall and rapid recharge pathways (e.g. focused, macropore flow) that are inconsistent with conventional recharge models assuming pore-matrix flow defined by the Darcy-Richards equation. Further the records highlight the substantial influence of land-use change (e.g. conversion of natural, perennial cover to croplands) on groundwater recharge. The compiled observations also provide, for the first time, a pan-African baseline to evaluate the performance of large-scale hydrological models and Land-Surface Models incorporating groundwater in this region. Our results suggest that the intensification of precipitation brought about by global warming favours groundwater replenishment in sub-Saharan Africa. As such, groundwater may prove to be a climate-resilient source of freshwater in the tropics, enabling adaptive strategies such as groundwater-fed irrigation and sustaining domestic and industrial water supplies.

  3. The Pan-African Damara Orogen of South West Africa/Namibia

    International Nuclear Information System (INIS)

    Miller, R.McG.

    1983-01-01

    The structural grain of the Damara orogen points to a reversal of spreading and to north-westward subduction of the African cratons below a South American craton and of the Kalahari Craton below the Congo Craton. D 1 recumbent folding was followed by intrusion of 650 m.y.-old granitic rocks, uplift and erosion and deposition of a northern molasse. D 2 deformation in the coastal arm marked the continental collision phase in this region. The final, large-scale deformational event in this region caused westward-vergent back folding which was followed by intrusion of 570 m.y.-old post-tectonic granites. In the Central Zone, widespread intrusion of 550 m.y.-old, syntectonic granites and extrusion of their volcanic equivalents in a 150 km-wide, high-temperature-low-pressure zone along the leading edge of the Congo Craton was accompanied by uplift, erosion and the deposition of K-rich greywackes as a fore-arc sequence above the earlier, spreading-phase deposits in the closing Southern Zone ocean. Sedimentological aspects of the Damara along the southern margin of the orogen suggest that the lower Nama Group, which contains a unique Ediacara fauna and was derived from easterly sources, was deposited between about 650 and 550 m.y. ago during deformation north of the Southern Zone ocean. During the final major deformation event in the Central Zone (D 3 doming), the fore-arc deposits and the underlying passive-margin sediments to the south were deformed. The Damaran granitic rocks are Hercynotype; granites make up 96 per cent of the more than 200 plutons. Average compositions have a slightly less calc-alkaline character than typical compressional margin granitic suites. Early granites have I-type chemistries and appear to have been derived from deep crustal sources, whereas most of the young granites have intermediate to S-type compositions and were generated at various crustal levels

  4. Early Silurian to Early Carboniferous ridge subduction in NW Junggar: Evidence from geochronological, geochemical, and Sr-Nd-Hf isotopic data on alkali granites and adakites

    Science.gov (United States)

    Zhang, Chen; Santosh, M.; Liu, Luofu; Luo, Qun; Zhang, Xin; Liu, Dongdong

    2018-02-01

    The Central Asian Orogenic Belt (CAOB) evolved through a long-lived orogeny involving multiple episodes of subduction and accretion marking a major phase of continental growth during the Paleozoic. The northern part of the Western Junggar region (NW Junggar) offers a window into these processes, particularly to constrain the timing of closure of the Paleo-Asian Ocean. Here we report geochemical, geochronological, and isotopic data from K-feldspar granites and adakitic rocks from the NW Junggar region. Zircon U-Pb ages suggest that the granites were emplaced during Early Silurian to the Early Carboniferous (434-328 Ma). The granites show geochemical characteristics similar to those of A-type granites, with high SiO2 (71.13-76.72 wt%), Na2O + K2O (8.00-9.59 wt%), and Al2O3 (12.28-14.08 wt%), but depleted Sr, Nb, Ta and Eu. They display moderate to high positive εNd(t) and εHf(t) values (4.26-8.21 and 7.69-14.60, respectively) and young Nd and Hf model ages (T2DM-Nd = 489-740 Ma and T2DM-Hf = 471-845 Ma), suggesting magma derivation through partial melting of lower crust in the Boshchekul-Chingiz and Zharma-Saur arcs. The adakites are characterized by high Sr content (406.5-751.6 ppm), and low Y (13.8-16.4 ppm) and Yb (1.5-1.8 ppm) content, yielding relatively high Sr/Y ratios (25.38-49.41) similar to those of modern adakites. They have high positive εNd(t) and εHf(t) values (7.85-8.25 and 13.23-15.97, respectively) and young Nd and Hf model ages (T2DM-Nd = 429-535 Ma and T2DM-Hf = 355-550 Ma), indicating that their source magmas were likely derived from partial melting of the oceanic crust beneath the Boshchekul-Chingiz arc. The petrogenesis and distribution of the A-type granites and adakites, as well as the tectonic architecture of the region, suggest that a ridge subduction event might have occurred during the Early Silurian to Early Carboniferous. In combination with previous studies in the Chinese Altai, we suggest a two-sided ridge subduction model for the

  5. Systematic reviews in context: highlighting systematic reviews relevant to Africa in the Pan African Medical Journal.

    Science.gov (United States)

    Wiysonge, Charles Shey; Kamadjeu, Raoul; Tsague, Landry

    2016-01-01

    contribute in enhancing the value of research in Africa, the Pan African Medical Journal will start a new regular column that will highlight priority systematic reviews relevant to the continent.

  6. Questionnaire survey of the pan-African trade in lion body parts.

    Science.gov (United States)

    Williams, Vivienne L; Loveridge, Andrew J; Newton, David J; Macdonald, David W

    2017-01-01

    The African lion is in decline across its range, and consumptive utilisation and trade of their body parts and skins has been postulated as a cause for concern. We undertook a pan-African questionnaire and literature survey to document informed opinion and evidence for the occurrence of domestic and international trade and consumption in African lion body parts across current and former range states. Sixty-five people from 18 countries participated in the online questionnaire survey (run from July 2014 to May 2015), with information provided for 28 countries (including 20 out of 24 countries believed to have extant populations). Respondents were experts within their professional spheres, and 77% had ≥6 years relevant experience within lion conservation or allied wildlife matters. Their opinions revealed wide sub-regional differences in consumptive use, drivers of trade, and access to lions that impact wild lion populations in different ways. Traditional medicine practices (African and Asian) were perceived to be the main uses to which lion body parts and bones are put domestically and traded internationally, and there is reason for concern about persistent imports from former lion range states (mainly in West Africa) for parts for this purpose. The domestic, rather than international, trade in lion body parts was perceived to be a bigger threat to wild lion populations. Parts such as skin, claws, teeth and bones are thought to be in most demand across the continent. The impact of international trade on wild populations was acknowledged to be largely unknown, but occasionally was judged to be 'high', and therefore vigilance is needed to monitor emerging detrimental impacts. Seventeen countries were nominated as priorities for immediate monitoring, including: South Africa, Tanzania, Zimbabwe, Mozambique, Zambia, Botswana, Kenya, Nigeria, and Cameroon. Reasons for their selection include: prevalence of trophy hunting, 'hot spots' for poaching, active domestic trade

  7. Questionnaire survey of the pan-African trade in lion body parts.

    Directory of Open Access Journals (Sweden)

    Vivienne L Williams

    Full Text Available The African lion is in decline across its range, and consumptive utilisation and trade of their body parts and skins has been postulated as a cause for concern. We undertook a pan-African questionnaire and literature survey to document informed opinion and evidence for the occurrence of domestic and international trade and consumption in African lion body parts across current and former range states. Sixty-five people from 18 countries participated in the online questionnaire survey (run from July 2014 to May 2015, with information provided for 28 countries (including 20 out of 24 countries believed to have extant populations. Respondents were experts within their professional spheres, and 77% had ≥6 years relevant experience within lion conservation or allied wildlife matters. Their opinions revealed wide sub-regional differences in consumptive use, drivers of trade, and access to lions that impact wild lion populations in different ways. Traditional medicine practices (African and Asian were perceived to be the main uses to which lion body parts and bones are put domestically and traded internationally, and there is reason for concern about persistent imports from former lion range states (mainly in West Africa for parts for this purpose. The domestic, rather than international, trade in lion body parts was perceived to be a bigger threat to wild lion populations. Parts such as skin, claws, teeth and bones are thought to be in most demand across the continent. The impact of international trade on wild populations was acknowledged to be largely unknown, but occasionally was judged to be 'high', and therefore vigilance is needed to monitor emerging detrimental impacts. Seventeen countries were nominated as priorities for immediate monitoring, including: South Africa, Tanzania, Zimbabwe, Mozambique, Zambia, Botswana, Kenya, Nigeria, and Cameroon. Reasons for their selection include: prevalence of trophy hunting, 'hot spots' for poaching, active

  8. Pan African Collisional Tectonics Along the Moroccan West African Craton Continued to Ediacaran-Cambrian Boundary

    Science.gov (United States)

    Hefferan, K. P.; Samson, S. D.; Rice, K.; Soulaimani, A.

    2016-12-01

    Precision geochronologic dating and field mapping in the Anti-Atlas Mountains of Morocco document a Neoproterozoic Pan African orogenic cycle consisting of three distinct orogenic events: Iriri-Tichibanine orogeny (760-700 Ma), Bou Azzer orogeny (680-640 Ma) and the WACadomian orogeny (620 Ma to either 555 or 544 Ma). The Iriri-Tichibanine and Bou Azzer orogenies involved northward directed subduction beneath island arc volcanic terranes. These orogenic events generated calc-alkaline magmatism and supra-subduction zone ophiolites exposed in the Bou Azzer and Siroua erosional inliers. The WACadomian orogeny involved subduction and collision of the Cadomia arc complex with the West African Craton and generation of clastic sedimentary basins. The termination of the WACadomian orogeny has been the subject of debate as calc-alkaline to high K magmatism and folding continued to 544 Ma: Was 620-544 Ma calc-alkaline to high K magmatism and clastic basin development due to a) continental rift basin tectonics or b) southward directed subduction and collisional tectonics with associated back arc basin tectonism? We present field and geochemical data supporting the continuation of subduction-collisional tectonics to the Ediacaran-Cambrian boundary 544 Ma. Field mapping in the Central Anti-Atlas (Agadir Melloul) clearly documents an angular unconformity between Ouarzazate Group and Adoudounian limestones (N 30°31'28.91", W07°48'29.12"). Volcaniclastic rocks of Ouarzazate Group (615-545 Ma) are clearly folded and unconformably overlain by Adoudou Formation (541-529 Ma) limestones to the north. Geochemical discrimination diagrams on Latest Neoproterozoic calc-alkaline to high K igneous rocks throughout the Anti-Atlas plot in subduction and collisional arc magma domains. Back arc basin tectonism is likely responsible for localized extensional basins but continental rift tectonics and passive margin sedimentation did not begin in the Anti-Atlas Mountains until Early

  9. Pan-African deformations in the basement of the Negele area, southern Ethiopia

    Science.gov (United States)

    Yihunie, Tadesse

    2002-03-01

    Polydeformed and metamorphosed Neoproterozoic rocks of the East African Orogen in the Negele area constituted three lithostructurally distinct and thrust-bounded terranes. These are, from west to east, the Kenticha, Alghe and Bulbul terranes. The Kenticha and Bulbul terranes are metavolcano-sedimentary and ultramafic sequences, representing parts of the Arabian-Nubian Shield (ANS), which are welded to the central Alghe gneissic terrane of the Mozambique Belt affinity along N-S-trending sheared thrust contacts. Structural data suggest that the Negele basement had evolved through three phases of deformation. During D1 (folding) deformation, north-south upright and inclined folds with north-trending axes were developed. East and west-verging thrusts, right-lateral shearing along the north-oriented Kenticha and Bulbul thrust contacts and related structural elements were developed during D2 (thrusting) deformation. The pervasive D1 event is interpreted to have occurred at 620-610 Ma and the D2 event ended prior to 554 Ma. Right-lateral strike-slips along thrust contacts are interpreted to have been initiated during late D2. During D3, left-lateral strike-slip along the Wadera Shear Zone and respective strike-slip movements along conjugate set of shear zones were developed in the Alghe terrane, and are interpreted to have occurred later than 557 Ma. The structural data suggest that eastward thrusting of the Kenticha and westward tectonic transport of the Bulbul sequences over the Alghe gneissic terrane of the Mozambique Belt, during D2, were accompanied by right-lateral strike-slip displacements along thrust contacts. Right-lateral strike-slip movements along the Kenticha thrust contact, further suggest northward movement of the Kenticha sequence during the Pan-African orogeny in the Neoproterozoic. Left-lateral strike-slip along the orogen-parallel NNE-SSW Wadera Shear Zone and strike-slip movements along a conjugate set of shear zones completed final terrane

  10. Isotopic signature of Pan-African rejuvenation in the Kerala Khondalite belt, southern India: implications for east Gondwana reassembly

    International Nuclear Information System (INIS)

    Unnikrishnan Warrier, C.

    1997-01-01

    Sm-Nd isotope systematics on mineral separates from sillimanite-and cordierite-bearing metapelite (khondalite), and garnet-and biotite-bearing gneiss (leptynite) from the Kerala Khondalite Belt (KKB), southern India, yielded mineral isochron ages (wr-feld-bio-gar) of 537±27 Ma (MSWD=0.9) and 534±26 Ma (MSWD=1.23) respectively. Rb-Sr systematics in the same samples gave wr-feld-bio mineral isochron ages of 437±9 Ma (MSWD=0.67) and 467±9 Ma (MSWD=0.76). These results provide the first mineral isochron ages for the regional metasedimentaries in the KKB. The ε (Nd T) values at 550 Ma for khondalite and leptynite are -22.7 and -21.8 respectively. These results demonstrate a complete rejuvenation of the crust during Pan-African times. Coeval alkaline plutons emplaced along fault-lineaments in this area suggest an extensional tectonic regime. Geochronologic correlations with the Lutzow-Holm bay complexes in east Antarctica, and the highland and southwestern complex of Sri Lanka show that a similar Pan-African tectono-thermal event manifested in all the east Gondwana crustal fragments. (author)

  11. Geochemical characteristics of granitoids and related mafic granulites from the Pan-African Dahomeyide belt, southeastern Ghana

    International Nuclear Information System (INIS)

    Aidoo, F.

    2012-07-01

    from the Pan-African Dahorncyidc belt in southeastern Ghana show subduction-related origin for their protoliths. (author)

  12. Mass-production of Cambro-Ordovician quartz-rich sandstone as a consequence of chemical weathering of Pan-African terranes: Environmental implications [rapid communication

    Science.gov (United States)

    Avigad, D.; Sandler, A.; Kolodner, K.; Stern, R. J.; McWilliams, M.; Miller, N.; Beyth, M.

    2005-12-01

    A vast sheet of mature quartz sand blanketed north Africa and Arabia from the Atlantic coast to the Persian Gulf in Cambro-Ordovician times. U-Pb geochronology of a representative section of Cambrian sandstone in southern Israel shows that these sediments are dominated by 550-650 Ma detrital zircons derived from Neoproterozoic Pan-African basement. The short time lag between magmatic consolidation of a Pan-African source and deposition of its erosional products indicates that, despite their significant mineralogical maturity, the voluminous quartz-rich sandstones on the northern margin of Gondwana are essentially first-cycle sediments. Mass production of these voluminous first-cycle quartz-rich sandstones resulted from widespread chemical weathering of the Pan-African continental basement. We suggest that conditions favoring silicate weathering, particularly a warm and humid climate, low relief and low sedimentation rates prevailed over large tracts of Gondwana in the aftermath of the Pan-African orogeny. An unusually corrosive Cambro-Ordovician atmosphere and humid climate enhanced chemical weathering on the vegetation-free landscape. We infer that late Neoproterozoic-Cambro-Ordovician atmospheric pCO 2 rose as a consequence of widespread late Neoproterozoic volcanism, followed by an uptake of CO 2 by chemical weathering to produce the Cambro-Ordovician sandstone as a negative feedback.

  13. African liberation and unity in Nkrumah's Ghana : a study of the role of "Pan-African Institutions" in the making of Ghana's foreign policy, 1957 - 1966

    NARCIS (Netherlands)

    Grilli, Matteo

    2015-01-01

    This dissertation contributes to the study of Nkrumah’s Pan-African policy by examining the role played by three Ghanaian institutions specifically created to support African liberation and unity: the Bureau of African Affairs, the African Affairs Centre, and the Kwame Nkrumah Ideological Institute

  14. From union of tyrants to power to the people? The significance of the Pan-African Parliament for the African Union

    NARCIS (Netherlands)

    Walraven, van K.

    2004-01-01

    This article analyses the significance of the newly established Pan-African Parliament. As one of the few genuinely new institutions of the African Union (AU) - itself the successor of the Organization of African Unity (OAU) -, the Parliament's birth could provide the institutional transformations

  15. The Pan-African Rabies Control Network (PARACON): A unified approach to eliminating canine rabies in Africa.

    Science.gov (United States)

    Scott, T P; Coetzer, A; de Balogh, K; Wright, N; Nel, L H

    2015-12-01

    Even though Africa has the highest per capita death rate from rabies of any continent, and the disease is almost entirely transmitted by the bites of rabid dogs, there has been no coordinated pan-African approach to controlling canine rabies. In order to attain an inclusive and unified network, the Pan-African Rabies Control Network (PARACON) was established in 2014. By following the 'One Health' concept, which involves close coordination between animal and human health sectors across national, regional and continental levels, PARACON will provide a platform to facilitate and promote coordinated and sustainable control strategies and programmes. Meetings will take place at regular intervals and will be centred on the involvement by key focal persons from the medical and veterinary sectors. The inaugural meeting was held in South Africa in June, 2015 and was focused around interactive discussions and workshops, whilst updating country representatives on the tools available to aid them in developing and implementing sustainable rabies intervention strategies. Experts from various global organizations, institutions and industry participated in the discussions and shared their experience and expertise. The workshops focused on the latest format of the Rabies Blueprint platform (www.rabiesblueprint.com), which in the broadest sense assists with control and elimination campaigns, including educational and advocacy drives, improvement of surveillance and diagnosis and the systematic monitoring of progress. Together with the Stepwise Approach towards Rabies Elimination, the Blueprint is a planning tool to help countries free themselves from canine-transmitted rabies. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Investigating high zircon concentrations in the fine fraction of stream sediments draining the Pan-African Dahomeyan Terrane in Nigeria

    International Nuclear Information System (INIS)

    Key, Roger M.; Johnson, Christopher C.; Horstwood, Matthew S.A.; Lapworth, Dan J.; Knights, Katherine V.; Kemp, Simon J.; Watts, Michael; Gillespie, Martin; Adekanmi, Michael; Arisekola, Tunde

    2012-01-01

    Sixteen hundred stream sediments (<150 μm fraction) collected during regional geochemical surveys in central and SW Nigeria have high median and maximum concentrations of Zr that exceed corresponding Zr concentrations found in stream sediments collected from elsewhere in the World with similar bedrock geology. X-ray diffraction studies on a sub-set of the analysed stream sediments showed that Zr is predominantly found in detrital zircon grains. However, the main proximal source rocks (Pan-African ‘Older Granites’ of Nigeria and their Proterozoic migmatitic gneiss country rocks) are not enriched in zircon (or Zr). Nevertheless, U–Pb LA-ICP-MS dating with cathodoluminescence imaging on detrital zircons, both from stream sediment samples and underlying Pan-African ‘Older Granites’ confirms a local bedrock source for the stream sediment zircons. A combination of tropical/chemical weathering and continuous physical weathering, both by ‘wet season’ flash flooding and ‘dry season’ unidirectional winds are interpreted to have effectively broken down bedrock silicate minerals and removed much of the resultant clay phases, thereby increasing the Zr contents in stream sediments. The strong correlation between winnowing index (Th/Al) and Zr concentration across the study area support this interpretation. Therefore, ‘anomalous’ high values of Zr, as well as other elements concentrated in resistant ‘heavy’ minerals in Nigeria’s streams may not reflect proximal bedrock concentrations of these elements. This conclusion has important implications for using stream sediment chemistry as an exploration tool in Nigeria for primary metal deposits associated with heavy minerals.

  17. The search for the youngest granites in the southern part of the Natal Metamorphic Province

    International Nuclear Information System (INIS)

    Thomas, R.J.; Eglington, B.M.

    1990-01-01

    It is clear that the Belmont Pluton and the dykes are geochemically, isotopically and therefore, genetically distinct. The Belmont pluton is probably related to the garnet leucogranite phase of the Margate Complex. It is suggested that the dykes (∼ 965 Ma) are younger than the Belmont pluton (∼1055 Ma). The relatively low initial 87 Sr/ 86 Sr are typical of the granites intruded at ∼1000 Ma. The age of the dykes is comparable with the 951 ± 16 Ma (R o =.70320 ± 13) given for the Sezela pluton. The high R o (∼0.715) of the dykes is similar to other, minor granite sheets from southern Natal, and is compatible with an origin by late-stage melting of pre-existing radiogenic material. Both the dykes and the Sezela pluton are unequivocally younger than the D 3 deformation, whereas the young dates from the Oribi Gorge Suite are controversial. Thus, although it is possible that some of the minor, intrusive granitic sheets could yet be shown to be of Pan-African age, it is evident that no significant Pan-African magmatism or thermal overprinting has affected the Natal sector of the Namaqua-Natal-Maudheim belt. 1 fig., 7 refs

  18. Isotopic dating of low-grade metamorphic shales in northern Namibia (South West Africa) and implications for the orogenic evolution of the Pan-African Damara Belt

    International Nuclear Information System (INIS)

    Kroener, A.; Clauer, N.

    1979-01-01

    The fine mineral fractions (<2 μm) from pelitic sediments of the molasse-type Mulden Group in the Pan-African Damara belt of Namibia were dated by the Rb-Sr and K-Ar methods. The sediments contain two major parageneses of metamorphic origin which can be related to two separate low-grade regional tectono-thermal events of anchizonal intensity at about 535 (545) Ma and 455 (465) Ma respectively. (Auth.)

  19. Evidence for Nb-Ta Occurrences in the Syn-Tectonic Pan-African Mayo Salah Leucogranite (Northern Cameroon: Constraints from Nb-Ta Oxide Mineralogy, Geochemistry and U-Pb LA-ICP-MS Geochronology on Columbite and Monazite

    Directory of Open Access Journals (Sweden)

    Periclex Martial Fosso Tchunte

    2018-04-01

    of Nb-Ta-ore formation in Africa associated to Pan-African times.

  20. H3ABioNet, a sustainable pan-African bioinformatics network for human heredity and health in Africa

    Science.gov (United States)

    Mulder, Nicola J.; Adebiyi, Ezekiel; Alami, Raouf; Benkahla, Alia; Brandful, James; Doumbia, Seydou; Everett, Dean; Fadlelmola, Faisal M.; Gaboun, Fatima; Gaseitsiwe, Simani; Ghazal, Hassan; Hazelhurst, Scott; Hide, Winston; Ibrahimi, Azeddine; Jaufeerally Fakim, Yasmina; Jongeneel, C. Victor; Joubert, Fourie; Kassim, Samar; Kayondo, Jonathan; Kumuthini, Judit; Lyantagaye, Sylvester; Makani, Julie; Mansour Alzohairy, Ahmed; Masiga, Daniel; Moussa, Ahmed; Nash, Oyekanmi; Ouwe Missi Oukem-Boyer, Odile; Owusu-Dabo, Ellis; Panji, Sumir; Patterton, Hugh; Radouani, Fouzia; Sadki, Khalid; Seghrouchni, Fouad; Tastan Bishop, Özlem; Tiffin, Nicki; Ulenga, Nzovu

    2016-01-01

    The application of genomics technologies to medicine and biomedical research is increasing in popularity, made possible by new high-throughput genotyping and sequencing technologies and improved data analysis capabilities. Some of the greatest genetic diversity among humans, animals, plants, and microbiota occurs in Africa, yet genomic research outputs from the continent are limited. The Human Heredity and Health in Africa (H3Africa) initiative was established to drive the development of genomic research for human health in Africa, and through recognition of the critical role of bioinformatics in this process, spurred the establishment of H3ABioNet, a pan-African bioinformatics network for H3Africa. The limitations in bioinformatics capacity on the continent have been a major contributory factor to the lack of notable outputs in high-throughput biology research. Although pockets of high-quality bioinformatics teams have existed previously, the majority of research institutions lack experienced faculty who can train and supervise bioinformatics students. H3ABioNet aims to address this dire need, specifically in the area of human genetics and genomics, but knock-on effects are ensuring this extends to other areas of bioinformatics. Here, we describe the emergence of genomics research and the development of bioinformatics in Africa through H3ABioNet. PMID:26627985

  1. Pan-African tectonic evolution in central and southern Cameroon: transpression and transtension during sinistral shear movements

    Science.gov (United States)

    Ngako, V.; Affaton, P.; Nnange, J. M.; Njanko, Th.

    2003-04-01

    Kinematic analysis of the central Cameroon shear zone (CCSZ) and its Sanaga fault relay, indicate early sinistral shear movement (phase D 2) that was later followed by a dextral shear movement (phase D 3) during the Pan-African orogeny. The correlation of tectonic events among the CCSZs, thrusting of the Yaounde Group and the deformation in the Lom Group indicate a diachronous deposition history of these groups, where the Yaounde Group is pre-kinematic while the sedimentary and magmatic rocks of the Lom basin are syn-kinematic. Sinistral shear movements along the CCSZ and Sanaga faults are correlated with metamorphism and thrusting of the Yaounde granulites onto the Congo craton, on one hand, and to the opening of the Lom pull-apart basin, oblique to the shear zone, on the other. Kinematic interactions between shear and thrust movements characterize transpression, whereas interactions between shear and oblique normal fault movements characterize transtension. Resulting kinematic indicators show that the Lom basin represents a sinistral transtensional relay of the Sanaga fault. Greenschist-facies metamorphism in the Lom Group rocks dominantly affected by a monophase tectonic evolution were achieved during the late dextral shear movements along the Sanaga fault.

  2. Tectonometamorphic evolution of the gneissic Kidal assemblage related to the Pan-African thrust tectonics (Adrar des Iforas, Mali)

    Science.gov (United States)

    Champenois, M.; Boullier, A. M.; Sautter, V.; Wright, L. I.; Barbey, P.

    In the central part of the Adrar des Iforas (Mali), the 2 Ba Eburnean granulatic unit has been thrust above a high-grade gneissic unit, the so-called 'Kidal assemblage', during an early event of the Pan-African orogeny. The Kidal assemblage can be defined as a tectonic mixing of an Eburnean granulitic basement, its sedimentary cover of Middle to Upper Proterozoic age (quartzites, marbles, basalts and metavolcanics) and various pretectonic rocks: ultrabasic to basic rocks, diorites, tonalites. All these rocks have been deformed during at least four main events and metamorphosed together. Thrusting of the Iforas Granulitic Unit above the Kidal assemblage happened during the first event D1. The movement direction was roughly N-S, as shown by the stretching lineation. Some field criteria indicate a sense of displacement towards the north. The lattice preferred orientation of quartz c- and axes indicate that the slip was dominantly on prismatic and probably pyramidal planes along an direction; consequently D1 deformation was achieved at high temperature or low-strain rate. The quartz c- and axes do not show any constant asymmetry, so they do not indicate a sense of shear. Two metamorphic stages have been found in the Kidal assemblage: the first one is characterized by kyanite in aluminous metasediments and by the occurrence of garnet-clinopyroxene-bearing boundis of basic rocks. The P-T range of this event is located at 700 ± 50°C and around 10 Kb. The second event is a syntectonic high temperature (600-650°C) low pressure (3.5 Kb) stage accompanied by migmatization. Such a tangential deformation in barrowian-type metamorphic conditions and with N-S transport direction is known along the entire Trans-Saharan belt and cannot be related in a simple way to the collision between West African Craton and the mobile belt.

  3. Thrusting and multiple folding in the Neoproterozoic Pan-African basement of Wadi Hodein area, south Eastern Desert, Egypt

    Science.gov (United States)

    Abdeen, M. M.; Sadek, M. F.; Greiling, R. O.

    2008-09-01

    Detailed field mapping and structural studies of the area around the mouth of Wadi Hodein, some 20 km west of Shalatein at the Red Sea coast in the south Eastern Desert of Egypt, revealed four phases of structural deformation (D1-D4) affecting the Neoproterozoic Pan-African basement rocks. D1 is related to arc-arc collision and is represented by ENE-WSW oriented megascopic upright open folds associated with low angle thrusts and mesoscopic tight, overturned and recumbent F1 folds. Kinematic indicators indicate thrusting towards the SSE. D2 is represented by NNW-SSE oriented megascopic and mesoscopic folds, which are tight, verge towards the WSW and display a left-stepping en echelon pattern. D3 includes major NNW-SSE trending sinistral shear zones that show subordinate reverse fault components and dip steeply towards the ENE. These sinistral shear zones are comparable with the Najd Fault System, as they display a similar sense of movement and relationships to earlier structures. Therefore, they are interpreted to be the continuation of the Najd Shear System in southern Egypt. D2 and D3 are related to accretion of east and west Gondwana. D4 is represented by E-W oriented dextral faults with left-stepping segments. The first three deformation events are in agreement with the general evolutionary model for the East African Orogen in the Arabian-Nubian Shield that begins with NNW-SSE shortening, followed by ENE-WSW compression and subsequent deformation by the NNW-SSE striking Najd Fault System. The E-W dextral faults may be the conjugate shear fractures to the D3 NNW-SSE oriented sinistral wrench faults or are related to a subsequent event, D4. NW-SE oriented gold-bearing quartz veins originated during D1 and were subsequently deformed by D2-D4 events.

  4. Geochronology and geochemistry of upper proterozoic granites from Southern Benin

    International Nuclear Information System (INIS)

    Cordani, U.G.; Kawashita, K.; Vancini, K.R.B.; Cadoppi, P.; Sacchi, R.

    1993-01-01

    The Upper Proterozoic basement of Benin, like that of nearby Nigeria and like the polycyclic basement of Central Hoggar, belongs to the hinterland of the Pharusian Chain (Pan-African Trans-Saharan Belt) generated by the collision between the (passive) margin of the West African craton and the (reactivated) margin of the Tuareg Shield and its southern extension. Rb-Sr dating of sub alkaline, meta-aluminums, syn-Kinematic granite forming tabular bodies near Dassa-Zoume and near Save yielded two WR isochron ages of 650 ± 35 Ma (I.R. = 0.7043) and 705 ± 70 Ma (I.R. = 0.7045). Emplacement of these bodies was clearly controlled by trans current movements along the Kandi Fault System. The analyzed granites are comparable with those of Central Hoggar and North-Central Nigeria on the ground of field, geochronological and geochemical data; they also display some affinities with the late-tectonic granites of the Adrar des Iforas. They are expected to find their Brazilian continuation in the Chaval Granitoids west of Fortaleza, but data for comparison are inadequate. (author)

  5. Completion publication of abstracts presented at the scientific meetings of the pan-African pediatric surgical association

    Directory of Open Access Journals (Sweden)

    Abdulrasheed A Nasir

    2013-01-01

    Full Text Available Background: The expected knowledge translation from discovery into practice occurs when presentations from major scientific meetings are published in peer-reviewed literature. The purpose of this study was to determine the extent of complete publication of peer-reviewed articles arising from presentations at the biennial meetings of the Pan-African Pediatric Surgical Association (PAPSA. Materials and Methods: All the abstracts accepted for presentation at the biennial meeting of PAPSA between 2006 and 2010 were identified from the conference abstract booklets and published abstracts in the African Journal of Paediatric Surgery. The presentations were searched for publication in Medline/PubMed, Google Scholar, and African Journal OnLine through October 2012, using key words from the abstract title and names of authors listed in the abstracts. Results: A total of 164 abstracts were accepted for presentation, consisting of 118 (72% oral/podium presentations and 46 (28% poster presentations. One hundred and thirty-three abstracts (81.1% came from African countries and 31 (18.9% from outside Africa. Overall, 49 (29.9% abstracts resulted in full-text publications in 20 peer-reviewed journals. Thirty-eight of the publications were from Africa (representing 28.6% of abstracts from Africa and 11 from outside Africa (33.3% of abstracts from outside Africa. The median time to publication was 15 months [interquartile range (IQR 5-26 months]. The publication rate was statistically significantly correlated to the year of publication (P = 0.016 and the use of comparative statistics in the study (P = 0.005, but not to the study design, study subjects, or institution. The majority of the studies were published in the African Journal of Paediatric Surgery and Pediatric Surgery International (14 and 11 of the 49 reports, respectively. The H-index for international abstracts (median 35, IQR 35-76 was significantly higher than that of African abstracts (14, 3-35 (P

  6. Rb-Sr and K-Ar isotopic evidence for neoproterozoic (Pan-African) granulite metamorphism from the basement of Mumbai offshore basin, India

    International Nuclear Information System (INIS)

    Rathore, S.S.; Vijan, A.R.; Singh, M.P.; Misra, K.N.; Prabhu, B.N.

    2000-01-01

    Precambrian basement from well HBM-1 in the Heera oil field of Mumbai offshore basin has been dated by Rb-Sr and K-Ar methods. Five granulitic basement samples from three conventional drill cores have yielded Rb-Sr isochron age of 502±25 Ma with an initial Sr ratio of 0.70855±0.00013. This age has been interpreted as the time of granulite facies metamorphism of the basement rocks in the region. Two whole rock samples from the basement of this well have yielded mutually concordant K-Ar ages of 505±16 Ma and 507±17 Ma. The K-Ar ages are significantly similar to Rb-Sr age obtained from this well, suggesting complete isotopic reequilibration around 500 Ma ago. The time of secondary thermal heating around 500 Ma ago in the basement of Heera field coincides with the widespread neoproterozoic (Pan-African) thermo-tectonic event extending from the Arabian Peninsula and eastern Africa covering Madagascar, southern India. Sri Lanka and East Antarctica. This study widens the limit of the Pan-African zone, which hitherto was thought to be confined to the western part (presently southern part) of the Indian subcontinent, towards further east. (author)

  7. Sense of shear and displacement estimates in the Abeibara-Rarhous late Pan-African shear zone, Adrar des Iforas, Mali

    Science.gov (United States)

    Boullier, Anne-Marie

    The late Pan-African Abeibara-Rarhous shear zone in the Adrar des Iforas (Mali) is described and studied with the aim of defining the direction, sense of movement and amount of displacement along the zone. It is a strike-slip shear zone, the dextral sense of which is demonstrated at the scale of the map by the rotation of the related mylonitic foliation and at the scale of the thin section with characteristic microstructures. Preferred orientation of quartz c-axes is tentatively used; three quartz-rich samples of 35% or more quartz indicate dextral strike-slip movement, but other samples do not show preferred orientation of quartz c-axes. Strain measurements have been performed on one half of the shear zone using established techniques and a new technique using the thickness of mylonitic layering. The results vary along the length of the shear zone when using the same method and for the same cross-section when using the three methods together. A mean value of 4 km is obtained for total displacement which is low when considering the apparent width of the shear zone. This result is discussed in view of the assumptions involved in the strain estimation. The tectonic history of the Abeibara-Rarhous shear zone and its significance in the Trans-Saharan Pan-African collisional belt are discussed.

  8. Pan-Africanism

    Directory of Open Access Journals (Sweden)

    Raul Diaz Guevara

    2013-04-01

    Full Text Available This essaic-article goes against established conventions that there is anything ethno-cultural (and hence national about the so-called African tribes. Drawing largely from the culture history of precolonial/prepolitical Africans—that is, the Bantu/Cushitic-Ethiopians (Azanians—the author has demonstrated vividly that far from being distinct ethno-culture national communities, the so-called tribes of African states are better considered subculture groups, whose regional culture practices erstwhile paid tribute to their nation’s main culture center in Karnak. For example, using the culture symbols and practices of some local groups and linking them to the predynastic and dynastic Pharaonic periods, I argued that there is compelling evidence against qualifying Africa’s tribes as distinct ethno-culture national entities. In genuine culture context, I stressed that the Ritual of Resurrection and its twin culture process of the mummification of deceased indigenous Pharaohs tend to suggest that the object of the Bantu/Cushitic-Ethiopians national culture was life (in its eternal manifestation and then resurrection later, and that there are recurring (culturally sanctioned ethical examples among the culture custodians of these subculture groups that generally pay tribute to the overarching culture norm. Furthermore, the fact that the Ritual of Resurrection began in the Delta region and ended at the Sources of the Nile, where the spirit of the deceased indigenous Pharaohs was introduced into the spiritual world of their ancestors, contradicts conventional perceptions that ancient Egypt was a distinct national community isolated from precolonial/prepolitical Africa/Azania.

  9. Pan African Medical Journal

    African Journals Online (AJOL)

    Intérêt de la TEP-TDM dans le cancer broncho-pulmonaire primitif non à petite ..... framework governing herbal medicine use and practice in Kenya: a review ... of Nigerian children: effects of socio-economic, nutritional and housing factors ...

  10. Pan African Medical Journal

    African Journals Online (AJOL)

    abp

    2015-05-07

    /10/2014 ... The risk of sustaining a bodily injury was 1.3 times higher in drivers who had not received ... similar picture is reflected across the country, where in 2013 the .... The short recall period of 3 months was made in order ...

  11. U-Pb ages in zircon of some classic granites from the Borborema province

    International Nuclear Information System (INIS)

    Neves, Benjamin Bley de Brito; Basei, Miguel Angelo Stipp; Passarelli, Claudia Regina; Santos, Edilton Jose dos

    2003-01-01

    The Neoproterozoic evolution of the Borborema Province in the east-northeast part of the South American platform exhibits remarkable, much studied granitic plutonism. In 1967 F. F. Almeida and co-workers discriminated a series of granitic typologies as 'Conceicao type', 'Itaporanga type' etc, mostly based upon general geological features and petrographic grounds. This preliminary classification has somehow been maintained in all subsequent papers up to now, despite all the newly observed plutons and the newly generated tectonic, geochemical and isotopic data since then. Samples of these classical types of granites from their type-localities were analyzed geo chronologically using the U-Pb method in zircons in response to the felt needs of the geological community, because previous age-determinations involved less accurate methods. The new data have been added to all other preexisting U-Pb data (from other granitic bodies) obtained over the last decade, making it possible to recognize three main stages of granitic magmatism for the Borborema Province: 650-625 Ma, 580-570 Ma and 545-520 Ma. The last group of dates is closely association with the escape tectonics of the Brasiliano-Pan African collage, which preceded the assembly of the super continental landmass of Western Gondwana. (author)

  12. Uranium in granites

    International Nuclear Information System (INIS)

    Maurice, Y.T.

    1982-01-01

    Recent research activities of the Canadian Uranium in Granites Study are presented in 18 papers and 3 abstracts. 'Granites' is used as a generic term for granitoids, granitic rocks, and plutonic rocks

  13. 2005 dossier: granite; Dossier 2005: granite

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    This document makes a status of the researches carried out by the French national agency of radioactive wastes (ANDRA) about the geologic disposal of high-level and long-lived radioactive wastes in granite formations. Content: 1 - advantage of granitic formations for the geologic disposal; 2 - containers; 3 - design study of a disposal facility in granitic environment; 4 - understanding and modelling of granite; 5 - description of disposal concepts in granitic environment; 6 - long-term and safety aspects; 7 - conclusion. (J.S.)

  14. Isotopic age determineations on granitic and gneissic rocks from the Ubendian-Usagaran System in southern Tanzania

    International Nuclear Information System (INIS)

    Priem, H.N.A.; Boelrijk, N.A.I.M.; Hebeda, E.H.; Verdurmen, E.A.Th.; Verschure, R.H.; Oen, I.S.; Westra, L.

    1979-01-01

    Isotopic age measurements on granites and gneisses are reported from the Ubendian-Usagaran System in southern Tanzania. For the Lukumburu-Wino Granites a Rb-Sr whole-rock isochron (9 points) of 1771 +- 145 Ma with initial 87 Sr/ 86 Sr of 0.704 +- 0.003 was obtained (γ 87 Rb = 1.42 10 -11 a -1 ; errors 95% confidence level). Two samples from neighbouring granites and three gneisses from the contact zone of the Lukumburu-Wino Granites also fit to this isochron; inclusion into the isochron calculation yields an age of 1747 +- 85 Ma with the same initial Sr composition. Five parts of a banded Usagaran gneiss sample produce an isochron of 589 +- 70 Ma with initial 87 Sr/ 86 Sr of 0.7194 +- 0.0005. This internal isochron is interpreted as reflecting Sr isotopic equilibration through the sample during the main phase (or one of the main phases) of the Pan-African thermotectonic episode. Rb-Sr and K-Ar ages of 17 micas show a general resetting by the Pan-African thermotectonic episode. The Rb-Sr ages of the muscovites and the biotites average 528 Ma and 463 Ma, respectively, and are interpreted as reflecting subsequent stages in the cooling history after the termination of the event. Biotites have K-Ar ages persistently higher than the corresponding Rb-Sr ages, possibly reflecting a high partial 40 Ar pressure through the crust during the resetting of the biotite K-Ar systems. (Auth.)

  15. Possible zircon U-Pb evidence for Pan-African granulite-facies metamorphism in the Mozambique belt of southern Tanzania

    International Nuclear Information System (INIS)

    Coolen, J.J.M.M.M.

    1982-01-01

    Four zircon fractions of garnet-bearing two-pyroxene granulite, from the Furua granulite complex of southern Tanzania, plot very close to concordia. A discordia yields a lower intercept at 652 +- 10 Ma, an age slightly higher than the Rb-Sr whole-rock and mineral ages reported from the surrounding amphibolite-facies rocks. The U-Pb systematics indicate the presence of a very small amount of older (2-3 Ga) radiogenic lead. The zircon data may be interpreted as indicating an event of granulite-facies metamorphism during the Pan-African thermotectonic episode. This interpretation is at variance with current models postulating that the granulite complexes in the Mozambique belt are relicts of older, possibly Archaean events of metamorphism. (Auth.)

  16. Research on isotope geology. Assessment of heat production potential of granitic rocks and development of geothermal exploration techniques using radioactive/stable isotopes and fission track 2

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Seong Cheon; Chi, Se Jung [Korea Inst. of Geology Mining and Materials, Taejon (Korea, Republic of)

    1995-12-01

    Radioelements and heat production rates of granitic rocks and stable isotopes of groundwaters were analyzed to investigate the geothermal potential of Wolchulsan granite complex in the southern Yeongam area. Wolchulsan granite complex is composed mainly by Cretaceous pink alkali-feldspar granite and partly Jurassic biotite granite. The main target for the geothermal exploration is the alkali-feldspar granite that is known in general to be favorable geothermal reservoir(e.g., Shap granite in UK). To develop exploration techniques for geothermal anomalies, all geochemical data were compared to those from the Jeonju granite complex. Heat production rates(HPR) of the alkali-feldspar granite is 1.8 - 10.6 {mu}Wm{sup -3}. High radio-thermal anomalies were revealed from the central western and northern parts of the granite body. These are relatively higher than the Caledonian hot dry granites in the UK. The integrated assessment of Wolchulsan granite complex suggests potential of the Cretaceous alkali-feldspar granite as a geothermal targets. Groundwater geochemistry of the Yeongam area reflects simple evaporation process and higher oxidation environment. Stable isotope data of groundwaters are plotted on or close to the Meteoric Water Line(MWL). These isotopic data indicate a significant meteoric water dominance and do not show oxygen isotope fractionation between groundwater and wall rocks. In despite of high HPR values of the Yeongam alkali-feldspar granite, groundwater samples do not show the same geochemical properties as a thermal water in the Jeonju area. This reason can be well explained by the comparison with geological settings of the Jeonju area. The Yeongam alkali-feldspar granite does not possess any adjacent heat source rocks despite its high radio-thermal HPR. While the Jeonju granite batholith has later heat source intrusive and suitable deep fracture system for water circulation with sedimentary cap rocks. (Abstract Truncated)

  17. Plagiarism in the article Emphysematous cystitis and emphysematous pyelitis: a clinically misleading association. Mustapha Ahsaini et al. The Pan African Medical Journal. 2013;16:18. (doi:10.11604/pamj.2013.16.18.2505).

    Science.gov (United States)

    2015-01-01

    This retracts article Emphysematous cystitis and emphysematous pyelitis: a clinically misleading association. Mustapha Ahsaini, Amadou Kassogue, Mohammed Fadl Tazi, Anas Zaougui, Jalal Edine Elammari, Abdelhak Khallouk, Mohammed Jamal El Fassi, My Hassan Farih. The Pan African Medical Journal. 2013;16:18. (doi:10.11604/pamj.2013.16.18.2505).[This retracts the article DOI: 10.11604/pamj.2013.16.18.2505.].

  18. 2005 dossier: granite

    International Nuclear Information System (INIS)

    2005-01-01

    This document makes a status of the researches carried out by the French national agency of radioactive wastes (ANDRA) about the geologic disposal of high-level and long-lived radioactive wastes in granite formations. Content: 1 - advantage of granitic formations for the geologic disposal; 2 - containers; 3 - design study of a disposal facility in granitic environment; 4 - understanding and modelling of granite; 5 - description of disposal concepts in granitic environment; 6 - long-term and safety aspects; 7 - conclusion. (J.S.)

  19. The tardi-Pan-African granitoids of South-Westerner Anti-Atlas (Morocco: Evolution from magnesian to ferroan type. Example of the Ifni inlier

    Directory of Open Access Journals (Sweden)

    El Aouli, E. H.

    2007-06-01

    Full Text Available The study of the neoproterozoic granitoids in the Ifni Inlier and those of the other inliers in south-westerner Anti-Atlas shows that this magmatism evolves from magnesian to ferroan type. In the Ifni inlier, these granitoids outcrop within the sedimentary and volcanogenic formations of the Ouarzazate Super- Group SGO (615 to 540 My. They belong to two distinct magmatic episodes (i an early one composed of magnesian granitoids with alkali-calcic and metaluminous to slightly aluminous character (quartz bearing diorite, granodiorite and monzogranite intrusive in the lower formations of the SGO, and (ii a late episode associated to the summit of the SGO volcanites, which includes granites and sub-volcanic syenogranites of iron-bearing type and alkali-calcic to alkaline affinity. These magmatisms resulting from the partial melting of mixed material mark the end of the last Panafrican episode and would be set up in a transition from orogenic to anorogenic settings which announce the Paleozoic cycle. They would be contemporary to posterior with the exhumation of the extensive metamorphic domes of the Western Anti-Atlas.El estudio de los granitoides neoproterozoicos de la “boutonnière” (complejo plutono-metamórfico profundo con geometría subcircular de Ifni y de los de otras “boutonnières” del dominio suroccidental del Anti-Atlas, demuestra que este magmatismo evoluciona desde un tipo magnésico hacia un tipo férrico. En la “boutonnière” de Ifni, estos granitoides afloran en el interior de formaciones sedimentarias y volcano-sedimentarias del Supergrupo de Ouarzazate SGO (615 a 540 Ma. Pertenecen a dos episodios magmáticos diferentes (i un episodio precoz compuesto de granitoides magnésicos, calcoalcalinos y metaluminosos a poco aluminosos (dioritas con cuarzo, granodioritas y monzogranitos que intruyen en las formaciones inferiores del SGO, (ii un episodio tardío asociado con un vulcanismo terminal a techo del

  20. Petrography and petrology of the Ayghalesi granite, east of Takab area (northwest of Iran

    Directory of Open Access Journals (Sweden)

    Saeed Kamran

    2017-03-01

    Full Text Available The investigated granite intrusion is located at the north of Ayghalesi village, east of Takab The Ayghalesi granite has been intruded the Eocene sandstone and conglomerate rocks and low grade metamorphic hornfels have been metamorphosed host rocks. The main constituent minerals are K-feldspar, plagioclase, quartz and muscovite.and minor garnet. The main texture is granular but pegmatitic, myrmektitic, graphic and perthitic occur as minor textures. Chemically, the rocks are granite on the various classification diagrams. The Ayghalesi intrusion body is classified as S-type, peraluminous composition, calc-alkaline nature and is calcic-alkali to alkali-calcic on the base of modified alkali lime index (MALI. The investigated body, on the tectonic discrimination diagrams, fall on syn-collisional tectonic setting domain, suggesting that it was originated during collision of Central Iranian and Arabian plates Key words: granite,

  1. Africa has unique and urgent barriers to cleft care: lessons from practitioners at the Pan-African Congress on Cleft Lip and Palate.

    Science.gov (United States)

    Adetayo, Oluwaseun; Ford, Rachel; Martin, Mark

    2012-01-01

    The goals of this study were to delineate the protocols employed for managing patients with cleft lip and palate deformities, delineate the challenges facing practitioners and patients, and to determine the patient and physician barriers to cleft care delivery in the region. Survey questionnaires were administered to practitioners attending the second Pan-African Congress on Cleft Lip and Palate (PACCLIP), which took place in Ibadan, Nigeria, West Africa from February 4-7, 2007. The conference included 225 participants, representing 17 African countries Protocols for repair of cleft lip and palate deformities were varied, with Millard's and von Langenbeck's techniques being the preferred approach for the management of cleft lip and palate deformities, respectively. A large proportion of providers have limited access to core cleft care supporting teams, especially speech language pathologists, orthodontists, and audiologists. Several challenging barriers to cleft care were also identified at both the institutional and individual levels and are reported. Geographic separation in Africa presents a similar challenge due to isolationism as it does to surgeons in Europe. Specific to Africa are the increased barriers to care, and economic and financial hardship at various levels. A focus on funding, team building, infrastructural support, and patient education appear to be crucial in improving the care and lives of children with facial clefts in Africa.

  2. Analysis of pan-African Centres of excellence in health innovation highlights opportunities and challenges for local innovation and financing in the continent

    Directory of Open Access Journals (Sweden)

    Nwaka Solomon

    2012-07-01

    Full Text Available Abstract A pool of 38 pan-African Centres of Excellence (CoEs in health innovation has been selected and recognized by the African Network for Drugs and Diagnostics Innovation (ANDI, through a competitive criteria based process. The process identified a number of opportunities and challenges for health R&D and innovation in the continent: i it provides a direct evidence for the existence of innovation capability that can be leveraged to fill specific gaps in the continent; ii it revealed a research and financing pattern that is largely fragmented and uncoordinated, and iii it highlights the most frequent funders of health research in the continent. The CoEs are envisioned as an innovative network of public and private institutions with a critical mass of expertise and resources to support projects and a variety of activities for capacity building and scientific exchange, including hosting fellows, trainees, scientists on sabbaticals and exchange with other African and non-African institutions.

  3. Uranium rich granite and uranium productive granite in south China

    Energy Technology Data Exchange (ETDEWEB)

    Mingyue, Feng; Debao, He [CNNC Key Laboratory of Uranium Resource Exploration and Evaluation Technology, Beijing Research Institute of Uranium Geology (China)

    2012-07-15

    The paper briefly introduces the differences between uranium rich granite and uranium productive granite in the 5 provinces of South China, and discusses their main characteristics in 4 aspects, the uranium productive granite is highly developed in fracture, very strong in alteration, often occurred as two-mica granite and regularly developed with intermediate-basic and acid dikes. The above characteristics distinguish the uranium productive granite from the uranium rich granite. (authors)

  4. Uranium rich granite and uranium productive granite in south China

    International Nuclear Information System (INIS)

    Feng Mingyue; He Debao

    2012-01-01

    The paper briefly introduces the differences between uranium rich granite and uranium productive granite in the 5 provinces of South China, and discusses their main characteristics in 4 aspects, the uranium productive granite is highly developed in fracture, very strong in alteration, often occurred as two-mica granite and regularly developed with intermediate-basic and acid dikes. The above characteristics distinguish the uranium productive granite from the uranium rich granite. (authors)

  5. EXPLOITATION OF GRANITE BOULDER

    Directory of Open Access Journals (Sweden)

    Ivan Cotman

    1994-12-01

    Full Text Available The processes of forming, petrography, features, properties and exploitation of granite boulders are described. The directional drilling and black powder blasting is the succesful method in exploitation of granite boulders (boulder technology (the paper is published in Croatian.

  6. Timing of maturation of a Neoproterozoic oceanic arc during Pan-African Orogeny: the Asmlil complex (Anti-Atlas, South Morocco)

    Science.gov (United States)

    Triantafyllou, Antoine; Berger, Julien; Baele, Jean-Marc; Bruguier, Olivier; Diot, Hervé; Ennih, Nasser; Plissart, Gaëlle; Monnier, Christophe; Watlet, Arnaud; Vandycke, Sara

    2016-04-01

    Many intra-oceanic paleo-arcs are exposed in the Pan-African belt surrounding the West African Craton. In the Moroccan Anti-Atlas, remnants of Intra-Oceanic Subduction Zone (IOSZ) are preserved in few erosional windows moulded along the Anti-Atlas Major fault. These complexes highlight a Neoproterozoic paleo-suture made of 760 My back-arc ophiolites thrusted to the south onto a dismembered band of oceanic arc relics. The Asmlil arc complex, located in the southern part of the Bou Azzer inlier, is made of (i) 755 to 745 My- intermediate banded gneiss interpreted as metavolcanic products of a juvenile oceanic arc. This latter has been intruded by (ii) medium-grained hornblende-gabbro and dioritic magmas, in turn intruded by (iii) medium- to coarse grained hornblenditic-granodioritic decametric intrusions under sub-magmatic HT conditions. Hornblende-gabbros are made of garnet + amphibole/cpx relics + epidote + rutile paragenesis. Calculated pseudosections yielded P ~ 11-12 kbar for T ranging between 600 and 720°C for garnet growth. Measured Zr-in-rutile thermometer gave slightly higher temperature ranging between 710-790°C. On the field, garnet-rich leucocratic veinlets suggest that moderate partial melting of the mafic rock or localized dehydration reactions took place under garnet-granulite conditions (>800°C for hydrated chemical system). New geochronological data on garnet-bearing leucogabbros constrain their emplacement at 700 ±7 My (U-Pb zircon with low Th/U volcanic to subvolcanic massifs. Second event occurred around 700 My and results from mafic products intruding previous arc. A last event also dated at 660-650 My in the Sirwa window marks the emplacement of hot hornblenditic arc-magmas into older arc massifs during the tectonic extrusion of the arc section. This late event is also related to intense melt production at different level of the arc contributing to differentiation of the whole arc complex. We thus interpreted the Asmlil complex as the final

  7. Permian ultrafelsic A-type granite from Besar Islands group, Johor, peninsular Malaysia

    Science.gov (United States)

    Ghani, Azman A.; Hazad, Fatin Izzani; Jamil, Azmiah; Xiang, Quek Long; Atiqah Wan Ismail, Wan Nur; Chung, Sun-Lin; Lai, Yu-Ming; Roselee, Muhammad Hatta; Islami, Nur; Nyein, Kyaw Kyaw; Amir Hassan, Meor Hakif; Abu Bakar, Mohd Farid; Umor, Mohd Rozi

    2014-12-01

    The granitic rocks of the peninsula have traditionally been divided into two provinces, i.e., Western and Eastern provinces, corresponding to S- and I-type granite respectively. The Western Province granite is characterised by megacrystic and coarse-grained biotite, tin-mineralised, continental collision granite, whereas, the Eastern Province granite is bimodal I-type dominated by granodiorite and associated gabbroic of arc type granite. This paper reports the occurrence of an A-type granite from peninsular Malaysia. The rocks occur in the Besar, Tengah, and Hujung islands located in the southeastern part of the peninsula. The granite is highly felsic with SiO2 ranging from 75.70% to 77.90% (differentiation index = 94.2-97.04). It is weakly peraluminous (average ACNK =1.02), has normative hypersthene (0.09-2.19%) and high alkali content (8.32-8.60%). The granites have many A-type characteristics, among them are shallow level of emplacement, high Ga, FeT/MgO and low P, Sr, Ti, CaO and Nb. Calculated zircon saturation temperatures for the Besar magma ranging from 793 ∘ to 806 ∘C is consistent with high temperature partial melting of a felsic infracrustal source which is taken as one of the mechanisms to produce A-type magma. The occurrence of the A-type granite can be related to the extensional back arc basin in the Indo-China terrane during the earliest Permian.

  8. Pan African Medical Journal: Submissions

    African Journals Online (AJOL)

    Poor English of French do not prevent acceptance provided the paper's content is of ... Articles and associated material should be sent to any of the following email address: ... We encourage authors to write their Discussion in a structured way, ...

  9. Milk-alkali syndrome

    Science.gov (United States)

    Calcium-alkali syndrome; Cope syndrome; Burnett syndrome; Hypercalcemia; Calcium metabolism disorder ... Milk-alkali syndrome is almost always caused by taking too many calcium supplements, usually in the form of calcium carbonate. Calcium ...

  10. The Pan-African Kekem gabbro-norite (West-Cameroon), U-Pb zircon age, geochemistry and Sr-Nd isotopes: Geodynamical implication for the evolution of the Central African fold belt

    Science.gov (United States)

    Kwékam, Maurice; Affaton, Pascal; Bruguier, Olivier; Liégeois, Jean-Paul; Hartmann, Gerald; Njonfang, Emmanuel

    2013-08-01

    The Kekem shoshonitic gabbro-norite association is part of the high-K calc-alkaline (HKCA) post-collisional magmatism, a major feature of the Pan-African Belt in Cameroon. LA-ICP-MS U-Pb zircon analyses provide an age of 576 ± 4 Ma for the Kekem complex. This age is interpreted as dating the emplacement of the massif during the waning stage of the Pan-African orogeny. The latter is related to dextral movements along the Central Cameroon Shear Zone (CCSZ). The REE patterns display enriched LREE (LaN/YbN = 14.2-23.5) while HREE present a nearly flat profile (DyN/YbN = 1.3-1.7), and the La/Sm and Sm/Yb ratios led to propose that the Kekem gabbro-norites have been derived from the partial melting of a garnet-spinel lherzolite mantle source. The negative Nb-Ta and Ti anomalies and the positive Pb anomalies indicate that this mantle source was modified by contribution of a subduction-related material. The low Ce/Pb (2.6-10.4) and Th/Yb ratios associated to high Ba/La ratios, indicate that source enrichment could be related to slab derived fluids. As a whole, the Kekem geochemical features suggest that primary gabbro-noritic magmas derived from a subduction-modified mantle source (metasomatised lithospheric mantle). Moderately high 86Sr/87Sr initial ratios (0.7068-0.7082), low ɛNd (-5 to -9) and old Nd TDM model ages (1.6-1.8 Ga) are interpreted to result from contamination of Neoproterozoic mantle by the Paleoproterozoic crust. The ca. 576 Ma movements along the CCSZ are related to a Neoproterozoic metacratonization of the northern margin of the Congo craton during the Pan-African orogeny. This metacratonization led to vertical planar lithospheric delamination along lithospheric transcurrent faults, asthenospheric uprise and partial melting of the Paleoproterozoic lithospheric mantle.

  11. Geology, petrology and U-Pb geochronology of Serra da Rajada Granitic Pluton: implications about ediacaran magmatic evolution in NE portion of the Rio Piranhas-Serido Domain (NE of Borborema Province); Geologia, petrologia e geocronologia U-Pb do Pluton Granitico Serra da Rajada: implicacoes sobre a evolucao magmatica ediacarana na porcao do Dominio Rio Piranhas-Serido (NE da Provincia Borborema)

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Alan Pereira da; Dantas, Alexandre Ranier, E-mail: alan.costa@cprm.gov.br, E-mail: alexandre.dantas@cprm.gov.br [Servico Geologico do Brasil (CPRM), Natal, RN (Brazil). Nucleo de Apoio de Natal/Superintendencia Regional de Recife; Nascimento, Marcos Antonio Leite do; Galindo, Antonio Carlos, E-mail: marcos@geologia.ufrn.br, E-mail: galindo@geologia.ufrn.br [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Departamento de Geologia

    2015-12-15

    The Ediacaran plutonic activity, related to the Brazilian/Pan-African orogeny, is one of the most important geological features in the Borborema Province, formed by batholiths, stocks and dikes. The Serra da Rajada Granitic Pluton (SRGP), located in the central portion of the Rio Piranhas-Serido Domain, is an example of these bodies. This site is the target of cartographic, petrographic, lithochemical and geochronological studies. Its rocks are described as monzogranites consisting of K-feldspar, plagioclase (oligoclase-An{sub 23-24%}), quartz and biotite (main mafic), having as accessory minerals opaque, titanite, allanite, apatite and zircon. Chlorite, white mica and carbonate are alteration minerals. Lithochemical data from 15 samples show quite evolved rocks (SiO{sub 2} , 69% to 75%), rich in alkalis (Na{sub 2}O + K{sub 2}O ≥ 8.0%), depleted in MgO (≤ 0.45%), CaO (≤ 1.42%) and TiO{sub 2} (≤ 0.36%), and displaying moderate levels of Fe{sub 2}O{sub 3} t (2.16 to 3.53%). These rocks present a transitional nature between metaluminous and peraluminous (predominance of the latter) and have subalkaline/monzonitic affinity (high-K Calc-alkaline). Harker diagrams represent negative correlations in Fe{sub 2}O{sub 3}t, MgO and CaO, indicating fractionation of mafic and plagioclase. The REE spectrum show enrichment of light in relation to heavy REE (LaN/YbN = 23.70 to 10.13), with negative anomaly in Eu (Eu/ Eu* = 0.70 to 10.13) suggesting fractionation or accumulation in the feldspars source (plagioclase). Data integration allows correlating the SRGP rocks with those described as Equigranular high-K Calc-alkaline Suite. The U-Pb geochronology and Sm-Nd isotope dating indicate that the biotite monzogranite have a crystallization age of 557 ± 13 Ma and TDM model age of 2.36 Ga, respectively, and ε{sub Nd} value of - 20.10 for the crystallization age, allowing to infer a crustal source for the magma generated in the Paleoproterozoic age. (author)

  12. Granit, Prof. Ragnar Arthur

    Indian Academy of Sciences (India)

    Home; Fellowship. Fellow Profile. Elected: 1964 Honorary. Granit, Prof. Ragnar Arthur Nobel Laureate (Medicine) - 1967. Date of birth: 30 October 1900. Date of death: 11 March 1991. YouTube; Twitter; Facebook; Blog. Academy News. IAS Logo. 29th Mid-year meeting. Posted on 19 January 2018. The 29th Mid-year ...

  13. Greisen deposits associated to carboniferous post-orogenic granites with mineralization potential, Sierra de Fiambala, Catamarca, Argentina

    International Nuclear Information System (INIS)

    Fogliata, A. S.; Rubinstein, N. R.; Avila, J. C.; Baez, M.

    2008-01-01

    The Fiambala range is located in the central south part of the province of Catamarca, Western Sierras Pampeanas, Argentina. It is largely conformed by Precambrian metamorphic rocks, a Cambrian granitic intrusive, Ordovician basic and ultra basic rocks and epi zonal Carboniferous granites (Los Ratones, El Salto and Ayacucho Granites). The Carboniferous granites are sub alkaline, weakly peraluminous, high silica (except for the porphyritic facies of Los Ratones granite) and moderately enriched in K. Contents of trace elements and REE indicate that El S alto and Ayacucho granites and the granular facies of Los Ratones granite have characteristics of evolved and differentiated granite associated with hydrothermal systems. The variations of trace elements, particularly Sn, W, U, Rb, Ba, Zr and Sr suggest that they correspond to granites with mineralization potential. Genetically linked to these granites there are Sn, W, U and minor base metals greisen deposits. The hydrothermal process that yield to these deposits involved two main alteration stages, beginning with alkali metasomatism follow by greissenization. According to the isotopic ages the hydrothermal processes postdate about 1 Ma the magmatic activity. The analyses of the granites and the associated greisen deposits confirm that the post orogenic carboniferous magmatism is the major metallogenetic control of the ore deposits from the studied area. This metallogenetic control could be a useful tool in prospecting similar deposits in the rest of the Western Sierras Pampeanas. (Author)

  14. 40Ar/39Ar dating of 1.0-1.1 Ga magnetizations from the Sao Francisco and Kalahari cratons: tectonic implications for Pan-African and Brasiliano mobile belts

    International Nuclear Information System (INIS)

    Renne, P.R.; Onstott, T.C.; Agrella-Filho, M.S. d'; Pacca, I.G.; Teixeira, W.

    1990-01-01

    Paleomagnetic poles from 1.1-1.0 Ga dyke swarms in eastern Brazil (Sao Francisco Craton) are compared with 1.0 Ga poles from granulites of the Namaqua Province in southern Africa (Kalahari Graton). The intrusive ages of dykes are estimated from 40 Ar/ 39 Ar dating of outgassed biotites from baked country rocks. The age of magnetization for the granulites is derived by combining 40 Ar/ 39 Ar hornblende and biotite dates. When restored to a Mesozoic pre-drift configuration the paleomagnetic poles are in crude spatial agreement but are temporally discordant. To satisfy both paleomagnetic and geochronologic constraints, a reconstruction involving separation of the Sao Francisco and Kalahari cratons is required, indicating that the intervening Pan-African (Brasiliano) mobile belt may record a craton-craton collision. (orig.)

  15. Optimising design and cost-effective implementation of future pan-African dietary studies: a review of existing economic integration and nutritional indicators for scenario-based profiling and clustering of countries.

    Science.gov (United States)

    Aglago, Elom K; Landais, Edwige; Zotor, Francis; Nicolas, Genevieve; Gunter, Marc J; Amuna, Paul; Slimani, Nadia

    2018-02-01

    Most of the African countries are undergoing a complex nutrition and epidemiologic transition associated with a rapid increase in the prevalence of diverse non-communicable diseases. Despite this alarming situation, the still limited and fragmented resources available in Africa impede the implementation of effective action plans to tackle the current and projected diet-disease burden. In order to address these common needs and challenges, the African Union is increasingly supporting continental approaches and strategies as reflected in the launching of the Agenda 2063 and the African regional nutrition strategy 2015-2025, among others. To assure the successful implementation of pan-African nutritional and health initiatives, cost-effective approaches considering similarities/disparities in economy, regional integration, development and nutritional aspects between countries are needed. In the absence of pre-existing models, we reviewed regional economic integration and nutritional indicators (n 13) available in international organisations databases or governmental agencies websites, for fifty-two African countries. These indicators were used to map the countries according to common languages (e.g. Arabic, English, French, Portuguese), development status (e.g. human development index), malnutrition status (e.g. obesity) and diet (e.g. staples predominantly based on either cereals or tubers). The review of the indicators showed that there exist similarities between African countries that can be exploited to benefit the continent with cross-national experiences in order to avoid duplication of efforts in the implementation of future pan-African health studies. In addition, including present and future nutrition surveillance programmes in Africa into national statistical systems might be cost-effective and sustainable in the longer term.

  16. Petrogenesis of Karamaili alkaline A-type granites from East Junggar, Xinjiang (NW China) and their relationship with tin mineralization

    International Nuclear Information System (INIS)

    Su Yuping; Tang Hongfeng; Liu Congqiang; Hou Guangshun; Cong Feng; Sylvester, Paul J.; Qu Wenjun

    2007-01-01

    Several types of granites including alkaline granites and alkali feldspar granites are distributed in the Karamaili tectonic belt of East Junggar, Xinjiang, China. Some medium-small tin deposits are located within or near the contact zones of the granitic intrusions. The alkaline granites share all the features commonly observed in peralkaline A-type granites. They contain alkalic mafic minerals such as riebeckite and aegirine; have high contents of SiO 2 , alkalis, Rb, Th, Zr, Hf, REE (except Eu), and high ratios of FeO/MgO and Ga/Al; and show strong depletions in Ba, Sr, Eu in the spidergrams. Laser ablation-ICPMS U-Pb zircon geochronology indicates a crystallization age of ca. 305 Ma for the granites; TIMS analyses of the granites found high ε Nd (T) values of +5.9 to +6.5. Considering their geochemical features, alkaline granites most likely formed by fractional crystallization of graodioritic magmas, which were probably produced by partial melting of lower crustal basaltic to andesitic rocks formed from oceanic crustal materials that were deeply buried during late Palezoic subduction and accretion. Six molybdenite samples from the Sareshike tin deposit in East Junggar yielded an isochron age of 307±11 Ma (2σ) and a weighted mean model age of 306.5±3.4 Ma, consistent with zircon U-Pb ages of the alkaline granites. Low Re contents (0.323-0.961 ppm) in the molybdenite suggest that they originated from crustal sources related to the alkaline granites. Considering their identical ages, close spatial distribution, and similar sources, we argue that the A-type granites have a genetic relationship with the tin mineralization, and that the same association may be important elsewhere. (author)

  17. Geochronology and geochemistry of the granites from the Zhuxi W-Cu ore deposit in South China: Implication for petrogenesis, geodynamical setting and mineralization

    Science.gov (United States)

    Pan, Xiaofei; Hou, Zengqian; Zhao, Miao; Chen, Guohua; Rao, Jianfeng; Li, Yan; Wei, Jin; Ouyang, Yongpeng

    2018-04-01

    The giant Zhuxi tungsten deposit is located in the Taqian-Fuchun Ore Belt in northeastern Jiangxi province, and genetically associated with the Zhuxi granitic stocks and dykes. Three mineralization-related granites including granite porphyry dykes (GP), biotite granitic stocks (BG), and white granitic dykes (WG), were identified in the Zhuxi deposit. SHRIMP zircon U-Pb analysis for the three granitic rocks present ages ranging from 153.5 ± 1.0 Ma to 150.4 ± 1.0 Ma. The BG mainly contains quartz, microcline, albite, biotite and muscovite with minor accessory minerals including zircon, apatite, monazite, Ti/Fe oxides, and dolerite. However, the WG is mainly composed of quartz, microcline and albite with minor muscovite and accessory minerals. The GP is a medium-grained porphyritic granite and its phenocrysts include quartz, alkali feldspar, muscovite and plagioclase. All the Zhuxi granites have high SiO2 content (71.97 wt%-81.19 wt%) and total alkali (3.25 wt%-9.42 wt%), and their valid aluminum saturation index (ASI) values show a wide range of 1.03 to 2.49. High Rb/Sr ratios, low Sr content (data suggest that these highly fractionated I-S transform-type granites were originated from magmas which showed affinity with the Proterozoic continent and the Shuangqiaoshan Group and little mantle contribution was involved during the generation of Zhuxi granitic rocks. Extreme fractional crystallization resulted in further enrichment of tungsten in the evolved granitic magma. New data, presented together with previously published data, suggest that the Zhuxi granitic complex was likely to be formed during lithospheric compression setting during the late Jurassic to early Cretaceous. The biotite granite stock predominately contributed to the production of skarn alteration and mineralization, followed by the white granite dyke; the granite porphyry dykes have little effect.

  18. The Shahewan rapakivi-textured granite – quartz monzonite pluton, Qinling orogen, central China: mineral composition and petrogenetic significance

    Directory of Open Access Journals (Sweden)

    Xiaoxia Wang

    2002-01-01

    Full Text Available The Mesozoic Shahewan pluton consists of four texturally different types of biotite-hornblende quartz monzonite. In the porphyritic types alkali feldspar occurs as euhedral or ovoidal megacrysts that are often mantled by one or more plagioclase shells, and as smaller grains in the groundmass. Quartz, plagioclase (An20–28, biotite, and hornblende occur as inclusions in the alkali feldspar megacrystsand, more abundantly, in the groundmass. Euhedral quartz crystals in the groundmass are not as common and well developed as in typical rapakivi granite. Compared to typical rapakivi granites, the mafic minerals (biotite and hornblende are rich in Mg and poor in Fe, and the whole rock is low in Si, K, F, Ga, Zr, LREE, Fe/Mg, and K/Na. The rocks of the Shahewan pluton are thus regarded as rapakivi-textured quartz monzonites and granites but not true rapakivi granites.

  19. Alkali metal hydride formation

    International Nuclear Information System (INIS)

    1976-01-01

    The present invention relates to a method of producing alkali metal hydrides by absorbing hydrogen gas under pressure into a mixture of lower alkyl mono amines and alkali metal alkyl amides selected from sodium and potassium amides formed from said amines. The present invention also includes purification of a mixture of the amines and amides which contain impurities, such as is used as a catalytic exchange liquid in the enrichment of deuterium, involving the formation of the alkali metal hydride

  20. The rapakivi granite plutons of Bodom and Obbnäs, southern Finland: petrography and geochemistry

    Directory of Open Access Journals (Sweden)

    Kosunen, P.

    1999-12-01

    Full Text Available The Obbnäs and Bodom granite plutons of southernmost Finland show the typical petrographic and geochemical features of the Proterozoic rapakivi granites in Finland and elsewhere: they cut sharply across the 1900 Ma Svecofennian metamorphic bedrock and have the geochemical characteristics of subalkaline A-type granites. The Bodom pluton is composed of porphyritic granites (hornblende-, hornblende-biotite-, and biotite-bearing varieties and an even-grained granite that probably represent two separate intrusive phases. This lithologic variation does not occur in the Obbnäs pluton, which is almost entirely composed of porphyritic hornblende-biotite granite that gradually becomes more mafic to the southwest. Three types of hybrid granitoids resulting from magma mingling and mixing occur on the southwestern tip of the Obbnäs peninsula. The Bodom granites are syenogranites, whereas the composition of the Obbnäs granite varies from syeno- to monzogranite. The main silicates of both the Bodom and Obbnäs granites are quartz, microcline, plagioclase (An1541, biotite (siderophyllite, and generally also amphibole (ferropargasite or hastingsite. Plagioclase-mantled alkali feldspar megacrysts are absent or rare. The accessory minerals are fluorite, allanite, zircon, apatite, and iron-titanium oxides; the Obbnäs granite also contains titanite. The Bodom and Obbnäs granites are metaluminous to weakly peraluminous, with average A/CNK of 1.00 and 1.05, respectively, have high Fe/Mg (average FeOtot/[FeOtot+MgO] is 0.94 for the Bodom and 0.87 for the Obbnäs granites, and high Ga/Al (3.78 to 5.22 in Bodom and 2.46 to 4.18 in Obbnäs. The REE contents are high with LREE-enriched chondrite-normalized patterns and moderate (Obbnäs to relatively strong (Bodom negative Eu-anomalies. The Obbnäs granite is enriched in CaO, TiO2, MgO, and FeO, and depleted in SiO2 and K2O compared to the Bodom granites. Also, there are differences in the Ba, Rb, and Sr contents of

  1. Preliminary report on a glass burial experiment in granite

    International Nuclear Information System (INIS)

    Clark, D.E.; Zhu, B.F.; Robinson, R.S.; Wicks, G.G.

    1983-01-01

    Preliminary results of a two-year burial experiment in granite are discussed. Three compositions of simulated alkali borosilicate waste glasses were placed in boreholes approximately 350 meters deep. The glass sample configurations include mini-cans (stainless steel rings into which glass has been cast) and pineapple slices (thin sections from cylindrical blocks). Assemblies of these glass samples were prepared by stacking them together with granite, compacted bentonite and metal rings to provide several types of interfaces that are expected to occur in the repository. The assemblies were maintained at either ambient mine temperature (8 to 10 0 C) or 90 0 C. The glasses were analyzed before burial and after one month storage at 90 0 C. The most extensive surface degradation occurred on the glasses interfaced with bentonite. In general, very little attack was observed on glass surfaces in contact with the other materials. The limited field and laboratory data are compared

  2. Geochronology (Rb-Sr, Sm-Nd and Pb-Pb) of the proterozoic granulitic and granitic rocks around Usilampatti, Madurai district, Tamil Nadu: implication on age of various lithounits

    International Nuclear Information System (INIS)

    Pandey, U.K.; Pandey, B.K.; Krishnamurthy, P.

    2005-01-01

    Rb-Sr, Sm-Nd and Pb-Pb systematics on mafic granulites, intermediate- charnockites, charnockites, calc-granulites, orthogneisses, leptynites, granites and two (2) mineral samples (microcline and muscovite) from pegmatite have been studied. Sm-Nd model ages (T DM ) for most of the rocks cluster around 2.1 Ga. Calc-granulites gave Rb-Sr whole rock isochron age of 1339 ± 110 Ma with initial 87 Sr/ 86 Sr ratio (I.R.) = 0.709. Mesoproterozoic age for the Metasedimentary Group of rocks (calc-granulites) has been inferred based on their 87 Sr/ 86 Sr ratio also. Granites and leptynites have yielded Rb-Sr whole rock isochron ages of 823± 38 Ma, with I.R. = 0.713 and 894± 82 Ma, with I.R. = 0.708 respectively which are younger than the calc-granulites. Microcline and muscovite from pegmatite gave Rb-Sr model ages as 532 and 491 Ma respectively. Granites, leptynites and calc-granulites are derived from the crustal source as indicated by their high initial 87 Sr/ 86 Sr ratios. Most probably the protolith of the granitic and granulitic rocks is of Palaeoproterozoic age in this part of the Madurai Block. The minimum age of granulite grade of metamorphism has been inferred at c. 850 Ma, indirectly on the basis of Rb-Sr ages of leptynites, which normally form during the evolution of granulite facies assemblages. Both granulite facies metamorphism and granitic magmatism probably took place during Neoproterozoic period correlatable to the early phase of Pan-African orogeny. Later decompression, causing mineral scale resetting of the Rb-Sr and Sm-Nd systematics, around 450-550 Ma, may correspond to the final exhumation, which brought the middle to lower crustal granulites to upper crustal levels, during the last phase of Pan-African activity. As per ages obtained on various lithounits in the present study the Metasedimentary Group of rocks (Mesoproterozoic) are younger than the Charnockite Group of rocks (Palaeoproterozoic) followed by the rocks belonging to the Migmatite Complex

  3. Geochronology (Rb-Sr, Sm-Nd and Pb-Pb) of the proterozoic granulitic and granitic rocks around Usilampatti, Madurai District, Tamil Nadu: implication on age of various lithounits

    International Nuclear Information System (INIS)

    Pandey, U.K.; Pandey, B.K.; Krishnamurthy, P.

    2005-01-01

    Rb-Sr, Sm-Nd and Pb-Pb systematics on mafic granulites, intermediate-charnockites, charnockites, calc- granulites, orthogneisses, leptynites, granites and two (2) mineral samples (microcline and muscovite) from pegmatite have been studied. Sm-Nd model ages (T DM ) for most of the rocks cluster around 2.1 Ga. Calc-granulites gave Rb-Sr whole rock isochron age of 1339± 110 Ma with initial 87 Sr/ 86 Sr ratio (IR)= 0.709. Mesoproterozoic age for the metasedimentary group of rocks (calc-granulites) has been inferred based on their 86 Sr/ 86 Sr ratio also. Granites and leptynites have yielded Rb-Sr whole rock isochron ages of 823 ± 38 Ma, with I.R. = 0.713 and 894± 82 Ma, with I.R.= 0.708 respectively which are younger than the calc-granulites. Microcline and muscovite from pegmatite gave Rb-Sr model ages as 532 and 491 Ma respectively. Granites, leptynites and calc-granulites are derived from the crustal source as indicated by their high initial 87 Sr/ 86 Sr ratios. Most probably the protolith of the granitic and granulitic rocks is of Palaeoproterozoic age in this part of the Madurai Block. The minimum age of granulite grade of metamorphism has been inferred at c. 850 Ma, indirectly on the basis of Rb-Sr ages of leptynites, which normally form during the evolution of granulite facies assemblages. Both granulite facies metamorphism and granitic magmatism probably took place during Neoproterozoic period correlatable to the early phase of Pan-African orogeny. Later decompression, causing mineral scale resetting of the Rb-Sr and Sm-Nd systematics, around 450-550 Ma, may correspond to the final exhumation, which brought the middle to lower crustal granulites to upper crustal levels, during the last phase of Pan-African activity. As per ages obtained on various lithounits in the present study the Metasedimentary Group of rocks (Mesoproterozoic) are younger than the Charnockite Group of rocks (Palaeoproterozoic) followed by the rocks belonging to the Migmatite Complex

  4. Late Precambrian Balkan-Carpathian ophiolite — a slice of the Pan-African ocean crust?: geochemical and tectonic insights from the Tcherni Vrah and Deli Jovan massifs, Bulgaria and Serbia

    Science.gov (United States)

    Savov, Ivan; Ryan, Jeff; Haydoutov, Ivan; Schijf, Johan

    2001-10-01

    between the BCO and the Pan-African ophiolites from the Arabian-Nubian Shield. We suggest that the BCO is the missing link between the Pan-African and the Avalonian-Cadomian peripheral orogens of Murphy and Nance [Geology 19 (1995) 469].

  5. Magmatic evolution and controls on rare metal-enrichment of the Strange Lake A-type peralkaline granitic pluton, Québec-Labrador

    Science.gov (United States)

    Siegel, Karin; Vasyukova, Olga V.; Williams-Jones, Anthony E.

    2018-05-01

    Although it is well known that A-type granites are enriched in the rare earth elements (REE) and other high field strength elements (HFSE), the magmatic processes that concentrate these elements are still poorly understood. The 1.24 Ga Strange Lake pluton in northern Québec-Labrador provides an extraordinary example of hyper-enrichment in the REE, Zr, and Nb in a peralkaline A-type granite. The pluton consists of two hypersolvus granite units (southern and northern) and a transsolvus granite, all of which contain perthitic alkali feldspar as the earliest major mineral; the transsolvus granite also contains separate albite and microcline crystals. Arfvedsonite, a sodic amphibole, occurs exclusively as phenocrysts in the transsolvus granite, whereas in the hypersolvus granite it is present as a late, interstitial phase. The primary HFSE minerals are zircon, monazite-(Ce), gagarinite-(Ce) and the pyrochlore group minerals. Magma evolution was monitored by the alumina content in the bulk rock, which decreases from the southern to the northern hypersolvus granite and is lowest in the transsolvus granite. Alkalinity indices and bulk Si, Fe, Rb, REE, Zr, Nb concentrations show the opposite trend. Alkali feldspar compositions mirror the trend shown by the bulk rock, i.e., decreasing Al contents are accompanied by increasing Si, Fe3+, REE, Zr and Nb contents. The major driving forces for the evolution of the hypersolvus magma prior to emplacement were the early separation of a fluoride melt from the silicate melt and the crystallization of alkali feldspar and HFSE-rich phases (zircon, monazite-(Ce), pyrochlore group). An alkali feldspar-rich crystal-mush containing LREE-fluoride melt droplets was emplaced as the least evolved southern hypersolvus granite. Massive fractionation of alkali feldspar led to a sharp increase in ƒH2O and F- activity in the magma chamber that triggered the crystallization of arfvedsonite and was followed by emplacement of the northern hypersolvus

  6. Heat production in granitic rocks

    DEFF Research Database (Denmark)

    Artemieva, Irina; Thybo, Hans; Jakobsen, Kiki

    2017-01-01

    Granitic rocks play special role in the dynamics and evolution of the Earth and its thermal regime. First, their compositional variability, reflected in the distribution of concentrations of radiogenic elements, provides constraints on global differentiation processes and large scale planetary...... evolution, where emplacement of granites is considered a particularly important process for the formation of continental crust. Second, heat production by radioactive decay is among the main heat sources in the Earth. Therefore knowledge of heat production in granitic rocks is pivotal for thermal modelling...... of the continental lithosphere, given that most radiogenic elements are concentrated in granitic rocks of the upper continental crust whereas heat production in rocks of the lower crust and lithospheric mantle is negligible. We present and analyze a new global database GRANITE2017 (with about 500 entries...

  7. Climax granite test results

    Energy Technology Data Exchange (ETDEWEB)

    Ramspott, L.D.

    1980-01-15

    The Lawrence Livermore Laboratory (LLL), as part of the Nevada Nuclear Waste Storage Investigations (NNWSI) program, is carrying out in situ rock mechanics testing in the Climax granitic stock at the Nevada Test Site (NTS). This summary addresses only those field data taken to date that address thermomechanical modeling for a hard-rock repository. The results to be discussed include thermal measurements in a heater test that was conducted from October 1977 through July 1978, and stress and displacement measurements made during and after excavation of the canister storage drift for the Spent Fuel Test (SFT) in the Climax granite. Associated laboratory and field measurements are summarized. The rock temperature for a given applied heat load at a point in time and space can be adequately modeled with simple analytic calculations involving superposition and integration of numerous point source solutions. The input, for locations beyond about a meter from the source, can be a constant thermal conductivity and diffusivity. The value of thermal conductivity required to match the field data is as much as 25% different from laboratory-measured values. Therefore, unless we come to understand the mechanisms for this difference, a simple in situ test will be required to obtain a value for final repository design. Some sensitivity calculations have shown that the temperature field is about ten times more sensitive to conductivity than to diffusivity under the test conditions. The orthogonal array was designed to detect anisotropy. After considering all error sources, anisotropic efforts in the thermal field were less than 5 to 10%.

  8. Water Content of Lunar Alkali Fedlspar

    Science.gov (United States)

    Mills, R. D.; Simon, J. I.; Wang, J.; Alexander, C. M. O'D.; Hauri, E. H.

    2016-01-01

    Detection of indigenous hydrogen in a diversity of lunar materials, including volcanic glass, melt inclusions, apatite, and plagioclase suggests water may have played a role in the chemical differentiation of the Moon. Spectroscopic data from the Moon indicate a positive correlation between water and Th. Modeling of lunar magma ocean crystallization predicts a similar chemical differentiation with the highest levels of water in the K- and Th-rich melt residuum of the magma ocean (i.e. urKREEP). Until now, the only sample-based estimates of water content of KREEP-rich magmas come from measurements of OH, F, and Cl in lunar apatites, which suggest a water concentration of alkali feldspar, a common mineral in K-enriched rocks, can have approx. 20 ppm of water, which implies magmatic water contents of approx. 1 wt % in the high-silica magmas. This estimate is 2 to 3 orders of magnitude higher than that estimated from apatite in similar rocks. However, the Cl and F contents of apatite in chemically similar rocks suggest that these melts also had high Cl/F ratios, which leads to spuriously low water estimates from the apatite. We can only estimate the minimum water content of urKREEP (+ bulk Moon) from our alkali feldspar data because of the unknown amount of degassing that led to the formation of the granites. Assuming a reasonable 10 to 100 times enrichment of water from urKREEP into the granites produces an estimate of 100-1000 ppm of water for the urKREEP reservoir. Using the modeling of and the 100-1000 ppm of water in urKREEP suggests a minimum bulk silicate Moon water content between 2 and 20 ppm. However, hydrogen loss was likely very significant in the evolution of the lunar mantle. Conclusions: Lunar granites crystallized between 4.3-3.8 Ga from relatively wet melts that degassed upon crystallization. The formation of these granites likely removed significant amounts of water from some mantle source regions, e.g. later mare basalts predicting derivation from a

  9. Uranium enriched granites in Sweden

    International Nuclear Information System (INIS)

    Wilson, M.R.; Aakerblom, G.

    1980-01-01

    Granites with uranium contents higher than normal occur in a variety of geological settings in the Swedish Precambrian, and represent a variety of granite types and ages. They may have been generated by (1) the anatexis of continental crust (2) processes occurring at a much greater depth. They commonly show enrichement in F, Sn, W and/or Mo. Only in one case is an important uranium mineralization thought to be directly related to a uranium-enriched granite, while the majority of epigenetic uranium mineralizations with economic potential are related to hydrothermal processes in areas where the bedrock is regionally uranium-enhanced. (Authors)

  10. Granites and granitoids of the southern region - Granite molybdenite system

    International Nuclear Information System (INIS)

    Issler, R.S.

    1987-01-01

    Economic concentrations of molybdenum are genetically closely associated with acidic and moderately acid granitoids-granites, granodiorites, monzonites and diorites, and are located in two geotectonic settings: subduction-related and rift-related. The aim of this paper is twofold, first succinctly approach the geology, tectonic setting and chemical parameters of the 'granite molybdenite system' as defined by Mutschler and/or alcali granite porphyry bodies emplaced in the North American continent for occasion of a Mesozoic-Fanerozoic extensile event; second to relate the computer-assisted evaluation of 422 major element chemical analysis of granites and granitoids of southern region of Brazil, using chemical fingerprints (SiO 2 ≥ 74. Owt%, Na 2 O ≤ 3.6wt%, K 2 O ≥ 4.5wt%), and K 2 O/Na 2 O ratio > 1.5 developed and testified from North American and Finnish occurrences, may locate molybdenite-bearing granite bodies with high exploration potential. These techniques suggest that some late Precambrian to early Paleozoic granite-rhyolite assemblages inserted at domains of the SG. 22/23 Curitiba/Iguape, SH. 21/22 Uruguaiana/Porto Alegre and SI.22 Lagoa Mirim Sheets, have exploration potential for molybdenum. (author) [pt

  11. Artificial weathering of granite

    Directory of Open Access Journals (Sweden)

    Silva Hermo, B.

    2008-06-01

    Full Text Available This article summarizes a series of artificial weathering tests run on granite designed to: simulate the action of weathering agents on buildings and identify the underlying mechanisms, determine the salt resistance of different types of rock; evaluate consolidation and water-repellent treatment durability; and confirm hypotheses about the origin of salts such as gypsum that are often found in granite buildings. Salt crystallization tests were also conducted, using sodium chloride, sodium sulphate, calcium sulphate and seawater solutions. One of these tests was conducted in a chamber specifically designed to simulate salt spray weathering and another in an SO2 chamber to ascertain whether granite is subject to sulphation. The test results are analyzed and discussed, along with the shortcomings of each type of trial as a method for simulating the decay observed in monuments. The effect of factors such as wet-dry conditions, type of saline solution and the position of the planes of weakness on the type of decay is also addressed.En este trabajo se hace una síntesis de varios ensayos de alteración artificial realizados con rocas graníticas. Estos ensayos tenían distintos objetivos: reproducir las formas de alteración encontradas en los edificios para llegar a conocer los mecanismos que las generan, determinar la resistencia de las diferentes rocas a la acción de las sales, evaluar la durabilidad de tratamientos de consolidación e hidrofugación y constatar hipótesis acerca del origen de algunas sales, como el yeso, que aparecen frecuentemente en edificios graníticos. En los ensayos de cristalización de sales se utilizaron disoluciones de cloruro de sodio, sulfato de sodio, sulfato de calcio y agua de mar. Uno de estos ensayos se llevó a cabo en una cámara especialmente diseñada para reproducir la alteración por aerosol marino y otro se realizó en una cámara de SO2, con el objeto de comprobar si en rocas graníticas se puede producir

  12. Rétraction: plagiat aggravé dans l'article Aspergillose broncho-pulmonaire allergique lors d'un asthme réfractaire: à propos d'un cas clinique. Khalid Lahmadi, Hind El Youssi, Jawad Rochdi, BoughrineNawal, Er-Rami Mohammed. The Pan African Medical Journal. 2015;20:350. (doi:10.11604/pamj.2015.20.350.6572)

    Science.gov (United States)

    2015-01-01

    Cet article retracte l'article "Aspergillose broncho-pulmonaire allergique lors d'un asthme réfractaire: à propos d'un cas clinique. Khalid Lahmadi, Hind El Youssi, Jawad Rochdi, BoughrineNawal, Er-Rami Mohammed. The Pan African Medical Journal. 2015;20:350. (doi:10.11604/pamj.2015.20.350.6572)" PMID:26401219

  13. The Sao Jose do Rio Pardo mangeritic-granitic suite, south eastern Brazil

    International Nuclear Information System (INIS)

    Campos Neto, M.C.; Figueiredo, M.C.H.; Janasi, V.A.; Basei, M.A.S.; Fryer, B.J.

    1988-01-01

    In the Sao Jose do Rio Pardo region, Sao Paulo and Minas Gerais States, occur some intrusive, folded tabular bodies of mangerites associated with hornblende granitoids. The country rocks correspond to a complex association of gneisses and migmatites, locally with granulite facies assemblages. Both the magnerites and hornblende granitoids present a tectonic foliation with mineral flattening and stretching. Petrographically the mangeritic rocks are mainly dark green quartz mangerites with mesoperthite, plagioclase, quartz, hypersthene, clinopyroxene and variable amounts of hornblende, with zircon as conspicuous acessory. The pink hornblende granitoids are mainly granite s.s. exhibiting higher quartz and amphibole contents and lacking pyroxenes. Hololeucocratic alkali feldspar granites are locally associated to the hornblende granites. The textures of the mangerites and granites almost always show an important metamorphic overprinting, with relictic mesoperthite and pyroxene crystal into a granoblastic matrix. The magneritic-granitic suite is characterized by relatively high Fe/(Fe + Mg), K and HFS elements and low Ca contents, being comparable to typical anorogenic magneritic-granitic suites from Svcandinavia and North America. The Rb/Sr data indicate a Late Proterozoic metamorphic isotopic rehomogenization (930 Ma, Ro = 0.706). Geological evidence suggest that the intrusive age could be Middle Proterozoic, wich is reinforced by another Rb-Sr value of about 1300 Ma. (author) [pt

  14. Alkali metal ion battery with bimetallic electrode

    Science.gov (United States)

    Boysen, Dane A; Bradwell, David J; Jiang, Kai; Kim, Hojong; Ortiz, Luis A; Sadoway, Donald R; Tomaszowska, Alina A; Wei, Weifeng; Wang, Kangli

    2015-04-07

    Electrochemical cells having molten electrodes having an alkali metal provide receipt and delivery of power by transporting atoms of the alkali metal between electrode environments of disparate chemical potentials through an electrochemical pathway comprising a salt of the alkali metal. The chemical potential of the alkali metal is decreased when combined with one or more non-alkali metals, thus producing a voltage between an electrode comprising the molten the alkali metal and the electrode comprising the combined alkali/non-alkali metals.

  15. Uranium deposits in granitic rocks

    International Nuclear Information System (INIS)

    Nishimori, R.K.; Ragland, P.C.; Rogers, J.J.W.; Greenberg, J.K.

    1977-01-01

    This report is a review of published data bearing on the geology and origin of uranium deposits in granitic, pegmatitic and migmatitic rocks with the aim of assisting in the development of predictive criteria for the search for similar deposits in the U.S. Efforts were concentrated on the so-called ''porphyry'' uranium deposits. Two types of uranium deposits are primarily considered: deposits in pegmatites and alaskites in gneiss terrains, and disseminations of uranium in high-level granites. In Chapter 1 of this report, the general data on the distribution of uranium in igneous and metamorphic rocks are reviewed. Chapter 2 contains some comments on the classification of uranium deposits associated with igneous rocks and a summary of the main features of the geology of uranium deposits in granites. General concepts of the behavior of uranium in granites during crustal evolution are reviewed in Chapter 3. Also included is a discussion of the relationship of uranium mineralization in granites to the general evolution of mobile belts, plus the influence of magmatic and post-magmatic processes on the distribution of uranium in igneous rocks and related ore deposits. Chapter 4 relates the results of experimental studies on the crystallization of granites to some of the geologic features of uranium deposits in pegmatites and alaskites in high-grade metamorphic terrains. Potential or favorable areas for igneous uranium deposits in the U.S.A. are delineated in Chapter 5. Data on the geology of specific uranium deposits in granitic rocks are contained in Appendix 1. A compilation of igneous rock formations containing greater than 10 ppM uranium is included in Appendix 2. Appendix 3 is a report on the results of a visit to the Roessing area. Appendix 4 is a report on a field excursion to eastern Canada

  16. ALKALI RESISTANT CATALYST

    DEFF Research Database (Denmark)

    2008-01-01

    The present invention concerns the selective removal of nitrogen oxides (NOx) from gasses. In particular, the invention concerns a process, a catalyst and the use of a catalyst for the selective removal of nitrogen oxides in the presence of ammonia from gases containing a significant amount...... of alkali metal and/or alkali-earth compounds which process comprises using a catalyst combined of (i) a formed porous superacidic support, said superacidic support having an Hammett acidity stronger than Ho=-12, and (ii) a metal oxide catalytic component deposited on said superacidic support selected from...

  17. Methods of recovering alkali metals

    Science.gov (United States)

    Krumhansl, James L; Rigali, Mark J

    2014-03-04

    Approaches for alkali metal extraction, sequestration and recovery are described. For example, a method of recovering alkali metals includes providing a CST or CST-like (e.g., small pore zeolite) material. The alkali metal species is scavenged from the liquid mixture by the CST or CST-like material. The alkali metal species is extracted from the CST or CST-like material.

  18. ALKALI FUSION OF ROSETTA ZIRCON

    International Nuclear Information System (INIS)

    DAHER, A.

    2008-01-01

    The decomposition of Rosetta zircon by fusion with different types of alkalis has been investigated. These alkalis include sodium hydroxide, potassium hydroxide and eutectic mixture of both. The influences of the reaction temperature, zircon to alkalis ratio, fusion time and the stirring of the reactant on the fusion reaction have been evaluated. The obtained results favour the decomposition of zircon with the eutectic alkalis mixture by a decomposition efficiency of 96% obtained at 500 0 C after one hour

  19. Petrochemical characteristics of Serra do Meio alkaline granite (Campo Alegre de Lourdes - Bahia State)

    International Nuclear Information System (INIS)

    Matos Maia Leite, C. de; Froes, R.J.B.

    1989-01-01

    The Serra do Meio granite outcrops near the town of Campo Alegre de Lourdes, north-northeast of Bahia State. The granite is intrusive into micachists, which are correlatives of the Salgueiro-Cachoeirinha Group (Early Proterozoic), during early to the syn-tectonic shear phase. The geological setting also comprises a phosphatic rock-bearing carbonatitic complex and gabbroid complexes with one of the main world resources of Fe-Ti-V. The granite mineralogical composition grades from Aegerine-augite alkali-feldspar granite/syenites to Leuco alcali-feldspar granite. The geochemical analysis shows SiO 2 -enrichment (67 to 76%), in alkalis (Na 2 +K 2 O, 7,5 to 12,5%), Nb (up to 680ppm), Zr (up to 2,390ppm), Y (up to 250ppm) e REE (up to 796ppm). The geochemical behaviour is peculiar to alkaline series, denoting a silica-oversaturated, potassium-rich, magma. The chondrite-normalized REE patterns display a first group with smooth slopes from the La to Lu, and a second one with negative slopes. Negative Eu anomalies are displayed in all the patterns. The first group is HREE-enriched, with low fractionation ratios. Samples with milonytic fabrics and higher fractionation ratios are related to the second group, suggesting the interaction of metassomatic fluids and the alkaline magma. Discriminant diagrams for Nb, Y and Rb, coupled with geophysical data, point to an intrusive granite in an extensional within a plate tectonic setting of attenuated continental crust. (author) [pt

  20. Spectra of alkali atoms

    International Nuclear Information System (INIS)

    Santoso, Budi; Arumbinang, Haryono.

    1981-01-01

    Emission spectra of alkali atoms has been determined by using spectrometer at the ultraviolet to infra red waves range. The spectra emission can be obtained by absorption spectrophotometric analysis. Comparative evaluations between experimental data and data handbook obtained by spark method were also presented. (author tr.)

  1. Status of LLNL granite projects

    International Nuclear Information System (INIS)

    Ramspott, L.D.

    1980-01-01

    The status of LLNL Projects dealing with nuclear waste disposal in granitic rocks is reviewed. This review covers work done subsequent to the June 1979 Workshop on Thermomechanical Modeling for a Hardrock Waste Repository and is prepared for the July 1980 Workshop on Thermomechanical-Hydrochemical Modeling for a Hardrock Waste Repository. Topics reviewed include laboratory determination of thermal, mechanical, and transport properties of rocks at conditions simulating a deep geologic repository, and field testing at the Climax granitic stock at the USDOE Nevada Test Site

  2. Granites petrology, structure, geological setting, and metallogeny

    CERN Document Server

    Nédélec, Anne; Bowden, Peter

    2015-01-01

    Granites are emblematic rocks developed from a magma that crystallized in the Earth’s crust. They ultimately outcrop at the surface worldwide. This book, translated and updated from the original French edition Pétrologie des Granites (2011) is a modern presentation of granitic rocks from magma genesis to their crystallization at a higher level into the crust. Segregation from the source, magma ascent and shapes of granitic intrusions are also discussed, as well as the eventual formation of hybrid rocks by mingling/mixing processes and the thermomechanical aspects in country rocks around granite plutons. Modern techniques for structural studies of granites are detailed extensively. Granites are considered in their geological spatial and temporal frame, in relation with plate tectonics and Earth history from the Archaean eon. A chapter on granite metallogeny explains how elements of economic interest are concentrated during magma crystallization, and examples of Sn, Cu, F and U ore deposits are presented. Mi...

  3. Extra-terrestrial igneous granites and related rocks: A review of their occurrence and petrogenesis

    Science.gov (United States)

    Bonin, Bernard

    2012-11-01

    The telluric planets and the asteroid belt display the same internal structure with a metallic inner core and a silicate outer shell. Experimental data and petrological evidence in silicate systems show that granite can be produced by extreme igneous differentiation through various types of igneous processes. On Moon, 4.4-3.9 Ga granite clasts display dry mineral assemblages. They correspond to at least 8 discrete intrusive events. Large K/Ca enrichment and low REE abundances in granite relative to KREEP are consistent with silicate liquid immiscibility, a process observed in melt inclusions within olivine of lunar basalts and in lunar meteorites. Steep-sided domes identified by remote sensing can represent intrusive or extrusive felsic formations. On Mars, black-and-white rhythmic layers observed on the Tharsis rise along the flanks of the peripheral scarps of the Tharsis Montes giant volcanoes suggest the possible eruption of felsic pyroclastites. Though no true granites were found so far in the Martian SNC meteorites, felsic glasses and mesostases were identified and a component close to terrestrial continental (granitic) crust is inferred from trace element and isotope systematics. Venus has suffered extensive volcanic resurfacing, whereas folded and faulted areas resemble terrestrial continents. Near large shield volcanoes, with dominant basaltic compositions, steep-sided domes have been interpreted as non-degassed silicic extrusions. The hypothesis of a granitic component is "tantalising". Extra-terrestrial granite is frequently found as clasts and mesostases in asteroidal meteorites. Porphyritic textures, with alkali feldspar crystals up to several centimetres in size, were observed in silicate enclaves within iron meteorites. In the chondrite clan, polymict breccias can contain granitic clasts, whose provenance is debated. One clast from the Adzhi-Bogdo meteorite yields a 4.53 ± 0.03 Ga Pb-Pb age, making it the oldest known granite in the solar system. The

  4. Radon exhalation from granitic rocks

    International Nuclear Information System (INIS)

    Del Claro, Flávia; Paschuk, Sergei A.; Corrêa, Janine N.; Mazer, Wellington; Narloch, Danielle Cristine; Martin, Aline Cristina; Denyak, Valeriy

    2017-01-01

    Naturally occurring radionuclides such as radon ( 222 Rn), its decay products and other elements from the radioactive series of uranium ( 238 U and 235 U) and thorium ( 232 Th) are an important source of human exposure to natural radioactivity. The worldwide evaluation of health radiobiological effects and risks from population exposure to natural radionuclides is a growing concern. About 50% of personal radiation annual dose is related to radionuclides such as radon ( 222 Rn), thoron ( 220 Rn), radium ( 226 Ra), thorium ( 232 Th) and potassium ( 40 K), which are present in modern materials commonly used in construction of dwellings and buildings. The radioactivity of marbles and granites is of big concern since under certain conditions the radioactivity levels of these materials can be hazardous to the population and require the implementation of mitigation procedures. Present survey of the 222 Rn and 220 Rn activity concentration liberated in the air was performed using commercialized Brazilian granite rocks at national market as well as exported to other countries. The 222 Rn and 220 Rn measurements were performed using the AlphaGUARD instant monitor and RAD7 detector, respectively. This study was performed at the Applied Nuclear Physics Laboratory of the Federal University of Technology – Paraná (UTFPR). Obtained results of radon concentration activity in air exhaled studied samples of granites varied from 3±1 Bq/m 3 to 2087±19 Bq/m 3 , which shows that some samples of granitic rocks represent rather elevated health risk the population. (author)

  5. Alkali cyanides; destructive distillation

    Energy Technology Data Exchange (ETDEWEB)

    Clancy, J C

    1925-12-02

    The destructive distillation of carbonaceous substances can be accomplished by heating them in a bath of molten alkali and cyanide. Liquid hydrocarbons are produced. The separation of the cyanide from the coke or carbonaceous residues by filtration leaves a substantial quantity of cyanide absorbed by the carbon. A feasible method for removal has been developed by mixing the mixture of cyanide and coke with sodium carbonate or other alkali in the molten state, then treating this substance with nitrogen with or without ammonia to convert most of the carbon to cyanide. The carbonaceous material may be mixed with a liquid hydrocarbon such as petroleum, shale oil, or heavy tar oil, heated, and introduced below the surface of the liquid cyanide which partially decomposes and hydrogenates the coal to increase the yield of hydrocarbons. Dry ammonia may be bubbled through the reaction mixture to effect agitation and to form more cyanide.

  6. Charnockites and granites of the western Adirondacks, New York, USA: a differentiated A-type suite

    Science.gov (United States)

    Whitney, P.R.

    1992-01-01

    Granitic rocks in the west-central Adirondack Highlands of New York State include both relatively homogeneous charnockitic and hornblende granitic gneisses (CG), that occur in thick stratiform bodies and elliptical domes, and heterogeneous leucogneisses (LG), that commonly are interlayered with metasedimentary rocks. Major- and trace-element geochemical analyses were obtained for 115 samples, including both types of granitoids. Data for CG fail to show the presence of more than one distinct group based on composition. Most of the variance within the CG sample population is consistent with magmatic differentiation combined with incomplete separation of early crystals of alkali feldspar, plagioclase, and pyroxenes or amphibole from the residual liquid. Ti, Fe, Mg, Ca, P, Sr, Ba, and Zr decrease with increasing silica, while Rb and K increase. Within CG, the distinction between charnockitic (orthopyroxene-bearing) and granitic gneisses is correlated with bulk chemistry. The charnockites are consistently more mafic than the hornblende granitic gneisses, although forming a continuum with them. The leucogneisses, while generally more felsic than the charnockites and granitic gneisses, are otherwise geochemically similar to them. The data are consistent with the LG suite being an evolved extrusive equivalent of the intrusive CG suite. Both CG and LG suites are metaluminous to mildly peraluminous and display an A-type geochemical signature, enriched in Fe, K, Ce, Y, Nb, Zr, and Ga and depleted in Ca, Mg, and Sr relative to I- and S-type granites. Rare earth element patterns show moderate LREE enrichment and a negative Eu anomaly throughout the suite. The geochemical data suggest an origin by partial melting of biotite- and plagioclase-rich crustal rocks. Emplacement occurred in an anorogenic or post-collisional tectonic setting, probably at relatively shallow depths. Deformation and granulite-facies metamorphism with some partial melting followed during the Ottawan phase

  7. Alkali metal hafnium oxide scintillators

    Science.gov (United States)

    Bourret-Courchesne, Edith; Derenzo, Stephen E.; Taylor, Scott Edward

    2018-05-08

    The present invention provides for a composition comprising an inorganic scintillator comprising an alkali metal hafnate, optionally cerium-doped, having the formula A2HfO3:Ce; wherein A is an alkali metal having a valence of 1, such as Li or Na; and the molar percent of cerium is 0% to 100%. The alkali metal hafnate are scintillators and produce a bright luminescence upon irradiation by a suitable radiation.

  8. Cataloging the Pan-African Experience

    Science.gov (United States)

    Hayes, Dianne

    2012-01-01

    Of all the honors and accolades bibliophile and noted authority on the Underground Railroad Charles Blockson has received, being bequeathed recently with some of Harriet Tubman's personal items by her great-niece is one of the most significant experiences of his life. A longtime collector of books and rare items by and about African-Americans,…

  9. Pan African Medical Journal - Vol 10 (2011)

    African Journals Online (AJOL)

    Kyste hydatique du foie rompu dans la paroi abdominale et dans le muscle psoas .... practices of female healthcare professionals towards breast cancer, Morocco .... A rare cause of proximal intestinal obstruction in adults - annular pancreas: A ...

  10. Xanthelasma | Elghazi | Pan African Medical Journal

    African Journals Online (AJOL)

    A full lipid profile including total cholesterol, HDL, LDL assay and blood triglycerides was required and showed hypercholesterolemia 4.2 g/L with HDL 0.5 g/l and LDL 2.5 g/l. Xanthelasma are yellowish patch on the eyelids caused by an accumulation of cholesterol and lipids. They appear as bumps or small skin growths on ...

  11. Hiatal hernia | Samkari | Pan African Medical Journal

    African Journals Online (AJOL)

    Initial evaluation revealed paraesophageal hernia. EGD finding is grade II esophagitis with nodular mucosa and superficial ulceration, Distal part of the funds, body and the Antrum were rolled back into thoracic cavity. Abdominal computed tomography (CT) showed undulating diaphragm and large complex hiatal hernia.

  12. Amniotic amputation | Ayadi | Pan African Medical Journal

    African Journals Online (AJOL)

    Amniotic band syndrome (ABS) is an uncommon, congenital fetal abnormality. Lower extremity limb defects are the common manifestations of ABS. The most common features include congenital distal ring constrictions, intrauterine amputations, and acrosyndactyly. Rare cases of craniofacial and visceral defects were ...

  13. Bronchiectasis: a bacteriological profile | Bopaka | Pan African ...

    African Journals Online (AJOL)

    ... Mycoplasma pneumoniae, Acinetobacter baumannii and Staphylococcus aureus in one case each. Through this work, the authors highlight that Streptococcus pneumoniae and Pseudomonas aeruginosa are the most commonly- identified microbes in their patients. It is necessary to have a full bacterial examination and to ...

  14. Amoebic pleuropericarditis | Amine | Pan African Medical Journal

    African Journals Online (AJOL)

    Chest X-ray revealed pleural effusion with extensive calcifications on the anterior and inferior surfaces of the heart. Thoracic computed tomography confirmed pleural effusion with pericardial thickening and calcification. Echocardiography was suggestive of constrictive pericarditis, thoracenthesis revealed milk chocolate ...

  15. Mechanical properties of Stripa granite

    International Nuclear Information System (INIS)

    Stephansson, O.; Swan, G.; Leijon, B.

    1978-01-01

    For the determination of the mechanical properties of Stripa Granite samples were taken from the boreholes in the vicinity of the test site. The granite type taken from these different sources is of variable character. For the purpose of numerical calculations performed in projects related to the waste storage research program the following parameters have been determined: Young's modulus, Poisson's ratio, compressive fracture stress and expansion coefficient as a function of temperature 20< T<200C; Young's modulus and compressive fracture stress as a function of confining pressure; Brazilian tensile fracture stress; residual shear stress as a function of normal stress; anisotropy ratio for Young's modulus and compressive fracture stress; dilatational wave velocity and deduced dynamic Young's modulus. A brief description of the test methods and the results for each test are presented

  16. Thermal expansion behaviour of granites

    Czech Academy of Sciences Publication Activity Database

    Plevová, Eva; Vaculíková, Lenka; Kožušníková, Alena; Ritz, M.; Simha Martynková, G.

    2016-01-01

    Roč. 123, č. 2 (2016), s. 1555-1561 ISSN 1388-6150 R&D Projects: GA MŠk ED2.1.00/03.0082; GA MŠk(CZ) LO1406 Institutional support: RVO:68145535 Keywords : thermomechanical analysis * differential thermal analysis * granites Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.953, year: 2016 http://link.springer.com/article/10.1007/s10973-015-4996-z

  17. Radon exhalation from granitic rocks

    Energy Technology Data Exchange (ETDEWEB)

    Del Claro, Flávia; Paschuk, Sergei A.; Corrêa, Janine N.; Mazer, Wellington; Narloch, Danielle Cristine; Martin, Aline Cristina [Universidade Tecnológica Federal do Paraná (UTFPR), Curitiba, PR (Brazil); Denyak, Valeriy, E-mail: flaviadelclaro@gmail.com, E-mail: spaschuk@gmail.com, E-mail: janine_nicolosi@hotmail.com, E-mail: denyak@gmail.com [Instituto de Pesquisa Pelé Pequeno Príncipe (IPPP), Curitiba, PR (Brazil)

    2017-07-01

    Naturally occurring radionuclides such as radon ({sup 222}Rn), its decay products and other elements from the radioactive series of uranium ({sup 238}U and {sup 235}U) and thorium ({sup 232}Th) are an important source of human exposure to natural radioactivity. The worldwide evaluation of health radiobiological effects and risks from population exposure to natural radionuclides is a growing concern. About 50% of personal radiation annual dose is related to radionuclides such as radon ({sup 222}Rn), thoron ({sup 220}Rn), radium ({sup 226}Ra), thorium ({sup 232}Th) and potassium ({sup 40}K), which are present in modern materials commonly used in construction of dwellings and buildings. The radioactivity of marbles and granites is of big concern since under certain conditions the radioactivity levels of these materials can be hazardous to the population and require the implementation of mitigation procedures. Present survey of the {sup 222}Rn and {sup 220}Rn activity concentration liberated in the air was performed using commercialized Brazilian granite rocks at national market as well as exported to other countries. The {sup 222}Rn and {sup 220}Rn measurements were performed using the AlphaGUARD instant monitor and RAD7 detector, respectively. This study was performed at the Applied Nuclear Physics Laboratory of the Federal University of Technology – Paraná (UTFPR). Obtained results of radon concentration activity in air exhaled studied samples of granites varied from 3±1 Bq/m{sup 3} to 2087±19 Bq/m{sup 3}, which shows that some samples of granitic rocks represent rather elevated health risk the population. (author)

  18. Geology and geochemistry of the Redrock Granite and anorthosite xenoliths (Proterozoic in the northern Burro Mountains, Grant County, New Mexico, USA

    Directory of Open Access Journals (Sweden)

    Virginia T. McLemore

    2002-01-01

    Full Text Available Mineral ages from the A-type granites and anorthosite xenoliths in the Redrock area in the northwestern Burro Mountains in southwestern New Mexico cluster around ~1220–1225 Ma and provide yet another example of bimodal igneous activity during this time period in the southwestern United States. The metaluminous to peraluminous, marginally alkaline to subalkaline Redrock Granite exhibits the textural, mineralogical, and geochemical features of A-type granitethat was emplaced at a relatively high crustal level. Field relationships, whole rock and mineral geochemical and isotopic trends suggest that the four phases of the Redrock Granite are genetically related, with the miarolitic biotite/alkali feldspar granite being the youngest phase. Spatial relationships and geochemical data suggest that the anorthosite xenoliths were coeval with the RedrockGranite, which is consistent with the anorthosite being derived from the upper mantle, possibly due to deep mantle upwellings, and the Redrock Granite from the lower crust. The process involved melting in the upper mantle, emplacement of anorthosite in the crust resulting in partial crustal melting and thinning, and, finally, intrusion of shallow silicic plutons, the Redrock Granite. The Redrock Granite and anorthosite were presumably derived from sources characterized by subtle, long-term LREE depletion, with εNd (at 1220 Ma values on theorder of +1 to +2.

  19. Heidelberg polarized alkali source

    International Nuclear Information System (INIS)

    Kraemer, D.; Steffens, E.; Jaensch, H.; Philipps Universitaet, Marburg, Germany)

    1984-01-01

    A new atomic beam type polarized alkali ion source has been installed at Heidelberg. In order to improve the beam polarization considerably optical pumping is applied in combination with an adiabatic medium field transition which results in beams in single hyperfine sublevels. The m state population is determined by laser-induced fluorescence spectroscopy. Highly polarized beams (P/sub s/ > 0.9, s = z, zz) with intensities of 30 to 130 μA can be extracted for Li + and Na + , respectively

  20. A hybrid composite dike suite from the northern Arabian Nubian Shield, southwest Jordan: Implications for magma mixing and partial melting of granite by mafic magma

    Science.gov (United States)

    Jarrar, Ghaleb H.; Yaseen, Najel; Theye, Thomas

    2013-03-01

    The Arabian Nubian Shield is an exemplary juvenile continental crust of Neoproterozoic age (1000-542 Ma). The post-collisional rift-related stage (~ 610 to 542 Ma) of its formation is characterized among others by the intrusion of several generations of simple and composite dikes. This study documents a suite of hybrid composite dikes and a natural example of partial melting of granite by a mafic magma from the northernmost extremity of Arabian Nubian Shield in southwest Jordan. The petrogenesis of this suite is discussed on the basis of field, petrographic, geochemical, and Rb/Sr isotopic data. These dikes give spectacular examples of the interaction between basaltic magma and the granitic basement. This interaction ranges from brecciation, partial melting of the host alkali feldspar granite to complete assimilation of the granitic material. Field structures range from intrusive breccia (angular partially melted granitic fragments in a mafic groundmass) to the formation of hybrid composite dikes that are up to 14 m in thickness. The rims of these dikes are trachyandesite (latite) with alkali feldspar ovoids (up to 1 cm in diameter); while the central cores are trachydacite to dacite and again with alkali feldspar ovoids and xenoliths from the dike rims. The granitic xenoliths in the intrusive breccia have been subjected to at least 33% partial melting. A seven-point Rb/Sr isochron from one of these composite dikes yields an age of 561 ± 33 Ma and an initial 87Sr/86Sr ratio of 0.70326 ± 0.0003 (2σ) and MSWD of 0.62. Geochemical modeling using major, trace, rare earth elements and isotopes suggests the generation of the hybrid composite dike suite through the assimilation of 30% to 60% granitic crustal material by a basaltic magma, while the latter was undergoing fractional crystallization at different levels in the continental crust.

  1. Geochemical and isotopic characterization of the granitic magmatism along the Remígio - Pocinhos shear zone, Borborema Province, NE Brazil

    Science.gov (United States)

    de Lima, Jefferson V.; Guimarães, Ignez de P.; Santos, Lucilene; Amorim, José Victor A.; Farias, Douglas José S.

    2017-04-01

    Two granitoid plutons (Pilõezinhos and Curral de Cima) intruded along the Remígio - Pocinhos shear zone, eastern part of the Borborema Province. The Pilõezinhos and Curral de Cima granites were dated at 566 ± 3 Ma and 618 ± 5 Ma respectively. The granitoids from both plutons have distinct initial 143Nd/144Nd ratios, expressed by εNd(t) values, i.e. the granitoids of Pilõezinhos pluton have lower εNd(t) values (-15.47 to -15.81) and negative εHf (t = 570 Ma) values (-16.0 to -18.6), while the granitoids of the Curral de Cima pluton have εNd(t) values between -1.12 and -5.23. The granitoids of the Curral de Cima pluton are epidote bearing, magnesian calcalkaline I-type granitoids, crystallized under high fO2 conditions. The granitoids of the Pilõezinhos pluton are alkaline, low-fO2, ferroan, ilmenite-series, A2-type granite intrusions. The geochemical and isotopic signatures suggest that the origin of magma of the Curral de Cima granitoids involved mixing/mingling at depth between crustal and mantle magmas, associated to decompression (lateral escape) during the convergent stage of Brasiliano/Pan/African orogeny, which lead the asthenosphere melts to rise into the lower crust. The source of magma of the granitoids of the Pilõezinhos pluton involved a strong crustal component with geochemical and isotopic signatures similar to the orthogneisses of the Serrinha-Pedro Velho Complex, and small mantle component. The emplacement of the Pilõezinhos pluton is associated to an extensional space formed during high-T strike-slip shearing developed by the synchronic movement of the Matinhas sinistral shear zone and Remígio - Pocinhos dextral shear zone.

  2. Natural radionuclide distribution in Brazilian commercial granites

    International Nuclear Information System (INIS)

    Anjos, R.M.; Veiga, R.; Soares, T.; Santos, A.M.A.; Aguiar, J.G.; Frasca, M.H.B.O.; Brage, J.A.P.; Uzeda, D.; Mangia, L.; Facure, A.; Mosquera, B.; Carvalho, C.; Gomes, P.R.S.

    2005-01-01

    The dimension stones sector in Brazil produces several varieties of granites, marbles, slates and basalts. More than half of this production corresponds to around 200 different commercial types of granites with specific names, geographical and geological origins and mineral compositions. The well-known natural radioactivity present in rocks, where high radiation levels are associated with igneous rocks such as granite, can be used to determine their general petrologic features. This subject is important in environmental radiological protection, since granites are widely used as building and ornamental stones. In this paper, it is applied to correlate the petrographic characteristics of commercial granites with their corresponding dose rates for natural radioactivity. Amounts of thorium, uranium and potassium concentrations have been reported in several Brazilian commercial granite samples

  3. Purification of alkali metal nitrates

    Science.gov (United States)

    Fiorucci, Louis C.; Gregory, Kevin M.

    1985-05-14

    A process is disclosed for removing heavy metal contaminants from impure alkali metal nitrates containing them. The process comprises mixing the impure nitrates with sufficient water to form a concentrated aqueous solution of the impure nitrates, adjusting the pH of the resulting solution to within the range of between about 2 and about 7, adding sufficient reducing agent to react with heavy metal contaminants within said solution, adjusting the pH of the solution containing reducing agent to effect precipitation of heavy metal impurities and separating the solid impurities from the resulting purified aqueous solution of alkali metal nitrates. The resulting purified solution of alkali metal nitrates may be heated to evaporate water therefrom to produce purified molten alkali metal nitrate suitable for use as a heat transfer medium. If desired, the purified molten form may be granulated and cooled to form discrete solid particles of alkali metal nitrates.

  4. Fracture patterns and stresses in granite

    International Nuclear Information System (INIS)

    Price, N.J.

    1979-01-01

    If granite bodies are to be used as receptacles for toxic waste materials, the presence or absence of barren fractures and the virgin stresses in the granite are of fundamental importance. Unfortunately, very little is known regarding the incidence of fractures, or stresses, which exist at depths (of about 1 km) in granite bodies. A simple analysis is presented of a hypothetical intrusion which indicates the magnitudes of stresses and the possible fracture development which may be expected in such bodies. (auth)

  5. "Gris Quintana": a Spanish granite from the Past into the Future.

    Science.gov (United States)

    José Tejado, Juan; Mota, M. Isabel; Pereira, Dolores

    2014-05-01

    "Gris Quintana" is a medium-grained, biotite and amphibole granodiorite extracted in the Pluton of Quintana de la Serena (Extremadura, Spain). It is a constant light grey granite from the Hercynian geologic with excellent physicomechanical and physicochemical properties. The granodiorite is composed of plagioclase, biotite, quartz and alkali feldspar, with accessory allanite, titanite, apatite, zircon and ilmenite, mostly as inclusions within the biotite crystals. This commercial variety is extracted from many quarries in the late Hercynian plutons located in the Iberian Massif in Spain period (transition between Central Iberian and Ossa-Moren Zones), having large reserves of granite. Many of the quarries have their own transformation factory (high production zone), with which the sector is offered an endless variety of finishes and constructive rock typologies. A wide range of solutions to architects and designers are offered. Gris Quintana granite is one of the materials with highest technological benefits that are used in arquitecture. "Gris Quintana" granite has been used since ancient times, not only at a regional, but also at national and international level: paving, building (structural, exterior façadas, interior uses), urban decoration and funeral art. It can be found in monuments and more recently, in buildings of different styles and uses, that stand out in beauty and splendor, lasting in time. Some singular works in "Gris Quintana" granite all over the world: extension to the "Congreso de Diputados" (Parliament) in Madrid, "Puerta de San Vicente" in Madrid, Andalucia Parliament columns in Sevilla, New Senate Buiding in Madird, "Gran Vía" pavement in Madrid, "Teatro Real façade" in Madrid… "Gris Quintana" granite accomplishes all the requirements for its nomination as Global Heritage Stone Resource, for both its use in construction and for artistic purposes.

  6. Isotopic data revaluation from Cabo province, with base in Cabo granite petrographic studies

    International Nuclear Information System (INIS)

    Legrand, J.M.; Figueiredo Filho, O.A.

    1979-01-01

    The Sto Agostinho's Cape granite (NE-Brazil) is formed by two successive instrusions: the first riolitic or migmatitic, replaced by the alkali granite. This process is indicated by the potassic feldspar phenocrystals porpliroblastic assimilation of the riolites, conglobating the re-cristalized matrix minerals. This two times formation is confirmed by geochronological studies in magmatic province. The diagram of the different rocks with alkaline differentiation is distributed in two isochrons. The first isochron age of 135 m.y +- 0,7 λ=1,42x10 -11 ) with a Ri = 0,7023, the second determine to the Cape granite 104 m.y +- 0,7 (λ=1,42x10 -11 ) with a Ri=0,7058. The first pulsation value of 0,7023, indicate a crust origin to the granite. The more elevated value in the second magmatic dike can be explain by the mixture of more or less 99% of crust magma and 1% of plutonic rocks. (C.D.G.) [pt

  7. Alkali metal and alkali earth metal gadolinium halide scintillators

    Science.gov (United States)

    Bourret-Courchesne, Edith; Derenzo, Stephen E.; Parms, Shameka; Porter-Chapman, Yetta D.; Wiggins, Latoria K.

    2016-08-02

    The present invention provides for a composition comprising an inorganic scintillator comprising a gadolinium halide, optionally cerium-doped, having the formula A.sub.nGdX.sub.m:Ce; wherein A is nothing, an alkali metal, such as Li or Na, or an alkali earth metal, such as Ba; X is F, Br, Cl, or I; n is an integer from 1 to 2; m is an integer from 4 to 7; and the molar percent of cerium is 0% to 100%. The gadolinium halides or alkali earth metal gadolinium halides are scintillators and produce a bright luminescence upon irradiation by a suitable radiation.

  8. Gamma-spectrometric surveys in differentiated granites. II: the Joaquim Murtinho Granite in the Cunhaporanga Granitic Complex, Parana, SE Brazil; Levantamentos gamaespectrometricos em granitos diferenciados. II: O exemplo do Granito Joaquim Murtinho, Complexo Granitico Cunhaporanga, Parana

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Francisco Jose Fonseca [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Dept. de Geologia. Lab. de Pesquisas em Geofisica Aplicada; Fruchting, Allan [Votorantim Metais, Sao Paulo, SP (Brazil)], e-mail: allan.fruchting@vmetais.com.br; Guimaraes, Gilson Burigo [Universidade Estadual de Ponta Grossa (UEPG), PR (Brazil). Dept. de Geociencias], e-mail: gburigo@ig.com.br; Alves, Luizemara Soares [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)], e-mail: luizemara@petrobras.com.br; Martin, Victor Miguel Oliveira; Ulbrich, Horstpeter Herberto Gustavo Jose [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Geociencias. Dept. de Mineralogia e Geotectonica], e-mail: vicmartin6@ig.com.br, e-mail: hulbrich@usp.br

    2009-07-01

    Detailed mapping at the NW corner of the large Neo proterozoic Cunhaporanga Granitic Complex (CGC), Parana state, SE Brazil, redefined the Joaquim Murtinho Granite (JMG), a late intrusion in CGC with an exposed area of about 10 km{sup 2}, made up mainly by evolved 'alaskites' (alkali-feldspar leuco granites). This unit is in tectonic contact with the Neoproterozoic-Eocambrian volcano-sedimentary Castro Group, to the W, and is intrusive into other less evolved granitic units of the CGC to the E. Petrographically, JMG shows mainly mesoperthite and quartz, with subordinate amounts of altered micas and some accessory phases, mainly zircon. The equi to inequigranular granites are usually deformed with cataclastic textures, are often brecciated, and may have miarolitic structures. Formation of late albite, sericite, carbonate and hematite was caused by deuteric and hydrothermal alteration. A gamma-ray spectrometric survey at 231 stations which measured total counts (TC), Ueq K%, eU ppm and eTh ppm was used to construct several direct and derived maps. Compared to neighboring units the JMG has significant anomalies, especially in the TC, %K, eTh and eU maps, although the differences are less obvious in some derived maps. These evolved granites are enriched in these three elements. Geochemical behavior of K, Th and U is used to analyse the results observed in maps. Enhanced weathering under a subtropical climate with moderate to high average temperatures and heavy rainfall affects mainly feldspars and biotite, and may also destabilize most U and Th-bearing accessory phases. Th is most likely retained in restite minerals in soils, being relatively immobile, while part of U may migrate as uranyl ion in oxidizing media. K is especially affected by feldspar alteration to K-free clays (mainly kaolinite), and may be completely leached. Gamma-ray spectrometric methods are valid tools to study facies in granitic rocks, especially in those that are enriched in K, Th and U

  9. A-type and I-type granitoids and mylonitic granites of Hassan Salaran area of SE Saqqez, Kurdistan, Iran

    Science.gov (United States)

    Abdullah, Fakhraddin Mohammad; Saeed Ahmad, Sheler

    2014-05-01

    The Hassan Salarn area is located 20km to southeast of Saqqez city in Kurdistan Province, western Iran. In this area there are two distinct granitic rock suites consisting A-type and I-type granites and also mylonitic granites. These A-type and I-type granites have various petrological and geochemical characteristics. They also have different origins and petrogenesis. A-type granitoids comprise alkali feldspar granite, syenogranite and quartz alkali feldspar syenite, whereas I-type granitoids are composed of monzogranite, granodiorite and tonalite. Geochemically, A-type granitoids are peralkaline and acmite-normative but I-type granitoids are subalkaline (calc-alkaline), metaluminous and diopside-normative. A-type granitoids are also ferroan alkali and ferroan alkali-calcic whereas I-type granitoids are magnesian and calcic. A-type granitoids resemble to within plate granites and post-orogenic granites whereas I-type granitoids resemble to volcanic arc granites. A-type granitoids contain higher concentrations of alkalies, Zr, Rb, Nb, Y, Th, Ce, high FeO/MgO ratios and lower concentrations of Mg, Ca and Sr, resembling post-orogenic A-type granites. It is possible that heat from a mantle-derived magma which intruded into the lower crust, and/or rapid crustal extension have been essential generation of approriate melts producing A-type granitoids. Thus we can conclude that A-type granitoids were generated from a mixed mantle-crust source. Negative Nb anomalies and low contents of Ti and P probably indicate a subduction-related origin for protolith of I-type granitoids. Negative Nb anomalies and enrichment in Ce relative to its adjacent elements can be related to involvement of continental crust in magmatic processes. I-type granitoids are also enriched in Rb, Ba, K, Th, Ce and depleted in Nb, Zr and Y, indicating that they have had interacted with crust. I-type granitoids may result from contamination of mantle-derived magmas by continental crust during a subduction

  10. Geology, petrography and geochemistry of the A-type granites from the Morro Redondo Complex (PR-SC, southern Brazil, Graciosa Province

    Directory of Open Access Journals (Sweden)

    FREDERICO C.J. VILALVA

    2014-03-01

    Full Text Available The Morro Redondo Complex is one of the most important occurrences of the Graciosa A-type Province, southern Brazil. It consists of the Papanduva and Quiriri granitic plutons and a contemporaneous bimodal volcanic association. The Papanduva Pluton includes massive and deformed peralkaline alkali-feldspar granites with Na-Ca and Na-amphiboles and clinopyroxenes. The deformed types are the most evolved rocks in the province and carry rare ‘agpaitic’ minerals, some being described for the first time in granites from Brazil. The larger Quiriri Pluton comprises massive, slightly peraluminous, biotite syeno- and monzogranites with rare Ca-amphibole. Biotite compositions are relatively homogeneous, whereas sodic amphiboles and clinopyroxenes show increasing Na and Fe3+ evolving paths. The Morro Redondo granites are ferroan, with high SiO2, alkalis and HFSE contents; the peralkaline types registering the highest fe#. LILE and HFSE abundances increase with the agpaitic index and the most evolved are HHP granites, with radiogenic heat production up to 5.7 µWm–3. Geothermobarometric estimates indicate emplacement under low pressures (∼100 MPa, at temperatures up to 850-800 °C, and relatively reduced (QFM and oxidized (+1 REPLACE_LT ΔQFM REPLACE_LT +3 environments for the Papanduva and Quiriri Plutons, respectively. In both cases, melts evolved to relatively high oxidation states upon crystallization progress.

  11. Upgrading platform using alkali metals

    Science.gov (United States)

    Gordon, John Howard

    2014-09-09

    A process for removing sulfur, nitrogen or metals from an oil feedstock (such as heavy oil, bitumen, shale oil, etc.) The method involves reacting the oil feedstock with an alkali metal and a radical capping substance. The alkali metal reacts with the metal, sulfur or nitrogen content to form one or more inorganic products and the radical capping substance reacts with the carbon and hydrogen content to form a hydrocarbon phase. The inorganic products may then be separated out from the hydrocarbon phase.

  12. P-T path fluid evolution in the Gross Spitzkoppe granite stock, Namibia

    Directory of Open Access Journals (Sweden)

    Stephen Frindt

    2002-01-01

    Full Text Available The Gross Spitzkoppe granite stock (GSS is a zoned 30 km^2 epizonal intrusion that consists of three main granites: 1 medium-grained biotite granite (marginal, 2 a coarse-grained biotite granite, and 3 a central, porphyritic granite. The stock contains pegmatites as banded marginal stockscheiders and isolated pockets composed of large alkali feldspar and quartz, dark mica, interstitial fluorite, and euhedral topaz and beryl crystals. In the porphyritic granite there are local wolframite-bearing greisens and hydrothermal fluorite and topaz-rich veins.Fluid inclusion studies were conducted on: 1 topaz and quartz crystals from the marginal stockscheider; 2 quartz, topaz, fluorite and beryl crystals from isolated pegmatites; 3 topaz from a miarolitic pegmatite; 4 beryl and quartz veins from greisenized porphyritic granite; and 5 fluorite from a late fluorite vein inthe coarse-grained biotite granite. Preliminary data indicate the presence of three compositionally distinct primary and pseudosecondary inclusion types that are of late magmatic-hydrothermal origin.Type 1. Low salinity (0–10 eq. wt% NaCl H2O (± CO2 inclusions that homogenize to the liquid phase in the temperature range of 300 to 550˚C. These inclusions are from quartz, topaz and beryl. Inclusions in fluorite from the fluorite vein homogenize at ~170˚C and have a salinity of ca. 1–2 eq. wt% NaCl.Type 2. Saline (25–30 eq. wt% NaCl halite-bearing H2O (± CO2 inclusions that homogenize to the liquid phase in the temperature range of 300 to 400˚C. These inclusions are from quartz.Type 3. Low salinity (0–3 eq. wt% NaCl H2O-CO2 inclusions that homogenize to vapor phase in the temperature range of 330 to 550˚C. These inclusions are from quartz and topaz.Hydrothermal fluids from greisen minerals are represented by type 1 and type 2 H2O inclusions. They are predominantly of low salinity (~8 eq. wt% NaCl and homogenize to the liquid phase in the temperature range of 300 to 500

  13. Alkali silica reaction (ASR) in cement free alkali activated sustainable concrete.

    Science.gov (United States)

    2016-12-19

    This report summarizes the findings of an experimental evaluation into alkali silica : reaction (ASR) in cement free alkali-activated slag and fly ash binder concrete. The : susceptibility of alkali-activated fly ash and slag concrete binders to dele...

  14. The research frontier and beyond: granitic terrains

    Science.gov (United States)

    Twidale, C. R.

    1993-07-01

    Investigations of granite forms and landscapes over the past two centuries suggest that many features, major and minor, are shaped by fracture-controlled subsurface weathering, and particularly moisture-driven alteration: in other words etch forms are especially well represented in granitic terrains. Commonly referred to as two stage forms, many are in reality multistage in origin, for the structural contrasts exploited by weathering and erosion that are essential to the mechanism originated as magmatic, thermal or tectonic events in the distant geological past. Fracture patterns are critical to landform and landscape development in granitic terrains, but other structural factors also come into play. Location with respect to water table and moisture contact are also important. Once exposed and comparatively dry, granite forms tend to stability; they are developed and diversified, and many are gradually destroyed as new, epigene, forms evolve, but many granite forms persist over long ages. Reinforcement effects frequently play a part in landform development. Several granite forms are convergent, i.e. features of similar morphology evolve under the influence of different processes, frequently in contrasted environments. On the other hand many landforms considered to be typical of granitic terrains are also developed in bedrock that is petrologically different but physically similar to granite; and in particular is subdivided by fractures of similar pattern and density. To date, most of the general statements concerning the evolution of granitic terrains have been based in work in the tropics but other climatic settings, and notably those of cold land, are now yielding significant results. Future research will extend and develop these avenues, but biotic factors, and particularly the role of bacteria, in such areas as weathering, will take on a new importance. Structural variations inherited from the magnetic, thermal and tectonic events to which granite bodies have

  15. Thermal expansion of granite rocks

    International Nuclear Information System (INIS)

    Stephansson, O.

    1978-04-01

    The thermal expansion of rocks is strongly controlled by the thermal expansion of the minerals. The theoretical thermal expansion of the Stripa Granite is gound to be 21 . 10 -6 [deg C] -1 at 25 deg C and 38 . 10 -6 [deg C] -1 at 400 deg C. The difference in expansion for the rock forming minerals causes micro cracking at heating. The expansion due to micro cracks is found to be of the same order as the mineral expansion. Most of the micro cracks will close at pressures of the order of 10 - 20 MPa. The thermal expansion of a rock mass including the effect of joints is determined in the pilot heater test in the Stripa Mine

  16. Automated tone grading of granite

    International Nuclear Information System (INIS)

    Catalina Hernández, J.C.; Fernández Ramón, G.

    2017-01-01

    The production of a natural stone processing plant is subject to the intrinsic variability of the stone blocks that constitute its raw material, which may cause problems of lack of uniformity in the visual appearance of the produced material that often triggers complaints from customers. The best way to tackle this problem is to classify the product according to its visual features, which is traditionally done by hand: an operator observes each and every piece that comes out of the production line and assigns it to the closest match among a number of predefined classes, taking into account visual features of the material such as colour, texture, grain, veins, etc. However, this manual procedure presents significant consistency problems, due to the inherent subjectivity of the classification performed by each operator, and the errors caused by their progressive fatigue. Attempts to employ automated sorting systems like the ones used in the ceramic tile industry have not been successful, as natural stone presents much higher variability than ceramic tiles. Therefore, it has been necessary to develop classification systems specifically designed for the treatment of the visual parameters that distinguish the different types of natural stone. This paper describes the details of a computer vision system developed by AITEMIN for the automatic classification of granite pieces according to their tone, which provides an integral solution to tone grading problems in the granite processing and marketing industry. The system has been designed to be easily trained by the end user, through the learning of the samples established as tone patterns by the user. [es

  17. Two-mica granites of northeastern Nevada.

    Science.gov (United States)

    Lee, D.E.; Kistler, R.W.; Friedman, I.; Van Loenen, R. E.

    1981-01-01

    The field settings are described and analytical data are presented for six two-mica granites from NE Nevada. High delta 18O and 87Sr/86Sr values indicate that all are S-type granite, derived from continental crust. The major element chemistry and accessory mineral contents of these rocks also are characteristic of S-type granites. Chemical, X ray, and other data are presented for the micas recovered from these granites. The muscovites are notably high in Fe2O3, FeO, and MgO. Except for one hydrobiotite, each of the biotites has an MgO content near 6.0 wt%. Two different types of two-mica granites are recognized in the area of this study. One type is distinguished by the presence of many biotite euhedra within muscovite phenocrysts and by an unusual suite of accessory minerals completely devoid of opaque oxides. This type probably resulted from anatexis of late Precambrian argillites under conditions of relatively low oxygen fugacity, along a line that roughly coincides with the westward disappearance of continental basement. In the other textural type of two-mica granite the micas are equigranular and there is a greater variety of accessory minerals. The magmatic evolution of this type also appears to reflect the influence of late Precambrian argillites; there may be age differences between the two types of two-mica granites.-Author

  18. Process for the disposal of alkali metals

    International Nuclear Information System (INIS)

    Lewis, L.C.

    1979-01-01

    The invention describes a method of disposing of alkali metals by forming a solid waste for storage. The method comprises preparing an aqueous disposal solution of at least 55 weight percent alkali metal hydroxide, heating the alkali metal to melting temperature to form a feed solution, and spraying the molten feed solution into the disposal solution. The alkali metal reacts with the water in the disposal solution in a controlled reaction which produces alkali metal hydroxide, hydrogen and heat and thereby forms a solution of alkali metal hydroxides. Water is added to the solution in amounts sufficient to maintain the concentration of alkali metal hydroxides in the solution at 70 to 90 weight percent, and to maintain the temperature of the solution at about the boiling point. Removing and cooling the alkali metal hydroxide solution thereby forms a solid waste for storage. The method is particularly applicable to radioactive alkali metal reactor coolant. (auth)

  19. Geochemistry of the Serra das Melancias Pluton in the Serra da Aldeia Suite: a classic post-collisional high Ba-Sr granite in The Riacho do Pontal Fold Belt, NE Brazil

    Directory of Open Access Journals (Sweden)

    Marcela Paschoal Perpétuo

    Full Text Available ABSTRACT: The Serra da Aldeia Suite is composed by circular or oval-shaped plutons, intrusive in meta-sedimentary and meta-volcanosedimentary rocks in the Riacho do Pontal Fold Belt, NE Brazil. The Serra das Melancias Pluton, belonging to Serra da Aldeia Suite, is located southeastern of Piaui state, near Paulistana city. These plutons represent a major magmatic expression in this area and contain important information about the late magmatic/collisional geologic evolution of the Brasiliano Orogeny. Based on petrographic and geochemical data, three facies were defined in the Serra das Melancias Pluton: granites, syenites and quartz monzonites. The rocks display high-K and alkaline to shoshonitic affinities, are metaluminous and show ferrous character. They are enriched in Light Rare Earth Elements and Large Ion Lithophile Elements, with negative anomalies in Nb, Ta and Ti. Their high Ba, Sr, K/Rb, low Rb, relatively low U, Th, Nb to very low Heavy Rare Earth Elements and Y resemble those of typical high Ba-Sr granitoids. The geochemical data suggest the emplacement of Serra das Melancias Pluton in a transitional, late to post-orogenic setting in the Riacho do Pontal Fold Belt during the late Brasiliano-Pan African Orogeny.

  20. Uranium-enriched granites in Sweden

    International Nuclear Information System (INIS)

    Wilson, M.R.; Aakerblom, G.

    1980-01-01

    Granites with uranium contents higher than normal occur in a variety of geological settings in the Swedish Precambrian, and represent a variety of granite types and ages. They may have been generated by the anatexis of continental crust or processes occurring at a much greater depth. They commonly show enrichment in F, Sn, W and/or Mo. Only in one case is an important uranium mineralization thought to be directly related to a uranium-enriched granite, while the majority of epigenetic uranium mineralizations with economic potential are related to hydrothermal processes in areas where the bedrock is regionally uranium-enhanced. (author)

  1. Geochemistry of mylonitic tourmaline-bearing granite- gneiss pluton in the northeast of June mine

    Directory of Open Access Journals (Sweden)

    Arezoo Moradi

    2017-07-01

    Full Text Available Introduction Studied mylonitic granite-gneiss body is located in the Northwest of the Azna region in the Lorestan province close to the June dimension stone mine. It is a part of the metamorphic- magmatic complex including granite-gneiss, amphibolite, marble and schist. The crystalline basement is attributed to late-Neoproterozoic and it indicates a Panafrican basement, which yields a laser-ablation ICP–MS U–Pb zircon ages of 608 ± 18 Ma and 588 ± 41 Ma (Shakerardakani et al., 2015. There are two granite-gneiss plutons in the complex that are Galeh– Dezh (Shabanian et al., 2009, and June plutons. The Galeh-Doz pluton are previously proposed as syn-deformation pluton with a major S-shaped bend which has been imparted during dextral shearing with a Late Cretaceous (Mohajjel and Fergusson, 2000. However, new age dating on the pluton using U–Pb in the magmatic zircon produced the late-Neoproterozoic dates (Nutman et al., 2014; Shakerardakani et al., 2015. The granite-gneiss plutons show mylonitic fabrics and microstructures (Shabanian et al., 2010. The geochemical characteristics of mylonitic granite-gneiss body near June mine in NW Azna, is in the focus of our research. Materials and methods Petrographic investigations of 30 thin sections were made. Then eight samples were selected and analyzed for whole rock major, trace and REE compositions by ICP-emission spectrometry and ICP-mass spectrometry using natural rock standards as reference samples for calibration at the ACME Analytical Laboratories in Vancouver, British Columbia, Canada. Results The studied gneiss- granitic body has lepido-granoblastic texture as its major texture. It variably shows evidence of dynamic deformation from ultramylonite to protomylonite. The gneiss- granite consists of quartz, alkali feldspar (mostly as perthite, plagioclase, biotite, white mica (muscovite and phengitic muscovite. Accessory phases in the granitoid include, tourmaline, zircon, magmatic epidote

  2. Ultraviolet optical absorption of alkali cyanides and alkali halide cyanides

    International Nuclear Information System (INIS)

    Souza Camargo Junior, S.A. de.

    1982-09-01

    The ultraviolet absorption spectra of alkali cyanide and mixed alkali halide cyanide crystals were measured at temperatures ranging from 300K down to 4.2K. A set of small absorption peaks was observed at energies near 6 eV and assigned to parity forbidden X 1 Σ + →a' 3 Σ + transitions of the CN - molecular ions. It was observed that the peak position depends on the alkali atom while the absorption cross section strongly depends on the halogen and on the CN - concentration of the mixed crystals. These effects are explained in terms of an interaction between the triplet molecular excitons and charge transfer excitons. The experimental data were fit with a coupling energy of a few meV. The coupling mechanism is discussed and it is found to be due to the overlap between the wave functions of the two excitations. (Author) [pt

  3. Alkali-vapor laser-excimer pumped alkali laser

    International Nuclear Information System (INIS)

    Yue Desheng; Li Wenyu; Wang Hongyan; Yang Zining; Xu Xiaojun

    2012-01-01

    Based on the research internal and overseas, the principle of the excimer pumped alkali laser (XPAL) is explained, and the advantages and disadvantages of the XPAL are analyzed. Taking into consideration the difficulties that the diode pumped alkali laser (DPAL) meets on its development, the ability to solve or avoid these difficulties of XPAL is also analyzed. By summing up the achievements of the XPAL, the possible further prospect is proposed. The XPAL is of possibility to improve the performance of the DPAL. (authors)

  4. Determination of dispersity of crushed granite

    International Nuclear Information System (INIS)

    Liu Dejun; Fan Xianhua; Zhang Yingjie; Yao Jun; Zhou Duo; Wang Yong

    2004-01-01

    The experimental crushed granite column breakthrough curves, using 99 Tc as spike tracer and 3 H as invariant tracer, are analyzed by different linear regression techniques. Dispersity of crushed granite and retardation factor of 99 TcO 4 - on the crushed granite are determined simultaneously by one linear regression technique. Dispersity of crushed granite is also obtained with 3 H as invariant tracer by the other linear regression technique. The dispersities found by spike source and invariant source methods are compared. The experimental results show that the dispersity found by spike source method is close to that found by invariant source method. It indicates that dispersity is only the characteristic of dispersion medium

  5. Determination of dispersity of crushed granite

    International Nuclear Information System (INIS)

    Liu, D.J.; Fan, X.H.

    2005-01-01

    Experimental crushed granite column breakthrough curves, using 99 Tc as spike tracer and 3 H as invariant tracer, were analyzed by different linear regression techniques. Dispersity of crushed granite and the retardation factor of 99 TcO 4 - on the crushed granite were determined simultaneously by one linear regression. Dispersity of crushed granite was also obtained with 3 H as invariant tracer by the other linear regression. The dispersities found by spike source and invariant source methods are compared. Experimental results show that the dispersity found by the spike source method is close to that found by the invariant source method. This indicates that dispersity is only a characteristic of the dispersion medium. (author)

  6. AMS studies in Portuguese variscan granites

    Science.gov (United States)

    Sant'Ovaia, Helena; Martins, Helena; Noronha, Fernando

    2014-05-01

    A large volume of Variscan granitic rocks outcrop in Central Iberian Zone which are well documented concerning geological mapping, petrography and geochemistry but whose magnetic characteristics and fabric remain unknown. In this study we summarize the available AMS data from approximately 644 sampling stations (5152 samples) on different massifs of Variscan Portuguese granites. Despite their different geological, petrographic and geochemical characteristics, magnetic susceptibility (K) values obtained for the majority of the studied granites range from 15 to 300 × 10-6 SI. The dominant paramagnetic behaviour of the granite bodies reflects the presence of ilmenite as the main iron oxide. This feature indicates the reduced conditions involved in the granite melt formation during the Variscan orogeny. The two-mica granites show K values ranging between 15 to 70 × 10-6 SI which are lower than values displayed by the biotite-rich facies scattered within the interval of 70 and 300 × 10-6 SI. The magnetite-bearing granites are scarce but represented in Lavadores, Gerês and Manteigas. Even so, only the Lavadores body could be considered as a true magnetite-type granite (K >3.0 × 10-3 SI) in face of its K, comprised between 1550 and 19303 × 10-6 SI. Magnetic anisotropy can be used as a "marker" for the deformation experienced by granite mushes during their crustal emplacement and further cooling. Magnetic anisotropy can thus be correlated with the finite deformation of a rock, as record by mineral fabrics. Post-tectonic granites, such as those from Vila Pouca de Aguiar, Pedras Salgadas, Caria, Vila da Ponte, Chaves and Lamas de Olo, have a magnetic anisotropy <2.5% which corresponds to a deformation hardly visible to the naked eye. Nevertheless, at microscopic scale, these granites display almost ubiquitous magmatic to submagmatic microstructures (rare wavy extinction in quartz, erratic subgrain boundaries in quartz and, eventually, folded or kinked biotites). For

  7. Limit of the radionuclides in granite

    International Nuclear Information System (INIS)

    Wang Shaling; Jiang Rangrong

    2003-01-01

    Granite is an important sort of building materials. Their radionuclide contents are limited by the national standard GB6566-2001 just as other building materials. This standard divides them into main materials and decorative materials, and relaxes the limit of the latter obviously. Owing to the consideration of public dose limit and environment protection, this method needs discussion. Otherwise, red granite contains high radionuclide contents relatively, especially the sort of Indian Red, and need be paid more attention

  8. Granite Exfoliation, Cosumnes River Watershed, Somerset, California

    Science.gov (United States)

    Crockett, I. Q.; Neiss-Cortez, M.

    2015-12-01

    In the Sierra Nevada foothills of California there are many exposed granite plutons within the greater Sierra Nevada batholith. As with most exposed parts of the batholith, these granite slabs exfoliate. It is important to understand exfoliation for issues of public safety as it can cause rock slides near homes, roads, and recreation areas. Through observation, measuring, and mapping we characterize exfoliation in our Cosumnes River watershed community.

  9. Petrography, geochemistry and Sm-Nd isotopes of the granites from eastern of the Tapajós Domain, Pará state

    Directory of Open Access Journals (Sweden)

    Flávio Robson Dias Semblano

    Full Text Available ABSTRACT: The Tapajós Domain, located in the southern portion of the Amazonian Craton, is a tectonic domain of the Tapajós-Parima Province, a Paleoproterozoic orogenic belt adjacent to a reworked Archean crust, the Central Amazonian Province. This domain has been interpreted as the product of an assemblage of successive magmatic arcs followed by post-orogenic A-type magmatism formed ca. 1880 Ma-old granites of the Maloquinha Intrusive Suite. The study presented here was carried out in four granitic bodies of this suite (Igarapé Tabuleiro, Dalpaiz, Mamoal and Serra Alta from the eastern part of the Tapajós Domain, as well as an I-type granite (Igarapé Salustiano related to the Parauari Intrusive Suite. The A-type granites are syenogranites and monzogranites, and alkali feldspar granites and quartz syenites occur subordinately. These rocks are ferroan, alkalic-calcic to alkalic and dominantly peraluminous, with negative anomalies of Ba, Sr, P and Ti and high rare earth elements (REE contents with pronounced negative Eu anomaly. This set of features is typical of A-type granites. The Igarapé Salustiano granite encompasses monzogranites and quartz monzonites, which are magnesian, calcic to calc-alkalic, high-K and mainly metaluminous, with high Ba and Sr contents and depleted pattern in high field strength elements (HFSE and heavy rare earth elements (HREE, characteristic of I-type granites. The source of magma of these A-type granites is similar to post-collisional granites, while the I-type granite keeps syn-collisional signature. Most of the studied granites have εNd (-3.85 to -0.76 and Nd TDM model ages (2.22 to 2.46 Ga compatible with the Paleoproterozoic crust of the Tapajós Domain. We conclude that the Archean crust source (εNd of -5.01 and Nd TDM of 2.6 Ga was local for these A-type granites.

  10. Alkali-aggregate reactivity (AAR) facts book.

    Science.gov (United States)

    2013-03-01

    This document provides detailed information on alkali-aggregate reactivity (AAR). It primarily discusses alkali-silica reaction (ASR), covering the chemistry, symptoms, test methods, prevention, specifications, diagnosis and prognosis, and mitigation...

  11. Method of making alkali metal hydrides

    Science.gov (United States)

    Pecharsky, Vitalij K.; Gupta, Shalabh; Pruski, Marek; Hlova, Ihor; Castle, Andra

    2017-05-30

    A method is provided for making alkali metal hydrides by mechanochemically reacting alkali metal and hydrogen gas under mild temperature (e.g room temperature) and hydrogen pressure conditions without the need for catalyst, solvent, and intentional heating or cooling.

  12. Mechanical filter for alkali atoms

    CERN Document Server

    Toporkov, D K

    2000-01-01

    A device for separating gases of different mass is discussed. Such a device could be used in a laser-driven spin exchange source of polarized hydrogen atoms to reduce the contamination of alkali atoms. A Monte Carlo simulation has shown that the suggested apparatus based on a commercial turbo pump could reduce by a factor of 10-15 the concentration of the alkali-metal atoms in the hydrogen flow from a laser driven polarized source. This would greatly enhance the effective polarization in hydrogen targets.

  13. Electrolytic method to make alkali alcoholates using ion conducting alkali electrolyte/separator

    Science.gov (United States)

    Joshi, Ashok V [Salt Lake City, UT; Balagopal, Shekar [Sandy, UT; Pendelton, Justin [Salt Lake City, UT

    2011-12-13

    Alkali alcoholates, also called alkali alkoxides, are produced from alkali metal salt solutions and alcohol using a three-compartment electrolytic cell. The electrolytic cell includes an anolyte compartment configured with an anode, a buffer compartment, and a catholyte compartment configured with a cathode. An alkali ion conducting solid electrolyte configured to selectively transport alkali ions is positioned between the anolyte compartment and the buffer compartment. An alkali ion permeable separator is positioned between the buffer compartment and the catholyte compartment. The catholyte solution may include an alkali alcoholate and alcohol. The anolyte solution may include at least one alkali salt. The buffer compartment solution may include a soluble alkali salt and an alkali alcoholate in alcohol.

  14. Construction of thermionic alkali-ion sources

    International Nuclear Information System (INIS)

    Ul Haq, F.

    1986-01-01

    A simple technique is described by which singly charged alkali ions of K, Na, Li, Rb and Cs are produced by heating ultra-pure chemical salts of different alkali metals on tungsten filaments without employing a temperature measuring device. The character of alkali-ion currents at different heating powers and the remarkably constant ion emission current for prolonged periods are discussed. (author)

  15. Alkali binding in hydrated Portland cement paste

    NARCIS (Netherlands)

    Chen, Wei; Brouwers, Jos

    2010-01-01

    The alkali-binding capacity of C–S–H in hydrated Portland cement pastes is addressed in this study. The amount of bound alkalis in C–S–H is computed based on the alkali partition theories firstly proposed by Taylor (1987) and later further developed by Brouwers and Van Eijk (2003). Experimental data

  16. Rapakivi texture in porphyritic dikes within the Karavanke Granitic Massif (Slovenia

    Directory of Open Access Journals (Sweden)

    Giuliano Bellieni

    2002-01-01

    Full Text Available The northern Karavanke Granitic Massif straddles the Slovenian–Austrian border. The investigated area lies in northern Slovenia, and extends from the western Slovenian–Austrian border to the east for about 30 km, with a maximum width of 2 km. The massif exhibits a bimodal magmatic association comprising mainly syenogranite and syenite with contemporaneous gabbroic rocks. Rocks of intermediate composition are less abundant and show field, textural and chemical features suggesting that they have formed as a result of the interaction (mixing and mingling between felsic and mafic magmas. Plagioclasemantled alkali feldspars occur in dikes of porphyritic syenite, which cut larger bodies of gabbroic rocks. Field, mineralogical, petrographic and geochemical evidences suggest that the porphyritic syenite is a hybrid rock, formed by the interaction of mafic and felsic magmas. The formation of plagioclase-mantled alkali feldspar can be explained by the introduction of alkali feldspar from felsic, syenogranitic magma into more mafic magma, causing local undercooling in the portion of mafic magma surrounding the crystals. This resulted in the growth of cellular plagioclase, with quartz infilling, in a thermally and compositionally equilibrating system.

  17. From Compression to Extension: Cretaceous A-type Granite as Indicator of Geodynamic Changes in the Adria Part of the European Neotethys Suture Zone

    Science.gov (United States)

    Balen, D.; Schneider, P.; Massonne, H. J.; Opitz, J.; Petrinec, Z.

    2017-12-01

    The Cretaceous suture zone between the colliding plates of European and Adria (Gondwana) marks the closure of the W Neotethys branch. This zone, partly located in the northern Croatia, comprises reddish alkali granite which is mainly composed of alkali feldspar and quartz, with small amounts of albite, white mica and hematite with ilmenite exsolutions. Accessory minerals include zircon, apatite and Fe-(Ti)-oxides. This granite shows a geochemical signature typical for A2-type granite characterized by a highly siliceous composition and an enrichment in alkalies (high-K calc-alkaline series) and Al (strongly peraluminous, ASI>1.1). The rock belongs to the group of oxidized and ferroan granites with low CaO, MgO, MnO and FeO* contents. Characteristic trace element ratios, primitive mantle and OIB normalized spider-diagrams show significant positive anomalies of Rb, Th, U, K, Zr and Pb accompanied with clear negative anomalies of Ba, Nb, Sr, P, Eu and Ti. The negative anomalies suggest fractionation of plagioclase, apatite and Fe-Ti oxide. Based on the geochemical characteristics the magma originated mainly from melting of lower continental crust (granulite facies metasediments) although a mantle contribution cannot be excluded. The melting process could have been triggered by a heat from the upwelling upper mantle as inferred from zircon typology (D and J5 types prevail), as well from the zircon and whole-rock chemistry accompanied with high zircon saturation temperatures (T=860-950°C). Subsequent ascent of granitic magma was localized along the Europe-Adria suture i.e. the Sava Zone segment of the Late Cretaceous collisional zone where granite was emplaced at ca. 20 km depth. The emplacement followed a long period of Mesozoic orogenic compressional activity. Typical for A-type granites, although in our case related to the subduction of the Adria plate underneath the European plate, is their formation in an extensional tectonic regime. Thus, the studied A

  18. Exciton emissions in alkali cyanides

    International Nuclear Information System (INIS)

    Weid, J.P. von der.

    1979-10-01

    The emissions of Alkali Cyanides X irradiated at low temperature were measured. In addition to the molecular (Frenkel Type) exciton emissions, another emitting centre was found and tentatively assigned to a charge transfer self trapped exciton. The nature of the molecular exciton emitting state is discussed. (Author) [pt

  19. Age of Pedra Branca granite (Goias) and possible geotectonic implications

    International Nuclear Information System (INIS)

    Marini, O.J.; Botelho, N.F.; Macambira, M.J.B.; Provost, A.

    1986-01-01

    Rb-Sr geochronologic dating of granites from the Pedra Branca Granite Massif (Nova Roma, Goias) shown an age of 1405 ± 21My. and a questionable initial Sr 87 /Sr 86 ratio of 0,7004 ± 0,006. Rhyolite from the base of the Arai Group is probably of the same age as the granitic intrusion. The 475 ± 19 My. age for the granitic intrusion is evidence of the Brasiliano Cycle imprint in Pedra Branca region. The age attributed to the Pedra Branca Granite is lower than known ages of the Goias tin granites giving rise to new geotectonic interpretations. It is possible that the Pedra Branca Granite represents a low-level intrusion emplaced at the beginning of structuration and deposition of the Arai basin. It may be correlated with granitic intrusions related to a rift stage above mantle hot spots, like the Nigerian tin younger granites. (author)

  20. The Pedregal granite (Portugal: petrographic and geochemical characterization of a peculiar granitoid

    Directory of Open Access Journals (Sweden)

    Ferreira, J. A.

    2014-12-01

    Full Text Available The Pedregal granite outcrops in the Central Iberian Zone, northern Portugal, in the eastern border of a synorogenic variscan granite-migmatite complex sub-concordant with the regional metamorphic structures. It is a granitoid (ca. 3 km2 with an elongated NW-SE shape intruded in staurolite-micaschist and banded gneiss-migmatite rocks, with local igneous breccias in the contact. The country rocks belong to a metapelitic and metasammitic sequence of Edicarian-Cambrian age, known as the “Complexo Xisto-Grauváquico” (CXG which shows a main regional foliation with a NW-SE to NNW-SSE direction. The Pedregal granite is peraluminous (its A/CNK parameter ranges from 1.18 to 1.62, with a magnesian and alkali to alkali-calcic signature. The peculiar features of the granite are high contents of Zr (389 to 435 ppm and a LREE flat pattern, which are uncommon characteristics for granitic rocks, as well as the corroded shape of the biotite, and the large amount of secondary muscovite. These peculiar features distinguish it from the adjacent synorogenic granites. The field, petrographical and chemical features of the Pedregal granite are in accordance with a second phase of partial melting of a residuum, depleted by melt segregation during a first melting episode with the involvement of peritectic garnet and abundant residual biotite with LREE- and Zr-bearing accessory minerals. Besides, the intrusive character of the granite, and the presence of metasedimentary xenoliths point out to a secondary diatexite.El granito de Pedregal aflora en la Zona Centro-Ibérica, en el norte de Portugal, en el borde oriental de un complejo granito-migmatítico sinorogénico varisco, subconcordante con las estructuras metamórficas regionales. Es un granitoide (ca. 3 km2 de forma elongada NW-SE, que intruye en micaesquistos estaurolíticos y en rocas gneissico- migmatíticas bandeadas, con brechas ígneas locales en el contacto. Las rocas encajantes pertenecen a una

  1. Structure peculiarities of mixed alkali silicate glasses

    International Nuclear Information System (INIS)

    Bershtein, V.A.; Gorbachev, V.V.; Egorov, V.

    1980-01-01

    The thermal porperties and structure of alkali and mixed alkali (Li, Na, K) silicate glasses by means of differential scanning calorimetry (DSC), the positron annihilation method, X-ray fluorescence and infrared (300-30 cm -1 ) spectroscopy were studied. Introduction of different alkali cations in glass results in nonadditive change in their electron structure (bond covalence degree growth) and the thermal behaviour. The different manifestations of mixed alkali effect can be explained by the lessening of long distance Coulomb interactions and strengthening the short-range forces in the mixed alkali glasses. (orig.)

  2. Rare metal granites and related rocks of the Ukrainian shield

    Directory of Open Access Journals (Sweden)

    Esipchuk, K.Ye.

    1993-12-01

    Full Text Available Two rare metal leucocratic granites, Perga and Kamennaya complexes, can be distinquished on the Ukrainian shield. The Perga complex consists of medium- and coarse grained, mainly porphyric, biotite, riebeckite and aegirine granites, granite porphyries, microclinites and albitites with rare metal mineralization (genthelvite, phenacite, tantalite, cassiterite and wolframite etc.. Granites from several stocks (up to 30 km2 in the northwestern part of the shield, situated along the fracture zone, restricted the large Korosten pluton of rapakivi granites to the northwest. The age of these granites (Pb-Pb and U-Pb methods on zircon and monazite practically coincide with the age of rapakivi granites being 1750 Ma. Within the Korosten complex of rapakivi granites we consider that zinnwaldite granites, which are characterized by fluorite and topazine mineralization, represent the final phase of pluton. These granites differ from the Perga ones by their low content of rare metals. The Kamennaya Mogila complex lies in the southeastern part of the Ukrainian shield. It consists of biotite and muscovite-biotite, medium- and coarse-grained (also porphyric, and occasionally greisining granites with rare metal mineralization (cassiterite, columbite, molybdenite, wolframite and beryl. Granites form several stocks (5-30 km2 situated 10-30 km to the west-northwest of the South-Kalchik gabbro-syenite-granite pluton. Granitoids in both of these complexes have similar isotopic ages (1800 Ma. Leucocratic subalkaline granites (the Novoyanisol type are known within the pluton itself, occupying an intermediate position between the above mentioned in terms of mineral and geochemical composition. The gabbro-syenite-granite formation of the Nearazov region has a substantial similarity to the anorthosite-rapakivi-granite formation. In this respect the relation of each of them to rare metal granites is rather remarkable. This relation is, most probably, not only spatial, but

  3. PREVALENCE OF METABOLIC SYNDROME IN GRANITE WORKERS

    Directory of Open Access Journals (Sweden)

    Srilakshmi

    2015-10-01

    Full Text Available BACKGROUND: The prevalence of the metabolic syndrome (MS has significantly increased over the last few decades and has become a main health challenge worldwide. Prevalence of MS is quickly rising in developing countries due to changing lifestyle. It was considered worthwhile to study MS and its components in granite workers since granite factories are situated in and around Khammam area. Moreover, no studies of MS in granite workers have been reported in literature. OBJECTIVES: Aim of our study is to assess the prevalence of metabolic syndrome and its components in granite workers. MATERIALS AND METHODS: 210 male workers in the age group of 20 - 50 working in granite industries located in and around the Khammam town of Telangana State are selected for the present study. Blood pressures (BP, waist circumference (WC were measured. Fasting blood samples were collected for the estimation of glucose and lipids. RESULTS: 69 subjects out of 210 were identified as having MS based on updated National cholesterol education programme - Adult Treatment Panel III (NCEP - ATP III guidelines. CONCLUSION: MS should be identified and remedial measures may be suggested, so that the risk of hypertension, cardiovascular risk, diabetes and the resultant morbidity is minimized and can be delayed

  4. Radiometric analysis of Chinese commercial granites

    International Nuclear Information System (INIS)

    Xinwei, L.; Lingqing, W.; Xiaodan, J.

    2006-01-01

    Due to the widespread use of granites as building and ornamental materials, measurements of 226 Ra, 232 Th and 40 K activities in commercial granites have been carried out using a NaI(Tl) γ-ray spectrometer with a matrix-inversion-based spectral stripping technique. The concentrations of 226 Ra, 232 Th and 40 K in Chinese commercial granite range from 14.5 to 204.7 Bq x kg -1 , 16.7 to 186.7 Bq x kg -1 and 185.7 to 1745.6 Bq x kg -1 , respectively. The mean values of the activity concentrations of 226 Ra, 232 Th and 40 K in red and pink commercial granites are all higher than those in black and gray commercial ones. The radium equivalent activity (Ra eq ), the external hazard index (H ex ), the internal hazard index (H in ) and the annual gonadal dose equivalent (AGDE) were also calculated and compared to the international recommended values. Six types of red commercial granites (CBR, MLR, QXR, PBR, JXR, LQR, YDR and TSR) of China do not satisfy the universal standards. (author)

  5. On-line alkali monitoring - Part 1

    International Nuclear Information System (INIS)

    Andersson, Christer; Ljung, P.; Woxlin, H.

    1997-02-01

    As a consequence of the increased knowledge of the environmental impact of combustion based heat and power generation, the use of renewable biofuels will be increased. An obstacle associated to biofuel combustion compared to other fuels is the large release of alkali. Alkali compounds in flue gases are known to cause severe operational problems. Three of the major problems are; fouling of superheating tubes (causing reduced heat transfer and possibly corrosion), agglomeration of the bed material in fluidized beds, and poisoning of SCR catalysts. Yet another alkali related problem arises when, in order to increase the electric efficiency of combustion power plants, combined-cycle technology is used. Alkali vapour present in the fuel gas for the gas turbine is condensed to particles which increase corrosion and erosion of the turbine blades. The research on ash related operational problems has to be extended in order to ensure future use of biofuels in heat and power generation. In all successful research, adequate tools are necessary. To investigate ash related problems the key issue is to be able to perform continuous alkali measurements. This pilot study has investigated the need of continuous alkali measurements, which alkali species are harmful in the different applications and also available instrumentation capable of measuring the specific alkali species. The report gives a short summary presenting alkali related operational problems. In addition a schematic overview is given, showing the alkali species that possibly can exist in various parts of the power plant. 48 refs, 13 figs, 4 tabs

  6. Geochemistry and petrogenesis of Proterozoic granitic rocks from ...

    Indian Academy of Sciences (India)

    Geochemistry and petrogenesis of Proterozoic granitic ... This study presents the geochemical characteristics of granitic rocks located on the northern ... Frost and Frost 2013). ...... King P L, White A J R, Chappell B W and Allen C M 1997.

  7. The Early Jurassic Bokan Mountain peralkaline granitic complex (southeastern Alaska): geochemistry, petrogenesis and rare-metal mineralization

    Science.gov (United States)

    Dostal, Jaroslav; Kontak, Daniel J.; Karl, Susan M.

    2014-01-01

    The Early Jurassic (ca. 177 Ma) Bokan Mountain granitic complex, located on southern Prince of Wales Island, southernmost Alaska, cross-cuts Paleozoic igneous and metasedimentary rocks of the Alexander terrane of the North American Cordillera and was emplaced during a rifting event. The complex is a circular body (~3 km in diameter) of peralkaline granitic composition that has a core of arfvedsonite granite surrounded by aegirine granite. All the rock-forming minerals typically record a two-stage growth history and aegirine and arfvedsonite were the last major phases to crystalize from the magma. The Bokan granites and related dikes have SiO2 from 72 to 78 wt. %, high iron (FeO (tot) ~3-4.5 wt. %) and alkali (8-10 wt.%) concentrations with high FeO(tot)/(FeO(tot)+MgO) ratios (typically >0.95) and the molar Al2O3/(Na2O+K2O) ratio Nd values which are indicative of a mantle signature. The parent magma is inferred to be derived from an earlier metasomatized lithospheric mantle by low degrees of partial melting and generated the Bokan granitic melt through extensive fractional crystallization. The Bokan complex hosts significant rare-metal (REE, Y, U, Th, Nb) mineralization that is related to the late-stage crystallization history of the complex which involved the overlap of emplacement of felsic dikes, including pegmatite bodies, and generation of orthomagmatic fluids. The abundances of REE, HFSE, U and Th as well as Pb and Nd isotopic values of the pluton and dikes were modified by orthomagmatic hydrothermal fluids highly enriched in the strongly incompatible trace elements, which also escaped along zones of structural weakness to generate rare-metal mineralization. The latter was deposited in two stages: the first relates to the latest stage of magma emplacement and is associated with felsic dikes that intruded along the faults and shear deformations, whereas the second stage involved ingress of hydrothermal fluids that both remobilized and enriched the initial

  8. Geochemical constraints on genesis of Paleoproterozoic A-type granite in the south margin of North China Craton

    Science.gov (United States)

    Xue, Shuo; Xu, Yang; Ling, Ming-Xing; Kang, Qing-Qing; Jiang, Xiao-Yan; Sun, Sai-Jun; Wu, Kai; Zhang, Zhe-Kun; Luo, Ze-Bin; Liu, Yu-Long; Sun, Weidong

    2018-04-01

    Paleoproterozoic A-type granites are widely outcropped in the North China Craton (NCC), particularly in the Trans-North China Orogen. However, their genesis and tectonic significance remain obscure. Here we report systematic studies on geochronology and geochemical characteristics of A-type granite in Huayangchuan, south margin of the NCC. The samples are enriched in total alkali (K2O + Na2O > 8.97 wt%), and depleted in MgO (0.84-0.93 wt%), CaO (1.28-1.90 wt%) and P2O5 (0.18-0.20 wt%), with high FeOT/MgO (5.69-6.67). They are characterized by high Zr + Y + Nb + Ce values (1293-1392 ppm) and 10,000 × Ga/Al ratios (3.14-3.35), which are typical characteristics of A-type granite. The Huayangchuan A-type granite can be further classified as A1-type subgroup based on particular geochemical features, e.g., low Y/Nb (0.87-1.00) and Yb/Ta (0.88-1.10). High precision zircon U-Pb dating of the A-type granite by secondary ion mass spectrometry (SIMS) yields Paleoproterozoic 207Pb/206Pb ages of 1829.5 ± 2.5 Ma. The low zircon ɛHf(t) values (-6.97 to -10.45), along with zircon Hf model age of 2.7-2.9 Ga, indicate that the Huayangchuan A-type granite was derived from partial melting of the ancient continental crust with contribution of enriched mantle components. The low zircon δ18O composition (4.00 to 6.78‰) indicates that the zircons were crystallized from low δ18O magmas, which derived from the crust metasomatized by low δ18O mantle fluids or melts. The E-W trend A1-type granitic plutons in the NCC are generally outcropped in a rift tectonic regime, which is consistent with the development of the mantle plume in the Xiong'er district. The large volume of basaltic magmas, generated by mantle plume head, underplated the lower continental crust and formed the Huayangchuan A-type granite.

  9. Tasmanian tin and tungsten granites - their radiometric characteristics

    International Nuclear Information System (INIS)

    Yeates, A.N.

    1982-01-01

    A radiometric survey of Tasmanian granites has shown, with one exception, that tin and tungsten-bearing granites have high radioactivity, largely owing to increased uranium. Many have a high uranium/thorium ratio as well. Radiometric measurements can also delineate different granite types within composite bodies

  10. Processing and finishing of granite surfaces

    OpenAIRE

    Klich, J. (Jiří); Hlaváček, P. (Petr); Ščučka, J. (Jiří); Sitek, L. (Libor); Foldyna, J. (Josef); Georgiovská, L. (Lucie); Souček, K. (Kamil); Staš, L. (Lubomír); Bortolussi, A.

    2013-01-01

    The article deals with granite surface processing and finishing by various methods including bush hammering, flaming, polishing, continuous and pulsating water jetting. Both optical and CT X-ray methods are used for analysis of surface and subsurface areas of tested samples. Advantages of pulsating water jetting compared to other techniques are discussed.

  11. Liquid alkali metals and alkali-based alloys as electron-ion plasmas

    International Nuclear Information System (INIS)

    Tosi, M.P.

    1981-06-01

    The article reviews the theory of thermodynamic and structural properties of liquid alkali metals and alkali-based alloys, within the framework of linear screening theory for the electron-ion interactions. (author)

  12. K-Ca Dating of Alkali-Rich Fragments in the Y-74442 and Bhola LL-Chondritic Breccias

    Science.gov (United States)

    Yokoyama, T; Misawa, K.; Okano, O; Shih, C. -Y.; Nyquist, L. E.; Simon, J. I.; Tappa, M. J.; Yoneda, S.

    2013-01-01

    Alkali-rich igneous fragments in the brecciated LL-chondrites, Krahenberg (LL5) [1], Bhola (LL3-6) [2], Siena (LL5) [3] and Yamato (Y)-74442 (LL4) [4-6], show characteristic fractionation patterns of alkali and alkaline elements [7]. The alkali-rich fragments in Krahenberg, Bhola and Y-74442 are very similar in mineralogy and petrography, suggesting that they could have come from related precursor materials [6]. Recently we reported Rb-Sr isotopic systematics of alkali-rich igneous rock fragments in Y-74442: nine fragments from Y-74442 yield the Rb-Sr age of 4429 plus or minus 54 Ma (2 sigma) for lambda(Rb-87) = 0.01402 Ga(exp -1) [8] with the initial ratio of Sr-87/Sr-86 = 0.7144 plus or minus 0.0094 (2 sigma) [9]. The Rb-Sr age of the alkali-rich fragments of Y-74442 is younger than the primary Rb-Sr age of 4541 plus or minus 14 Ma for LL-chondrite whole-rock samples [10], implying that they formed after accumulation of LL-chondrite parental bodies, although enrichment may have happened earlier. Marshall and DePaolo [11,12] demonstrated that the K-40 - Ca-40 decay system could be an important chronometer as well as a useful radiogenic tracer for studies of terrestrial rocks. Shih et al. [13,14] and more recently Simon et al. [15] determined K-Ca ages of lunar granitic rocks, and showed the application of the K-Ca chronometer for K-rich planetary materials. Since alkali-rich fragments in the LL-chondritic breccias are highly enriched in K, we can expect enhancements of radiogenic Ca-40. Here, we report preliminary results of K-Ca isotopic systematics of alkali-rich fragments in the LL-chondritic breccias, Y-74442 and Bhola.

  13. Identification of granite varieties from colour spectrum data.

    Science.gov (United States)

    Araújo, María; Martínez, Javier; Ordóñez, Celestino; Vilán, José Antonio

    2010-01-01

    The granite processing sector of the northwest of Spain handles many varieties of granite with specific technical and aesthetic properties that command different prices in the natural stone market. Hence, correct granite identification and classification from the outset of processing to the end-product stage optimizes the management and control of stocks of granite slabs and tiles and facilitates the operation of traceability systems. We describe a methodology for automatically identifying granite varieties by processing spectral information captured by a spectrophotometer at various stages of processing using functional machine learning techniques.

  14. Portuguese granites associated with Sn-W and Au mineralizations

    OpenAIRE

    Ana M.R. Neiva

    2002-01-01

    In northern and central Portugal, there are different tin-bearing granites. Most of them are of S-type, others have mixed characteristics of I-type and S-type granites and a few are of I-type. Tin-tungsten deposits are commonly associated with Hercynian tin-bearing S-type granites. Some quartz veins with wolframite are associated with an I-type granite, which has a low Sn content. In suites of tin-bearing S-type granitic rocks, Sn content increases as a function of the degree of fractional cr...

  15. Effect of Bacillus subtilis on Granite Weathering: A Laboratory Experiment

    Science.gov (United States)

    Song, W.; Ogawa, N.; Oguchi, C. T.; Hatta, T.; Matsukura, Y.

    2006-12-01

    We performed a comparative experiment to investigate how the ubiquitous soil bacterium Bacillus subtilis weathers granite and which granite-forming minerals weather more rapidly via biological processes. Batch type experiments (granite specimen in a 500 ml solution including NaCl, glucose, yeast extract and bacteria Bacillus subtilis at 27°E C) were carried out for 30 days. Granite surfaces were observed by SEM before and after the experiment. Bacillus subtilis had a strong influence on granite weathering by forming pits. There were 2.4 times as many pits and micropores were 2.3 times wider in granite exposed to Bacillus subtilis when compared with bacteria-free samples. Bacillus subtilis appear to preferentially select an optimum place to adhere to the mineral and dissolve essential elements from the mineral to live. Plagioclase was more vulnerable to bacterial weathering than biotite among the granite composing minerals.

  16. 2005 dossier: granite. Tome: phenomenological evolution of the geologic disposal

    International Nuclear Information System (INIS)

    2005-01-01

    This document makes a status of the researches carried out by the French national agency of radioactive wastes (ANDRA) about the phenomenological aspects of the geologic disposal of high-level and long-lived radioactive wastes (HLLL) in granite formations. Content: 1 - introduction: ANDRA's research program on disposal in granitic formation; 2 - the granitic environment: geologic history, French granites; 3 - HLLL wastes and disposal design concepts; 4 - identification, characterization and modeling of a granitic site: approach, geologic modeling, hydrologic and hydro-geochemical modeling, geomechanical and thermal modeling, long-term geologic evolution of a site; 5 - phenomenological evolution of a disposal: main aspects of the evolution of a repository with time, disposal infrastructures, B-type wastes disposal area, C-type wastes disposal area; spent fuels disposal area, radionuclides transfer and retention in the granitic environment; 6 - conclusions: available knowledge, methods and tools for the understanding and modeling of the phenomenological evolution of a granitic disposal site. (J.S.)

  17. Hydrothermal alteration of Hercynian granites, its significance to the evolution of geothermal systems in granitic rocks

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Jose M.; Matias, Maria J.; Basto, Maria J.; Aires-Barros, Luis A. [Instituto Superior Tecnico, Centro de Petrologia e Geoquimica, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon (Portugal); Carreira, Paula M. [Instituto Tecnologico e Nuclear, Estrada Nacional n 10, 2686 - 953 Sacavem (Portugal); Goff, Fraser E. [Earth and Planetary Sciences Department, Univ. of New Mexico, Albuquerque, NM 87131 (United States)

    2010-06-15

    We discuss geochemical and isotopic ({sup 18}O/{sup 16}O, {sup 2}H/{sup 1}H and {sup 87}Sr/{sup 86}Sr) data recording the hydrothermal alteration of northern Portuguese Hercynian granites by Na-HCO{sub 3}-CO{sub 2}-rich mineral waters. Whole-rock samples from drill cores of Vilarelho da Raia granite have {delta}{sup 18}O values in the +11.47 to +10.10 permille range. The lower values correspond to highly fractured granite samples displaying vein and pervasive alteration. In the pervasive alteration stage, which probably results from a convective hydrothermal system set up by the intrusion of the granites, the metamorphic waters are in equilibrium with hydrous minerals. In contrast, the vein alteration of these granitic rocks was caused by water of meteoric origin. The oxygen ratios between water (W) and rock (R), the so-called W/R ratios, obtained for the open system (where the heated water is lost from the system by escape to the surface) range between 0.05 and 0.11, suggesting that the recrystallization of the veins was influenced by a small flux of meteoric water. Stable isotope analyses performed on the cores show that the vein alteration stage relates to post-emplacement tectonic stresses acting on the granite, probably of late Hercynian age. Our results are consistent with the existence of two separate alteration events (pervasive and vein) caused by hydrothermal waters of different isotopic characteristics. The studies presented in this paper should be viewed as a natural analogue that uses the alteration features observed in a fossil geothermal system at Vilarelho da Raia to assess possible water-rock reactions presently occurring at depth in granitic rocks of the nearby Chaves area. (author)

  18. 2005 dossier: granite. Tome: phenomenological evolution of the geologic disposal; Dossier 2005: Granite. Tome evolution phenomenologique du stockage geologique

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    This document makes a status of the researches carried out by the French national agency of radioactive wastes (ANDRA) about the phenomenological aspects of the geologic disposal of high-level and long-lived radioactive wastes (HLLL) in granite formations. Content: 1 - introduction: ANDRA's research program on disposal in granitic formation; 2 - the granitic environment: geologic history, French granites; 3 - HLLL wastes and disposal design concepts; 4 - identification, characterization and modeling of a granitic site: approach, geologic modeling, hydrologic and hydro-geochemical modeling, geomechanical and thermal modeling, long-term geologic evolution of a site; 5 - phenomenological evolution of a disposal: main aspects of the evolution of a repository with time, disposal infrastructures, B-type wastes disposal area, C-type wastes disposal area; spent fuels disposal area, radionuclides transfer and retention in the granitic environment; 6 - conclusions: available knowledge, methods and tools for the understanding and modeling of the phenomenological evolution of a granitic disposal site. (J.S.)

  19. Process for the disposal of alkali metals

    International Nuclear Information System (INIS)

    Lewis, L.C.

    1977-01-01

    Large quantities of alkali metals may be safely reacted for ultimate disposal by contact with a hot concentrated caustic solution. The alkali metals react with water in the caustic solution in a controlled reaction while steam dilutes the hydrogen formed by the reaction to a safe level. 6 claims

  20. The chemistry of the liquid alkali metals

    International Nuclear Information System (INIS)

    Addison, C.C.

    1984-01-01

    A study of liquid alkali metals. It encourages comparison with molecular solvents in chapter covering the nature and reactivity of dissolved species, solvation, solubility and electrical conductivity of solutions. It demonstrates lab techniques unique to liquid alkali metals. It discusses large-scale applications from storage batteries to sodium-cooled reactors and future fusion reactors, and associated technological problems. Contents: Some Basic Physical and Chemical Properties; Manipulation of the Liquids; The Chemistry of Purification Methods; Species Formed by Dissolved Elements; Solubilities and Analytical Methods; Alkali Metal Mixtures; Solvation in Liquid Metal; Reactions Between Liquid Alkali Metals and Water; Reactions of Nitrogen with Lithium and the Group II Metals in Liquid Sodium; The Formation, Dissociation and Stability of Heteronuclear Polyatomic Anions; Reactions of the Liquid Alkali Metals and Their Alloys with Simple Alipatic Hydrocarbons; Reactions of the Liquid Alkali Metals with Some Halogen Compounds; Hydrogen, Oxygen and Carbon Meters; Surface Chemistry and Wetting; Corrosion of Transition Metals by the Liquid Alkali Metals; Modern Applications of the Liquid Alkali Metals

  1. Method of handling radioactive alkali metal waste

    Science.gov (United States)

    Wolson, R.D.; McPheeters, C.C.

    Radioactive alkali metal is mixed with particulate silica in a rotary drum reactor in which the alkali metal is converted to the monoxide during rotation of the reactor to produce particulate silica coated with the alkali metal monoxide suitable as a feed material to make a glass for storing radioactive material. Silica particles, the majority of which pass through a 95 mesh screen or preferably through a 200 mesh screen, are employed in this process, and the preferred weight ratio of silica to alkali metal is 7 to 1 in order to produce a feed material for the final glass product having a silica to alkali metal monoxide ratio of about 5 to 1.

  2. Method of handling radioactive alkali metal waste

    International Nuclear Information System (INIS)

    Mcpheeters, C.C.; Wolson, R.D.

    1980-01-01

    Radioactive alkali metal is mixed with particulate silica in a rotary drum reactor in which the alkali metal is converted to the monoxide during rotation of the reactor to produce particulate silica coated with the alkali metal monoxide suitable as a feed material to make a glass for storing radioactive material. Silica particles, the majority of which pass through a 95 mesh screen or preferably through a 200 mesh screen, are employed in this process, and the preferred weight ratio of silica to alkali metal is 7 to 1 in order to produce a feed material for the final glass product having a silica to alkali metal monoxide ratio of about 5 to 1

  3. Petrography, mineral chemistry and lithochemistry of the albitite and granite-gneissics rocks of anomaly 35 from Lagoa Real uranium province

    International Nuclear Information System (INIS)

    Santos, Camila Marques dos

    2016-01-01

    In the northwestern portion of the Lagoa Real Uranium Province (LRUP), located in south-central Bahia, it is located one of the most promising uranium anomalies Brazil (an35, Gameleira I deposit), the reserves and proximity to the Cachoeira mine. Other anomalies of this sector (eg. 31 AN and AN34), are also considered strategic for the content of radioactive minerals and REE. The objective was to develop a study of a representative drill core of an35, where the main rocks PULR are present. The research focused on the mineralogical and chemical changes observed in the passages of a lithology to another, from the rock to the meta granitic albitites, through gneiss and transitional rocks, and making comparisons with similar lithologies sampled on testimonies of AN31 and 34. The granites are classified as hypersolvus coarse alkali-feldspar granite and are variably deformed. The main mineral assemblage in granites are perthitic orthoclase+hedenbergite+ quartz +hastingsite + biotite, and zircon, apatite, ilmenite and titanite are accessories. The reddening of these rocks are characterized by feldspars sericitization and hematitization and the presence of 'vazios'. The gneisses are mainly gray and reach milonitic to protomilonitics terms. These rocks have characteristics of subsolidus changes as swapped rims and metasomatic perthites. The tardi-magmatic association (amphibole+biotite) indicates final crystallization or late influx by superficial fluids resulting in an increase in water and volatiles, such as F and Cl in the system, which must also have carried rare-earth elementsGranites have geochemical affinity with A-type ferroan granite, A2, reduced and are post-collisional. Their patterns of incompatible elements and rare earths are comparable to Sao Timoteo Granite, but their petrographic features indicate that it is a less common granite facies. Albitites were classified as garnet albitites, magnetite albitites and biotite albitites. Contacts between

  4. Sorption of Np (Ⅴ) on Beishan granite fracture filling materials

    International Nuclear Information System (INIS)

    Jiang Tao; Wang Bo; Bao Liangjin; Zhou Duo; Long Haoqi; Song Zhixin; Chen Xi

    2012-01-01

    The sorption behaviors of Np (Ⅴ) on the granite fracture filling materials were studied by batch experiments under anaerobic in Beishan groundwater. The impact of pH of groundwater, CO 3 2- , humic acid and different components of granite fracture filling materials on sorption of Np (Ⅴ) was investigated. The results show that the granite fracture filling materials have strong capacity of Np (Ⅴ) adsorption. The value of K d , for Np (Ⅴ) sorption on the granite fracture filling materials is 843 mL/g. With the increase of pH, the value of K d increases at first and then decreases. K d of Np sorption on granite fracture filling materials in the presence of CO 3 2- and humic acid decreases. The chlorite and feldspar are major contributors to the sorption of Np (Ⅴ) on Beishan granite fracture filling materials. (authors)

  5. Rare-earth elements in granites: concentration and distribution pattern

    International Nuclear Information System (INIS)

    Galindo, A.C.

    1983-01-01

    The geochemistry of rare earth elements in granites is studied. The rare earth element (REE) distribution pattern in granites is characterized by a smooth curve with decreasing concentrations from La to Lu, and frequently a marked Eu negative anomaly. It seems to exist relationship between granite genesis and its REE pattern, in that bodies of primary (magmatic differentiation) origin always show this negative Eu anomaly, while those bodies generated by crustal anatexis do not show this anomaly. (E.G.) [pt

  6. Portuguese granites associated with Sn-W and Au mineralizations

    Directory of Open Access Journals (Sweden)

    Ana M.R. Neiva

    2002-01-01

    Full Text Available In northern and central Portugal, there are different tin-bearing granites. Most of them are of S-type, others have mixed characteristics of I-type and S-type granites and a few are of I-type. Tin-tungsten deposits are commonly associated with Hercynian tin-bearing S-type granites. Some quartz veins with wolframite are associated with an I-type granite, which has a low Sn content. In suites of tin-bearing S-type granitic rocks, Sn content increases as a function of the degree of fractional crystallization. Greisenizations of two-mica S-type granites associated with tin-tungsten mineralizations are accompanied by an increase in SiO2, H2O+, Sn, W, Nb, Ta, Rb, Zn, and Pb and decrease in MgO, Na2O, V, Sc,Zr, and Sr. The granite associated with the Jales gold deposit is of S-type and strongly differentiated like the tin-bearing S-type granites, but it has a very low Sn content. During fractional crystallization, Si, Rb, Sn, Pb, Au, As, Sb, and S increase. During increasing degree of hydrothermal alteration of this granite at the gold-quartz vein walls, there are progressive increases in K2O, H2O+, Sn, Cs, Cu, Pb, Au, Sb, As, and S.

  7. Process to separate alkali metal salts from alkali metal reacted hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, John Howard; Alvare, Javier; Larsen, Dennis; Killpack, Jeff

    2017-06-27

    A process to facilitate gravimetric separation of alkali metal salts, such as alkali metal sulfides and polysulfides, from alkali metal reacted hydrocarbons. The disclosed process is part of a method of upgrading a hydrocarbon feedstock by removing heteroatoms and/or one or more heavy metals from the hydrocarbon feedstock composition. This method reacts the oil feedstock with an alkali metal and an upgradant hydrocarbon. The alkali metal reacts with a portion of the heteroatoms and/or one or more heavy metals to form an inorganic phase containing alkali metal salts and reduced heavy metals, and an upgraded hydrocarbon feedstock. The inorganic phase may be gravimetrically separated from the upgraded hydrocarbon feedstock after mixing at a temperature between about 350.degree. C. to 400.degree. C. for a time period between about 15 minutes and 2 hours.

  8. Alkali metal for ultraviolet band-pass filter

    Science.gov (United States)

    Mardesich, Nick (Inventor); Fraschetti, George A. (Inventor); Mccann, Timothy A. (Inventor); Mayall, Sherwood D. (Inventor); Dunn, Donald E. (Inventor); Trauger, John T. (Inventor)

    1993-01-01

    An alkali metal filter having a layer of metallic bismuth deposited onto the alkali metal is provided. The metallic bismuth acts to stabilize the surface of the alkali metal to prevent substantial surface migration from occurring on the alkali metal, which may degrade optical characteristics of the filter. To this end, a layer of metallic bismuth is deposited by vapor deposition over the alkali metal to a depth of approximately 5 to 10 A. A complete alkali metal filter is described along with a method for fabricating the alkali metal filter.

  9. Density of mixed alkali borate glasses: A structural analysis

    International Nuclear Information System (INIS)

    Doweidar, H.; El-Damrawi, G.M.; Moustafa, Y.M.; Ramadan, R.M.

    2005-01-01

    Density of mixed alkali borate glasses has been correlated with the glass structure. It is assumed that in such glasses each alkali oxide associates with a proportional quantity of B 2 O 3 . The number of BO 3 and BO 4 units related to each type of alkali oxide depends on the total concentration of alkali oxide. It is concluded that in mixed alkali borate glasses the volumes of structural units related to an alkali ion are the same as in the corresponding binary alkali borate glass. This reveals that each type of alkali oxide forms its own borate matrix and behaves as if not affected with the presence of the other alkali oxide. Similar conclusions are valid for borate glasses with three types of alkali oxide

  10. Simulation of bentonite colloid migration through granite

    International Nuclear Information System (INIS)

    Rosicka, Dana; Hokr, Milan

    2012-01-01

    Document available in extended abstract form only. Full text of publication follows: Colloidal bentonite particles generate at the interface of buffer and host rock in spent nuclear fuel repository due to an erosion process and migrate through granite by the water flow. Stability of these colloids and their migration possibilities have been studied on account of radionuclide transport possibility as colloid could carry adsorbed radionuclides in groundwater through granite. That is why a simulation of bentonite colloid migration in the surrounding of a repository might be requested. According to chemical condition as ionic strength and pH, the colloidal particles coagulate into clusters and that influence the migration of particles. The coagulation kinetics of natural bentonite colloids were experimentally studied in many articles, for example by light scattering techniques. We created a model of coagulation of bentonite colloids and simulation of a chosen experiment with use of the multicomponent reactive transport equation. The coagulation model describes clustering of particles due to attractive van der Waals forces as result of collision of particles due to heat fluctuation and different velocity of particles during sedimentation and velocity gradient of water flow. Next, the model includes influence of repulsive electrostatic forces among colloidal particles leading to stability of particles provided high surface charge of colloids. In the model, each group of clusters is transported as one solution component and the kinetics of coagulation are implemented as reactions between the components: a shift of particles among groups of particles with similar migration properties, according to size of the clusters of colloids. The simulation of migration of bentonite colloid through granite using the coagulation model was calibrated according to experiment results. On the basis of the simulation, one can estimate the basic processes that occur during bentonite colloid

  11. Contribution to uranium geochemistry in intrusive granites

    International Nuclear Information System (INIS)

    Coulomb, R.

    1959-01-01

    This work aims to define the position of a certain number of French granitic deposits within the field of the geochemistry of granites in general, and of the geochemistry of uranium in particular. The regions concerned are: - 3 French Hercynian ranges, in the Vendee, in Brittany and in the Morvan, - 1 African range, probably precambrian, of the Hoggar. For each range, the petrochemical framework is first of all determined and then the degree of chemical homogeneity of the rocks is evaluated. In the petrochemical groups thus obtained the geochemical behaviour of the uranium is studied. From a point of view of the geochemistry of the granites under investigation, a comparison of the laws of distribution of the major elements in the 4 ranges shows up a convergence of average composition which was not anticipated by geological and petrographic considerations alone. The statistical and geochemical distribution laws of the total uranium as a function of the petrochemical variations are established. A study of the chemical forms of uranium in the rocks has drawn an attention to the qualitative and quantitative importance of the fraction of this uranium soluble in dilute acids. We have therefore reconsidered on the one hand, the laws of distribution of the insoluble uranium, which represents essentially the uranium fixed in crystalline structures (zircon, allanite...), and we have justified on the other hand the interest presented by the soluble uranium: this, although more complex in character, presents a geochemical unity in post magmatic phenomena which makes possible to find a genetic connection between the uraniferous deposits and the intrusive massifs. Finally we have given a plan of the geochemical cycle of uranium, in which we hope to have provided some more accurate data on the igneous phase. (author) [fr

  12. Petrogenesis of peralkaline granite dykes of the Straumsvola complex, western Dronning Maud Land, Antarctica

    Science.gov (United States)

    Harris, Chris; Dreyer, Tanya; le Roux, Petrus

    2018-01-01

    the granites by assimilation are unfeasible, unless an unexposed high-δ18O contaminant is invoked. Instead, it is proposed that the peralkaline syenite and granite dykes formed by partial melting of alkali-metasomatised gneiss that surrounds the nepheline syenite, followed by fractional crystallization.

  13. Microstructural modeling of Vienne granite damage

    International Nuclear Information System (INIS)

    Homand, F.; Hoxha, D.

    2002-01-01

    The microstructural approach in damage modeling, which is presented in this paper describes the evolution of micro-crack geometry as a function of history loading. If the crack geometry is known, the effective properties could then be calculated foe any cracked rock by the mean of a micro-mechanical model. The P L evolution law which is necessary in the describing of crack geometry evolution is hardly based on the crack microscope observation as well as on the theory of fabric tensors. This approach is applied in the modeling of mechanical behaviour of Vienne granite. The result of model simulations are compared with laboratory tests. (author)

  14. Deep fracturation of granitic rock mass

    International Nuclear Information System (INIS)

    Bles, J.L.; Blanchin, R.; Bonijoly, D.; Dutartre, P.; Feybesse, J.L.; Gros, Y.; Landry, J.; Martin, P.

    1986-01-01

    This documentary study realized with the financial support of the European Communities and the CEA aims at the utilization of available data for the understanding of the evolution of natural fractures in granitic rocks from the surface to deep underground, in various feasibility studies dealing with radioactive wastes disposal. The Mont Blanc road tunnel, the EDF Arc-Isere gallerie, the Auriat deep borehole and the Pyrenean rock mass of Bassies are studied. In this study are more particularly analyzed the relationship between small fractures and large faults, evolution with depth of fracture density and direction, consequences of rock decompression and relationship between fracturation and groundwater [fr

  15. GRANITE- A steroscopic imaging Chernkov telescope system

    International Nuclear Information System (INIS)

    Shubnell, M.; Akerlof, C.W.; Cawley, M.F.; Chantell, M.; Fegan, D.J.; Fennell, S.; O'Flaherty, K.S.; Freeman, S.; Frishman, D.; Gaidos, J.A.; Hagan, J.; Harris, K.; Hillas, A.M.; Kerrick, A.D.; Lamb, R.C.; Lappin, T.; Lawrence, M.A.; Levy, H.; Lewis, D.A.; Meyer, D.I.; Mohanty, G.; Punch, M.; Reynolds, P.T.; Rovero, A.C.; Sembroski, G.; Weaverdyck, C.; Weekes, T.C.; Whitaker, T.; Wilson, C.

    1993-01-01

    A second 10 meter class imaging telescope was constructed on Mt. Hopkins, Arizona, the site of the original 10 meter Whipple Cherenkov telescope. The twin telescope system with a 140 meter base line will allow both a reduction in the energy threshold and an improvement in the rejection of the hardonic background. The new telescope started operation in December 1991. With the final completion of the first installation stage (GRANITE I) during spring 92, it is now operating simultaneously with the orginal reflector. We describe in this paper design and construction of the new instrument and demonstrate the capability of the experiment to record coincident events

  16. Relaxation of quadrupole orientation in an optically pumped alkali vapour

    Energy Technology Data Exchange (ETDEWEB)

    Bernabeu, E; Tornos, J

    1985-04-01

    The relaxation of quadrupole orientation (alignment) in an optically pumped alkali vapour is theoretically studied by taking into account the relaxation processes by alkali-buffer gas, alkali-alkali with spin exchange and alkali-cell wall (diffusion process) collisions. The relaxation transients of the quadrupole orientation are obtained by introducing a first-order weak-pumping approximation (intermediate pumping) less restrictive than the usually considered (zeroth order) one.

  17. Milk Alkali and Hydrochlorothiazide: A Case Report

    Directory of Open Access Journals (Sweden)

    Babar Parvez

    2011-01-01

    Full Text Available Hypercalcemia is a relatively common clinical problem in both outpatient and inpatient settings. Primary pathophysiology is the entry of calcium that exceeds its excretion into urine or deposition in bone into circulation. Among a wide array of causes of hypercalcemia, hyperparathyroidism and malignancy are the most common, accounting for greater than 90 percent of cases. Concordantly, there has been a resurgence of milk-alkali syndrome associated with the ingestion of large amounts of calcium and absorbable alkali, making it the third leading cause of hypercalcemia (Beall and Scofield, 1995 and Picolos et al., 2005. This paper centers on a case of over-the-counter calcium and alkali ingestion for acid reflux leading to milk alkali with concordant use of thiazide diuretic for hypertension.

  18. A discussion on the tectonic implications of Ediacaran late- to post-orogenic A-type granite in the northeastern Arabian Shield, Saudi Arabia

    Science.gov (United States)

    Robinson, F. A.; Bonin, B.; Pease, V.; Anderson, J. L.

    2017-03-01

    The transition from late-orogenic to post-orogenic magmatism following major orogenic episodes such as the Neoproterozoic to Cambrian East African Orogen (EAO) is an important, yet not well-understood geological event marking the cessation of subduction-controlled magmatism between buoyant lithospheric fragments. Forming the northern part of the EAO in the Arabian-Nubian Shield are three granitic suites that successively intruded the same northeastern area and post-date the 640 Ma major orogenic episode: (1) 620-600 Ma alkali feldspar (hypersolvous) granite with alkaline/ferroan/A-type geochemistry, (2) 599 Ma granite cumulates (some garnet-bearing) with calc-alkaline/magnesian affinities, and (3) 584-566 Ma alkali feldspar (hypersolvous) granite (aegirine-bearing) with a distinctive peralkaline/ferroan/A-type signature. Combining whole-rock geochemistry from the southern and northern Arabian Shield, suites 1 and 2 are suggested to be products of late-orogenic slab tear/rollback inducing asthenospheric mantle injection and lower crustal melting/fractionation toward A-type/ferroan geochemistry. Suite 3, however, is suggested to be produced by post-orogenic lithospheric delamination, which replaced the older mantle with new asthenospheric (rare earth element-enriched) mantle that ultimately becomes the thermal boundary layer of the new lithosphere. Major shear zones, such as the 620-540 Ma Najd Fault System (NFS), are some of the last tectonic events recorded across the Arabian Shield. Data presented here suggest that the NFS is directly related to the late-orogenic (620-600 Ma) slab tear/rollback in the northeastern Shield as it met with opposing subduction polarity in the southern Shield. Furthermore, this study infers that east and west Gondwana amalgamation interacted with opposing convergence reflected by the NFS.

  19. Alkali metals and group IIA metals

    International Nuclear Information System (INIS)

    Fenton, D.E.

    1987-01-01

    This chapter on the coordination complexes of the alkali metals of group IIA starts with a historical perspective of their chemistry, from simple monodentate ligands, metal-β-diketonates to the macrocyclic polyethers which act as ligands to the alkali and akaline earth metals. Other macrocyclic ligands include quarterenes, calixarenes, porphyrins, phthalocyanines and chlorophylls. A section on the naturally occurring ionophores and carboxylic ionophores is included. (UK)

  20. Calcium silicate hydrate: Crystallisation and alkali sorption

    International Nuclear Information System (INIS)

    Hong, S.

    2000-01-01

    Homogeneous single C-S-H gels has been prepared for the investigation of alkali binding potential and crystallisation. A distribution coefficient, R d , was introduced to express the partition of alkali between solid and aqueous phases at 25 deg. C. R d is independent of alkali hydroxide concentration and depends only on Ca:Si ratio over wide ranges of alkali concentration. The trend of numerical values of R d indicates that alkali bonding into the solid improves as its Ca:Si ratio decreases. Reversibility is demonstrated, indicating a possibility of constant R d value of the material. Al has been introduced to form C-A-S-H gels and their alkali sorption properties also determined. Al substituted into C-S-H markedly increases R d , indicating enhancement of alkali binding. However, the dependence of R d on alkali concentration is non-ideal with composition. A two-site model for bonding is presented. Crystallisation both under saturated steam and 1 bar vapour pressure has been investigated. It has been shown that heat treatment by saturated steam causes crystallisation of gels. The principal minerals obtained were (i) C-S-H gel and Ca(OH) 2 at -55 deg. C, (ii) 1.1 nm tobermorite, jennite and afwillite at 85 -130 deg. C, and (iii) xonotlite, foshagite and hillebrandite at 150-180 deg. C. Properties of crystalline C-S-H were also reported for reversible phase transformation, pH conditioning ability, seeding effect and solubility. At 1 bar pressure, crystallisation is slower than in saturated steam due to lower water activity. Tobermorite-like nanodomains develop during reaction at low Ca/Si ratios. In some Ca-rich compositions, Ca(OH) 2 is exsolved and occurs as nano-sized crystallites. (author)

  1. The 'Granite' collegial mission of dialogue. Report

    International Nuclear Information System (INIS)

    Boisson, P.; Huet, Ph.; Mingasson, J.

    2000-06-01

    The aim of the 'Granite' collegial mission of dialogue is to inform the French authorities, associations and population about the project of construction of an underground laboratory for the study of the disposal of high level and long-life radioactive wastes in a granitic environment. The aim of the dialogue was not to select a site but to collect the public reactions and advices about such a project. However, such a dialogue has partially failed because of a misunderstanding of the population about the aims of the mission. However, the mission has collected many point of views and questions which are developed in this report. The first and second chapters recall the process of the mission and its progress, while a third chapter stresses on the questions asked by the public and which concern the fear of nuclear wastes and the incompatibility between the disposal of wastes and the socio-economical development of the region concerned. Thanks to the lessons drawn from this experience, the mission has formulated some recommendations (chapter 4) concerning the need for a better information of the population about any topic in relation with the radioactive wastes. Some complementary information is provided in appendixes. (J.S.)

  2. Warren Hunt to test granite well

    International Nuclear Information System (INIS)

    Harvie, W.

    1996-01-01

    Various theories which purport to explain the existence of the Alberta oil sands, were discussed briefly. One theory, held among others by Warren Hunt, speculates that oil is formed deep in the Precambrian basement and not in the higher sedimentary rock. According to this theory, methane in the crust is the abiogenic product that results from hydrogen reacting with silicon carbide in the lower mantle. As it rises through the fractures, it encounters the microbiota, and hydrogen is stripped away making larger molecules until only bitumen remains. Hunt and other adherents of this theory believe that hydrocarbon reservoirs are replenished as oil is produced, hence there is no end to the world's oil supply. This theory is about to be tested by retesting a granite well near Fort McMurray, which was suspended in September 1994, when funding dried up. Kaleeda Enterprises, owners of the well, believe that the well bottom is currently in a granite pool, and oil will be found by deepening the well to 2,150 metres from the current 1,650 metres. While this is not universally accepted, if true, the abiogenic theory would go a long way towards explaining the origin of the oil sands

  3. Aqueous phase transport through granitic rocks

    International Nuclear Information System (INIS)

    Bradbury, M.H.; Green, A.

    1984-03-01

    Using Scottish granites of UK origin it has been established that : (1) pore connectivity exists over metre distances and does not vary significantly with distance. (2) The formation factor may show an increase by a factor of approx. 2 for thin samples (approx. 1 cm). Since diffusion samples are of this order of thickness, laboratory measurements may be overestimating the diffusion coefficient appropriate for use in migration model calculations by a factor of approx. 2. (3) The effect of confining pressures up to approx. 16 MPa is to reduce diffusion coefficients by 50 to 60%. This implies that diffusion coefficients appropriate to granite at depths of approx. 500 m are approximately a factor of two lower than those obtained in the laboratory. (4) Diffusion rates through weathered fissure surfaces can be significantly greater (up to approx. 200 times) than through 'good' rock and are strongly dependent on the severity of the weathering. No evidence for pore blocking by weathering products was found. (5) Latex colloids having a diameter of 0.312 μm neither cause pore blocking nor do they penetrate the pore structure. (author)

  4. Soil Radon In The Nigerian Younger Granites | Dewu | Nigerian ...

    African Journals Online (AJOL)

    ... not had enough time to attain equilibrium with its daughters. In general, the results suggest that with proper control, soil radon measurements over the Younger Granite can be used for uranium exploration in the region. Keywords: Radon, younger granite, soil uranium, half-lifeand thorium. Nigerian Journal of Physics Vol.

  5. Petrogenesis of the postcollisional Middle Devonian monzonitic to granitic magmatism of the Sierra de San Luis, Argentina

    Science.gov (United States)

    López de Luchi, Mónica G.; Siegesmund, Siegfried; Wemmer, Klaus; Nolte, Nicole

    2017-09-01

    Middle Devonian granitoids intruded the Eastern Sierras Pampeanas basement ca. 600 km east of the inferred proto-Pacific margin of Gondwana along which a ca. 390 Ma collisional event developed. In the Sierra de San Luis, voluminous Middle Devonian (393-382 Ma) batholiths are composed of I- to A-type hybrid Monzonite and Granite suites. Shoshonite and subordinated high-K series, stocks, synplutonic dikes and enclaves make up the Monzonite Suite; rocks are metaluminous alkali-calcic magnesian porphyritic or equigranular monzonite, quartz monzonite, monzodiorite and scarce monzogabbro. High-K and subordinated shoshonite series metaluminous to mildly peraluminous magnesian alkali-calcic to calc-alkalic porphyritic or equigranular quartz monzonite, granodiorite, monzogranite and equigranular leucomonzogranites make up the Granite Suite plutons and batholiths. Only a small group of highly evolved granites are ferroan. SiO2 (46-62%), Cr, Ni, V, Sc, LILE, LREE, Th, Zr and variable, Sr/Y, (La/Yb)N and (Tb/Yb)N, smooth Eu/Eu*, moderate Na2O (ca 3.5), and troughs at Nb and Ta for Monzonite Suite rocks suggest an subduction-related enriched lithospheric mantle source. Sm-Nd data (TDM 0.98-1.08 Ga, εNd(380 Ma) 0.66-1.47) and 87Sr/86Sri (0.703520-0.704203) are compatible with an enriched mantle source. The metaluminous porphyritic quartz monzonite-monzogranite and the mildly peraluminous equigranular biotite monzogranites of the Granite Suite are characterized by relatively moderate Al2O3, CaO, and 87Sr/86Sri, high LILE, Cr, variable Sr/Y, (La/Yb)N and Eu/Eu* and low Rb/Sr ( 1.5, ASI 1.05-1.18, and Ga/Al 2.6-3.9, εNd(380 Ma) - 3.74 to - 3.95 and (87Sr/86Sr)i 0.710743-0.712955 which would point to metasedimentary or felsic igneous crustal sources. Nevertheless their TDM 1.36-1.38 Ga is considerably younger than the mean 1.8-1.6 Ga Eastern Sierras Pampeanas crustal residence age and less radiogenic. Middle Devonian magmatism would record an episode of crustal growth by enriched

  6. Adsorption behavior of Am(III) on granite

    International Nuclear Information System (INIS)

    Zhang Yingjie; Feng Xiaogui; Liang Junfu; Chen Jing; Su Rui; Wang Ju; Liu Chunli

    2009-01-01

    The adsorption behavior of Am(III) on granite (sampled from drilling well BS01 at Beishan (BS) area--a potential candidate site for China's high-level radioactive waste repository, the granite sample's depth about 300 m) was studied in BS03 well groundwater by a batch technique at (25±1) degree C. The influences of pH, sulphate ion, total carbonate ion, humic acid, and concentration of the Am(III) on the adsorption behavior were also studied, and the possible adsorption mechanism was discussed. Experimental results show that the adsorption distribution rate of Am(III) on granite increases with increasing pH of aqueous phase. The chemical composition of the groundwater is the main factor which influences the species of Am(III) and adsorption behavior. The adsorption mechanism of Am(III) on granite is surface complexation. The adsorption isotherm of Am(III) on granite can be described by Freundlich's equation. (authors)

  7. Studies on the alkali-silica reaction rim in a simplified calcium-alkali-silicate system

    NARCIS (Netherlands)

    Zheng, Kunpeng; Adriaensens, Peter; De Schutter, Geert; Ye, G.; Taerwe, Luc

    2016-01-01

    This work is intended to provide a better understanding about the properties and roles of the reaction rim in an alkali-silica reaction. A simplified calcium-alkali-silicate system was created to simulate the multiple interactions among reactive silica, alkaline solution and portlandite near the

  8. Chemical characteristics of zircon from A-type granites and comparison to zircon of S-type granites

    Czech Academy of Sciences Publication Activity Database

    Breiter, Karel; Lamarão, C. N.; Krás Borges, R. M.; Dall'Agnol, R.

    1192/195, April (2014), s. 208-225 ISSN 0024-4937 Institutional support: RVO:67985831 Keywords : zircon * A-type granites * S-type granites * Wiborg batholith * Brazil * Krušné hory/Erzgebirge Subject RIV: DD - Geochemistry Impact factor: 4.482, year: 2014

  9. Alkali metal and alkali metal hydroxide intercalates of the layered transition metal disulfides

    International Nuclear Information System (INIS)

    Kanzaki, Y.; Konuma, M.; Matsumoto, O.

    1981-01-01

    The intercalation reaction of some layered transition metal disulfides with alkali metals, alkali metal hydroxides, and tetraalkylammonium hydroxides were investigated. The alkali metal intercalates were prepared in the respective metal-hexamethylphosphoric triamide solutions in vaccuo, and the hydroxide intercalates in aqueous hydroxide solutions. According to the intercalation reaction, the c-lattice parameter was increased, and the increase indicated the expansion of the interlayer distance. In the case of alkali metal intercalates, the expansion of the interlayer distance increased continuously, corresponding to the atomic radius of the alkali metal. On the other hand, the hydroxide intercalates showed discrete expansion corresponding to the effective ionic radius of the intercalated cation. All intercalates of TaS 2 amd NbS 2 were superconductors. The expansion of the interlayer distance tended to increase the superconducting transition temperature in the intercalates of TaS 2 and vice versa in those of NbS 2 . (orig.)

  10. Questioning the Sedimentary Paradigm for Granites

    Science.gov (United States)

    Glazner, A. F.; Bartley, J. M.; Coleman, D. S.; Boudreau, A.; Walker, J. D.

    2007-12-01

    A critical question regarding volcano-pluton links is whether plutons are samples of magma that passed through on its way to eruption, or residues left behind after volcanic rocks were extracted. A persistent theme of recent work on granites sensu lato is that many are sedimentary accumulations of crystals that lost significant volumes of magmatic liquid. This view is based on observations of structures that clearly seem to reflect deposition on a magma chamber floor (e.g., flows of chilled mafic magma into silicic magma) and on the inference that many other structures, such as modal layering, truncated layering, and crystal accumulations, reflect crystal sedimentation on such chamber floors. There are significant physical and geochemical reasons to question this view, based on observations in the Sierra Nevada of California and similar results from other batholiths. First, few granites show the enrichments in Ba, Sr, and relative Eu that feldspar accumulation should produce. Second, sedimentary features such as graded bedding and cross-bedding form in highly turbulent flows, but turbulence is unachievable in viscous silicic liquids, where velocities on the order of 104 m/s would be required to induce turbulence in a liquid with η=104 Pa s. Third, tabular modally layered domains commonly cut surrounding modal layering on both sides, and orientations of modal layering and of the troughs of "ladder dikes" commonly scatter widely within hectare-sized areas; it is difficult to reconcile these features with gravity-driven settling. Fourth, accumulations of K-feldspar megacrysts are typically inferred to be depositional, but this is precluded by crystallization of most K- feldspar after rheologic lock-up occurs. Finally, accumulations of K-feldspar and hornblende are typically packed too tightly to be depositional. With analogy to layered mafic intrusions, many features attributed to crystal sedimentation in granites may be better explained by crystal aging and other in

  11. Total exploitation of an ornamental granite quarry

    Directory of Open Access Journals (Sweden)

    Taboada, J.

    2005-09-01

    Full Text Available In this paper we propose a methodology to estimate the recovery percentage for each of the products which can be obtained from the exploitation of an ornamental granite quarry: block, semiblock, masonry-transverse stone, and the smaller materials that can be used to obtain construction aggregates. This methodology ensures that quarry exploitation is exhaustive, thereby minimising the production of spoils and the consequent negative impact on the environment. The analysis is based on a detailed and exhaustive compilation of discontinuity data from the research fronts, which are then interpreted statistically and projected over the three weakness planes that are a particular feature of ornamental granite deposits. Using this information, and bearing in mind the minimum commercially viable sizes for each kind of granite, the corresponding recovery rates are calculated for each material in each plane. The results are then integrated using spatial techniques, and the result is an evaluation of quarry contents with a view to total exploitation. This methodology was applied to a quarry in the opening phase in order to carry out an a priori assessment of the economic feasibility of the quarry.

    En este trabajo se propone una metodología para estimar el porcentaje de recuperación de cada uno de los productos que se pueden obtener en la explotación de una cantera de granito ornamental: bloque, semibloque, manpostería y per piaños, y material restante destinado a la obtención de áridos. De esta manera se logra un aprovechamiento integral de la cantera, evitándose la generación de estériles y el subsiguiente impacto ambiental producido por éstos. La metodología de análisis se basa en la recopilación detallada y exhaustiva de datos de discontinuidades en los frentes de investigación, que se interpretan estadísticamente y se proyectan sobre los tres planos de debilidad propios del granito ornamental. Con esta información, y las

  12. Globalisation, Higher Education and Pan-Africanism: A Critical Compromise.

    Science.gov (United States)

    Sylvester, Meagan A.

    This paper discusses the relationship between globalization and higher education by highlighting the changes and challenges that beset institutions of higher learning within the new globalizing economy. There are two overarching conditions that are transforming the structures and practices of higher education: (1) globalization; and (2) the…

  13. Pan-Africanism: Beyond survival to renaissance | mama | New ...

    African Journals Online (AJOL)

    New Agenda: South African Journal of Social and Economic Policy. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 53 (2014) >. Log in or Register to get access to full text downloads.

  14. Educational Adaptation and Pan-Africanism: Trends in Africa.

    Science.gov (United States)

    Marah, John Karefah

    1987-01-01

    European colonialists believed that Africans should be educated in African traditional values, and that Africans should be made into dedicated workers, not holders of power. The African nationalists of the 1960s, in contrast, rejected most of the arduous aspects of European education as instruments of domination, and lay the foundation for the…

  15. Pan African Medical Journal - Vol 28, No 1 (2017)

    African Journals Online (AJOL)

    Intérêt de la TEP-TDM dans le cancer broncho-pulmonaire primitif non à petite ..... of Nigerian children: effects of socio-economic, nutritional and housing factors ... among antenatal attendees at health facilities in West Pokot county, Kenya ...

  16. Pan African Medical Journal - Vol 10, No 1 (2011)

    African Journals Online (AJOL)

    Gervais Ondobo Andze, Abel Namsenmo, Benoit Kebella Illunga, Ditu Kazambu, Dieula Delissaint, Christopher Kuaban, Francois-Xavier Mbopi-Kéou, Wilfred Gabsa, Leopold Mulumba, Jean Pierre ... Raymond Tweheyo, Christine Nalwadda, Nicholas Ayebazibwe, David Mukanga, Elizeus Rutebemberwa, William Bazeyo ...

  17. Bruns Syndrome: a deadly sign | Oudrhiri | Pan African Medical ...

    African Journals Online (AJOL)

    A 52 years old man was admitted to the intensive care unit for a sudden onset coma. His Glasgow Coma Scale was 4/15 with fixed dilated pupils. He has been experiencing paroxystic episodes of headaches, vomiting and vertigo for 6 months that went undiagnosed.Diagnoses include acute hydrocephalous, syncopes, and ...

  18. Pan African Medical Journal - Vol 5, No 1 (2010)

    African Journals Online (AJOL)

    Specialty preferences among medical students in a Kenyan university · EMAIL FREE ... Current knowledge, attitudes and practices of women on breast cancer and ... Knowledge and practice of prevention of mother-to-child transmission of HIV ...

  19. Aquifers productivity in the Pan-African context

    Indian Academy of Sciences (India)

    , including 14 near existing boreholes for comparison. Aquifer parameters of hydraulic conductivity and transmissivity were obtained by analyzing pumping test data from existing boreholes. An empirical relationship between hydraulic ...

  20. Harlequin color change in preterm infant | Hamida | Pan African ...

    African Journals Online (AJOL)

    Harlequin phenomenon is a rare event that consists of sudden and transient episodes of demarcated erythema forming on the dependent half of the body of newborns, with pallor of the uppermost half. The infant appears as if a line was drawn on the midline dividing two hemibodies. It occurs preferentially in lateral position.

  1. Pan African Medical Journal - Vol 12, No 1 (2012)

    African Journals Online (AJOL)

    Health insurance education strategies for increasing the insured among older .... Gestational thrombocytopenia among pregnant Ghanaian women · EMAIL FREE FULL ... Dental caries and oral health practices among 12 year old children in ...

  2. Pan-African - Mediterranean Migrations: Implications for Education and Society

    Science.gov (United States)

    Napier, Diane Brook

    2011-01-01

    The purpose of this study was to examine features of the contemporary migrant and refugee flows across Africa northward to the Mediterranean and then to European countries (sometimes called the "new mass migration" and also migrant flows southward to South Africa. In addition, the purpose was to examine dimensions of response and…

  3. Pan African Medical Journal - Vol 25, No 1 (2016)

    African Journals Online (AJOL)

    Hémodialyse chronique et dépression au Centre Hospitalier Universitaire Sylvanus Olympio de Lomé (Togo). Mawufemo Yawovi Tsevi, Saliou Salifou, Akomola Kossi Sabi .... Complication inhabituelle de la radiothérapie: la perforation cornéenne: à propos d'un cas. Taha Elghazi, Youssef Omor, Zouheir Hafidi, Amine Eljai, ...

  4. Pan African Medical Journal - Vol 14, No 1 (2013)

    African Journals Online (AJOL)

    Multisegmental tubercular spinal epidural abscess · EMAIL FREE FULL TEXT EMAIL ... Factors associated with severe occupational injuries at mining company in .... Risk factors of falls among elderly living in Urban Suez - Egypt · EMAIL FREE ... Unusual case of cavitary lung metastasis from squamous cell carcinoma of the ...

  5. Pan African Medical Journal - Vol 9, No 1 (2011)

    African Journals Online (AJOL)

    Giant aneurysm of the right intra thoracic sub-clavian artery presenting as a dysphonia · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. A Mechchat, MM El Hammoumi, A EL Mesnaoui, B Lekehal, Y Bensaid. http://dx.doi.org/10.4314/pamj.v9i1.71217 ...

  6. Pan African Medical Journal - Vol 17, No 1 (2014)

    African Journals Online (AJOL)

    ... lesions in a group of sub-Saharan African patients on maintenance hemodialysis ... Perceived barriers to the implementation of Isoniazid preventive therapy for ... Adherence to antiepileptic drugs among children attending a tertiary health ...

  7. Pan African Medical Journal - Vol 18, No 1 (2014)

    African Journals Online (AJOL)

    oriental du Maroc · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. Noufissa Benajiba, Yousra EL Boussaadni, Mohammed Aljabri, Yassamine Bentata, Rim Amrani, Maria Rkain ...

  8. Pan African Medical Journal - Vol 22, No 1 (2015)

    African Journals Online (AJOL)

    Tumeur pseudopapillaire et solide du pancréas: une cause rare de masse abdominale ... Nontyphoidal Salmonella Septic arthritis of the elbow in a healthy infant ...... Hypoglycemia revealing arachnoidocele in infant · EMAIL FREE FULL TEXT ...

  9. Stroke in young adults: about 128 cases | Chraa | Pan African ...

    African Journals Online (AJOL)

    Ischemic stroke is rare in young adults, but it is genuinely a serious situation giving the fact that it touch a very active part of our society. We report a series of 128 cases. The purpose is to analyze the risk factors, etiologies and outcomes of ischemic stroke in young adults in Marrakesh. Retrospective study performed at the ...

  10. Pan African Medical Journal - Vol 24, No 1 (2016)

    African Journals Online (AJOL)

    Central nervous system tumours in children in Ibadan, Nigeria: a ...... Strong family history and early onset of schizophrenia: about 2 families in Northern Nigeria ... Misplaced left internal jugular venous catheter with an exceptional location ...

  11. Enchondroma of the scaphoid: a case report | Ali | Pan African ...

    African Journals Online (AJOL)

    Enchondroma represents a common bone tumor of the hand. The scaphoid is a rare location. We report the case of a scaphoid enchondroma presenting as chronic wrist pain following a relatively minor trauma. The diagnosis was suggested by radiological study and then confirmed by histological study after biopsy.

  12. Pan African Medical Journal - Vol 23, No 1 (2016)

    African Journals Online (AJOL)

    Perceptions and uptake of health insurance for maternal care in rural Kenya: a .... Knowledge and awareness of medical doctors, medical students and nurses ..... Upper extremity deep vein thrombosis after elbow trauma: a case report of a ...

  13. Natural wetland in China | Pan | African Journal of Environmental ...

    African Journals Online (AJOL)

    As it is known to all, wetland is one of the most crucial ecosystems in the world, with large varieties in China. How to protect wetland in China has become a more serious problem and five typical wetlands were selected in the article to illustrate the condition. Through the comparison between the past and present of wetland, ...

  14. Changes in platelet parameters in leukocytosis | Ozturk | Pan African ...

    African Journals Online (AJOL)

    Methods: white blood cell counts count and all platelet parameters were evaluated in 341 results of normal complete blood count (of which the white blood cell counts were within reference range, ... Results: there was a significant difference between these two groups in PLT counts and PCT values, being higher in Group 2.

  15. Prostatic fossa calculus | El Abiad | Pan African Medical Journal

    African Journals Online (AJOL)

    As part of the evaluation, a plain radiograph was performed and incidentally showed a radiopaque prostatic calculus (Red arrows). A retrograde urethrocystography, performed after a 10-days course of antibiotics, confirmed the presence of an approximately 35 mm non-obstructive calculus occupying almost the whole ...

  16. Fibroadenoma in women in Ghana | Bewtra | Pan African Medical ...

    African Journals Online (AJOL)

    Background: Fibroadenoma is the commonest benign tumor of female breast. It is particularly common in young women in Africa. Method: This paper describes the clinicopathologic features of fibroadenoma of breast in African women from central Ghana and compares them to the data from African-American women.

  17. Malignant skin lesions in Oshogbo, Nigeria | Oseni | Pan African ...

    African Journals Online (AJOL)

    Results: ninety- eight patients presented with skin cancers out of which 60 ... Malignant melanoma affects male more than female and it commonly affects lower ... Conclusion: skin malignancies pose a burden to the economy of the country.

  18. Pan African Medical Journal - Vol 21, No 1 (2015)

    African Journals Online (AJOL)

    De novo autoimmune hepatitis following liver transplantation for primary biliary cirrhosis: an unusual cause of late grafts dysfunction · EMAIL FREE FULL TEXT EMAIL .... Prevalence and predictors of sub-optimal medication adherence among patients with severe mental illnesses in a tertiary psychiatric facility in Maiduguri, ...

  19. Cutaneous metastasis reveling lung cancer | Elfatoiki | Pan African ...

    African Journals Online (AJOL)

    Cutaneous metastasis reveling lung cancer. FZ Elfatoiki, F Hali. Abstract. No Abstract. Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT · AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about ...

  20. Vaginal metastasis of pancreatic cancer | Benhayoune | Pan African ...

    African Journals Online (AJOL)

    Vaginal metastasis from pancreatic cancer is an extreme case and often indicates a poor prognosis. We present a case of pancreatic carcinoma with metastasis to the vagina that was discovered by vaginal bleeding. To our knowledge, this is the third case in the world of a primary pancreatic adenocarcinoma discovered of ...

  1. Blueberry muffin syndrome | Benmiloud | Pan African Medical Journal

    African Journals Online (AJOL)

    Le Blueberry Muffin Baby est un syndrome cutané rare observé en période néonatale. Il est caractérisé par des papulo-nodules disséminés inflammatoires traduisant des réactions d'hématopoïèse dermique. Plusieurs causes doivent être recherchées, notamment les infections congénitales, une hémolyse sévère et les ...

  2. Un cas de trichobezoard gastrique | Moujahid | Pan African Medical ...

    African Journals Online (AJOL)

    Le trichobézoard est défini par la présence d'un corps étranger intra gastrique formé par des cheveux ou des fibres textiles. C'est une pathologie rare qui survient habituellement chez des adolescents présentant des troubles psychiques. La symptomatologie clinique est très variée et le diagnostic est souvent suspecté à la ...

  3. Morphea on the breast and pregnancy | Benchat | Pan African ...

    African Journals Online (AJOL)

    If you would like more information about how to print, save, and work with PDFs, Highwire Press provides a helpful Frequently Asked Questions about PDFs. Alternatively, you can download the PDF file directly to your computer, from where it can be opened using a PDF reader. To download the PDF, click the Download link ...

  4. Diet and non-Hodgkin's lymphoma risk | Mozaheb | Pan African ...

    African Journals Online (AJOL)

    Background: The role of dietary factors in the epidemiology of Non-Hodgkin's lymphoma (NHL) remains largely undefined. Dietary habits may play a role in the etiology of NHL by influencing the immune system. Methods: Dietary patterns and the risk of NHL were analyzed in a case control study; including 170 NHL cases ...

  5. Pan African Medical Journal - Vol 13, No 1 (2012)

    African Journals Online (AJOL)

    Effect of intervention on the control of Highly Pathogenic Avian Influenza in Nigeria ... Knowledge, attitude and practice of prophylactic mastectomy among patients ... Comparative regional morphometric changes in human uterine artery before ...

  6. Artemisia absinthium: burning plant! | El Makrini | Pan African ...

    African Journals Online (AJOL)

    Absinthe is gently used in herbal medicine for her virtues tonic , antispasmodic, antipyretic, anthelmintic, stimulating ...However, this plant may contain toxic agents (such as thujone, malic acid, alcohol ...) responsible for adverse reactions. In our case, use for cosmetic purposes has caused redness and sensitivity of the face, ...

  7. Pan African Medical Journal - Vol 11, No 1 (2012)

    African Journals Online (AJOL)

    Physical activity and cardiovascular disease risk factors among young and .... A pharmacovigilance study of adults on highly active antiretroviral therapy, South .... with cutaneous psoriasis as the presenting feature of coeliac disease: A case ...

  8. Cerebral tuberculoma: an entity not to ignore | Frioui | Pan African ...

    African Journals Online (AJOL)

    Symptoms and radiologic features are nonspecific, leading sometimes to misdiagnosis. We report the case of a 60-year-old male, with a history of diffuse bilateral infiltrative pulmonary disease at the stage of fibrosis, he made two generalized seizures associated with occipital headaches. CT scan showed a left frontal tumor, ...

  9. Le syndrome de Heerfordt | Hammoune | Pan African Medical Journal

    African Journals Online (AJOL)

    La sarcoïdose est une granulomatose systémique de cause inconnue, caractérisée par son polymorphisme clinique et une grande variété de ses modes de présentation. L'association de fièvre, d'uvéite, de parotidite et d'une paralysie faciale périphérique réalise le syndrome de Heerfordt qui présente une manifestation ...

  10. Jomo Kenyatta: An Epitome of Indigenous Pan-Africanism ...

    African Journals Online (AJOL)

    ... and political and economic co-operation that would lead to the political unity of Africa. ... It is the outstanding African scholars, political scientists, historians and ... the inter-related issues of power, identity politics, self-assertion and autonomy ...

  11. Butterfly hematoma after traumatic intercourse | Hajji | Pan African ...

    African Journals Online (AJOL)

    Butterfly hematoma after traumatic intercourse. F Hajji, A Ameur. Abstract. No Abstract. http://dx.doi.org/10.11604/pamj.2015.20.317.6660 · AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use · Contact ...

  12. Oral lichenoid reaction to tobacco | Panta | Pan African Medical ...

    African Journals Online (AJOL)

    A differential diagnosis of lichen planus, oral lichenoid reaction and discoid lupus erythematosis were considered. On microscopic examination, there was focal perivascular infiltrate and plasma cells in the connective tissue. After correlating clinically, a diagnosis of "lichenoid reaction" was confirmed. Oral lichenoid ...

  13. Pan African Medical Journal - Vol 20, No 1 (2015)

    African Journals Online (AJOL)

    Syndrome de Gougerot-Sjögren primitif du sujet âgé: Caractéristiques cliniques ... Secondary peritoneal hydatidosis, the challenges of echinococcal disease in South ... Prevention of mother-to-child transmission of the Human Immunodeficiency ..... Health-care seeking behaviour and the use of traditional medicine among ...

  14. Images of bronchiectasis in thoracic surgery | Ayegnon | Pan African ...

    African Journals Online (AJOL)

    The bronchial dilations also called bronchiectasis are permanent and irreversible increase in the bronchial tubes. They can be extended or localized especially in pulmonary tuberculosis sequelae. This affection is serious, because it is at the origin of an embarrassing obstructive pulmonary disease, leading to social ...

  15. Amputation des quatre members | Feruzi | Pan African Medical Journal

    African Journals Online (AJOL)

    , Mireille Kakinga Zabibu, Jules Panda Mulefu, Francois Tshilombo Katombe. Abstract. Les auteurs présentent les cas d'amputation des quatre membres réalisée chez trois patients différents. Ce sont des amputations réalisées pour chaque ...

  16. Une dermatophytie en "rosette" | Bounniyt | Pan African Medical ...

    African Journals Online (AJOL)

    Moreover skin appendage examination showed alopecia of the scalp(C) with shaved head. According to child's mom this condition had started one year before and evolved since then. Skin lesions primarily evoked dermatitis herpetiformis, but the presence of patchy alopecia and the wish to avoid skin biopsy, which would ...

  17. The Oldest Granites of Russia: Paleoarchean (3343 Ma) Subalkali Granites of the Okhotsk Massif

    Science.gov (United States)

    Kuzmin, V. K.; Bogomolov, E. S.; Glebovitskii, V. A.; Rodionov, N. V.

    2018-02-01

    The Paleoarchean age (3.34 Ga) of subalkali granite magmatism first established for the Kukhtui uplift of the Okhotsk Massif suggests a formation time of the mature continental K-rich crust in this region as early as the Paleoarchean. According to the geological structural, mineralogical-geochemical, geochronological, and isotopic-geochemical data, the Kukhtui uplift can be considered as the most ancient Paleoarchean province in Russia: the ancient consolidation core of the sialic protocrust of the Okhotsk-Omolon Craton.

  18. Alkaline lixiviation of uranium in granitic pegmatite

    International Nuclear Information System (INIS)

    Jambor, S.

    1980-06-01

    The work described herein concerns the determination of the experimental optimum conditions for the alkaline lixiviation of uranium based on the following parameters: time, pH, temperature, density and grane size. The samples were obtained from the Supamo complex, near the Currupia river in the Piar District of the Bolivar State in Venezuela. They have a granitic composition and graphitic texture. The uranium was found in them as a secondary oxidized mineral of green-yellow colour localized in fractures fissures, intergranular spaces and also in the mica as. Secondary uranitite. The lixiviation process was carried out using Na 2 CO 3 /NaHCO 3 buffer solution and for 100 gr. samples the best values for an efficient process were found by using 170 mesh grane size and 500 ml of pH buffer at 70 0 C for a 24 hour time period. (author)

  19. Sorption of actinides in granitic rock

    International Nuclear Information System (INIS)

    Allard, B

    1982-11-01

    The sorption of americium (III), neptunium(V) and plutonium on geologic media under oxic conditions has been measured by a batch technique. The aqueous phase was a synthetic groundwater or 4M NaCl solution. The solid phase was a pure mineral, representative of igneous rocks, or granite. Altogether 40 different minerals and rocks were used. The effects of pH and the ionic strength of the aqueous phase as well as of the cation exchange capacity and the surface/mass ratio of the solid sorbent are discussed. Empirical equations giving the distribution coefficient as a function of pH in the environmental pH-range 7-9 are suggested. Some observations and conclusions concerning sorption mechanisms are given. (author)

  20. Example of fracture characterization in granitic rock

    International Nuclear Information System (INIS)

    Thorpe, R.K.

    1981-03-01

    A detailed study of geologic discontinuities for an underground heater test in highly fractured granitic rock is reported. Several prominent shear fractures were delineated within a 6 x 30 x 15 m rock mass by correlating surface mapping and borehole fracture logs. Oblique-reverse faulting is suspected on at least one of the surfaces, and its inferred borehole intercepts appear to be collinear in the direction of slickensiding observed in the field. Four distinct joint sets were identified, one of which coincides with the shear fractures. Another lies nearly horizontal, and two others are steeply inclined and orthogonal. Fracture lengths and spacings for the four joint sets are represented by lognormal probability distributions

  1. Paleo-redox boundaries in fractured granite

    DEFF Research Database (Denmark)

    Dideriksen, K.; Christiansen, B. C.; Frandsen, Cathrine

    2010-01-01

    dissolved iron to the groundwater. During such cycling, the Fe isotopes fractionate to an extent that is expected to depend on temperature. In this study, we report on the use of Fe-oxides as paleoredox indicators, using their structure, morphology and Fe-composition as a clue for formation conditions....... In samples taken from similar to 120 m drill cores in granite from SE Sweden, X-ray amorphous, superparamagnetic, nanometre-sized Fe-oxides are confined to fractures of the upper,-,50 m, whereas well-crystalline Fe-oxides, with particle sizes typical for soils, occur down to similar to 110 m. We also...... identified hematite with a particle size of 100 nm, similar to hematite of hydrothermal origin. The Fe isotope composition of the fine-grained Fe-oxides (-1 parts per thousand

  2. Radionuclide sorption on granitic drill core material

    International Nuclear Information System (INIS)

    Eriksen, T.E.; Locklund, B.

    1987-11-01

    Distribution ratios were determined for Sr-85, Cs-134 and Eu-152 on crushed granite and fissure coating/filling material from Stripa mines. Measurements were also carried out on intact fissure surfaces. The experimental data for Sr-85, Cs-134 on crushed material can be accomodated by a sorption model based on the assumption that the crushed material consists of porous spheres with outer and inner surfaces available for sorption. In the case of Eu-152 only sorption on the outer surfaces of the crushed material was observed. The absence of sorption on inner surfaces is most probably due to high depletion of the more strongly sorbed Eu-152 in the water phase and very low diffusivity of Eu-152 in the sorbed state. (orig./HP)

  3. Distribution of radioactive minerals in a granite

    Energy Technology Data Exchange (ETDEWEB)

    Coppens, R

    1949-04-04

    The study, by means of a photographic plate, of the radioactivity of a Brittany granite, both of a pulverized sample and of a polished sample, has resulted in a complete determination of the radioactivity present. The ratio of the concentration of Th to that of U i.e., C/sub Th/C/sub U/, was determined as approximately 2.8 using the relationship between the concentration of these elements and the number of ..beta.. particles in a particular range which were detected. Using this ratio and measuring the average number of ..cap alpha.. particles emitted/cm/sup 2//sec, the average activities were found to correspond to concentrations of the order of 10/sup -5/ of both metals. The lack of uniformity in the distribution of the radioactivity within the crystal is noted.

  4. Granitic rocks from the southern Gyeongsang basin, southeastern Korea, (1)

    International Nuclear Information System (INIS)

    Lee, Yoon-Jong

    1980-01-01

    In southern Gyeongsang basin, southeastern Korea, there are many granitic rock masses. They were divided into 7 groups according to their geological evidences. K-Ar age was determined on 36 samples obtained from the respective groups. Group A: pre-Gyeongsang granitic rock (Pre-Cretaceous), A 1 220 m.y., A 2 166 m.y.; group B: outer zone granitic rock (Cretaceous), 115-72 m.y.; group C: ditto (ditto), 97-70 m.y.; group D: ditto (ditto), 89-68 m.y.; group E: ditto (ditto), 82-68 m.y.; group F: inner zone granitic rock (Cretaceous), 75-74 m.y.; group G: Tertiary granitic rock, 63-41 m.y. The large part of the Cretaceous granitic masses show the double elongated ring form. Most of the Tertiary granitic rocks were probably emplaced in close relation with the Eonyang fault line and Ulsan fault line/or their extension line of the area. (J.P.N.)

  5. Muonium centers in the alkali halides

    International Nuclear Information System (INIS)

    Baumeler, H.; Kiefl, R.F.; Keller, H.; Kuendig, W.; Odermatt, W.; Patterson, B.D.; Schneider, J.W.; Savic, I.M.

    1986-01-01

    Muonium centers (Mu) in single crystals and powdered alkali halides have been studied using the high-timing-resolution transverse field μSR technique. Mu has been observed and its hyperfine parameter (HF) determined in every alkali halide. For the rocksalt alkali halides, the HF parameter A μ shows a systematic dependence on the host lattice constant. A comparison of the Mu HF parameter with hydrogen ESR data suggests that the Mu center is the muonic analogue of the interstitial hydrogen H i 0 -center. The rate of Mu diffusion can be deduced from the motional narrowing of the nuclear hyperfine interaction. KBr shows two different Mu states, a low-temperature Mu I -state and a high-temperature Mu II -state. (orig.)

  6. The source rock characters of U-rich granite

    Energy Technology Data Exchange (ETDEWEB)

    Mingyue, Feng; Debao, He [CNNC Key Laboratory of Uranium Resources Exploration and Evaluation Technology, Beijing Research Institute of Uranium Geology (China)

    2012-03-15

    This paper discusses the stratum composition, lithological association, uranium content of crust and the activation, migration, concentration of uranium at each tectonic cycle in South China. The authors point out that the source rock of U-rich granite is U-rich continental crust which is rich in Si, Al and K. The lithological association is mainly composed of terrestrial clastic rocks formation of mudstone and sandstone, mingled with intermediate-acidic, mafic pyroclastic rocks and carbonate rocks formation. During tectonic movements, the rocks had undergone regional metamorphism, migmatitization, granitization, and formed U-rich granites finally. (authors)

  7. The source rock characters of U-rich granite

    International Nuclear Information System (INIS)

    Feng Mingyue; He Debao

    2012-01-01

    This paper discusses the stratum composition, lithological association, uranium content of crust and the activation, migration, concentration of uranium at each tectonic cycle in South China. The authors point out that the source rock of U-rich granite is U-rich continental crust which is rich in Si, Al and K. The lithological association is mainly composed of terrestrial clastic rocks formation of mudstone and sandstone, mingled with intermediate-acidic, mafic pyroclastic rocks and carbonate rocks formation. During tectonic movements, the rocks had undergone regional metamorphism, migmatitization, granitization, and formed U-rich granites finally. (authors)

  8. Design of a dosimetric evaluation protocol workers granite quarries

    International Nuclear Information System (INIS)

    Guillen, J.; Tejado, J. J.; Baeza, A.

    2011-01-01

    The Autonomous Community of Extremadura is one of the major regions of Spain as far as the extraction of granite and further processing of products derived from it are concerned. One of the most industrialized areas of the sector presents a serious problem for non-radiological occupational health of workers, particularly silicosis. Since in this area of activity levels of granites can be classified as medium-high within the precipitates ranges, the question is whether in addition to this occupational disease, there is a radiological impact associated with the activity NORM extraction and manufacturing of granite.

  9. 2005 dossier: granite. Tome: phenomenological evolution of the geologic disposal; Dossier 2005: Granite. Tome evolution phenomenologique du stockage geologique

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    This document makes a status of the researches carried out by the French national agency of radioactive wastes (ANDRA) about the phenomenological aspects of the geologic disposal of high-level and long-lived radioactive wastes (HLLL) in granite formations. Content: 1 - introduction: ANDRA's research program on disposal in granitic formation; 2 - the granitic environment: geologic history, French granites; 3 - HLLL wastes and disposal design concepts; 4 - identification, characterization and modeling of a granitic site: approach, geologic modeling, hydrologic and hydro-geochemical modeling, geomechanical and thermal modeling, long-term geologic evolution of a site; 5 - phenomenological evolution of a disposal: main aspects of the evolution of a repository with time, disposal infrastructures, B-type wastes disposal area, C-type wastes disposal area; spent fuels disposal area, radionuclides transfer and retention in the granitic environment; 6 - conclusions: available knowledge, methods and tools for the understanding and modeling of the phenomenological evolution of a granitic disposal site. (J.S.)

  10. A procedure for preparing alkali metal hydrides

    International Nuclear Information System (INIS)

    Lemieux, R.U.; Sanford, C.E.; Prescott, J.F.

    1976-01-01

    A plain low cost, procedure for the continuous, low temperature preparation of sodium or potassium hydrides using cheap reagents is presented. Said invention is especially concerned with a process of purifying of a catalytic exchange liquid used for deuterium enrichment, in which an alkali metal hydride is produced as intermediate product. The procedure for producing the sodium and potassium hydrides consists in causing high pressure hydrogen to be absorbed by a mixture of at least a lower monoalkylamine and an alkylamide of an alkali metal from at least one of said amines [fr

  11. Salts of alkali metal anions and process of preparing same

    Science.gov (United States)

    Dye, James L.; Ceraso, Joseph M.; Tehan, Frederick J.; Lok, Mei Tak

    1978-01-01

    Compounds of alkali metal anion salts of alkali metal cations in bicyclic polyoxadiamines are disclosed. The salts are prepared by contacting an excess of alkali metal with an alkali metal dissolving solution consisting of a bicyclic polyoxadiamine in a suitable solvent, and recovered by precipitation. The salts have a gold-color crystalline appearance and are stable in a vacuum at -10.degree. C. and below.

  12. 40 CFR 721.4740 - Alkali metal nitrites.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkali metal nitrites. 721.4740... Substances § 721.4740 Alkali metal nitrites. (a) Chemical substances and significant new use subject to reporting. (1) The category of chemical substances which are nitrites of the alkali metals (Group IA in the...

  13. 40 CFR 721.5278 - Substituted naphthalenesulfonic acid, alkali salt.

    Science.gov (United States)

    2010-07-01

    ..., alkali salt. 721.5278 Section 721.5278 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.5278 Substituted naphthalenesulfonic acid, alkali salt. (a) Chemical... as a substituted naphthalenesulfonic acid, alkali salt (PMN P-95-85) is subject to reporting under...

  14. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for the...

  15. 40 CFR 721.8900 - Substituted halogenated pyridinol, alkali salt.

    Science.gov (United States)

    2010-07-01

    ..., alkali salt. 721.8900 Section 721.8900 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.8900 Substituted halogenated pyridinol, alkali salt. (a) Chemical... as substituted halogenated pyridinols, alkali salts (PMNs P-88-1271 and P-88-1272) are subject to...

  16. Tectonic imprints within a granite exposed near Srinagar, Rajasthan ...

    Indian Academy of Sciences (India)

    Partial melting in the middle to lower crustal level produces melts of granitic composition ..... of D1G generations with a steep easterly dipping limb and gently westerly ..... The great circles represent the average fracture orientation for each set.

  17. On the sources of uranium in some Scottish Caledonian granites

    International Nuclear Information System (INIS)

    Halliday, A.N.

    1982-01-01

    The lead isotope systematics, zircon uranium concentrations and whole-rock rubidium concentrations of 11 Scottish Caledonian granites are examined for clues to the origin of their uranium. A positive correlation between U in zircon and initial lead isotope ratios suggests that U and Pb were derived from the same source which, as some of these granites contain their U in inherited zircons, is likely to have been within the crust. It is argued, therefore, that most of the uranium in these granites had a crustal derivation but lead isotope ratios indicate that any Lewisian contribution was minor in comparison with those from postulated Grenville, Morarian or Caledonian metamorphic reservoirs. However, additional data are required before this conclusion can be extended to include uraniferous Caledonian granites such as Cairngorm. (author)

  18. Characteristics of pegmatoidal granite exposed near Bayalan, Ajmer ...

    Indian Academy of Sciences (India)

    near Bayalan, Ajmer district, Rajasthan. Nilanjan ... eastern flank of the South Delhi Fold Belt (Sinha. Roy 1984 .... gneisses in a lit-par-lit manner producing alternate layers of granite and ... shows a point concentration (table 1) with a mean.

  19. Mechanical properties of granitic rocks from Gideaa, Sweden

    International Nuclear Information System (INIS)

    Ljunggren, C.; Stephansson, O.; Alm, O.; Hakami, H.; Mattila, U.

    1985-10-01

    The elastic and mechanical properties were determined for two rock types from the Gideaa study area. Gideaa is located approximately 30 km north-east of Oernskoeldsvik, Northern Sweden. The rock types that were tested were migmatitic gneiss and migmatitic granite. The following tests were conducted: - sound velocity measurements; - uniaxial compression tests with acoustic emission recording; - brazilian disc tests; - triaxial tests; - three point bending tests. All together, 12 rock samples were tested with each test method. Six samples of these were migmatic gneiss and six samples were migmatitic granite. The result shows that the migmatitic gneiss has varying strength properties with low compressive strength in comparison with its high tensile strength. The migmatitic granite, on the other hand, is found to have parameter values similar to other granitic rocks. With 15 refs. (Author)

  20. Shoshonitic intrusion magmatism in Pajeu-Paraiba belt: the Bom Jardim complex

    International Nuclear Information System (INIS)

    Guimaraes, I.P. de; Silva Filho, A.F. da

    1990-01-01

    The Bom Jardim complex is a multi phase intrusion emplaced within the basement of the Pajeu-Paraiba belt, in the Borborema province, N.E., Brazil, during the Pan African (Brasiliano) orogeny, 600 Ma ago. The Bom Jardim complex is primarily composed of monzonites and syenites with subordinated granites. The major and trace elements geochemistry has established a shoshonitic affinity for the monzonite-syenite assemblages, whereas the granites are clearly of a high-K calc-alkaline character. The main geochemical trends determined for the complex are the result of fractionation of mainly amphibole, biotite, alkali feldspar ±clinopyroxene within the developing magmas. The enrichment in transition metal elements, LILE and high LILE/HSFE ratios, coupled with an initial Sr sup(87)/Sr sup(86) ratio of 0.70709 is consistent with a subduction related magma source. (author)

  1. Porous alkali activated materials with slow alkali release dynamic. Role of composition

    International Nuclear Information System (INIS)

    Bumanis, G.; Bajare, D.

    2018-01-01

    Alkali activated materials (AAM) based on calcined metakaolin or illite clay together with waste by-products, such as waste glass or aluminium scrap recycling waste, were tested as value-added materials for pH stabilization in biogas technology where decrease of pH should be avoided. Porous materials with ability to slowly leach alkalis in the water media thus providing continuous control of the pH level were obtained. XRD, FTIR, SEM and titration methods were used to characterize AAM and their leaching properties. It is clear that composition of the material has an important effect on the diffusion of alkali from structure. Namely, higher Si/Al and Na/Al molar ratios may increase pore solution transfer to the leachate. The leaching rate of alkalis from the structure of AAM is high for the first few days, decreasing over time. It was possible to calculate the buffer capacity from the mixture design of AAM. [es

  2. Chemical effects of alkali atoms on critical temperature in superconducting alkali-doped fullerides

    Science.gov (United States)

    Hetfleisch, F.; Gunnarsson, O.; Srama, R.; Han, J. E.; Stepper, M.; Roeser, H.-P.; Bohr, A.; Lopez, J. S.; Mashmool, M.; Roth, S.

    2018-03-01

    Alkali metal doped fullerides (A3C60) are superconductors with critical temperatures, Tc, extending up to 38 K. Tc is known to depend strongly on the lattice parameter a, which can be adjusted by physical or chemical pressure. In the latter case an alkali atom is replaced by a different sized one, which changes a. We have collected an extensive data base of experimental data for Tc from very early up to recent measurements. We disentangle alkali atom chemical effects on Tc, beyond the well-known consequences of changing a. It is found that Tc, for a fixed a, is typically increased as smaller alkali atoms are replaced by larger ones, except for very large a. Possible reasons for these results are discussed. Although smaller in size than the lattice parameter contribution, the chemical effect is not negligible and should be considered in future physical model developments.

  3. Alkali resistant optical coatings for alkali lasers and methods of production thereof

    Science.gov (United States)

    Soules, Thomas F; Beach, Raymond J; Mitchell, Scott C

    2014-11-18

    In one embodiment, a multilayer dielectric coating for use in an alkali laser includes two or more alternating layers of high and low refractive index materials, wherein an innermost layer includes a thicker, >500 nm, and dense, >97% of theoretical, layer of at least one of: alumina, zirconia, and hafnia for protecting subsequent layers of the two or more alternating layers of high and low index dielectric materials from alkali attack. In another embodiment, a method for forming an alkali resistant coating includes forming a first oxide material above a substrate and forming a second oxide material above the first oxide material to form a multilayer dielectric coating, wherein the second oxide material is on a side of the multilayer dielectric coating for contacting an alkali.

  4. Granite-related hypothermal uranium mineralization in South China

    International Nuclear Information System (INIS)

    Liu, X.; Wu, J.; Pan, J.; Zhu, M.

    2014-01-01

    As one of the important geological types, granite-related uranium deposits account for about 29% of the total discovered natural uranium resources in China. Most of the granite-related uranium deposits located in Taoshan - Zhuguang uranium metallogenic belt, South China. In addition to the typical pitchblende vein-type uranium mineralization of epithermal metallogenic system, a new type of granite-related uranium mineralization with characteristics of hypothermal matallogenic system was discovered in South China by current studies. However, hypothermal is contact thermal to epithermal mineralization, and not the conventional intrusive high temperature mineralization. Hypothermal uranium mineralization is presented by disseminated uraninite or pitchblende stockwork in fissures in granites normally with extensive alkaline alteration. The high temperature mineral assemblage of uraninite associate with scheelite and tourmaline was identified in hypothermal uranium mineralization. Fluid inclusion studies on this type mineralization indicated the middle to high temperature (>250℃) mineralization with the mixing evidence of ore forming solution derived from deep level, and the boiling and mixing of ore forming solution are regarded as the dominant mineralization mechanism for the precipitating of uranium. In contrast to the mineralization ages of 67 Ma to 87 Ma for typical pitchblende vein mineralization of epithermal metallogenic system, the mineralization age is older than 100 Ma for hypothermal uranium mineralization in granite. In the Shituling deposit, Xiazhuang uranium ore field, uraninite and pitchblende micro veins with extensive potassic alteration, chloritization and sericitization are hosted in fissures of Indo-Chinese epoch granites with the uranium mineralization age of 130 Ma to 138 Ma with a mineralization temperature of 290℃ to 330℃ indicated. Other examples sharing the similar characters of hypothermal uranium mineralization have been recognized in

  5. Alkali metals in fungi of forest soil

    International Nuclear Information System (INIS)

    Vinichuk, M.; Taylor, A.; Rosen, K.; Nikolova, I.; Johanson, K.J.

    2009-01-01

    The high affinity of forest soil fungi for alkali metals such as potassium, rubidium, caesium as well as radiocaesium is shown and discussed. Good positive correlation was found between K: Rb concentration ratios in soil and in fungi, when correlation between K: Cs concentration ratios was less pronounced. (LN)

  6. Corrosion and compatibility in liquid alkali metals

    International Nuclear Information System (INIS)

    Anon.

    1978-01-01

    The literature dealing with liquid alkali metal corrosion of vanadium and its alloys is reviewed in the following subsections. Attention is given to both lithium and sodium data. Preceding this review, a brief outline of the current state of understanding of liquid metal corrosion mechanisms is provided

  7. Alkali slagging problems with biomass fuels

    Energy Technology Data Exchange (ETDEWEB)

    Miles, T.R.; Miles, T.R. Jr.; Baxter, L.L.; Jenkins, B.M.; Oden, L.L.

    1993-12-31

    Biomass fueled power boilers are unable to burn more than minor percentages of annually generated agricultural fuels. Determining the mechanisms of deposit formation, and developing means of increasing the proportion of these annual biofuels to be fired are the aims of the ongoing Alkali Deposit Investigation sponsored by DOE/NREL with matching funds from industry sponsors, combining Science, Engineering and Industry.

  8. High effective silica fume alkali activator

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Growing demands on the engineering properties of cement based materials and the urgency to decrease unsuitable ecologic impact of Portland cement manufacturing represent significant motivation for the development of new cement corresponding to these aspects. One category represents prospective alkali.

  9. Complexes in polyvalent metal - Alkali halide melts

    International Nuclear Information System (INIS)

    Akdeniz, Z.; Tosi, M.P.

    1991-03-01

    Experimental evidence is available in the literature on the local coordination of divalent and trivalent metal ions by halogens in some 140 liquid mixtures of their halides with alkali halides. After brief reference to classification criteria for main types of local coordination, we focus on statistical mechanical models that we are developing for Al-alkali halide mixtures. Specifically, we discuss theoretically the equilibrium between (AlF 6 ) 3- and (AlF 4 ) - complexes in mixtures of AlF 3 and NaF as a function of composition in the NaF-rich region, the effect of the alkali counterion on this equilibrium, the possible role of (AlF 5 ) 2- as an intermediate species in molten cryolite, and the origin of the different complexing behaviours of Al-alkali fluorides and chlorides. We also present a theoretical scenario for processes of structure breaking and electron localization in molten cryolite under addition of sodium metal. (author). 26 refs, 2 tabs

  10. luminescence in coloured alkali halide crystals

    Indian Academy of Sciences (India)

    have studied the effect of annealing in chlorine gas on the ML of X-rayed KCl crystals. ..... high temperature because of the thermal bleaching of the coloration in alkali halide ..... [31] J Hawkins, Ph.D. Thesis (University of Reading, 1976).

  11. Terahertz radiation in alkali vapor plasmas

    International Nuclear Information System (INIS)

    Sun, Xuan; Zhang, X.-C.

    2014-01-01

    By taking advantage of low ionization potentials of alkali atoms, we demonstrate terahertz wave generation from cesium and rubidium vapor plasmas with an amplitude nearly one order of magnitude larger than that from nitrogen gas at low pressure (0.02–0.5 Torr). The observed phenomena are explained by the numerical modeling based upon electron tunneling ionization

  12. Movement of fossil pore fluids in granite basement, Illinois

    International Nuclear Information System (INIS)

    Couture, R.A.; Seitz, M.G.

    1986-01-01

    The compositions of pore fluids in granite cores from the Precambrian basement in northern Illinois were determined. The estimated chloride concentration in the aqueous phase increases from near zero at the upper contact with sandstone to 2.7 M at 624 m below the contact. Traces of aliphatic oil are present in the overlying sandstone and the upper 516 m of granite, and oil occupies most of the pore space in one sample of unaltered granite 176 m below the contact. The oil has a Δ 13 C of -25%, about the same as average petroleum. The high concentrations of salt more than 500 m below the contact imply that little or no fresh water has reached these levels of the granite by flow. Lower concentrations near the contact are consistent with replacement of brine in the sandstone by fresh water at least 11 m.y. ago and subsequent upward diffusion of salt from the granite. Geologic data suggest that the time of replacement was about 130 Ma. The purpose of the investigation is to study the record of movement of intergranular fluids within a granite pluton. The composition and movement of ground waters can determine the extent that hazardous or radioactive wastes disposed in igneous rock will remain isolated

  13. Quality control chart for crushed granite concrete

    Directory of Open Access Journals (Sweden)

    Ewa E. DESMOND

    2016-07-01

    Full Text Available A chart for assessing in-situ grade (strength of concrete, has been developed in this study. Four grades of concrete after the Nigerian General Specification for Roads and bridges (NGSRB-C20, C25, C30 and C35, is studied at different water-cement ratios for medium and high slump range. The concrete mixes are made from crushed granite rock as coarse aggregate with river sand as fine aggregate. Compression test on specimens are conducted at curing age of 1, 3, 7, 14, 21, 28 and 56 days. Results on concrete workability from slump values, and water-cement ratios revealed that specimens with lower water-cement ratio were less workable but had higher strength, compared to mixes with higher water cement ratio. A simple algorithm using nonlinear regression analysis performed on each experimental data set produced Strength-Age (S-A curves which were used to establish a quality control chart. The accuracy of these curves were evaluated by computing average absolute error (AAS, the error of estimate (EoE and the average absolute error of estimate (Abs EoE for each concrete mix. These were done based on the actual average experimental strengths to measure how close the predicted values are to the experimental data set. The absolute average error of estimate (Abs. EoE recorded was less than ±10% tolerance zone for concrete works.

  14. Hydraulic fracturing in granite under geothermal conditions

    Science.gov (United States)

    Solberg, P.; Lockner, D.; Byerlee, J.D.

    1980-01-01

    The experimental hydraulic fracturing of granite under geothermal conditions produces tensile fracture at rapid fluid injection rates and shear fracture at slow injection rates and elevated differential stress levels. A sudden burst of acoustic emission activity accompanies tensile fracture formation whereas the acoustic emission rate increases exponentially prior to shear fracture. Temperature does not significantly affect the failure mechanism, and the experimental results have not demonstrated the occurrence of thermal fracturing. A critical result of these experiments is that fluid injection at intermediate rates and elevated differential stress levels increases permeability by more than an order of magnitude without producing macroscopic fractures, and low-level acoustic emission activity occurs simultaneously near the borehole and propagates outward into the specimen with time. Permeability measurements conducted at atmospheric pressure both before and after these experiments show that increased permeability is produced by permanent structural changes in the rock. Although results of this study have not demonstrated the occurrence of thermal fracturing, they suggest that fluid injection at certain rates in situ may markedly increase local permeability. This could prove critical to increasing the efficiency of heat exchange for geothermal energy extraction from hot dry rock. ?? 1980.

  15. Electrical conductivity of sandstone, limestone, and granite

    Energy Technology Data Exchange (ETDEWEB)

    Duba, A.; Piwinskii, A.J.; Santor, M.; Weed, H.C.

    1978-01-01

    The electrical conductivity of cylindrical cores of Westerly granite, Indiana limestone and Nugget, St Peter and Kayenta sandstones was measured at about 25/sup 0/C in vacuo, in air, and after saturation in distilled water, tap water, and 0.1 M NaCl solution. The three-electrode technique with a guard ring and the two-electrode technique without a guard ring were used. Core aspect ratio over the range of 2.00 to 0.25, as well as frequency over the range of 50 Hz to 10 kHz, influences the conductivity of all rocks, especially those measured in vacuo. Measurements from water-saturated samples using a guard ring are not appreciably different from those obtained without a guard ring. The conductivity of rocks saturated in 0.1 M NaCl solution changes least with a change in aspect ratio; for these rocks a linear relationship, known as Archie's Law, exists between log porosity and log conductivity. No simple correlation was found between those factors in rocks saturated with tap or distilled water. Thus, it appears Archie's Law is of questionable value for correlating laboratory data from rocks saturated with low-conductivity fluids.

  16. Heat transfer studies in salt and granite

    International Nuclear Information System (INIS)

    Just, R.A.

    1978-10-01

    Results are presented of a scoping study on the feasibility of using a multi-layer terminal repository design in both salt and granite formations to store either high-level waste or spent fuel. Calculations have been made to determine temperature profiles within the repository and to provide an estimate of the thermal uplift that can be expected. Near-field models developed to compare temperature profiles in the regions close to the waste canisters indicated that maximum thermal gradients and maximum temperature increases could be significantly reduced by changing from a single to a multi-layer repository design. For both high-level waste and for spent fuel, the maximum temperature increase in the multi-level repositories was reduced to approximately 60 percent of the temperature increase predicted for the single-level repositories at the same areal loading. After the near-field models had verified that maximum thermal gradients and temperature increases could be reduced by using a multilevel repository design, a series of far-field models was developed. The far-field models used to provide qualitative comparisons of the maximum thermal uplift indicate that the thermal uplift is roughly proportional to the energy supplied to the formation. Changing from a single- to a multi-layer repository but keeping the areal loading constant results in increased thermal uplifts

  17. Groundwater evolution of the granite area, Korea

    International Nuclear Information System (INIS)

    Kim, C.S.; Bae, D.S.; Koh, Y.K.; Kim, K.S.; Kim, G.Y.

    2001-01-01

    The geochemistry and environmental isotopes of groundwater in the Cretaceous granite of the Yeongcheon area has been investigated. The hydrochemistry of groundwater belongs to the Ca-HCO 3 type. The oxygen-18 and deuterium data are clustered along the meteoric water line, indicating that the groundwater is of meteoric water origin. Tritium data show that the groundwaters were mostly recharged before pre-thermonuclear period and have been mixed with younger surface water flowing rapidly along fractured zones. Based on the mass balance and reaction simulation approaches using both the hydrochemistry of groundwater and the secondary mineralogy of fracture-filling materials, the low-temperature hydrogeochemical evolution of groundwater in the area has been modeled. The results of geochemical simulation show that the concentrations of Ca, Na and HCO 3 and pH of waters increase progressively owing to the dissolution of reactive minerals in flow paths. The concentrations of Mg and K first increase with the dissolution of reactant minerals, but later decrease when montmorillonite and illitic material are precipitated respectively. The continuous adding of reactive minerals, i. e. the progressively larger degrees of water/rock interaction, causes the formation of secondary minerals with the following sequence: hematite > gibbsite > kaolinite > montmorillonite > illitic material > microcline. The results of reaction simulation agree well with the observed water chemistry and secondary mineralogy, indicating the successful applicability of this simulation technique to delineate the complex hydrogeochemistry of bedrock groundwaters. (author)

  18. Uranium occurrences in the Granite Zone

    International Nuclear Information System (INIS)

    Nyegaard, P.; Armour-Brown, A.

    1986-04-01

    This report describes the work and results of the South Greenland Exploration Programme (Sydex) during the 1984 field season in the Granite Zone, and discusses the results and conclusions that can be drawn from them. It also contains a structural analysis of the Ivigtut-Julianehaab region, which will help in future exploration by indicating the likely directions of uraniferous faults and fractures. It also includes suggestions for future work with both exploration and scientific aspects. The project was carried out by the Geological Survey Greenland (GGU) in co-operation with Risoe National Laboratory. It was financed by the Danish Ministry of Energy. The structural analysis was carried out using previous geological maps, our own field observations and an analysis of lineament frequencies taken from aerial photographs and satellite images. Major lineaments in the region are due to E-W sinistral wrench faults and NE-SW normal faults. Analysis of the minor lineaments showed that the region could be divided into three blocks which have each reacted differently to the same regional stress field which was active throughout the Gardar period. A northern block which has been influenced by an older system of faults in the Archaean gneiss, a central block dominated by a graben, and a southern block where there is a change to a less intensively faulted area. 2 maps, 27 refs. (EG)

  19. Workability of glass reinforced concrete (GRC) with granite and silica sand aggregates

    Science.gov (United States)

    Moceikis, R.; Kičaitė, A.; Keturakis, E.

    2017-10-01

    Glass fiber reinforced concrete (GRC) opens the door for lightweight and complex shaped innovative construction, adding architectural value to buildings. With panel thickness down to 15 mm, considerable amount of total loads and materials per square meter of facade can be saved, if compared to conventionally used 80 mm thickness outer layer in insulated precast concrete wall elements. Even though GRC is used for over 50 years in such countries as Great Britain, USA and Japan, there are very few examples and little research done in Eastern Europe with this building material. European Commission propagates sustainable design as commitment to energy efficiency, environmental stewardship and conservation. For this reason, GRC plays important role in mowing toward these goals. In this paper, GRC premix recipes including fine granite and silica sands, reinforced with 13mm length alkali resistant glass fibers are investigated. Two CEM I 52,5R cements with different particle sizes were used and severe water dissociation noticed in one of concrete mixes. Cement particle size distribution determined with laser diffraction particle analyser Cilas 1090LD. To determine modulus of rupture (M.O.R.) and limit of proportionality (L.O.P), plates thickness 15 and 20 mm were produced and tested for flexural resistance according to 4-point bending scheme. Concrete workability tests were made according EN 1170-1.

  20. Thermodynamic properties of alkali borosilicate gasses and metaborates

    International Nuclear Information System (INIS)

    Asano, Mitsuru

    1992-01-01

    Borosilicate glasses are the proposed solidifying material for storing high level radioactive wastes in deep underground strata. Those have low melting point, and can contain relatively large amount of high level radioactive wastes. When borosilicate glasses are used for this purpose, they must be sufficiently stable and highly reliable in the vitrification process, engineered storage and the disposal in deep underground strata. The main vaporizing components from borosilicate glasses are alkali elements and boron. In this report, as for the vaporizing behavior of alkali borosilicate glasses, the research on thermodynamic standpoint carried out by the authors is explained, and the thermodynamic properties of alkali metaborates of monomer and dimer which are the main evaporation gases are reported. The evaporation and the activity of alkali borosilicate glasses, the thermodynamic properties of alkali borosilicate glasses, gaseous alkali metaborates and alkali metaborate system solid solution and so on are described. (K.I.)

  1. The 'Granite' collegial mission of dialogue. Report; Mission collegiale de concertation Granite. Rapport

    Energy Technology Data Exchange (ETDEWEB)

    Boisson, P; Huet, Ph; Mingasson, J

    2000-06-01

    The aim of the 'Granite' collegial mission of dialogue is to inform the French authorities, associations and population about the project of construction of an underground laboratory for the study of the disposal of high level and long-life radioactive wastes in a granitic environment. The aim of the dialogue was not to select a site but to collect the public reactions and advices about such a project. However, such a dialogue has partially failed because of a misunderstanding of the population about the aims of the mission. However, the mission has collected many point of views and questions which are developed in this report. The first and second chapters recall the process of the mission and its progress, while a third chapter stresses on the questions asked by the public and which concern the fear of nuclear wastes and the incompatibility between the disposal of wastes and the socio-economical development of the region concerned. Thanks to the lessons drawn from this experience, the mission has formulated some recommendations (chapter 4) concerning the need for a better information of the population about any topic in relation with the radioactive wastes. Some complementary information is provided in appendixes. (J.S.)

  2. The 'Granite' collegial mission of dialogue. Report; Mission collegiale de concertation Granite. Rapport

    Energy Technology Data Exchange (ETDEWEB)

    Boisson, P.; Huet, Ph.; Mingasson, J

    2000-06-01

    The aim of the 'Granite' collegial mission of dialogue is to inform the French authorities, associations and population about the project of construction of an underground laboratory for the study of the disposal of high level and long-life radioactive wastes in a granitic environment. The aim of the dialogue was not to select a site but to collect the public reactions and advices about such a project. However, such a dialogue has partially failed because of a misunderstanding of the population about the aims of the mission. However, the mission has collected many point of views and questions which are developed in this report. The first and second chapters recall the process of the mission and its progress, while a third chapter stresses on the questions asked by the public and which concern the fear of nuclear wastes and the incompatibility between the disposal of wastes and the socio-economical development of the region concerned. Thanks to the lessons drawn from this experience, the mission has formulated some recommendations (chapter 4) concerning the need for a better information of the population about any topic in relation with the radioactive wastes. Some complementary information is provided in appendixes. (J.S.)

  3. Determination of Matrix Diffusion Properties of Granite

    International Nuclear Information System (INIS)

    Holtta, Pirkko; Siitari-Kauppi, Marja; Huittinen, Nina; Poteri, Antti

    2007-01-01

    Rock-core column experiments were introduced to estimate the diffusion and sorption properties of Kuru Grey granite used in block-scale experiments. The objective was to examine the processes causing retention in solute transport through rock fractures, especially matrix diffusion. The objective was also to estimate the importance of retention processes during transport in different scales and flow conditions. Rock-core columns were constructed from cores drilled into the fracture and were placed inside tubes to form flow channels in the 0.5 mm gap between the cores and the tube walls. Tracer experiments were performed using uranin, HTO, 36 Cl, 131 I, 22 Na and 85 Sr at flow rates of 1-50 μL.min -1 . Rock matrix was characterized using 14 C-PMMA method, scanning electron microscopy (SEM), energy dispersive X-ray micro analysis (EDX) and the B.E.T. method. Solute mass flux through a column was modelled by applying the assumption of a linear velocity profile and molecular diffusion. Coupling of the advection and diffusion processes was based on the model of generalised Taylor dispersion in the linear velocity profile. Experiments could be modelled applying a consistent parameterization and transport processes. The results provide evidence that it is possible to investigate matrix diffusion at the laboratory scale. The effects of matrix diffusion were demonstrated on the slightly-sorbing tracer breakthrough curves. Based on scoping calculations matrix diffusion begins to be clearly observable for non-sorbing tracer when the flow rate is 0.1 μL.min -1 . The experimental results presented here cannot be transferred directly to the spatial and temporal scales that prevail in an underground repository. However, the knowledge and understanding of transport and retention processes gained from this study is transferable to different scales from laboratory to in-situ conditions. (authors)

  4. Thermomechanical studies in granite at Stripa, Sweden

    International Nuclear Information System (INIS)

    Cook, N.G.W.; Myer, L.R.

    1981-01-01

    Media other than rock salt are being considered for the deep, geologic disposal of nuclear wastes. The disposal of high-level nuclear waste in a deep, underground repository will subject the rock to a thermal pulse that will induce displacements, strains, and stresses in the rock. Thermomechanical experiments, with electrical heaters simulating the thermal output of waste canisters, were carried out in granite at a depth of 340 m below surface adjacent to a defunct iron ore mine at Stripa, Sweden. Changes in temperature, displacement, and stress in the rock around these heaters were measured, and the measurements were compared with predictions calculated from the theory of linear thermoelasticity. Measured temperature changes agreed well with predictions, but measured displacements and stresses were consistently less than those predicted with constant values for the coefficient of thermal expansion and elastic properties of the rock. A laboratory test program to measure these coefficients over ranges of stress and temperature representing those in the field experiment has been initiated. Test specimens were taken from cores recovered from the instrumentation holes in the Stripa experiments. Preliminary results from laboratory tests on specimens free of joints indicate that the values of Young's modulus and Poisson's ratio increase from about 60 to 80 MPa and from 0.15 to 0.22, respectively, as the confining stress is increased from 2 to 55 MPa; these values decrease with increasing temperature, more so at 2 MPa than at 55 MPa. The linear coefficient of thermal expansion at a confining stress of 30 MPa increases from about 10 x 10 - 6 / 0 C at 40 0 C to about 14 x 10 - 6 / 0 C. The magnitudes of these changes are not sufficient to resolve the disparity between measured and predicted results. Perhaps the properties of test specimens containing joints will show greater variations in the values of the thermomechanical coefficients with temperature and pressure

  5. U(VI) sorption on granite: prediction and experiments

    International Nuclear Information System (INIS)

    Nebelung, C.; Brendler, V.

    2010-01-01

    One widely accepted approach - component additivity (CA) - to describe the sorption of contaminants onto complex materials such as rocks or soils is based on the assumption that the surface of a complex mineral assemblage is composed of a mixture of mineral constituents whose surface properties are known from independent studies. An internally consistent SCM (surface complexation model) database can be developed that describes the adsorption reactions of solutes to each phase. Here, the capability of such a methodology was tested, using the code MINTEQA2 including thermodynamic data of the NEA-TDB, and literature data for SCM, namely the DDL model. The sorption characteristics of U(VI) on granite (from Eibenstock, Saxony, Germany, with the main components quartz, albite, orthoclase, and muscovite) was predicted and then compared to batch experiments. Granite plays an important role in the remediation of former uranium ore mining and milling sites, but is also one of the host rocks considered for final disposal of nuclear materials. Safety assessment requires a detailed understanding of this system and its retention potential with regard to hazardous components. Namely the sorption of uranium in this complex rock is not fully understood yet. The experiments thus also provided a better understanding of the far-field behaviour in granitic geological nuclear repositories. The robustness of the prediction was tested by variation of the granite composition and the variation of the specific surface area (SSA) - first all components were predicted with a uniform granite SSA, second with a distinct SSA for each granite component (determined on pure minerals for the same grain size fractions). Changes in compositions yielded only marginal differences in the prediction. Different approaches to SSA showed somewhat larger deviations. In conclusion, the CA methodology is a valid and robust approach to U(VI) sorption onto complex substrates such as granite, provided sufficient

  6. Effect of alkali lignins with different molecular weights from alkali pretreated rice straw hydrolyzate on enzymatic hydrolysis.

    Science.gov (United States)

    Li, Yun; Qi, Benkun; Luo, Jianquan; Wan, Yinhua

    2016-01-01

    This study investigated the effect of alkali lignins with different molecular weights on enzymatic hydrolysis of lignocellulose. Different alkali lignins fractions, which were obtained from cascade ultrafiltration, were added into the dilute acid pretreated (DAP) and alkali pretreated (AP) rice straws respectively during enzymatic hydrolysis. The results showed that the addition of alkali lignins enhanced the hydrolysis and the enhancement for hydrolysis increased with increasing molecular weights of alkali lignins, with maximum enhancement being 28.69% for DAP and 20.05% for AP, respectively. The enhancement was partly attributed to the improved cellulase activity, and filter paper activity increased by 18.03% when adding lignin with highest molecular weight. It was found that the enhancement of enzymatic hydrolysis was correlated with the adsorption affinity of cellulase on alkali lignins, and the difference in surface charge and hydrophobicity of alkali lignins were responsible for the difference in affinity between cellulase and lignins. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Petrographic and mineralogical features of the uraniferous pink granites in the north eastern desert of egypt

    International Nuclear Information System (INIS)

    Atawiya, M.Y.; Salman, A.B.; El-Bayyomi, R.M.

    1998-01-01

    The present work is concerned with the petrological, mineralogical and geochemical studies of some uranium bearing younger granites in the north eastern desert of egypt particularly Gebel Gattar area. The area around Gebel Gattar comprises the following rock units (starting from the oldest): meta volcanic, diorite-grano-diorite complex- Dokhan volcanics- Hammamat sediments, younger granites and dykes. The most significant structural features are represented by NNE-ENE dominantly trending faults and joints. Petrographicaly, the pink granites are divided into normal and mineralized (uraniferous) granites. Normal granites are classified into three types; a) leucocratic perthitic granite, b) hornblende- biotite perthitic granite and c) two feldspars perthitic granite. Mineralized granites are sheared, deformed, pinkish brown in colour and strongly altered. A remarkable secondary uranium mineralization has been recorded along fault and fracture zones

  8. The transition from granite to banded aplite-pegmatite sheet complexes: An example from Megiliggar Rocks, Tregonning topaz granite, Cornwall

    Science.gov (United States)

    Breiter, K.; Ďurišová, J.; Hrstka, T.; Korbelová, Z.; Vašinová Galiová, M.; Müller, A.; Simons, B.; Shail, R. K.; Williamson, B. J.; Davies, J. A.

    2018-03-01

    The genetic relationship between a granite pluton and adjacent complex of rare-metal pegmatite-aplite-banded sheets (Megiliggar Sheet Complex - MSC) has been studied at the border of the Tregonning topaz granite at Megiliggar Rocks, Cornwall, SW England. Similarities in whole-rock chemical and mineralogical compositions, together with a gradual change in textures away from the granite margin, provide strong evidence for a genetic link between the Tregonning Granite and MSC. The sheets are likely to represent apophyses of residual melt which escaped from the largely crystallized roof of the granite pluton. The escaping melt was peraluminous, had a composition near the F, B, Li slightly enriched granite minimum, and, in comparison with other Cornish granites, was enriched in F, Li, Rb, Cs, Sn, W, Nb, Ta, and U, and depleted in Fe, Mg, Ca, Sr, Th, Zr, and REE. With increasing distance from the Tregonning Granite, the silicate melt crystallized as homogeneous leucogranite sheets and banded complex sheets (i.e. combinations of bands with granitic, aplitic and pegmatitic textures), then layered aplite-pegmatites; this sequence becoming progressively more depleted in the fluxing and volatile elements F, Li, Rb, and Cs, but showing no change in Zr/Hf ratios. The fixed Zr/Hf ratio is interpreted as indicating a direct genetic link (parental melt) between all rock types, however the melt progressively lost fluxing and volatile elements with distance from the granite pluton, probably due to wall-rock reaction or fluid exsolution and migration via fractures. Differentiation of the primary melt into Na-Li-F-rich and separate K-B-rich domains was the dominant chemical process responsible for the textural and mineral diversity of the MSC. On a large (cliff-section) scale, the proximal Na-Li-F-rich leucogranite passes through complex sheets into K-B-rich aplite-pegmatites, whilst at a smaller (<1 m) scale, the K-B-rich bands are interspersed (largely overlain) by Na

  9. Geology of Muntok area and the potency of menumbang granite as source of Uranium and Thorium

    International Nuclear Information System (INIS)

    Kurniawan Dwi Saksama; Ngadenin

    2013-01-01

    In the West Bangka there are some granites namely Menumbing, Pelangas, Tempilang, and Jebus granite. The granites is granite tin belt that stretches from Thailand-Malaysia-Bangka Belitung. Granite tin belt or granite source of tin (cassiterite) can act as a source of U and Th. Aims of the study is to find out the information on the geology of Muntok area and its surrounding and to determine the potency of Menumbing granite as a source of U and Th. The methods used is surface geological mapping in Muntok areas and its surrounding with scale 1 : 25.000, measurement grade of uranium and thorium in Menumbing granite areas and petrographic and grain size analysis of sample of Menumbing granite. Determination of granites a source of U and Th is based on content of radioactive mineral, anomaly of U and Th, megascopic and microscopic observation of granite. Morphology of Muntok areas and its surrounding is denudasional undulating plains to hills with an elevation ranging from 0 to 455 meters. Stratigraphy of research areas from old to young is meta sandstone units, granite intrusion of Menumbing and alluvial. Evolving fault is a fault trending West-East. Based on the presence of radioactive minerals, grade of U and Th as well as the type of granite, it was concluded that the Menumbing granite is a source of Th and not sources of U. (author)

  10. Local structure of alkalis in mixed-alkali borate glass to elucidate the origin of mixed-alkali effect

    Directory of Open Access Journals (Sweden)

    Yomei Tokuda

    2015-12-01

    Full Text Available We report the structural analysis of Na+ and Cs+ in sodium cesium borate crystals and glasses using 23Na and 133Cs magic-angle spinning nuclear magnetic resonance (MAS NMR spectroscopy. The composition dependence of NMR spectra of the borate was similar to that of the silicate: (1 the peak position of cesium borate crystals shifted to upfield for structures with larger Cs+ coordination numbers, (2 the MAS NMR spectra of xNa2O-yCs2O-3B2O3 (x = 0, 0.25, 0.5, 0.75, 1.0, x + y = 1 glass showed that the average coordination number (CN of both the alkali cations decreases with increasing Cs+/(Na+ + Cs+ ratio. However, the degree of decrement in borates is much smaller than that in silicates. We have considered that the small difference in CN is due to 4-coordinated B, because it is electrically compensated by the alkali metal ions resulting in the restriction of having various coordinations of O to alkali metal.

  11. Smolt Monitoring at the Head of Lower Granite Reservoir and Lower Granite Dam, 2002 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Buettner, Edwin W.; Putnam, Scott A. [Idaho Department of Fish and Game

    2009-02-18

    This project monitored the daily passage of Chinook salmon Oncorhynchus tshawytscha, steelhead trout O. mykiss, and sockeye salmon smolts O. nerka during the 2002 spring out-migration at migrant traps on the Snake River and Salmon River. In 2002 fish management agencies released significant numbers of hatchery Chinook salmon and steelhead trout above Lower Granite Dam that were not marked with a fin clip or coded-wire tag. Generally, these fish were distinguishable from wild fish by the occurrence of fin erosion. Total annual hatchery Chinook salmon catch at the Snake River trap was 11.4 times greater in 2002 than in 2001. The wild Chinook catch was 15.5 times greater than the previous year. Hatchery steelhead trout catch was 2.9 times greater than in 2001. Wild steelhead trout catch was 2.8 times greater than the previous year. The Snake River trap collected 3,996 age-0 Chinook salmon of unknown rearing. During 2002, the Snake River trap captured 69 hatchery and 235 wild/natural sockeye salmon and 114 hatchery coho salmon O. kisutch. Differences in trap catch between years are due to fluctuations not only in smolt production, but also differences in trap efficiency and duration of trap operation associated with flow. The significant increase in catch in 2002 was due to a 3.1 fold increase in hatchery Chinook production and a more normal spring runoff. Trap operations began on March 10 and were terminated on June 7. The trap was out of operation for a total of four days due to mechanical failure or debris. Hatchery Chinook salmon catch at the Salmon River trap was 4.2 times greater and wild Chinook salmon catch was 2.4 times greater than in 2001. The hatchery steelhead trout collection in 2002 was 81% of the 2001 numbers. Wild steelhead trout collection in 2002 was 81% of the previous year's catch. Trap operations began on March 10 and were terminated on May 29 due to high flows. The trap was out of operation for four days due to high flow or debris. The

  12. Smolt Monitoring at the Head of Lower Granite Reservoir and Lower Granite Dam, 2003 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Buettner, Edwin W.; Putnam, Scott A. [Idaho Department of Fish and Game

    2009-02-18

    This project monitored the daily passage of Chinook salmon Oncorhynchus tshawytscha, steelhead trout O. mykiss, and sockeye salmon O. nerka smolts during the 2003 spring out-migration at migrant traps on the Snake River and Salmon River. In 2003 fish management agencies released significant numbers of hatchery Chinook salmon and steelhead trout above Lower Granite Dam that were not marked with a fin clip or coded-wire tag. Generally, these fish were distinguishable from wild fish by the occurrence of fin erosion. Total annual hatchery Chinook salmon catch at the Snake River trap was 2.1 times less in 2003 than in 2002. The wild Chinook catch was 1.1 times less than the previous year. Hatchery steelhead trout catch was 1.7 times less than in 2002. Wild steelhead trout catch was 2.1 times less than the previous year. The Snake River trap collected 579 age-0 Chinook salmon of unknown rearing. During 2003, the Snake River trap captured five hatchery and 13 wild/natural sockeye salmon and 36 coho salmon O. kisutch of unknown rearing. Differences in trap catch between years are due to fluctuations not only in smolt production, but also differences in trap efficiency and duration of trap operation associated with flow. The significant differences in catch between 2003 and the previous year were due mainly to low flows during much of the trapping season and then very high flows at the end of the season, which terminated the trapping season 12 days earlier than in 2002. Trap operations began on March 9 and were terminated on May 27. The trap was out of operation for a total of zero days due to mechanical failure or debris. Hatchery Chinook salmon catch at the Salmon River trap was 16.8% less and wild Chinook salmon catch was 1.7 times greater than in 2002. The hatchery steelhead trout collection in 2003 was 5.6% less than in 2002. Wild steelhead trout collection was 19.2% less than the previous year. Trap operations began on March 9 and were terminated on May 24 due to high

  13. Uranium distribution in Brazilian granitic rocks. Identification of uranium provinces

    International Nuclear Information System (INIS)

    Tassinari, C.G.G.

    1993-01-01

    The research characterized and described uranium enriched granitoids in Brazil. They occur in a variety of tectonic environments and are represented by a variety granite types of distinct ages. It may be deduced that in general they have been generated by partial melting process of continental crust. However, some of them, those with tonality composition, indicate a contribution from mantle derived materials, thus suggesting primary uranium enrichment from the upper mantle. Through this study, the identification and characterization of uranium enriched granite or uranium provinces in Brazil can be made. This may also help identify areas with potential for uranium mineralization although it has been note that uranium mineralization in Brazil are not related to the uranium enrichment process. In general the U-anomalous granitoids are composed of granites with alkaline composition and granite ''sensu strictu'' which comprise mainly of syenites, quartz-syenites and biotite-hornblende granites, with ages between 1,800 - 1,300 M.a. The U-anomalous belongings to this period present high Sr initial ratios values, above 0.706, and high Rb contents. Most of the U-enriched granitoids occur within ancient cratonic areas, or within Early to Mid-Proterozoic mobile belts, but after their cratonization. Generally, these granitoids are related to the border zones of the mobile belts or deep crustal discontinuity. Refs, 12 figs, 3 tabs

  14. Distribution of monazite in granite and alluvial of South Bangka

    International Nuclear Information System (INIS)

    Ngadenin

    2011-01-01

    Monazite is one source of thorium (Th), which has significant economic value and potential as an alternative fuel of nuclear power plants. The aims of research is to find out the distribution monazite alternative fuel of nuclear power plants. The aims of research is to find out the distribution monazite and its potential as a resource of radioactive minerals on the Bangka Island, then the data will be used and its potential as a resource of radioactive minerals on the Bangka Island, then the data will be used as a reference in the development of radioactive minerals exploration areas in the coming year. The research location is in the Bencah and Gadung villages, South Bangka Regency. The method used is the geological mapping, sampling of rock for petrographic, mineragraphic and autoradiographic analysis and heavy mineral for grains counting analysis. The results showed that lithologic area of Bencah Village composed of clay stone and alluvial deposits, while the Gadung Village composed by granite and alluvial deposits. Granite Gadung is predicted as the ilmenite series granite and tend to be of S type, while the material of Bencah alluvial is predicted come from the Klabat granite groups. In general, distribution of monazite in the alluvial slightly more potent of monazite than in the granite so that the development of radioactive minerals exploration will be prioritized in the alluvial areas. (author)

  15. Juvenile crustal recycling in an accretionary orogen: Insights from contrasting Early Permian granites from central Inner Mongolia, North China

    Science.gov (United States)

    Yuan, Lingling; Zhang, Xiaohui; Xue, Fuhong; Liu, Fulin

    2016-11-01

    Coeval high-K calc-alkaline to alkaline granites constitute important components of post-collisional to post-orogenic igneous suites in most orogenic belts of various ages on Earth and their genesis harbors a key to ascertaining critical geodynamic controls on continental crustal formation and differentiation. This zircon U-Pb dating and geochemical study documents three contrasting Early Permian granites from Erenhot of central Inner Mongolia, eastern Central Asian Orogenic Belt (CAOB) and reveals concurrent high-K calc-alkaline to alkaline granite association derived from successive partial melting of distinct protoliths. The ca. 280 Ma Gancihuduge (GCG) pluton shows a calc-alkaline I-type character, with initial 87Sr/86Sr ratios of 0.7035 to 0.7039, εNd(t) of + 1.87 to + 4.70, zircon εHf(t) of + 8.0 to + 13.2 and δ18O from 7.4 to 8.7‰. The ca. 276 Ma Cailiwusu (CLS) pluton is magnesian and peraluminous, with initial 87Sr/86Sr ratios of 0.7036 to 0.7040, εNd(t) of + 1.9 to + 2.4, zircon εHf(t) of + 6.5 to + 12.1 and δ18O from 9.7 to 10.9‰. These features are consistent with partial melts of mixed sources composed of newly underplated meta-basaltic to -andesitic protoliths and variable supracrustal components, with distinctively higher proportion of the latter in the CLS pluton. By contrast, the ca. 279 Ma Kunduleng (KDL) suite exhibits an A-type magmatic affinity, with typical enrichment in alkalis, Ga, Zr, Nb and Y, εNd(t) of + 2.39 to + 3.55, zircon εHf(t) from + 8.3 to + 12.3 and δ18O values from 6.8 to 7.5‰. These features suggest that they stem from high-temperature fusion of dehydrated K-rich mafic to intermediate protoliths. Besides presenting a snapshot into a stratified crustal architecture in δ18O, these contrasting granites could not only serve as a temporal marker for monitoring post-collisional extension in the aftermath of a retreating subduction zone, but also present spatial magmatic proxy for tracing crustal formation and

  16. Pyrolysis characteristic of kenaf studied with separated tissues, alkali pulp, and alkali li

    Directory of Open Access Journals (Sweden)

    Yasuo Kojima

    2015-12-01

    Full Text Available To estimate the potential of kenaf as a new biomass source, analytical pyrolysis was performed using various kenaf tissues, i.e., alkali lignin and alkali pulp. The distribution of the pyrolysis products from the whole kenaf was similar to that obtained from hardwood, with syringol, 4-vinylsyringol, guaiacol, and 4-vinylguaiacol as the major products. The phenols content in the pyrolysate from the kenaf core was higher than that from the kenaf cuticle, reflecting the higher lignin content of the kenaf core. The ratios of the syringyl and guaiacyl compounds in the pyrolysates from the core and cuticle samples were 2.79 and 6.83, respectively. Levoglucosan was the major pyrolysis product obtained from the kenaf alkali pulp, although glycol aldehyde and acetol were also produced in high yields, as previously observed for other cellulosic materials. Moreover, the pathways for the formation of the major pyrolysis products from alkali lignin and alkali pulp were also described, and new pyrolysis pathways for carbohydrates have been proposed herein. The end groups of carbohydrates bearing hemiacetal groups were subjected to ring opening and then they underwent further reactions, including further thermal degradation or ring reclosing. Variation of the ring-closing position resulted in the production of different compounds, such as furans, furanones, and cyclopentenones.

  17. The instrumental neutron-activation analysis of granites from the Bushveld Complex

    International Nuclear Information System (INIS)

    Watterson, J.I.W.

    1978-01-01

    Three methods of instrumental neutron-activation analysis, 14MeV, reactor thermal, and reactor epithermal, are compared for the analysis of granites form the Bushveld Complex. A total of 34 elements can be determined in the granites by these methods. Samples from the Zaaiplaats area were analysed by thermal neutron activation, and 22 elements were determined in all of them. These elements were used to distinguish between the mineralized Bobbejaankop and Lease granites and the Main granite by the use of multivariate statistics. The Bobbejaankop granite appears as a more-differentaited rock carrying greater amounts of the incompatible elements than does the Main granite [af

  18. Thermal investigation of alkali metal hexacyanoruthenate (2)

    International Nuclear Information System (INIS)

    Okorskaya, A.P.; Sergeeva, A.N.; Pavlenko, L.I.; Semenishin, D.I.

    1978-01-01

    Thermal stability of Li, Na, K, Rb and Cs hexacyanoruthenates has been investigated. It has been established, that thermal decomposition of complexes depends upon outer spherical cations; complex compound stability decreasing with the rize of cation ionization potential. According to their thermal stability, alkali metal hexacyanoruthenates can be placed in the following row: Li < Na < K < Rb < Cs. Decomposition of Na, Rb and Cs complexes is accompanied by formation of thermally stable cyanides of these metals

  19. Alkali Metal Heat Pipe Life Issues

    International Nuclear Information System (INIS)

    Reid, Robert S.

    2004-01-01

    One approach to fission power system design uses alkali metal heat pipes for the core primary heat-transfer system. Heat pipes may also be used as radiator elements or auxiliary thermal control elements. This synopsis characterizes long-life core heat pipes. References are included where information that is more detailed can be found. Specifics shown here are for demonstration purposes and do not necessarily reflect current Nasa Project Prometheus point designs. (author)

  20. Alkali metal protective garment and composite material

    Science.gov (United States)

    Ballif, III, John L.; Yuan, Wei W.

    1980-01-01

    A protective garment and composite material providing satisfactory heat resistance and physical protection for articles and personnel exposed to hot molten alkali metals, such as sodium. Physical protection is provided by a continuous layer of nickel foil. Heat resistance is provided by an underlying backing layer of thermal insulation. Overlying outer layers of fireproof woven ceramic fibers are used to protect the foil during storage and handling.

  1. Decalcification resistance of alkali-activated slag

    Energy Technology Data Exchange (ETDEWEB)

    Komljenovic, Miroslav M., E-mail: miroslav.komljenovic@imsi.rs [Institute for Multidisciplinary Research, University of Belgrade, Kneza Viseslava 1, 11030 Belgrade (Serbia); Bascarevic, Zvezdana, E-mail: zvezdana@imsi.bg.ac.rs [Institute for Multidisciplinary Research, University of Belgrade, Kneza Viseslava 1, 11030 Belgrade (Serbia); Marjanovic, Natasa, E-mail: natasa@imsi.bg.ac.rs [Institute for Multidisciplinary Research, University of Belgrade, Kneza Viseslava 1, 11030 Belgrade (Serbia); Nikolic, Violeta, E-mail: violeta@imsi.bg.ac.rs [Institute for Multidisciplinary Research, University of Belgrade, Kneza Viseslava 1, 11030 Belgrade (Serbia)

    2012-09-30

    Highlights: Black-Right-Pointing-Pointer The effects of decalcification on properties of alkali-activated slag were studied. Black-Right-Pointing-Pointer Decalcification was performed by concentrated NH{sub 4}NO{sub 3} solution (accelerated test). Black-Right-Pointing-Pointer Portland-slag cement (CEM II/A-S 42.5 N) was used as a benchmark material. Black-Right-Pointing-Pointer Decalcification led to strength decrease and noticeable structural changes. Black-Right-Pointing-Pointer Alkali-activated slag showed significantly higher resistance to decalcification. - Abstract: This paper analyses the effects of decalcification in concentrated 6 M NH{sub 4}NO{sub 3} solution on mechanical and microstructural properties of alkali-activated slag (AAS). Portland-slag cement (CEM II/A-S 42.5 N) was used as a benchmark material. Decalcification process led to a decrease in strength, both in AAS and in CEM II, and this effect was more pronounced in CEM II. The decrease in strength was explicitly related to the decrease in Ca/Si atomic ratio of C-S-H gel. A very low ratio of Ca/Si {approx}0.3 in AAS was the consequence of coexistence of C-S-H(I) gel and silica gel. During decalcification of AAS almost complete leaching of sodium and tetrahedral aluminum from C-S-H(I) gel also took place. AAS showed significantly higher resistance to decalcification in relation to the benchmark CEM II due to the absence of portlandite, high level of polymerization of silicate chains, low level of aluminum for silicon substitution in the structure of C-S-H(I), and the formation of protective layer of polymerized silica gel during decalcification process. In stabilization/solidification processes alkali-activated slag represents a more promising solution than Portland-slag cement due to significantly higher resistance to decalcification.

  2. Earth's youngest exposed granite and its tectonic implications: the 10-0.8 Ma Kurobegawa Granite.

    Science.gov (United States)

    Ito, Hisatoshi; Yamada, Ryuji; Tamura, Akihiro; Arai, Shoji; Horie, Kenji; Hokada, Tomokazu

    2013-01-01

    Although the quest for Earth's oldest rock is of great importance, identifying the youngest exposed pluton on Earth is also of interest. A pluton is a body of intrusive igneous rock that crystallized from slowly cooling magma at depths of several kilometers beneath the surface of the Earth. Therefore, the youngest exposed pluton represents the most recent tectonic uplift and highest exhumation. The youngest exposed pluton reported to date is the Takidani Granodiorite (~ 1.4 Ma) in the Hida Mountain Range of central Japan. Using LA-ICP-MS and SHRIMP U-Pb zircon dating methods, this study demonstrates that the Kurobegawa Granite, also situated in the Hida Mountain Range, is as young as ~ 0.8 Ma. In addition, data indicate multiple intrusion episodes in this pluton since 10 Ma with a ~ 2-million-year period of quiescence; hence, a future intrusion event is likely within 1 million years.

  3. Smolt Monitoring at the Head of Lower Granite Reservoir and Lower Granite Dam, 1994 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Buettner, Edwin W.; Brimmer, Arnold F.

    1994-10-01

    This project monitored the daily passage of chinook salmon Oncorhynchus tshawytscha and steelhead trout O. mykiss smolts during the 1994 spring outmigration at migrant traps on the Snake River, Clearwater River, and Salmon River. The 1994 snowpack was among the lowest since the beginning of the present drought, and the subsequent runoff was very poor. All hatchery chinook salmon released above Lower Granite Dam were marked with a fin clip in 1994. Total annual (hatchery + wild) chinook salmon catch at the Snake River trap was 1.5 times greater than in 1993. Hatchery and wild steelhead trout catches were similar to 1993. The Snake River trap collected 30 age 0 chinook salmon. Hatchery chinook salmon catch at the Clearwater River trap was 3.5 times higher than in 1993, and wild chinook salmon catch was 4.2 times higher. Hatchery steelhead trout trap catch was less than half of 1993 numbers because the trap was fishing near the north shore during the majority of the hatchery steelhead movement due to flow augmentations from Dworshak. Wild steelhead trout trap catch was 2 times higher than in 1993. The Salmon River trap was operated for about a month longer in 1994 than in 1993 due to extremely low flows. Hatchery chinook salmon catch was 1.4 times greater in 1994 than the previous year. Wild chinook salmon catch was slightly less in 1994. The 1994 hatchery steelhead trout collection did not change significantly from 1993 numbers. Wild steelhead trout collection in 1994 was 59% of the 1993 catch. Fish tagged with Passive Integrated Transponder (PIT) tags at the Snake River trap were interrogated at four dams with PIT tag detection systems (Lower Granite, Little Goose, Lower Monumental, and McNary dams). Because of the addition of the fourth interrogation site (Lower Monumental) in 1993, cumulative interrogation data is not comparable with the prior five years (1988-1992).

  4. Geochemistry, mineralogy, and zircon U-Pb-Hf isotopes in peraluminous A-type granite xenoliths in Pliocene-Pleistocene basalts of northern Pannonian Basin (Slovakia)

    Science.gov (United States)

    Huraiová, Monika; Paquette, Jean-Louis; Konečný, Patrik; Gannoun, Abdel-Mouhcine; Hurai, Vratislav

    2017-08-01

    Anorogenic granite xenoliths occur in alkali basalts coeval with the Pliocene-Pleistocene continental rifting of the Pannonian Basin. Observed granite varieties include peraluminous, calcic to peralkalic, magnesian to ferroan types. Quartz and feldspars are dominant rock-forming minerals, accompanied by minor early ilmenite and late magnetite-ulvöspinel. Zircon and Nb-U-REE minerals (oxycalciopyrochlore, fergusonite, columbite) are locally abundant accessory phases in calc-alkalic types. Absence of OH-bearing Fe, Mg-silicates and presence of single homogeneous feldspars (plagioclase in calcic types, anorthoclase in calc-alkalic types, ferrian Na-sanidine to anorthoclase in alkalic types) indicate water-deficient, hypersolvus crystallization conditions. Variable volumes of interstitial glass, absence of exsolutions, and lacking deuteric hydrothermal alteration and/or metamorphic/metasomatic overprint are diagnostic of rapid quenching from hypersolidus temperatures. U-Pb zircon ages determined in calcic and calc-alkalic granite xenoliths correspond to a time interval between 5.7 and 5.2 Ma. Positive ɛHf values (14.2 ± 3.9) in zircons from a 5.2-Ma-old calc-alkalic granite xenolith indicate mantle-derived magmas largely unaffected by the assimilation of crustal material. This is in accordance with abundances of diagnostic trace elements (Rb, Y, Nb, Ta), indicating A1-type, OIB-like source magmas. Increased accumulations of Nb-U-REE minerals in these granites indicate higher degree of the magmatic differentiation reflected in Rb-enrichment, contrasting with Ba-enrichment in barren xenoliths. Incipient charnockitization, i.e. orthopyroxene and ilmenite crystallization from interstitial silicate melt, was observed in many granite xenoliths. Thermodynamic modeling using pseudosections showed that the orthopyroxene growth may have been triggered by water exsolution from the melt during ascent of xenoliths in basaltic magma. Euhedral-to-skeletal orthopyroxene growth

  5. Fluid fractionation of tungsten during granite-pegmatite differentiation and the metal source of peribatholitic W quartz veins: Evidence from the Karagwe-Ankole Belt (Rwanda)

    Science.gov (United States)

    Hulsbosch, Niels; Boiron, Marie-Christine; Dewaele, Stijn; Muchez, Philippe

    2016-02-01

    The identification of a magmatic source for granite-associated rare metal (W, Nb, Ta and Sn) mineralisation in metasediment-hosted quartz veins is often obscured by intense fluid-rock interactions which metamorphically overprinted most source signatures in the vein system. In order to address this recurrent metal sourcing problem, we have studied the metasediment-hosted tungsten-bearing quartz veins of the Nyakabingo deposit of the Karagwe-Ankole belt in Central Rwanda. The vein system (992 ± 2 Ma) is spatiotemporal related to the well-characterised B-rich, F-poor G4 leucogranite-pegmatite suite (986 ± 10 Ma to 975 ± 8 Ma) of the Gatumba-Gitarama area which culminated in Nb-Ta-Sn mineralisation. Muscovite in the Nyakabingo veins is significantly enriched in granitophile elements (Rb, Cs, W and Sn) and show alkali metal signatures equivalent to muscovite of less-differentiated pegmatite zones of the Gatumba-Gitarama area. Pegmatitic muscovite records a decrease in W content with increasing differentiation proxies (Rb and Cs), in contrast to the continuous enrichment of other high field strength elements (Nb and Ta) and Sn. This is an indication of a selective redistribution for W by fluid exsolution and fluid fractionation. Primary fluid inclusions in tourmaline of these less-differentiated pegmatites demonstrate the presence of medium to low saline, H2O-NaCl-KCl-MgCl2-complex salt (e.g. Rb, Cs) fluids which started to exsolve at the G4 granite-pegmatite transition stage. Laser ablation inductively coupled plasma mass-spectrometry shows significant tungsten enrichment in these fluid phases (∼5-500 ppm). Fractional crystallisation has been identified previously as the driving mechanism for the transition from G4 granites, less-differentiated biotite, biotite-muscovite towards muscovite pegmatites and eventually columbite-tantalite mineralised pegmatites. The general absence of tungsten mineralisation in this magmatic suite, including the most differentiated

  6. Alteration of alkali reactive aggregates autoclaved in different alkali solutions and application to alkali-aggregate reaction in concrete (II) expansion and microstructure of concrete microbar

    International Nuclear Information System (INIS)

    Lu Duyou; Mei Laibao; Xu Zhongzi; Tang Mingshu; Mo Xiangyin; Fournier, Benoit

    2006-01-01

    The effect of the type of alkalis on the expansion behavior of concrete microbars containing typical aggregate with alkali-silica reactivity and alkali-carbonate reactivity was studied. The results verified that: (1) at the same molar concentration, sodium has the strongest contribution to expansion due to both ASR and ACR, followed by potassium and lithium; (2) sufficient LiOH can completely suppress expansion due to ASR whereas it can induce expansion due to ACR. It is possible to use the duplex effect of LiOH on ASR and ACR to clarify the ACR contribution when ASR and ACR may coexist. It has been shown that a small amount of dolomite in the fine-grained siliceous Spratt limestone, which has always been used as a reference aggregate for high alkali-silica reactivity, might dedolomitize in alkaline environment and contribute to the expansion. That is to say, Spratt limestone may exhibit both alkali-silica and alkali-carbonate reactivity, although alkali-silica reactivity is predominant. Microstructural study suggested that the mechanism in which lithium controls ASR expansion is mainly due to the favorable formation of lithium-containing less-expansive product around aggregate particles and the protection of the reactive aggregate from further attack by alkalis by the lithium-containing product layer

  7. Alkali adsorption on Ni(1 1 1) and their coadsorption with CO and O

    International Nuclear Information System (INIS)

    Politano, A.; Formoso, V.; Chiarello, G.

    2008-01-01

    The adsorption of alkalis (Na, K) on Ni(1 1 1) and their coadsorption with CO and O were studied by high-resolution electron energy loss spectroscopy. Loss measurements of clean alkali adlayers provided the expected behaviour of the alkali-substrate vibration energy as a function of the alkali coverage. This result was achieved by eliminating any trace of CO contamination from the alkali adlayer. As a matter of fact, a significant softening of the alkali-Ni vibration energy was revealed in the alkali + CO coadsorbed phase. Moreover, alkali coadsorption with oxygen caused a weakening of the O-Ni bond and a strengthening of the alkali-Ni bond

  8. Radiatives elements distribution in Serra do Carambei granite, Parana, Brazil

    International Nuclear Information System (INIS)

    Pinto-Coelho, C.V.; Siedlecki, K.N.

    1988-01-01

    In the Serra do Carambei Granite, the uranium present in the rock in anomalous concentration is hosted, preferentially, in accessory mineralogical phases-zircon, xenotime, magnetite and ilmenite, and, in lesser proportion, in the essential minerals of the rock-potassium feldspar and also iron oxydes/hydroxydes and alterated biotite. Optical petrography, autorradiomicrography, scanning electronic microscopy, and the utilization of correlation matrixes and the respective dendrograms revealed a distribution of radioactive elements basically controlled by autometassomatic, tardi/pos-magmatic or supergene processes. Intrusive felsic dikes in the Serra do Carambei Granite have radioelement concentration level approximately four times higher than the enclosing granite, where uranium as well as thorium is preferentially found in metamictized accessory minerals-zircon and allanite. (author) [pt

  9. Figure-Ground Processing: A Reassessment of Gelb and Granit.

    Science.gov (United States)

    Nelson, Rolf; Hebda, Nicholas

    2018-03-01

    In 1923, Adhemar Gelb and Ragnar Granit, two prominent researchers in early Gestalt perceptual theory, reported a lower threshold for detection of a target (a small colored dot) on the ground region of an image than on an adjacent figural region. Although their results had a wide influence on the understanding of figure-ground perception, they are at odds with more recent investigations in which figural regions appear to have a processing advantage over ground regions. The two present studies replicated Gelb and Granit's experiment using a similar figure-ground stimulus albeit with a two-alternative forced choice procedure rather than their original method of adjustment. Experiment 1 found that, contrary to Gelb and Granit's findings, a detection advantage was found for the figural over the ground region. Experiment 2 indicated that explicit contours might have played a role in detection.

  10. Analysis of Shield Construction in Spherical Weathered Granite Development Area

    Science.gov (United States)

    Cao, Quan; Li, Peigang; Gong, Shuhua

    2018-01-01

    The distribution of spherical weathered bodies (commonly known as "boulder") in the granite development area directly affects the shield construction of urban rail transit engineering. This paper is based on the case of shield construction of granite globular development area in Southern China area, the parameter control in shield machine selection and shield advancing during the shield tunneling in this special geological environment is analyzed. And it is suggested that shield machine should be selected for shield construction of granite spherical weathered zone. Driving speed, cutter torque, shield machine thrust, the amount of penetration and the speed of the cutter head of shield machine should be controlled when driving the boulder formation, in order to achieve smooth excavation and reduce the disturbance to the formation.

  11. Laboratory studies of radionuclide transport in fractured Climax granite

    International Nuclear Information System (INIS)

    Failor, R.; Isherwood, D.; Raber, E.; Vandergraaf, T.

    1982-06-01

    This report documents our laboratory studies of radionuclide transport in fractured granite cores. To simulate natural conditions, our laboratory studies used naturally fractured cores and natural ground water from the Climax Granite Stock at the Nevada Test Site. For comparison, additional tests used artificially fractured granite cores or distilled water. Relative to the flow of tritiated water, 85 Sr and /sup 95m/Tc showed little or no retardation, whereas 137 Cs was retarded. After the transport runs the cores retained varying amounts of the injected radionuclides along the fracture. Autoradiography revealed some correlation between sorption and the fracture fill material. Strontium and cesium retention increased when the change was made from natural ground water to distilled water. Artificial fractures retained less 137 Cs than most natural fractures. Estimated fracture apertures from 18 to 60 μm and hydraulic conductivities from 1.7 to 26 x 10 -3 m/s were calculated from the core measurements

  12. Alkali Influence on Synthesis of Solid Electrolyte Based on Alkali Nitrate-Alumina

    International Nuclear Information System (INIS)

    Yustinus Purwamargapratala; Purnama, S.; Purwanto, P.

    2008-01-01

    Research of solid electrolyte based on alumina with addition of alkali materials of barium nitrate, calcium nitrate, sodium nitrate and lithium nitrate has been done. Aluminium hydroxide and alkali nitrate were mixed in mole ratio of 1 : 1 in water media and pyrolyzed at 300 o C for 1 hour Pyrolysis result were then mixed with alumina in mole ratio of 1 : 1, compacted and heated at 600 o C for 3 hours. To characterize the sample, XRD (X-Ray Diffractometers) and LCR meter (impedance, capacitance, and resistance) were used for analysis the phase and conductivity properties. The result showed formation of alkali-aluminate in which Li-base have the highest room temperature conductivity of 3.1290 x 10 -5 S.cm -1 , while Ba-base have the lowest conductivity of 5.7266 x 10 -8 S.cm -1 . (author)

  13. Alkali depletion and ion-beam mixing in glasses

    International Nuclear Information System (INIS)

    Arnold, G.W.

    1983-01-01

    Ion-implantation-induced alkali depletion in simple alkali-silicate glasses (12M 2 O.88SiO 2 ) has been studied for implantations at room temperature and near 77K. Results are consistent with a mechanism for alkali removal, by heavy ion bombardment, based on radiation-enhanced migration and preferential removal of alkali from the outermost layers. Similar results were obtained for mixed-alkali glasses ((12-x)Cs 2 .O.xM 2 O.88SiO 2 ) where, in addition, a mixed-alkali effect may also be operative. Some preliminary experiments with ion implantation through thin Al films on SiO 2 glass and on a phosphate glass show that inter-diffusion takes place and suggest that this ion-mixing technique may be a useful method for altering the physical properties of glass surfaces

  14. Method for the safe disposal of alkali metal

    International Nuclear Information System (INIS)

    Johnson, T.R.

    1977-01-01

    Alkali metals such as those employed in liquid metal coolant systems can be safely reacted to form hydroxides by first dissolving the alkali metal in relatively inert metals such as lead or bismuth. The alloy thus formed is contacted with a molten salt including the alkali metal hydroxide and possibly the alkali metal carbonate in the presence of oxygen. This oxidizes the alkali metal to an oxide which is soluble within the molten salt. The salt is separated and contacted with steam or steam--CO 2 mixture to convert the alkali metal oxide to the hydroxide. These reactions can be conducted with minimal hydrogen evolution and with the heat of reaction distributed between the several reaction steps. 5 claims, 1 figure

  15. Effect of alkali ion on relaxation properties of binary alkali-borate glasses

    International Nuclear Information System (INIS)

    Lomovskoj, V.A.; Bartenev, G.M.

    1992-01-01

    Method of relaxation spectrometry were used to analyze the data on internal friction spectra of lithium, sodium, potassium and rubidium alkali-borate glasses in wide range of temperatures and frequencies. The nature of two relaxation processes was clarified: β m -process, related with mobility of alkaline metal cations, and α-process (vitrification), conditioned by system transformation from viscous-flow to vitreous state. It is shown that atomic-molecular mechanism of vitrification process changes when passing from vitreous B 2 O 3 to alkali-borate glasses

  16. Physical and optical studies in mixed alkali borate glasses with three types of alkali ions

    International Nuclear Information System (INIS)

    Samee, M.A.; Awasthi, A.M.; Shripathi, T.; Bale, Shashidhar; Srinivasu, Ch.; Rahman, Syed

    2011-01-01

    Research highlights: → We report, for the first time, the mixed alkali effect in the (40-x)Li 2 O-xNa 2 O-10K 2 O-50B 2 O 3 glasses through optical properties, density and modulated DSC studies. → Optical band gap (E opt ) and Urbach energy (ΔE) have been evaluated. → The values of E opt and ΔE show non-linear behavior with compositional parameter showing the mixed alkali effect. → The glass stability S is observed to be less which may be important for the present glasses as promising material for non-optical applications. - Abstract: So far only a handful of publications have been concerned with the study of the mixed alkali effect in borate glasses containing three types of alkali ions. In the present work, the mixed alkali effect (MAE) has been investigated in the glass system (40-x)Li 2 O-xNa 2 O-10K 2 O-50B 2 O 3 . (0 ≤ x ≤ 40 mol%) through density and modulated DSC studies. The density and glass transition temperature of the present glasses varies non-linearly exhibiting mixed alkali effect. The glass stability is observed to be less which may be important for the present glasses as promising material for non-optical applications. We report, for the first time, the mixed alkali effect in the present glasses through optical properties. From the absorption edge studies, the values of indirect optical band gap (E opt ), direct optical band gap and Urbach energy (ΔE) have been evaluated. The values of E opt and ΔE show non-linear behavior with compositional parameter showing the mixed alkali effect. The average electronic polarizability of oxide ions α O 2- , optical basicity Λ, and Yamashita-Kurosawa's interaction parameter A have been examined to check the correlations among them and bonding character. Based on good correlation among electronic polarizability of oxide ions, optical basicity and interaction parameter, the present Li 2 O-Na 2 O-K 2 O-B 2 O 3 glasses are classified as normal ionic (basic) oxides.

  17. Survival probability in small angle scattering of low energy alkali ions from alkali covered metal surfaces

    International Nuclear Information System (INIS)

    Neskovic, N.; Ciric, D.; Perovic, B.

    1982-01-01

    The survival probability in small angle scattering of low energy alkali ions from alkali covered metal surfaces is considered. The model is based on the momentum approximation. The projectiles are K + ions and the target is the (001)Ni+K surface. The incident energy is 100 eV and the incident angle 5 0 . The interaction potential of the projectile and the target consists of the Born-Mayer, the dipole and the image charge potentials. The transition probability function corresponds to the resonant electron transition to the 4s projectile energy level. (orig.)

  18. Leaching of gallium from gaiter granite, eastern desert, Egypt

    International Nuclear Information System (INIS)

    Zahran, M.A.; Mahmoud, KH.F.; Mahdy, M.A.; Abd El-Hamid, A.M.

    2006-01-01

    Preliminary leaching tests of gallium from some Egyptian granite rocks such as those of Gabal Gattar area was investigated by using 8 M HCl acid and sodium perchlorate as oxidant. To achieve the optimum leaching conditions, the factors affecting the leaching efficiency as the acid type and concentration, oxidant type and amount, leaching temperature, agitation time, solid / liquid ratio and the effect of grain size were studied. The complete chemical analysis of the collected samples was firstly carried out to determine the chemical features of the Gattarian granite. More than 97% of gallium content was leached when applying these optimum leaching conditions

  19. The Swedish Bohus granite - a stone with a fascinating history

    Science.gov (United States)

    Schouenborg, Björn; Eliasson, Thomas

    2015-04-01

    One of the most well-known and well spread Swedish stone types used as building stones is the Bonus granite. It outcrops in an area north of Gothenburgh (SW Sweden), along the coastline, approximately 35 km wide and 85 km long. The granite continues into Norway as the Iddefjord granite. The Bohus granite is one of Sweden's youngest granites. Isotopic dating shows that the magma cooled at about 920 M years ago and thus marking the end of the Sveconorwegian orogoney. It is a composite granite massif area with several granitic intrusions but with rather homogeneous mineralogy. However, colour and texture varies quite a lot and the colour ranges from red to reddish grey although some pure grey varieties occur sparsely. The grain size ranges from medium grained to coarse grained and even with some porphyric parts. Quarrying in an industrial scale started 1842. The merchant A C Kullgren opened the first quarry and produced stones for the construction of the 86 km long Trollhättan channel connecting lake Vänern and the Atlantic ocean in the SW Sweden The stone was used for constructing harbors and wharves along the channel. Several quarries opened in the late 1800 around 1870 - 1890 and the export increased steadily with deliveries to Germany, Denmark, Holland, England and even to South America. The stone industries in Bohuslän (Bohus county), at its peak in 1929, engaged around 7 000 employees. During the depression in 1930 almost all of them became unemployed. However, as a curiosity, production and export continued to Germany for construction of Germania, the future World capital city ("Welthauptstadt Germania"), planned by Adolf Hitler and Albert Speer. About 500 stone workers were kept employed for this project during the late thirties. Today several varieties are still produced: Evja/Ävja, Tossene, Brastad, Näsinge, Broberg, Nolby, Allemarken and Skarstad. However, the number of stone workers is far from that of the early 1900. The Swedish production is mainly

  20. Threshold Differences on Figure and Ground: Gelb and Granit (1923).

    Science.gov (United States)

    Kinateder, Max; Nelson, Rolf

    2017-01-01

    In 1923, Gelb and Granit, using a method of adjustment for a small red light, reported a lower threshold for the target when presented on a ground region than on an adjacent figural region. More recent work in perceptual organization has found precisely the opposite-a processing advantage seems to go to items presented on the figure, not the ground. Although Gelb and Granit continue to be cited for their finding, it has not previously been available as an English translation. Understanding their methodology and results is important for integrating early Gestalt theory with more recent investigations.

  1. Threshold Differences on Figure and Ground: Gelb and Granit (1923)

    Science.gov (United States)

    Kinateder, Max

    2017-01-01

    In 1923, Gelb and Granit, using a method of adjustment for a small red light, reported a lower threshold for the target when presented on a ground region than on an adjacent figural region. More recent work in perceptual organization has found precisely the opposite—a processing advantage seems to go to items presented on the figure, not the ground. Although Gelb and Granit continue to be cited for their finding, it has not previously been available as an English translation. Understanding their methodology and results is important for integrating early Gestalt theory with more recent investigations. PMID:28286640

  2. Determination of the common and rare alkalies in mineral analysis

    Science.gov (United States)

    Wells, R.C.; Stevens, R.E.

    1934-01-01

    Methods are described which afford a determination of each member of the alkali group and are successful in dealing with the quantities of the rare alkalies found in rocks and minerals. The procedures are relatively rapid and based chiefly on the use of chloroplatinic acid, absolute alcohol and ether, and ammonium sulfate. The percentages of all the alkalies found in a number of minerals are given.

  3. Interaction of alkali metal nitrates with calcium carbonate and kyanite

    International Nuclear Information System (INIS)

    Protsyuk, A.P.; Malakhov, A.I.; Karabanov, V.P.; Lebedeva, L.P.

    1978-01-01

    Thermographic, thermodynamic and X-ray phase studies have been made into the interaction of alkali metal nitrates with calcium carbonate and kyanite. Examined among other things was the effect of water vapor and carbon dioxide on the interaction between alkali metal nitrates and kyanite. The chemical mechanism of the occurring processes has been established. The interaction with calcium carbonates results in the formation of alkali metal carbonates and calcium oxide with liberation of nitrogen oxide and oxygen. The products of the interaction with kyanite are shown to be identical with the compounds forming when alkali metal carbonates are used

  4. Alkali absorption and citrate excretion in calcium nephrolithiasis

    Science.gov (United States)

    Sakhaee, K.; Williams, R. H.; Oh, M. S.; Padalino, P.; Adams-Huet, B.; Whitson, P.; Pak, C. Y.

    1993-01-01

    The role of net gastrointestinal (GI) alkali absorption in the development of hypocitraturia was investigated. The net GI absorption of alkali was estimated from the difference between simple urinary cations (Ca, Mg, Na, and K) and anions (Cl and P). In 131 normal subjects, the 24 h urinary citrate was positively correlated with the net GI absorption of alkali (r = 0.49, p origin of hypocitraturia. However, the normal dependence was maintained in CDS and in idiopathic hypocitraturia, suggesting that reduced citrate excretion was largely dietary in origin as a result of low net alkali absorption (from a probable relative deficiency of vegetables and fruits or a relative excess of animal proteins).

  5. Coprecipitation of alkali metal ions with calcium carbonate

    International Nuclear Information System (INIS)

    Okumura, Minoru; Kitano, Yasushi

    1986-01-01

    The coprecipitation of alkali metal ions Li + , Na + , K + and Rb + with calcium carbonate has been studied experimentally and the following results have been obtained: (1) Alkali metal ions are more easily coprecipitated with aragonite than with calcite. (2) The relationship between the amounts of alkali metal ions coprecipitated with aragonite and their ionic radii shows a parabolic curve with a peak located at Na + which has approximately the same ionic radius as Ca 2+ . (3) However, the amounts of alkali metal ions coprecipitated with calcite decrease with increasing ionic radius of alkali metals. (4) Our results support the hypothesis that (a) alkali metals are in interstitial positions in the crystal structure of calcite and do not substitute for Ca 2+ in the lattice, but (b) in aragonite, alkali metals substitute for Ca 2+ in the crystal structure. (5) Magnesium ions in the parent solution increase the amounts of alkali metal ions (Li + , Na + , K + and Rb + ) coprecipitated with calcite but decrease those with aragonite. (6) Sodium-bearing aragonite decreases the incorporation of other alkali metal ions (Li + , K + and Rb + ) into the aragonite. (author)

  6. Depositional features and stratigraphic sections in granitic plutons: implications for the emplacement and crystallization of granitic magma

    Science.gov (United States)

    Wiebe, R. A.; Collins, W. J.

    1998-09-01

    Many granitic plutons contain sheet-like masses of dioritic to gabbroic rocks or swarms of mafic to intermediate enclaves which represent the input of higher temperature, more mafic magma during crystallization of the granitic plutons. Small-scale structures associated with these bodies (e.g. load-cast and compaction features, silicic pipes extending from granitic layers into adjacent gabbroic sheets) indicate that the sheets and enclave swarms were deposited on a floor of the magma chamber (on granitic crystal mush and beneath crystal-poor magma) while the mafic magma was incompletely crystallized. These structures indicate 'way up', typically toward the interior of the intrusions, and appear to indicate that packages of mafic sheets and enclave concentrations in these plutons are a record of sequential deposition. Hence, these plutons preserve a stratigraphic history of events involved in the construction (filling, replenishment) and crystallization of the magma chamber. The distinctive features of these depositional portions of plutons allow them to be distinguished from sheeted intrusions, which usually preserve mutual intrusive contacts and 'dike-sill' relations of different magma types. The considerable thickness of material that can be interpreted as depositional, and the evidence for replenishment, suggest that magma chamber volumes at any one time were probably much less than the final size of the pluton. Thus, magma chambers may be constructed much more slowly than presently envisaged. The present steep attitudes of these structures in many plutons may have developed gradually as the floor of the chamber (along with the underlying solidified granite and country rock) sank during continuing episodes of magma chamber replenishment. These internal magmatic structures support recent suggestions that the room problem for granites could be largely accommodated by downward movement of country rock beneath the magma chamber.

  7. Late Triassic granites from Bangka, Indonesia: A continuation of the Main Range granite province of the South-East Asian Tin Belt

    Science.gov (United States)

    Ng, Samuel Wai-Pan; Whitehouse, Martin J.; Roselee, Muhammad H.; Teschner, Claudia; Murtadha, Sayed; Oliver, Grahame J. H.; Ghani, Azman A.; Chang, Su-Chin

    2017-05-01

    The South-East Asian Tin Belt is one of the most tin-productive regions in the world. It comprises three north-south oriented granite provinces, of which the arc-related Eastern granite province and the collision-related Main Range granite province run across Thailand, Singapore, and Indonesia. These tin-producing granite provinces with different mineral assemblages are separated by Paleo-Tethyan sutures exposed in Thailand and Malaysia. The Eastern Province is usually characterised by granites with biotite ± hornblende. Main Range granites are sometimes characterised by the presence of biotite ± muscovite. However, the physical boundary between the two types of granite is not well-defined on the Indonesian Tin Islands, because the Paleo-Tethyan suture is not exposed on land there. Both hornblende-bearing (previously interpreted as I-type) and hornblende-barren (previously interpreted as S-type) granites are apparently randomly distributed on the Indonesian Tin Islands. Granites exposed on Bangka, the largest and southernmost Tin Island, no matter whether they are hornblende-bearing or hornblende-barren, are geochemically similar to Malaysian Main Range granites. The average ɛNd(t) value obtained from the granites from Bangka (average ɛNd(t) = -8.2) falls within the range of the Main Range Province (-9.6 to -5.4). These granites have SIMS zircon U-Pb ages of ca. 225 Ma and ca. 220 Ma, respectively that are both within the period of Main Range magmatism (∼226-201 Ma) in the Peninsular Malaysia. We suggest that the granites exposed on Bangka represent the continuation of the Main Range Province, and that the Paleo-Tethyan suture lies to the east of the island.

  8. Smolt monitoring at the head of Lower Granite Reservoir and Lower Granite Dam, 1998.; ANNUAL

    International Nuclear Information System (INIS)

    2000-01-01

    This project monitored the daily passage of chinook salmon Oncorhynchus tshawytscha, steelhead trout O. mykiss, and sockeye salmon smolts O. nerka, during the 1998 spring outmigration at migrant traps on the Snake and Salmon rivers. All hatchery chinook salmon released above Lower Granite Dam 19 1998 were marked with a fin-clip. Total annual hatchery chinook salmon catch at the Snake River trap was 226% of the 1997 number and 110% of the 1996 catch. The wild chinook catch was 120% of the 1997 catch but was only 93% of 1996. Hatchery steelhead trout catch was 501% of 1997 numbers but only 90% of the 1996 numbers. Wild steelhead trout catch was 569% of 1997 and 125% of the 1996 numbers. The Snake River trap collected 106 age-0 chinook salmon. During 1998, for the first time, the Snake River trap captured a significant number of hatchery sockeye salmon (1,552) and hatchery coho salmon O. kisutch (166). Differences in trap catch between years are due to fluctuations not only in smolt production, but also differences in trap efficiency and duration of trap operation associated with high flows. Trap operations began on March 8 and were terminated for the season due to high flows on June 12. The trap was out of operation for 34 d during the season due to high flow and debris. Hatchery chinook salmon catch at the Salmon River trap was 476% and wild chinook salmon catch was 137% of 1997 numbers and 175% and 82% of 1996 catch, respectively. The hatchery steelhead trout collection in 1998 was 96% of the 1997 catch and 13% of the 1996 numbers. Wild steelhead trout collection in 1998 was 170% of the 1997 catch and 37% of the 1996 numbers. Travel time (d) and migration rate (km/d) through Lower Granite Reservoir for PIT-tagged chinook salmon and steelhead trout, marked at the head of the reservoir were affected by discharge. For fish tagged at the Snake River trap, statistical analysis of 1998 detected a significant relation between migration rate and discharge. For hatchery and

  9. Alkali content of fly ash : measuring and testing strategies for compliance : [tech transfer summary].

    Science.gov (United States)

    2015-04-01

    This study investigated the test methods used to determine the : alkali content of fly ash. It also evaluated if high-alkali fly ash : exacerbates alkali-silica reaction in laboratory tests and field : concrete.

  10. Alkali content of fly ash : measuring and testing strategies for compliance.

    Science.gov (United States)

    2015-04-01

    Sodium and potassium are the common alkalis present in fly ash. Excessive amounts of fly ash alkalis can cause efflorescence : problems in concrete products and raise concern about the effectiveness of the fly ash to mitigate alkali-silica reaction (...

  11. 76 FR 62758 - Wallowa-Whitman and Umatilla National Forests, Oregon Granite Creek Watershed Mining Plans

    Science.gov (United States)

    2011-10-11

    ... environmental analyses for proposed mining Plans in the portions of the Granite Creek Watershed under their... Granite Creek Watershed Mining Plans analysis area that meets the Purpose of and Need for Action. It is... Granite Creek Watershed Mining Plans AGENCY: Forest Service, USDA. ACTION: Notice of intent to prepare an...

  12. Granites of Zoz area, Baroda district, Gujarat and its economic significance

    International Nuclear Information System (INIS)

    Maithani, P.B.; Rathaiah, Y.V.; Varughese, Siby K.; Singh, Rajendra

    1998-01-01

    The granites around Zoz represent a differentiated, calc-alkaline, subaluminous, A-type granite with higher uranium content. The A-type affinity points to the possibility of encountering Sn, Mo, Bi, Nb, Ta and F mineralization in the area. The low Th/U ratio also favours vein type U-deposits within granites or in adjacent metasediments. (author)

  13. Alkali emissions of the PCFB-process

    International Nuclear Information System (INIS)

    Kuivalainen, R.; Eriksson, T.; Koskinen, J.; Lehtonen, P.

    1995-01-01

    Pressurized Circulating Fluidized Bed (PCFB) combustion technology has been developed by A. Ahlstrom Corporation since 1986. As a part of the development, a 10 MW PCFB Test Facility was constructed at Hans Ahlstrom Laboratory in Karhula, Finland in 1989. The Test Facility has been used for performance testing with different coal types through the years 1990-1994 in order to gain data for design and commercialization of the high-efficiency low- emission PCFB combustion technology. The project Y33 'Alkali emissions of the PCFB-process' was part of national LIEKKI 2 research program. The object of the project was to measure vapor phase Na and K concentrations in the PCFB flue gas after hot gas filter and investigate the effects of process conditions and sorbents on alkali release. The measured Na concentrations were between 0,03 and 0,21 ppm(w). The results of K were between 0,01 and 0,08 ppm(w). The accuracy of the results is about +-50 percent at this concentration range. The scatter of the data covers the effects of different process variables on the alkali emission . The measured emissions at 800-850 deg C are at the same order of magnitude as the guideline emission limits given by gas turbine manufacturers for flue gas at 1000-1200 deg C. The measurements and development of the analyses methods are planned to be continued during PcFB test runs in autumn 1995 in cooperation with laboratories of VTT Energy and Tampere University of Technology. (author)

  14. The Landforms of Granitic Rocks: An Annotated Bibliography

    Science.gov (United States)

    1990-05-01

    vertical joints are dominant. Duricrust and rock basins are common. The latter are independent of jointing and are associated with the older, thicker... duricrust . 15 Davis, W. M. 1933. Granitic domes of the Mohave Desert, California. Transactions of the San Diego Society of Natural History, vol. 7, pp

  15. Monte Carlo simulations for generic granite repository studies

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Shaoping [Los Alamos National Laboratory; Lee, Joon H [SNL; Wang, Yifeng [SNL

    2010-12-08

    In a collaborative study between Los Alamos National Laboratory (LANL) and Sandia National Laboratories (SNL) for the DOE-NE Office of Fuel Cycle Technologies Used Fuel Disposition (UFD) Campaign project, we have conducted preliminary system-level analyses to support the development of a long-term strategy for geologic disposal of high-level radioactive waste. A general modeling framework consisting of a near- and a far-field submodel for a granite GDSE was developed. A representative far-field transport model for a generic granite repository was merged with an integrated systems (GoldSim) near-field model. Integrated Monte Carlo model runs with the combined near- and farfield transport models were performed, and the parameter sensitivities were evaluated for the combined system. In addition, a sub-set of radionuclides that are potentially important to repository performance were identified and evaluated for a series of model runs. The analyses were conducted with different waste inventory scenarios. Analyses were also conducted for different repository radionuelide release scenarios. While the results to date are for a generic granite repository, the work establishes the method to be used in the future to provide guidance on the development of strategy for long-term disposal of high-level radioactive waste in a granite repository.

  16. Chemical Variations in a Granitic Pluton and Its Surrounding Rocks.

    Science.gov (United States)

    Baird, A K; McIntyre, D B; Welday, E E; Madlem, K W

    1964-10-09

    New techniques of x-ray fluorescence spectrography have provided, for the first time, abundant data regarding chemical variability of granitic rocks on different scales. The results suggest that current designs of sampling plans for trend surface analysis should be modified; in particular several specimens, preferably drillcores, may be required at each locality.

  17. Assessment of radioactivity in building material(granite) in Sudan

    International Nuclear Information System (INIS)

    Osman, Z. A; Salih, I; Albadwai, K. A; Salih, A. M; Salih, S. A.

    2016-01-01

    In the present work radioactivity in building materials (granite) central Sudan was evaluated. In general the building materials used in Sudan are derived either from rocks or soil. These contain trace amounts of naturally occurring radioactive materials(NORMs), so it contains radionuclides from uranium and thorium series and natural potassium. The levels of these radionuclides vary according to the geology of their site of origin. High levels increase the risk of radiation exposure in homes(especially exposure due to radon). Investigation of radioactivity in granite used of the building materials in Sudan is carried out, a total of 18 major samples of granite have been collected and measured using X- ray fluorescence system (30 mci). The activity concentrations have been determined for uranium ("2"3"8U), thorium ('2"3"2Th) and potassium("4"0K) in each sample. The concentrations of uranium have been found to range from 14.81 Bq/kg to 24.572 Bq/kg, thorium between 10.02 Bq/kg and 10.020-84.79 Bq/kg and the potassium concentration varies between 13.33 Bq/kg to 82.13 Bq/kg. Limits of radioactivity in the granite are based on dose criteria for controls. This study can be used as a reference for more extensive studies of the same subject in future. (Author)

  18. Granite-related Hypothermal Uranium Mineralization in South China

    International Nuclear Information System (INIS)

    Liu Xiaodong; Wu Jianhua; Pan Jiangyong; Zhu Mingqian

    2014-01-01

    Moer and more evidence indicates that there are multi-stages uranium mineralization in many granite-related uranium deposits in south China. The early stage mineralization shares the characters of hypothermal U mineralization and had close relations to alkaline alterations.

  19. Geochemical trends in the weathered profiles above granite gneiss ...

    African Journals Online (AJOL)

    Geochemical trends in the weathered profiles above granite gneiss and schist of Abeokuta area, southwestern Nigeria. Anthony T Bolarinwa, Anthony A Elueze. Abstract. No Abstract. Journal of Mining and Geology 2005, Vol. 41(1): 19-31. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT ...

  20. Extraction of Th and U from Swiss granites

    International Nuclear Information System (INIS)

    Bajo, C.

    1980-12-01

    The extraction, at the laboratory level, of U and Th from Swiss granites is discussed. The Mittagfluh, Bergell and Rotondo granites and the Giuv syenite offered a wide range of U and Th concentrations; 7.7 to 20.0 ppm U and 25.5 to 67.0 ppm Th. U and Th were determined in the leach solutions by the fission track method and by spectrophotometry, respectively. Samples containing less than 0.3 μg U and 4 μg Th, could be measured with an accuracy of 10% for U and 5% for Th. Leach tests were performed during which the following parameters were varied: granite-type, grain size, acid-type, acid concentration, temperature and time. There were very great leaching differences between the granites studied. Temperature was the most important parameter. Sharp differences in extraction occurred between 20 0 C, 50 0 C and 80 0 C. At 80 0 C, more than 85% U and Th were extracted. The extraction curve (percent extracted as a function of time) of aliquots sampled after 1, 2, 4, 8, 12 and 24 hours showed a plateau after 8 hours. The half life of the reaction was between one and two hours. As a general rule, Th was better extracted than U. (Auth.)

  1. Preliminary study of radioactive waste disposal in granitic underground caves

    International Nuclear Information System (INIS)

    Carvalho, J.F. de; Carajilescov, P.

    1984-01-01

    To date, the disposal of radioactive wastes is one of the major problems faced by the nuclear industry. The utilization of granitic underground caves surrounded by a clay envelope is suggested as a safe alternative for such disposal. A preliminary analysis of the dimensions of those deposits is done. (Author) [pt

  2. Cathode architectures for alkali metal / oxygen batteries

    Science.gov (United States)

    Visco, Steven J; Nimon, Vitaliy; De Jonghe, Lutgard C; Volfkovich, Yury; Bograchev, Daniil

    2015-01-13

    Electrochemical energy storage devices, such as alkali metal-oxygen battery cells (e.g., non-aqueous lithium-air cells), have a cathode architecture with a porous structure and pore composition that is tailored to improve cell performance, especially as it pertains to one or more of the discharge/charge rate, cycle life, and delivered ampere-hour capacity. A porous cathode architecture having a pore volume that is derived from pores of varying radii wherein the pore size distribution is tailored as a function of the architecture thickness is one way to achieve one or more of the aforementioned cell performance improvements.

  3. Etude de la diagraphie neutron du granite de Beauvoir. Effet neutron des altérations et de la matrice du granite. Calibration granite. Porosité totale à l'eau et porosité neutron Analysis of the Beauvoir Granite Neutron Log. Neutron Effect of Alterations and of the Granite Matrix. Granite Calibration. Total Water Porosity and Neutron Porosity

    Directory of Open Access Journals (Sweden)

    Galle C.

    2006-11-01

    Full Text Available Cet article rend compte des travaux effectués sur la porosité du granite de Beauvoir (Sondage GPF 1 d'Echassières, Massif Central français. L'objectif de notre étude est de pouvoir obtenir des valeurs représentatives de la saturation en eau (porosité totale à l'eau n du granite de Beauvoir à partir des mesures de porosité neutron PorositéN (diagraphie neutron BRGM sans avoir recours aux mesures sur carottes. Notre démarche est expérimentale et nous avons tenté d'approfondir certains problèmes liés à l'utilisation de la diagraphie neutron dans une roche granitique. Deux facteurs principaux conditionnent la réponse neutron : la concentration en hydrogène de la formation (eau libre et eau de constitution de certains minéraux et la présence d'éléments absorbeurs à forte section de capture comme le gadolinium, le cadmium, le bore, . . . et dans le cas du granite de Beauvoir, le lithium. A partir des mesures de porosité totale à l'eau n sur carottes, des essais de pertes au feu sur poudre qui nous permettent de déterminer la porosité neutron liée à l'eau de constitution PorositéN(OH- et des analyses chimiques avec lesquelles nous évaluons la porosité neutron thermique PorositéN(ox (Programme SNUPAR, Schlumberger liée à la capture neutronique, nous reconstituons la porosité neutron totale PorositéNR du granite de Beauvoir. Pour 7 échantillons caractéristiques du granite de Beauvoir, nous réalisons grâce à ces résultats une nouvelle calibration du taux de comptage neutron initial corrigé du gradient thermique et de l'effet de trou. Grâce à cette opération, il est possible de déterminer, pour les échantillons traités, la porosité neutron du granite avec une calibration granite (PorositéNg et non calcaire (PorositéNc. La connaissance de l'effet neutron de la matrice nous permet enfin d'évaluer la teneur en eau du granite (porosité totale à l'eau et de comparer celle-ci avec la porosité mesurée sur

  4. The transition from granite to banded aplite-pegmatite sheet complexes: An example from Megiliggar Rocks, Tregonning topaz granite, Cornwall

    Czech Academy of Sciences Publication Activity Database

    Breiter, Karel; Ďurišová, Jana; Hrstka, Tomáš; Korbelová, Zuzana; Vašinová Galiová, M.; Müller, A.; Simons, B.; Shail, R. K.; Williamson, B. J.; Davies, J. A.

    302/303, March 2018 (2018), s. 370-388 ISSN 0024-4937 R&D Projects: GA ČR GA14-13600S Institutional support: RVO:67985831 Keywords : granite * aplite * pegmatite * magmatic layering * Megiliggar Rocks * Cornwall Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Geology Impact factor: 3.677, year: 2016

  5. Possible applications of alkali-activated systems in construction

    OpenAIRE

    Boháčová, J.; Staněk, S.; Vavro, M. (Martin)

    2013-01-01

    This paper deals with the possibilities of using alkali-activated systems in construction. This article summarizes the advantages and disadvantages of geopolymer in comparison to Portland cement, summarizes research and practical applications of alkali-activated materials in our country and abroad, and provides an overview of directions where these alternative inorganic binders can be in the future very well applied.

  6. Structural, elastic, electronic and optical properties of bi-alkali ...

    Indian Academy of Sciences (India)

    The structural parameters, elastic constants, electronic and optical properties of the bi-alkali ... and efficient method for the calculation of the ground-state ... Figure 2. Optimization curve (E–V) of the bi-alkali antimonides: (a) Na2KSb, (b) Na2RbSb, (c) Na2CsSb, .... ical shape of the charge distributions in the contour plots.

  7. Thermochemical properties of the alkali hydroxides: A review

    International Nuclear Information System (INIS)

    Konings, R.J.M.; Cordfunke, E.H.P.

    1989-01-01

    The formation of volatile alkali hydroxides as a result of high-temperature steam corrosion plays an important role in nuclear technology. For the modeling of the volatilization processes, reliable thermodynamic data are required. In the present paper recent physico-chemical experiments by the authors will be discussed and the thermochemical properties of the alkali hydroxide series will be evaluated. (orig.)

  8. Language and Style in Zaynab Alkali's The Stillborn | Azuike ...

    African Journals Online (AJOL)

    This paper examines the language and style of Zaynab Alkali's The Stillborn. Alkali's style in The Stillborn lies in her effective deployment of linguo-literary resources to tell the story. The study scrutinizes the nexus of figures of speech and linguistic artifacts, which link the events and characters that populate her novel and ...

  9. 40 CFR 721.4660 - Alcohol, alkali metal salt.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alcohol, alkali metal salt. 721.4660 Section 721.4660 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4660 Alcohol, alkali metal sal...

  10. Alkali aggregate reactivity in concrete structures in western Canada

    International Nuclear Information System (INIS)

    Morgan, D.R.; Empey, D.

    1989-01-01

    In several regions of Canada, particularly parts of Ontario, Quebec and the Maritime Provinces, research, testing and evaluation of aged concrete structures in the field has shown that alkali aggregate reactivity can give rise to pronounced concrete deterioration, particularly in hydraulic structures subjected to saturation or alternate wetting and drying such as locks, dams, canals, etc. Concrete deterioration is mainly caused by alkali-silica reactions and alkali-carbonate reactions, but a third type of deterioration involves slow/late expanding alkali-silicate/silica reactivity. The alkalies NaOH and KOH in the concrete pore solutions are mainly responsible for attack on expansive rocks and minerals in concrete. Methods for evaluating alkali-aggregate reaction potential in aggregates, and field and laboratory methods for detecting deterioration are discussed. Examples of alkali-aggregate reactions in structures is western Canada are detailed, including a water reservoir at Canadian Forces Base Chilliwack in British Columbia, the Oldman River diversion and flume, the Lundbreck Falls Bridge, and the St Mary's Reservoir spillway, all in southern Alberta. Mitigative measures include avoidance of use of suspect aggregates, but if this cannot be avoided it is recommended to keep the total alkalies in the concrete as low as possible and minimize opportunities for saturation of concrete by moisture. 16 refs., 19 figs., 1 tab

  11. Metal analyses of ash derived alkalis from banana and plantain ...

    African Journals Online (AJOL)

    The objective of this work was to determine the metal content of plantain and banana peels ash derived alkali and the possibility of using it as alternate and cheap source of alkali in soap industry. This was done by ashing the peels and dissolving it in de-ionised water to achieve the corresponding hydroxides with pH above ...

  12. [Raman spectra of endospores of Bacillus subtilis by alkali stress].

    Science.gov (United States)

    Dong, Rong; Lu, Ming-qian; Li, Feng; Shi, Gui-yu; Huang, Shu-shi

    2013-09-01

    To research the lethal mechanism of spores stressed by alkali, laser tweezers Raman spectroscopy (LTRS) combined with principal components analysis (PCA) was used to study the physiological process of single spore with alkali stress. The results showed that both spores and germinated spores had tolerance with alkali in a certain range, but the ability of spores was obviously lower than that of spores due to the release of their Ca2+ -DPA which plays a key role in spores resistance as well as spores resistance to many stresses; A small amount of Ca2+ -DPA of spores was observed to release after alkali stress, however, the behavior of release was different with the normal Ca2+ -DPA release behavior induced by L-alanine; The data before and after alkali stress of the spores and g. spores with PCA reflected that alkali mainly injured the membrane of spores, and alkali could be easily enter into the inner structure of spores to damage the structure of protein backbone and injure the nucleic acid of spores. We show that the alkali could result in the small amount of Ca2+ -DPA released by destroying the member channel of spores.

  13. Conduction bands and invariant energy gaps in alkali bromides

    NARCIS (Netherlands)

    Boer, P.K. de; Groot, R.A. de

    1998-01-01

    Electronic structure calculations of the alkali bromides LiBr, NaBr, KBr, RbBr and CsBr are reported. It is shown that the conduction band has primarily bromine character. The size of the band gaps of bromides and alkali halides in general is reinterpreted.

  14. Formation of lysinoalanine in egg white under alkali treatment.

    Science.gov (United States)

    Zhao, Yan; Luo, Xuying; Li, Jianke; Xu, Mingsheng; Tu, Yonggang

    2016-03-01

    To investigate the formation mechanism of lysinoalanine (LAL) in eggs during the alkali treatment process, NaOH was used for the direct alkali treatment of egg white, ovalbumin, and amino acids; in addition, the amount of LAL formed during the alkali treatment process was measured. The results showed that the alkali treatment resulted in the formation of LAL in the egg white. The LAL content increased with increasing pH and temperature, with the LAL content first increasing and then leveling off with increasing time. The amount of LAL formed in the ovalbumin under the alkali treatment condition accounted for approximately 50.51% to 58.68% of the amount of LAL formed in the egg white. Thus, the LAL formed in the ovalbumin was the main source for the LAL in the egg white during the alkali treatment process. Under the alkali treatment condition, free L-serine, L-cysteine, and L-cystine reacted with L-lysine to form LAL; therefore, they are the precursor amino acids of LAL formed in eggs during the alkali treatment process. © 2016 Poultry Science Association Inc.

  15. Density functional study of ferromagnetism in alkali metal thin films

    Indian Academy of Sciences (India)

    thickness uniform jellium model (UJM), and it is argued that within LSDA or GGA, alkali metal thin films cannot be claimed to have an FM ground state. Relevance of these results to the experiments on transition metal-doped alkali metal thin films ...

  16. A Rb-Sr isotope study of a young granite sheet at Marble Delta, southern Natal

    International Nuclear Information System (INIS)

    Naidoo, D.D.; Eglington, B.M.; Harmer, R.E.

    1989-01-01

    Rb-Sr isotope data are presented for two apophyses of a granite sheet intrusive into marble at Marble Delta, southern Natal. Granite samples collected near the margins of these apophyses contain calcite and are thought to have been contaminated by the marble during intrusion of the granite magma. In contrast, those further away from contacts lack calcite. The 'uncontaminated' granite samples define an isochron date of 899 ± 11 Ma. This data is thought to represent the intrusive age of the granite sheet. 11 refs., 5 figs., 2 tabs

  17. The utilization of alkali-treated melon husk by broilers.

    Science.gov (United States)

    Abiola, S S; Amalime, A C; Akadiri, K C

    2002-09-01

    The effects of alkali treatment on chemical constituents of melon husk (MH) and performance characteristics of broilers fed alkali-treated MH (ATMH) diets were investigated. The chemical analysis showed that alkali treatment increased the ash content of MH (from 15.70% to 16.86%) and reduced the crude fibre content (from 29.00% to 14.00%). Result of feed intake was superior on 30% alkali diet with a value of 100.14 g/bird/day. Body weight gain decreased with increase in the level of ATMH in the diet. Highest dressing percentage of 66.33% and best meat/bone ratio of 2.57 were obtained on 10% and 20% alkali diets, respectively. Dietary treatments had significant effect (P poultry carcases and chicken meat with favourable shelf life.

  18. Electronic and atomic structures of liquid tellurium containing alkali elements

    International Nuclear Information System (INIS)

    Kawakita, Yukinobu; Yao, Makoto; Endo, Hirohisa.

    1997-01-01

    The measurements of electrical conductivity σ, density, EXAFS and neutron scattering were carried out for liquid K-Te and Rb-Te mixtures. The conductivity σ decreases rapidly with alkali concentration and a metal-semiconductor transition occurs at about 10 at.% alkali. It is found that the compositional variation of σ is nearly independent of the alkali species. The Te-Te bond length deduced from EXAFS and neutron scattering measurements is 2.8 A and changes little with alkali concentrations. The average distances from K and Rb atom to Te atoms are 3.6 A and 3.8 A, respectively. Two kinds of relaxation processes are observed in quasielastic neutron scattering for K 20 Te 80 . Upon the addition of alkali the interaction between the neighbouring Te chains, which is responsible for the metallic conduction, weaken considerably. (author)

  19. Zarzalejo granite (Spain). A nomination for 'Global Heritage Stone Resource'

    Science.gov (United States)

    Freire Lista, David Martin; Fort, Rafael; José Varas-Muriel, María

    2015-04-01

    Zarzalejo granite is quarried in the Sierra de Guadarrama (Spanish Central System) foothills, in and around Zarzalejo village, in the province of Madrid, Spain. It is an inequigranular monzogranite medium-to-coarse grained, with a slight porphyritic texture (feldspar phenocrysts) and mafic micro-grained enclaves. In this abstract the candidacy of Zarzalejo granite as a "Global Heritage Resource Stone" (GHSR) is presented. This stone ideally fits the newly proposed designation as it has been used in many heritage buildings and its good petrophysical properties and durability have allowed well preserved constructions such as a Roman road, San Pedro Church in Zarzalejo (1492), Descalzas Reales Monastery in Madrid (1559-1564) and the San Lorenzo del Escorial Royal Monastery (1563-1584), to be declared a World Heritage Site by UNESCO. This level of construction has been a landmark in the extraction and proliferation of historic quarries created due to the high demand that such colossal monuments and buildings with granite, have required for their construction. In the mid-20th century, More, Zarzalejo granite has also been used in restoration works including the Royal Palace and the Reina Sofía Museum (2001-2005), both buildings in Madrid, Spain. Extraction of granite ashlars from tors has been a very frequent activity in the Zarzalejo neighbourhood until mid-twentieth century. So there is also a need to preserve these historic quarries. This type of stone has created a landscape that has been preserved as an open-air museum today where you can see the marks left in the granite due to historic quarry operations. The granite industry has been one of the main pillars of the Zarzalejo regional economy. For centuries, the local community have been engaged in quarrying and have created a cultural landscape based on its building stone. A quarryman monument has been erected in Zarzalejo in honor of this traditional craft as well as an architecture museum at San Lorenzo del

  20. Experimental analysis on physical and mechanical properties of thermal shock damage of granite

    Directory of Open Access Journals (Sweden)

    He Xiao

    2017-01-01

    Full Text Available The purpose of this study was to explore the changes of mechanical and physical properties of granite under different thermal loading effects. Uniaxial compression experiments studying the rules of the influence of temperature load on mechanical properties of granite were carried out. After high-temperature heating at above 600 °C, granite tended to have stronger ductility and plasticity as well as declined peak stress and compressive strength. Thermogravimetry - differential scanning calorimetry (TG-DSC analysis results showed that, thermal load at different temperatures induced reactions such as water loss, oxidation and crystallization in the microstructure of granite, which led to physical changes of granite. Hence it is concluded that, heating can significantly weaken the mechanical performance of granite, which provides an important support for the optimization of heating assisted processing of granite. It also reveals that, heating assisted cutting technique can effectively lower energy consumption and improve processing efficiency.

  1. IRMPD Action Spectroscopy of Alkali Metal Cation-Cytosine Complexes: Effects of Alkali Metal Cation Size on Gas Phase Conformation

    NARCIS (Netherlands)

    Yang, B.; Wu, R.R.; Polfer, N.C.; Berden, G.; Oomens, J.; Rodgers, M.T.

    2013-01-01

    The gas-phase structures of alkali metal cation-cytosine complexes generated by electrospray ionization are probed via infrared multiple photon dissociation (IRMPD) action spectroscopy and theoretical calculations. IRMPD action spectra of five alkali metal cation-cytosine complexes exhibit both

  2. The alkali halide disk technique in infra-red spectrometry : Anomalous behaviour of some samples dispersed in alkali halide disks

    NARCIS (Netherlands)

    Tolk, A.

    1961-01-01

    Some difficulties encountered in the application of the alkali halide disk technique in infra-red spectrometry are discussed. Complications due to interaction of the sample with the alkali halide have been studied experimentally. It was found that the anomalous behaviour of benzoic acid, succinic

  3. Structure and electrical resistivity of alkali-alkali and lithium-based liquid binary alloys

    International Nuclear Information System (INIS)

    Mishra, A.K.; Mukherjee, K.K.

    1990-01-01

    Harmonic model potential, developed and used for simple metals is applied here to evaluate hardsphere diameters, which ensure minimum interionic pair potential for alkali-alkali (Na-K, Na-Rb, Na-Cs, K-Rb, K-Cs) and lithium-based (Li-Na, Li-Mg, Li-In, Li-Tl) liquid binary alloys as a function of composition for use in the determination of their partial structure factors. These structure factors are then used to calculate electrical resistivities of alloys considered. The computed values of electrical resistivity as a function of composition agree both, in magnitude and gradient reasonably well with experimental values in all cases except in Cs systems, where the disagreement is appreciable. (author)

  4. Mineral chemistry and geochemistry of the Late Neoproterozoic Gabal Abu Diab granitoids, Central Eastern Dessert, Egypt: Implications for the origin of rare metal post-orogenic A-type granites

    Science.gov (United States)

    Sami, Mabrouk; Ntaflos, Theodoros; Farahat, Esam S.; Ahmed, Awaad F.; Mohamed, Haroun A.

    2015-04-01

    within A-type granite worldwide. According to Zhang et al., 2012, the garnet crystallized at the expense of biotite from the MnO-rich evolved melt after fractionation of biotite, plagioclase, K-feldspar, zircon, apatite, and ilmenite. The granitoids are alkali feldspar granites showing distinct geochemical features and most likely, belong to the post-orogenic younger Egyptian granitoids. They are peraluminous A-type alkaline rocks but they have lower Fe2O3, MgO, MnO, CaO, TiO2, P2O5, Sr, Ba, V, and higher SiO2, Na2O, K2O, Nb, Ta, U, Zr, Th, Ga/Al and Rb than the typical rocks of this type. The positive correlation between Ba and Sr, and the negative correlation between Rb and K/Rb reveal fractional crystallization of alkali feldspar. The similarity in most geochemical characteristics suggests that Abu Diab granitoids are genetically related to each other and extremely enrichment in incompatible elements such as Nb and Ta, indicating that they crystallized from extremely differentiated magmas. References: Zhang, J., Ma, C. and She, Z., 2012. An Early Cretaceous garnet-bearing metaluminous A-type granite intrusion in the East Qinling Orogen, central China: Petrological, mineralogical and geochemical constraints. Geoscience Frontiers 3 (5), 635-646.

  5. Radon exhalation rates of some granites used in Serbia

    Directory of Open Access Journals (Sweden)

    Nikolić Mladen D.

    2015-01-01

    Full Text Available In order to address concern about radon exhalation in building material, radon exhalation rate was determined for different granites available on Serbian market. Radon exhalation rate, along with mass exhalation rate and effective radium content were determined by closed chamber method and active continuous radon measurement technique. For this research, special chambers were made and tested for back diffusion and leakage, and the radon concentrations measured were included in the calculation of radon exhalation. The radon exhalation rate ranged from 0.161 Bq/m2h to 0.576 Bq/m2h, the mass exhalation rate from 0.167 Bq/kgh to 0.678 Bq/kgh, while the effective radium content was found to be from 12.37 Bq/kg to 50.23 Bq/kg. The results indicate that the granites used in Serbia have a low level of radon exhalation.

  6. Quantized Ultracold Neutrons in Rough Waveguides: GRANIT Experiments and Beyond

    Directory of Open Access Journals (Sweden)

    M. Escobar

    2014-01-01

    Full Text Available We apply our general theory of transport in systems with random rough boundaries to gravitationally quantized ultracold neutrons in rough waveguides as in GRANIT experiments (ILL, Grenoble. We consider waveguides with roughness in both two and one dimensions (2D and 1D. In the biased diffusion approximation the depletion times for the gravitational quantum states can be easily expressed via each other irrespective of the system parameters. The calculation of the exit neutron count reduces to evaluation of a single constant which contains a complicated integral of the correlation function of surface roughness. In the case of 1D roughness (random grating this constant is calculated analytically for common types of the correlation functions. The results obey simple scaling relations which are slightly different in 1D and 2D. We predict the exit neutron count for the new GRANIT cell.

  7. Failure of Sierra White granite under general states of stress

    Science.gov (United States)

    Ingraham, M. D.; Dewers, T. A.; Lee, M.; Holdman, O.; Cheung, C.; Haimson, B. C.

    2017-12-01

    The effect of the intermediate principal stress on the failure of Sierra White granite was investigated by performing tests under true triaxial states of stress. Tests were performed under constant Lode angle conditions with Lode angles ranging from 0 to 30°, pure shear to axisymmetric compression. Results show that the failure of Sierra White granite is heavily dependent on the intermediate principal stress which became more dramatic as the mean stress increased. An analysis of the shear bands formed at failure was performed using an associated flow rule and the Rudnicki and Rice (1975) localization criteria. The localization analysis showed excellent agreement with experimental results. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA0003525.

  8. Maternal exposure to alkali, alkali earth, transition and other metals: Concentrations and predictors of exposure

    International Nuclear Information System (INIS)

    Hinwood, A.L.; Stasinska, A.; Callan, A.C.; Heyworth, J.; Ramalingam, M.; Boyce, M.; McCafferty, P.; Odland, J.Ø.

    2015-01-01

    Most studies of metals exposure focus on the heavy metals. There are many other metals (the transition, alkali and alkaline earth metals in particular) in common use in electronics, defense industries, emitted via combustion and which are naturally present in the environment, that have received limited attention in terms of human exposure. We analysed samples of whole blood (172), urine (173) and drinking water (172) for antimony, beryllium, bismuth, cesium, gallium, rubidium, silver, strontium, thallium, thorium and vanadium using ICPMS. In general most metals concentrations were low and below the analytical limit of detection with some high concentrations observed. Few factors examined in regression models were shown to influence biological metals concentrations and explained little of the variation. Further study is required to establish the source of metals exposures at the high end of the ranges of concentrations measured and the potential for any adverse health impacts in children. - This study has demonstrated exposure to alkali, alkali earth and transition metals in pregnant women with factors such as breastfeeding, fish oil use and diet affecting exposures

  9. Volcanic Origin of Alkali Halides on Io

    Science.gov (United States)

    Schaefer, L.; Fegley, B., Jr.

    2003-01-01

    The recent observation of NaCl (gas) on Io confirms our earlier prediction that NaCl is produced volcanically. Here we extend our calculations by modeling thermochemical equilibrium of O, S, Li, Na, K, Rb, Cs, F, Cl, Br, and I as a function of temperature and pressure in a Pele-like volcanic gas with O/S/Na/Cl/K = 1.518/1/0.05/0.04/0.005 and CI chondritic ratios of the other (as yet unobserved) alkalis and halogens. For reference, the nominal temperature and pressure for Pele is 1760 plus or minus 210 K and 0.01 bars based on Galileo data and modeling.

  10. Closed N-shell alkali spectra

    International Nuclear Information System (INIS)

    Ellis, D.G.; Curtis, L.J.

    1982-01-01

    Term values and ionization potentials have been calculated for several ions in the promethium (N = 61) isoelectronic sequence. As the nuclear charge is increased, the ground configuration changes from 4f 13 5s 2 to 4f 14 5s giving the upper portion of the sequence an alkali-like character. According to our most recent Hartree-Fock calculations with first-order relativistic corrections, the ground term is 5s 2 S for Z > 77 (Ir XVII) and the first excited term is 5p 2 P 0 for Z > 84 (P 0 XXIV). Comparisons are made with calculations of Cowan in W XIV. The prospects for observation of these spectra in fast ion beams are discussed. (orig.)

  11. Existence of hexachlorocerates (4) of alkali metals

    Energy Technology Data Exchange (ETDEWEB)

    Kiselev, Yu.M.; Filatov, I.Yu.; Popov, A.I.; Goryachenkova, S.A.; Martynenko, L.I.; Spitsyn, V.I. (Moskovskij Gosudarstvennyj Univ. (USSR))

    1985-01-01

    A possibility has been studied to prepare alkali metal hexachlorocerates (4) of the composition M/sub 2/CeCl/sub 6/ (M=Li, Na, K, Rb) according to the reaction 2MX + fH/sub 2/CeCl/sub 6/'' ..-->.. 2HX + M/sub 2/CeCl/sub 6/ (X=Cl/sup -/, NO/sub 3//sup -/). Using X-ray phase analysis and low-temperature hTA it has been shown, that under experimental conditions (-65 deg C) the rubidium-cerium chlorocomplex is formed, in which Ce is present in the form of Ce(4). The complex is unstable at approximately 20 deg C and under the effect of moisture gets hydrolyzed with the formation of Ce(3) derivatives. Isomorphism of Rb and Cs hexachlorocerates (4) is established. According to the data of the low-temperature DTA, the authors failed to prepare Li, Na, K hexachlorocerates (4).

  12. Radiation chemistry of the alkali halides

    International Nuclear Information System (INIS)

    Robinson, V.J.; Chandratillake, M.R.

    1987-01-01

    By far the most thoroughly investigated group of compounds in solid-state radiation chemistry are the alkali halides. Some of the reasons are undoubtedly practical: large single crystals of high purity are readily prepared. The crystals are transparent over a wide range of wavelengths. They are more sensitive to radiation damage than most other ionic solids. The crystals have simple well-defined structures, and the products of radiolysis have also in many cases been clearly identified by a variety of experimental techniques, the most important being optical methods and electron paramagnetic resonance (EPR). In recent years the application of pulse techniques-radiolysis and laser photolysis-has yielded a wealth of information concerning the mechanisms of the primary processes of radiation damage, on the one hand, and of thermal and photolytic reactions that the radiolysis products undergo, on the other

  13. Controlled in-situ dissolution of an alkali metal

    Science.gov (United States)

    Jones, Jeffrey Donald; Dooley, Kirk John; Tolman, David Donald

    2012-09-11

    A method for the controllable dissolution of one or more alkali metals from a vessel containing a one or more alkali metals and/or one or more partially passivated alkali metals. The vessel preferably comprising a sodium, NaK or other alkali metal-cooled nuclear reactor that has been used. The alkali metal, preferably sodium, potassium or a combination thereof, in the vessel is exposed to a treatment liquid, preferably an acidic liquid, more preferably citric acid. Preferably, the treatment liquid is maintained in continuous motion relative to any surface of unreacted alkali metal with which the treatment liquid is in contact. The treatment liquid is preferably pumped into the vessel containing the one or more alkali metals and the resulting fluid is extracted and optionally further processed. Preferably, the resulting off-gases are processed by an off-gas treatment system and the resulting liquids are processed by a liquid disposal system. In one preferred embodiment, an inert gas is pumped into the vessel along with the treatment liquid.

  14. Alkali elemental and potassium isotopic compositions of Semarkona chondrules

    Science.gov (United States)

    Alexander, C.M. O'D.; Grossman, J.N.

    2005-01-01

    We report measurements of K isotope ratios in 28 Semarkona chondrules with a wide range of petrologic types and bulk compositions as well as the compositions of CPX-mesostasis pairs in 17 type I Semarkona chondrules, including two chondrules with radial alkali zonation and 19 type II chondrules. Despite the wide range in K/Al ratios, no systematic variations in K isotopic compositions were found. Semarkona chondrules do not record a simple history of Rayleigh-type loss of K. Experimentally determined evaporation rates suggest that considerable alkali evaporation would have occurred during chondrule formation. Nevertheless, based on Na CPX-mesostasis distribution coefficients, the alkali contents of the cores of most chondrules in Semarkona were probably established at the time of final crystallization. However, Na CPX-mesostasis distribution coefficients also show that alkali zonation in type I Semarkona chondrules was produced by entry of alkalis after solidification, probably during parent body alteration. This alkali metasomatism may have gone to completion in some chondrules. Our preferred explanation for the lack of systematic isotopic enrichments, even in alkali depleted type I chondrule cores, is that they exchanged with the ambient gas as they cooled. ?? The Meteoritical Society, 2005.

  15. Concrete alkali-silica reaction and nuclear radiation damage

    International Nuclear Information System (INIS)

    Ichikawa, Tsuneki

    2008-01-01

    The deterioration of concrete by alkali-silica reaction of aggregates (ASR) and the effect of nuclear radiations on the ASR have been reviewed based on our studies on the mechanism of ASR and the effect of nuclear radiations on the resistivity of minerals to alkaline solution. It has been found that the ASR is initiated by the attack of alkaline solution in concrete to silicious aggregates to convert them into hydrated alkali silicate. The consumption of alkali hydroxide by the aggregates induces the dissolution of Ca 2+ ions into the solution. The alkali silicate surrounding the aggregates then reacts with Ca 2+ ions to convert to insoluble tight and rigid reaction rims. The reaction rim allows the penetration of alkaline solution but prevents the leakage of viscous alkali silicate, so that alkali silicate generated afterward is accumulated in the aggregate to give an expansive pressure enough for cracking the aggregate and the surrounding concrete. The effect of nuclear radiation on the reactivity of quartz and plagioclase, a part of major minerals composing volcanic rocks as popular aggregates, to alkaline solution has been examined for clarifying whether nuclear radiations accelerates the ASR. It has been found that the irradiation of these minerals converts them into alkali-reactive amorphous ones. The radiation dose for plagioclase is as low as 10 8 Gy, which suggests that the ASR of concrete surrounding nuclear reactors is possible to be accelerated by nuclear radiation. (author)

  16. Static and kinetic friction of granite at high normal stress

    Science.gov (United States)

    Byerlee, J.D.

    1970-01-01

    Frictional sliding on ground surfaces of granite, angle of sliding planes 30?? and 45??, was investigated as a function of confining pressure. Over the normal stress range of 2-12 kb, the static frictional shear stress ??s follows the relationship ??s = 0??5 + 0?? ??n and the kinetic frictional shear stress ??k was calculated to be ??k = 0??25 + 0??47 ??n. ?? 1970.

  17. 1997 Lower Granite dam smolt monitoring program : annual report.; ANNUAL

    International Nuclear Information System (INIS)

    Morrill, Charles; Ross, Doug; Verhey, Peter; Witalis, Shirley

    1997-01-01

    The 1997 fish collection season at Lower Granite was characterized by high spring flows, extensive spill, cool spring and early summer water temperatures and comparatively low numbers of fish, particularly yearling chinook. The Fish Passage Center's Smolt Monitoring Program is designed to provide a consistent, real-time database of fish passage and document the migrational characteristics of the many stocks of salmon and steelhead in the Columbia Basin

  18. Oxygen and hydrogen isotope studies of plutonic granitic rocks

    International Nuclear Information System (INIS)

    Taylor, H.P. Jr.

    1978-01-01

    The primary deltaD values of the biotites and hornblendes in granitic batholiths are remarkably constant at about -50 to -85, identical to the values in regional metamorphic rocks, marine sediments and greenstones, and most weathering products in temperate climates. Therefore the primary water in these igneous rocks is probably not 'juvenile', but is ultimately derived by dehydration and/or partial melting of the lower crust or subducted lithosphere. Most granitic rocks have delta 18 O = +7.0 to +10.0, probably indicating significant involvment of high- 18 O metasedimentary or altered volcanic rocks in the melting process; such an origin is demanded for many other granodiorites and tonalites that have delta 18 O = +10 to +13. Gigantic meteoric-hydrothermal convective circulation systems were established in the epizonal portions of all batholiths, locally producing very low delta 18 O values (particularly in feldspars) during subsolidus exchange. Some granitic plutons in such environments also were emplaced as low- 18 O magmas probably formed by melting or assimilation of hydrothermally altered roof rocks. However, the water/rock ratios were typically low enough that over wide areas the only evidence for meteoric water exchange in the batholiths is given by low D/H ratios (deltaK as low as -180); for example, because of latitudinal isotopic variations in meteoric waters, as one moves north through the Cordilleran batholiths of western North America an increasingly higher proportion of the granitic rocks have deltaD values lower than -120. The lowering of deltaD values commonly corelates with re-setting of K-Ar ages. (Auth.)

  19. Heat transfer experiment in a granite formation at Cornwall

    International Nuclear Information System (INIS)

    Bourke, P.J.; Hodgkinson, D.P.

    1985-01-01

    An experiment simulating a waste package was started in 1978 in Cornish granite. To obtain measurable temperature rises through large volumes of rock, an electrical heater at 50m depth was run for four years. The heater was then switched off and the cooling was monitored for another year. The results show that most of the heat transfer was by conduction but that some convection occurred and that temperatures can be predicted with some confidence

  20. Radiation damage in the alkali halide crystals

    International Nuclear Information System (INIS)

    Diller, K.M.

    1975-10-01

    A general review is given of the experimental data on radiation damage in the alkali halide crystals. A report is presented of an experimental investigation of irradiation produced interstitial dislocation loops in NaCl. These loops are found to exhibit the usual growth and coarsening behaviour during thermal annealing which operates by a glide and self-climb mechanism. It is shown that the recombination of defects in these crystals is a two stage process, and that the loss of interstitials stabilized at the loops is caused by extrinsic vacancies. The theoretical techniques used in simulating point defects in ionic crystals are described. Shell model potentials are derived for all the alkali halide crystals by fitting to bulk crystal data. The fitting is supplemented by calculations of the repulsive second neighbour interactions using methods based on the simple electron gas model. The properties of intrinsic and substitutional impurity defects are calculated. The HADES computer program is used in all the defect calculations. Finally the report returns to the problems of irradiation produced interstitial defects. The properties of H centres are discussed; their structure, formation energies, trapping at impurities and dimerization. The structure, formation energies and mobility of the intermediate and final molecular defects are then discussed. The thermodynamics of interstitial loop formation is considered for all the alklai halide crystals. The nucleation of interstitial loops in NaCl and NaBr is discussed, and the recombination of interstitial and vacancy defects. The models are found to account for all the main features of the experimental data. (author)

  1. Study of natural radioactivity in Mansehra granite, Pakistan: environmental concerns

    International Nuclear Information System (INIS)

    Qureshi, Aziz Ahmed; Manzoor, Shahid; Waheed, Abdul; Tubassam, Aneela; Khan Jadoon, Ishtiaq Ahmed; Wajid, Ali Abbas; Attique, Ahsan; Masood, Adil; Anees, Muhammad

    2014-01-01

    A part of Mansehra Granite was selected for the assessment of radiological hazards. The average activity concentrations of 226 Ra, 232 Th and 40 K were found to be 27.32, 50.07 and 953.10 Bq kg -1 , respectively. These values are in the median range when compared with the granites around the world. Radiological hazard indices and annual effective doses were estimated. All of these indices were found to be within the criterion limits except outdoor external dose (82.38 nGy h -1 ) and indoor external dose (156.04 nGy h -1 ), which are higher than the world's average background levels of 51 and 55 nGy h -1 , respectively. These values correspond to an average annual effective dose of 0.867 mSv y -1 , which is less than the criterion limit of 1 mSv y -1 (ICRP-103). Some localities in the Mansehra city have annual effective dose higher than the limit of 1 mSv y -1 . Overall, the Mansehra Granite does not pose any significant radiological health hazard in the outdoor or indoor. (authors)

  2. Lower Granite dam smolt monitoring program: annual report, 2000; ANNUAL

    International Nuclear Information System (INIS)

    Morrill, Charles

    2000-01-01

    The 2000 fish collection season at Lower Granite was characterized by lower than average spring flows and spill, low levels of debris, cool water temperatures, increased unclipped yearling and subyearling chinook smolts, and 8,300,546 smolts collected and transported compared to 5,882,872 in 1999. With the continued release of unclipped supplementation chinook and steelhead above Lower Granite Dam, we can no longer accurately distinguish wild chinook, steelhead, and sockeye/kokanee in the sample. Although some table titles in this report still show ''wild'' column headings, the numbers in these columns for 1999 and 2000 include wild and unclipped hatchery origin smolts. The increases over previous years reflect the increased supplementation. A total of 8,300,546 juvenile salmonids were collected at Lower Granite Dam. Of these, 187,862 fish were bypassed back to the river and 7,950,648 were transported to release sites below Bonneville Dam, 7,778,853 by barge and 171,795 by truck. A total of 151,344 salmonids were examined in daily samples. Nine research projects conducted by four agencies impacted a total of 1,361,006 smolts (16.4% of the total collection)

  3. Molybdenite in Pomona Island Granite at Lake Manapouri, Fiordland

    International Nuclear Information System (INIS)

    Scott, J.M.; Palin, J.M.

    2011-01-01

    A small occurrence of molybdenite (MoS 2 ) mineralisation has been discovered in the weakly A-type Pomona Island Granite on the shorelines of Lake Manapouri in eastern Fiordland. The disseminated appearance of molybdenite and the absence of quartz veins indicates that mineralisation is probably the product of magmatic and/or hydrothermal activity related to pluton crystallisation at c. 157 Ma, and not younger (c.128-116 Ma) shear zone-related mesothermal mineralisation as has been recently described from the Murchison Mountains to the north and Stewart Island to the south. Although apparently not of economic grade, the Pomona Island Granite locality is regionally important because it is the first direct pluton-related Mo-mineralisation event to be recognised in eastern Fiordland. This occurrence adds to the growing number and known styles of base metal occurrences within the Jurassic-Cretaceous magmatic arc (Outboard Median Batholith) that formed on or near the New Zealand Gondwana margin. Furthermore, the wide distribution of essentially uninvestigated A-type granites in the Outboard Median Batholith means that there may be further Mo-mineralised localities awaiting discovery. (author). 20 refs., 3 figs., 1 tab.

  4. New contributions to granite characterization by ultrasonic testing.

    Science.gov (United States)

    Cerrillo, C; Jiménez, A; Rufo, M; Paniagua, J; Pachón, F T

    2014-01-01

    Ultrasound evaluation permits the state of rocks to be determined quickly and cheaply, satisfying the demands faced by today's producers of ornamental stone, such as environmental sustainability, durability and safety of use. The basic objective of the present work is to analyse and develop the usefulness of ultrasound testing in estimating the physico-mechanical properties of granite. Various parameters related to Fast Fourier Transform (FFTs) and attenuation have been extracted from some of the studies conducted (parameters which have not previously been considered in work on this topic, unlike the ultrasonic pulse velocity). The experimental study was carried out on cubic specimens of 30 cm edges using longitudinal and shear wave transducers and equipment which extended the normally used natural resonance frequency range up to 500 kHz. Additionally, a validation study of the laboratory data has been conducted and some methodological improvements have been implemented. The main contribution of the work is the analysis of linear statistical correlations between the aforementioned new ultrasound parameters and physico-mechanical properties of the granites that had not previously been studied, i.e., resistance to salt crystallization and breaking load for anchors. Being properties that directly affect the durability and safety of use of granites, these correlations consolidate ultrasonics as a nondestructive method well suited to this type of material. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Properties of Hooked Steel Fibers Reinforced Alkali Activated Material Concrete

    OpenAIRE

    Faris M. A.; Abdullah Mohd Mustafa Al Bakri; Ismail Khairul Nizar; Muniandy Ratnasamy; Mahmad Nor Aiman; Putra Jaya Ramadhansyah; Waried Wazien A. Z.

    2016-01-01

    In this study, alkali activated material was produced by using Class F fly ash from Manjung power station, Lumut, Perak, Malaysia. Fly ash then was activated by alkaline activator which is consisting of sodium silicate (Na2SiO3) and sodium hydroxide (NaOH). Hooked end steel fibers were added into the alkali activated material system with percentage vary from 0 % – 5 %. Chemical compositions of fly ash were first analyzed by using x-ray fluorescence (XRF). All hardened alkali activated materia...

  6. Control of alkali species in gasification systems: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Turn, S.; Kinoshita, C.; Ishimura, D. Zhou, J.; Hiraki, T.; Masutani, S.

    2000-07-13

    Gas-phase alkali metal compounds contribute to fouling, slagging, corrosion, and agglomeration problems in energy conversion facilities. One mitigation strategy applicable at high temperature is to pass the gas stream through a fixed bed sorbent or getter material, which preferentially absorbs alkali via physical adsorption or chemisorption. This report presents results of an experimental investigation of high-temperature alkali removal from a hot filtered gasifier product gas stream using a packed bed of sorbent material. Two getter materials, activated bauxite and emathlite, were tested at two levels of space time by using two interchangeable reactors of different internal diameters. The effect of getter particle size was also investigated.

  7. (e, 2e) triple differential cross sections of alkali and alkali earth atoms: Na, K and Mg, Ca

    International Nuclear Information System (INIS)

    Hitawala, U; Purohit, G; Sud, K K

    2008-01-01

    Recently low-energy measurements have been reported for alkali targets Na and K and alkali earth targets Mg and Ca in coplanar symmetric geometry. We report the results of our calculation of triple differential cross section (TDCS) for electron impact single ionization (i.e. (e, 2e) processes) of alkali atoms Na, K and alkali earth atoms Mg, Ca in coplanar symmetric geometry. We have performed the present calculations using the distorted-wave Born approximation (DWBA) formalism at intermediate incident electron energies used in the recently performed experiments. Ionization takes place from the valence shell for all the targets investigated and the outgoing electrons share the excess energy equally. We have also considered the effect of target polarization in our DWBA calculations which may be an important quantity at incident electron energies used in the present investigation. We find that the DWBA formalism is able to reproduce most of the trend of experimental data and may provide a future direction for further investigation of ionization process on alkali and alkali earth metals. It is also observed that the second-order effects are more important to understand the collision dynamics of (e, 2e) processes on alkali earth targets

  8. Review of geomechanics data from French nuclear explosions in the Hoggar granite, with some comparisons to tests in US granite

    International Nuclear Information System (INIS)

    Heuze, F.E.

    1983-05-01

    Numerous unclassified reports on the French nuclear explosions in the Hoggar (1961-1966) were reviewed from the standpoint of geomechanics. The following aspects of the tests are summarized: spectral content of the tests compared to U.S. results; shock front positions with time; cavity radius as a function of yield, coupling, density of rock, rock shear strength, and overburden; radial pressure, tangential pressure and peak velocity as a function of distance and yield; pressure vs. time at various distances; mechanical properties of granite; scaling laws for acceleration, velocity and displacement as a function of yield and distance for all Hoggar shots; extent of tunnel damage as a function of distance and yield; time to collapse of chimney as a function of yield, or cavity radius; extent of granite crushing and disking as a function of distance and yield cavity height relation to cavity radius; faulting and jointing on the Taourirt Tan Afella massif; and influence of water content on cavity radius vs. yield. Whenever possible, these French data are compared to corresponding data obtained in the U.S. granite events Hard Hat, Shoal, and Piledriver. The following results emerge from the comparison: (1) agreement is found between the French and U.S. experience for: mechanical properties of the granites, rock damage due to the blast, and yield-scaled peak values of acceleration, velocity and displacement; and (2) lack of agreement exists for: cavity size, chminey height, and time to cavity collapse. Average spacing of rock joints also was about 5 times greater in the Hoggar

  9. Bluish granites from Extremadura (Spain): a radiological evaluation.

    Science.gov (United States)

    Pereira, Dolores; Neves, Luís.; Peinado, Mercedes; Pereira, Alcides; Rodríguez, Leticia; António Blanco, José

    2010-05-01

    We have found in the area of Trujillo (Extremadura, Spain) a variety of striking bluish granites, outcropping within the Plasenzuela pluton. They are all quarried under different names and are characterized by leucocratic minerals such as quartz, feldspar (both potassium and plagioclase), sometimes giving a fenocrystic texture and muscovite, with some biotite. As accessory phases, idiomorphic tourmaline is found. Recently a bluish phosphate distributed in the whole rock was detected, included within most mineral phases and fillings from stressed structures that are cutting the rock. We attribute the bluish color of the granites to this phosphate. Although biotite is almost always transformed to chlorite, the rock gives an excellent response to be polished. Physico-mechanical properties make this bluish granite a perfect option for most applications. Absorption coefficient is rather low and alteration by thermal changes has not been observed. A secondary facies with yellow colour also occurs, spatially close to the topographic surface, and probably represents an alteration product of the original granite. This facies is also commercialized as ornamental stone. A radiological survey was carried out in the field, using a gamma ray spectrometer. The radiological background is quite homogeneous in the pluton, without significant differences between gamma ray fluxes of both facies (altered and non altered). The average contents of U, Th and K2O determined in situ with the spectrometer are 7.4 ppm, 0.8 ppm and 3.67%, respectively (n=15). Using U as a Ra proxy, the I index of the EU technical document 112 can be determined, and results in a value of 0.64 for the referred composition. This implies that the rock can be used without any restrictions for building purposes. However, a marked difference was observed in radon exhalation tests carried out in laboratorial facilities. The dominant blue variety shows radon exhalation rates comprised between 0.02 and 0.04 Bq.kg-1.h-1

  10. Petrography, mineral chemistry and lithochemistry of the albitite and granite-gneissics rocks of anomaly 35 from Lagoa Real uranium province; Petrografia, quimica mineral e litoquimica do albitito e das rochas granito-gnaissicas da anomalia 35, provincia uranifera de Lagoa Real

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Camila Marques dos

    2016-07-01

    In the northwestern portion of the Lagoa Real Uranium Province (LRUP), located in south-central Bahia, it is located one of the most promising uranium anomalies Brazil (an35, Gameleira I deposit), the reserves and proximity to the Cachoeira mine. Other anomalies of this sector (eg. 31 AN and AN34), are also considered strategic for the content of radioactive minerals and REE. The objective was to develop a study of a representative drill core of an35, where the main rocks PULR are present. The research focused on the mineralogical and chemical changes observed in the passages of a lithology to another, from the rock to the meta granitic albitites, through gneiss and transitional rocks, and making comparisons with similar lithologies sampled on testimonies of AN31 and 34. The granites are classified as hypersolvus coarse alkali-feldspar granite and are variably deformed. The main mineral assemblage in granites are perthitic orthoclase+hedenbergite+ quartz +hastingsite + biotite, and zircon, apatite, ilmenite and titanite are accessories. The reddening of these rocks are characterized by feldspars sericitization and hematitization and the presence of 'vazios'. The gneisses are mainly gray and reach milonitic to protomilonitics terms. These rocks have characteristics of subsolidus changes as swapped rims and metasomatic perthites. The tardi-magmatic association (amphibole+biotite) indicates final crystallization or late influx by superficial fluids resulting in an increase in water and volatiles, such as F and Cl in the system, which must also have carried rare-earth elementsGranites have geochemical affinity with A-type ferroan granite, A2, reduced and are post-collisional. Their patterns of incompatible elements and rare earths are comparable to Sao Timoteo Granite, but their petrographic features indicate that it is a less common granite facies. Albitites were classified as garnet albitites, magnetite albitites and biotite albitites. Contacts between

  11. Magnetic properties of free alkali and transition metal clusters

    International Nuclear Information System (INIS)

    Heer, W. de; Milani, P.; Chatelain, A.

    1991-01-01

    The Stern-Gerlach deflections of small alkali clusters (N<6) and iron clusters (10< N<500) show that the paramagnetic alkali clusters always have a nondeflecting component, while the iron clusters always deflect in the high field direction. Both of these effects appear to be related to spin relaxation however in the case of alkali clusters it is shown that they are in fact caused by avoided level crossing in the Zeeman diagram. For alkali clusters the relatively weak couplings cause reduced magnetic moments where levels cross. For iron clusters however the total spin is strongly coupled to the molecular framework. Consequently this coupling is responsible for avoided level crossing which ultimately cause the total energy of the cluster to decrease with increasing magnetic field so that the iron clusters will deflect in one direction when introduced in an inhomogeneous magnetic field. Experiment and theory are discussed for both cases. (orig.)

  12. Saccharification of gamma-ray and alkali pretreated lignocellulosics

    International Nuclear Information System (INIS)

    Begum, A.; Choudhury, N.

    1988-01-01

    Enzymic saccharification of gamma ray and alkali pretreated sawdust, rice straw, and sugar cane bagasse showed higher release of reducing sugar from pretreated substrates. By gamma ray treatment alone (500 kGy) reducing sugar release of 2.8, 9.2, and 10 g/l was obtained from 7.5% (w/v) sawdust, rice straw, and bagasse and the same substrates showed reducing sugar release of 4.2, 30, and 20 g/l respectively when treated with alkali (0.1 g/g). Combination of gamma ray with alkali treatment further increased the reducing sugar release to 10.2, 33, and 36 g/l from sawdust, rice straw, and bagasse respectively. The effects of gamma ray and alkali treatment on saccharification varied with the nature of the substrate

  13. Reaction of alkali nitrates with PuO2

    International Nuclear Information System (INIS)

    Yamashita, T.; Ohuchi, K.; Takahashi, K.; Fujino, T.

    1990-01-01

    Improvement of solubility of plutonium dioxide (PuO 2 ) in acid solution is important to establish the nuclear fuel reprocessing technique for uranium-plutonium mixed oxide fuels. If insoluble PuO 2 can be converted into any soluble plutonium compounds, problems arising from the fuel dissolution process will be reduced to a great extent. Alkali metal plutonates and alkaline-earth plutonates are known to have enhanced solubility in mineral acids. However, the reaction conditions to form such plutonates and characterization thereof are not well elucidated. Then the reactivity and reaction conditions to form lithium and sodium plutonates from their nitrates and PuO 2 were studied at temperatures between 500 and 900 degree C and alkali metal to plutonium atom ratios between 0.5 and 6 by means of thermogravimetry as well as X-ray diffraction technique. The reaction behavior of alkali plutonates will be discussed in comparison with corresponding alkali uranates

  14. Dipole-dipole van der Waals interaction in alkali halides

    International Nuclear Information System (INIS)

    Thakur, B.N.; Thakur, K.P.

    1978-01-01

    Values of van der Waals dipole-dipole constants and interaction energetics of alkali halides are reported using the recent data. The values obtained are somewhat larger than those of earlier workers. (orig.) [de

  15. Alkali-bonded ceramics with hierarchical tailored porosity

    Czech Academy of Sciences Publication Activity Database

    Landi, E.; Medri, V.; Papa, E.; Dědeček, Jiří; Klein, Petr; Benito, P.; Vaccari, A.

    2013-01-01

    Roč. 73, SI (2013), s. 56-64 ISSN 0169-1317 Institutional support: RVO:61388955 Keywords : alkali-bonded ceramics * metalcaolin * geopolymerization parameters Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.703, year: 2013

  16. Mineralization dynamics of metakaolin-based alkali-activated cements

    Science.gov (United States)

    Gevaudan, Juan Pablo; Campbell, Kate M.; Kane, Tyler; Shoemaker, Richard K.; Srubar, Wil V.

    2017-01-01

    This paper investigates the early-age dynamics of mineral formation in metakaolin-based alkali-activated cements. The effects of silica availability and alkali content on mineral formation were investigated via X-ray diffraction and solid-state 29Si magic-angle spinning nuclear magnetic resonance spectroscopy at 2, 7, 14, and 28 days. Silica availability was controlled by using either liquid- (immediate) or solid-based (gradual) sodium silicate supplements. Mineral (zeolitic) and amorphous microstructural characteristics were correlated with observed changes in bulk physical properties, namely shrinkage, density, and porosity. Results demonstrate that, while alkali content controls the mineralization in immediately available silica systems, alkali content controls the silica availability in gradually available silica systems. Immediate silica availability generally leads to a more favorable mineral formation as demonstrated by correlated improvements in bulk physical properties.

  17. Method for intercalating alkali metal ions into carbon electrodes

    Science.gov (United States)

    Doeff, Marca M.; Ma, Yanping; Visco, Steven J.; DeJonghe, Lutgard

    1995-01-01

    A low cost, relatively flexible, carbon electrode for use in a secondary battery is described. A method is provided for producing same, including intercalating alkali metal salts such as sodium and lithium into carbon.

  18. Mineralization dynamics of metakaolin-based alkali-activated cements

    International Nuclear Information System (INIS)

    Gevaudan, Juan Pablo; Campbell, Kate M.; Kane, Tyler J.; Shoemaker, Richard K.; Srubar, Wil V.

    2017-01-01

    This paper investigates the early-age dynamics of mineral formation in metakaolin-based alkali-activated cements. The effects of silica availability and alkali content on mineral formation were investigated via X-ray diffraction and solid-state 29 Si magic-angle spinning nuclear magnetic resonance spectroscopy at 2, 7, 14, and 28 days. Silica availability was controlled by using either liquid- (immediate) or solid-based (gradual) sodium silicate supplements. Mineral (zeolitic) and amorphous microstructural characteristics were correlated with observed changes in bulk physical properties, namely shrinkage, density, and porosity. Results demonstrate that, while alkali content controls the mineralization in immediately available silica systems, alkali content controls the silica availability in gradually available silica systems. Immediate silica availability generally leads to a more favorable mineral formation as demonstrated by correlated improvements in bulk physical properties.

  19. Kinetics of molybdenite oxidizing leaching in alkali medium by ozone

    International Nuclear Information System (INIS)

    Medvedev, A.S.; Sokratova, N.B.; Litman, I.V.; Zelikman, A.N.

    1985-01-01

    On the basis of investigation of the process kinetics proposed is a model of oxidizing leaching of molybdenite in alkali medium while ozonization of the solution by ozoneair mixture. A kinetic equation is derived, that describes experimental data satisfactorily

  20. Dislocation unpinning model of acoustic emission from alkali halide ...

    Indian Academy of Sciences (India)

    The present paper reports the dislocation unpinning model of acoustic emis- sion (AE) from ... Acoustic emission; dislocation; alkali halide crystals; plastic deformation. ..... [5] T Nishimura, A Tahara and T Kolama, Jpn. Metal Inst. 64, 339 (2000).

  1. Dedolomitization and Alkali Reactions in Ohio-sourced Dolstone Aggregates

    Science.gov (United States)

    2017-11-01

    Concrete samples produced using NW-Ohio sourced aggregates were evaluated for susceptibility to degradation and premature failure due to cracks formed by the volume expansion during hydration of silica gels produced by alkali-silica reactions between...

  2. The 4843 Alkali Metal Storage Facility Closure Plan

    International Nuclear Information System (INIS)

    1991-06-01

    The 4843 AMSF has been used primarily to provide a centralized building to receive and store dangerous and mixed alkali metal waste, including sodium and lithium, which has been generated at the Fast Flux Test Facility and at various other Hanford Site operations that used alkali metals. Most of the dangerous and mixed alkali metal waste received consists of retired equipment from liquid sodium processes. The unit continues to store material. In general, only solid alkali metal waste that is water reactive is stored at the 4843 AMSF. The 4843 AMSF will be closed in a manner consistent with Ecology guidelines and regulations (WAC 173-303-610). The general closure procedure is detailed as follows

  3. Photoemission spectroscopy study of a multi-alkali photocathode

    CERN Document Server

    Ettema, A R H

    2000-01-01

    In this paper a photoemission study of the highest core levels of the elements and the electron escape barrier (work function) in a multi-alkali photocathode are presented. The core levels indicate that the alkali atoms are in an oxidized state and therefore the compound Na sub 2 KSb can be regarded as an ionic semiconductor. The measured escape barrier of the Cs sub 2 O surface layer is determined as 2.3 eV.

  4. Alkali promotion of N-2 dissociation over Ru(0001)

    DEFF Research Database (Denmark)

    Mortensen, Jens Jørgen; Hammer, Bjørk; Nørskov, Jens Kehlet

    1998-01-01

    Using self-consistent density functional calculations, we show that adsorbed Na and Cs lower the barrier for dissociation of N2 on Ru(0001). Since N2 dissociation is a crucial step in the ammonia synthesis reaction, we explain in this way the experimental observation that alkali metals promote th...... the ammonia synthesis reaction over Ru catalysts. We also show that the origin of this effect is predominantly a direct electrostatic attraction between the adsorbed alkali atoms and the dissociating molecule....

  5. Charge transfer in gold--alkali-metal systems

    International Nuclear Information System (INIS)

    Watson, R.E.; Weinert, M.

    1994-01-01

    Based on conventional electronegativity arguments, gold--alkali-metal compounds are expected to be among the most ''ionic'' of metallic compounds. The concepts of ionicity and charge transfer are difficult to quantify. However, the changes in bonding in the 50/50 Au--alkali-metal systems between the elemental metals and the compounds are so severe that observations can readily be made concerning their character. The results, as obtained from self-consistent electronic-structure calculations, lead to the apparently odd observation that the electron density at the alkali-metal sites in the compound increases significantly and this involves high l componennts in the charge density. This increase, however, can be attributed to Au-like orbitals spatially overlapping the alkali-metal sites. In a chemical sense, it is reasonable to consider the alkali-metal transferring charge to these Au orbitals. While normally the difference in heats of formation between muffin-tin and full-potential calculations for transition-metal--transition-metal and transition-metal--main-group (e.g., Al) compounds having high site symmetry are small, for the gold--alkali-metal systems, the changes in bonding in the compounds cause differences of ∼0.5 eV/atom between the two classes of potential. Any serious estimate of the electronic structure in these systems must account for these aspherical bonding charges. The origin of the semiconducting behavior of the heavy-alkali-metal Au compounds is shown to arise from a combination of the Au-Au separations and the ionic character of the compounds; the light-alkali-metal Au compounds, with their smaller Au-Au separations, do not have a semiconducting gap. Core-level shifts and isomer shifts are also briefly discussed

  6. Black and red granites in the Egyptian Antiquity Museum of Turin. A minero-petrographic and provenance study.

    Science.gov (United States)

    Serra, M.; Borghi, A.; Vaggelli, G.; D'Amicone, E.; Vigna, L.

    2009-04-01

    materials used for two of the best known masterpieces of Egyptian art. As regards to red granites, it has been observed that most of the exposed sculptures were made of rocks closely akin to Aswan granite. Just in one case, the Ram headed sphinx (cat. 836), macroscopic differences in colour index, grain size and isoorientation of feldspar phenocrysts, suggested a different provenance of the source material and determined the choice of picking up a small fragment for minero-petrographic analysis. The sample collected from the sarcophagus of Nefertari (suppl. 5153) during the recent restoration of the sculpture, was analysed in order to test the accuracy of the results, as the provenance of the material used for its realization was already certain. Petrographic observations and chemical analysis were undertaken by a scanning electron microscope equipped with an energy-dispersive spectrometer. Minero-petrographic data primarily showed that all samples vary in composition from granite (red granites) to granodiorite and tonalite (black granites). The main sialic phases are represented by plagioclase (albite to oligoclase), alkali-feldspar (microcline) and quartz, while femic phases are amphibole (green horneblende) and biotite (Fe- to Mg-biotite), always coexisting in variable relative percentages. Minor amount of apatite (≈ 1 wt.%), magnetite, ilmenite, often associated to sphene, zircon, pyrite and allanite also occur. The identification of some compositional markers in all samples suggested a common provenance for all the rocks used for the sculptures. Thus, it was supposed that they could all have been quarried in the famous district of Aswan, well known at least since Dynastic period. This provenance hypothesis was confirmed by geological literature and archeological evidences, considering the relative proximity of Aswan quarries to Nile river and to the key centres of power in the New Kingdom. Therefore, several geological samples were collected in Aswan area, in order

  7. Age of Pedra Branca granite (Goias) and possible geotectonic implications; Idade do granito Pedra Branca (Goias) e possiveis implicacoes geotectonicas

    Energy Technology Data Exchange (ETDEWEB)

    Marini, O J; Botelho, N F [Brasilia Univ., DF (Brazil). Dept. de Geociencias; Macambira, M J.B.; Provost, A [Para Univ., Belem, PA (Brazil). Nucleo de Ciencias Geofisicas e Geologicas

    1987-12-31

    Rb-Sr geochronologic dating of granites from the Pedra Branca Granite Massif (Nova Roma, Goias) shown an age of 1405 {+-} 21My. and a questionable initial Sr{sup 87}/Sr{sup 86} ratio of 0,7004 {+-} 0,006. Rhyolite from the base of the Arai Group is probably of the same age as the granitic intrusion. The 475 {+-} 19 My. age for the granitic intrusion is evidence of the Brasiliano Cycle imprint in Pedra Branca region. The age attributed to the Pedra Branca Granite is lower than known ages of the Goias tin granites giving rise to new geotectonic interpretations. It is possible that the Pedra Branca Granite represents a low-level intrusion emplaced at the beginning of structuration and deposition of the Arai basin. It may be correlated with granitic intrusions related to a rift stage above mantle hot spots, like the Nigerian tin younger granites. (author).

  8. Oxygen isotope studies of early Precambrian granitic rocks from the Giants Range batholith, northeastern Minnesota, U.S.A.

    Science.gov (United States)

    Viswanathan, S.

    1974-01-01

    Oxygen isotope studies of granitic rocks from the 2.7 b.y.-old composite Giants Range batholith show that: (1) ??(O18)quartz values of 9 to 10 permil characterize relatively uncontaminated Lower Precambrian, magmatic granodiorites and granites; (2) granitic rocks thought to have formed by static granitization have ??(O18)quartz values that are 1 to 2 permil higher than magmatic granitic rocks; (3) satellite leucogranite bodies have values nearly identical to those of the main intrusive phases even where they transect O18-rich metasedimentary wall rocks; (4) oxygen isotopic interaction between the granitic melts and their O18-rich wall rocks was minimal; and (5) O18/O18 ratios of quartz grains in a metasomatic granite are largely inherited from the precursor rock, but during the progression - sedimentary parent ??? partially granitized parent ??? metasomatic granite ??? there is gradual decrease in ??(O18)quartz by 1 to 2 permil. ?? 1974.

  9. Alkali-slag cements for the immobilization of radioactive wastes

    International Nuclear Information System (INIS)

    Shi, C.; Day, R.L.

    1996-01-01

    Alkali-slag cements consist of glassy slag and an alkaline activator and can show both higher early and later strengths than Type III Portland cement, if a proper alkaline activator is used. An examination of microstructure of hardened alkali-slag cement pastes with the help of XRD and SEM with EDAX shows that the main hydration product is C-S-H (B) with low C/S ratio and no crystalline substances exist such as Ca(OH) 2 , Al (OH) 3 and sulphoaluminates. Mercury intrusion tests indicate that hardened alkali-slag cement pastes have a lower porosity than ordinary Portland cement, and contain mainly gel pores. The fine pore structure of hardened alkali-slag cement pastes will restrict the ingress of deleterious substances and the leaching of harmful species such as radionuclides. The leachability of Cs + from hardened alkali-slag cement pastes is only half of that from hardened Portland cement. From all these aspects, it is concluded that alkali-slag cements are a better solidification matrix than Portland cement for radioactive wastes

  10. Two-phase alkali-metal experiments in reduced gravity

    International Nuclear Information System (INIS)

    Antoniak, Z.I.

    1986-06-01

    Future space missions envision the use of large nuclear reactors utilizing either a single or a two-phase alkali-metal working fluid. The design and analysis of such reactors require state-of-the-art computer codes that can properly treat alkali-metal flow and heat transfer in a reduced-gravity environment. A literature search of relevant experiments in reduced gravity is reported on here, and reveals a paucity of data for such correlations. The few ongoing experiments in reduced gravity are noted. General plans are put forth for the reduced-gravity experiments which will have to be performed, at NASA facilities, with benign fluids. A similar situation exists regarding two-phase alkali-metal flow and heat transfer, even in normal gravity. Existing data are conflicting and indequate for the task of modeling a space reactor using a two-phase alkali-metal coolant. The major features of past experiments are described here. Data from the reduced-gravity experiments with innocuous fluids are to be combined with normal gravity data from the two-phase alkali-metal experiments. Analyses undertaken here give every expectation that the correlations developed from this data base will provide a valid representation of alkali-metal heat transfer and pressure drop in reduced gravity

  11. The influence of alkali promoters on coadsorbed molecules

    International Nuclear Information System (INIS)

    Umbach, E.

    1986-01-01

    A model has been suggested recently based on the results of an extensive study of the coadsorbate system CO + K on Ru(001). It is introduced and discussed in this article based on previous results and on results obtained very recently for a similar coadsorbate system, CO + K/Ni(111). This model is in competition with a variety of differing or similar ideas and interpretations which are mostly based on similar experimental results. Some of these other models postulate a lying-down, or strongly tilted, molecule in the presence of alkali atoms, at least at low coverages. The CO molecule is usually considered to be attached to the substrate and to be closely coadsorbed to the alkali neighbor(s) but sometimes even a vertical or horizontal adsorption on top of the alkali layer has been suggested. The interaction between alkali and CO has been described as indirect via the substrate or direct by forming a ''π''-bond between adjacent alkalis and CO molecules or even by forming an ionic K/sub x/-CO/sub y/ complex. Some authors prefer a model in which the main (or exclusive) interaction comes from a charge transfer from the donating alkali into the 2π orbital of the coadsorbed CO, thus, enhancing the C- metal and reducing the C-O bond strength

  12. Vibrations of alkali metal overlayers on metal surfaces

    International Nuclear Information System (INIS)

    Rusina, G G; Eremeev, S V; Borisova, S D; Echenique, P M; Chulkov, E V; Benedek, G

    2008-01-01

    We review the current progress in the understanding of vibrations of alkalis adsorbed on metal surfaces. The analysis of alkali vibrations was made on the basis of available theoretical and experimental results. We also include in this discussion our recent calculations of vibrations in K/Pt(111) and Li(Na)/Cu(001) systems. The dependence of alkali adlayer localized modes on atomic mass, adsorption position and coverage as well as the dependence of vertical vibration frequency on the substrate orientation is discussed. The square root of atomic mass dependence of the vertical vibration energy has been confirmed by using computational data for alkalis on the Al(111) and Cu(001) substrates. We have confirmed that in a wide range of submonolayer coverages the stretch mode energy remains nearly constant while the energy of in-plane polarized modes increases with the increase of alkali coverage. It was shown that the spectrum of both stretch and in-plane vibrations can be very sensitive to the adsorption position of alkali atoms and substrate orientation

  13. Ionic interactions in alkali-aluminium tetrafluoride clusters

    International Nuclear Information System (INIS)

    Akdeniz, Z.; Cicek, Z.; Karaman, A.; Pastore, G.; Tosi, M.P.

    1999-08-01

    Complex anion structures ((AlF 4 ) - , (AlF 5 ) 2- and (AlF 6 ) 3- ) coexist in liquid mixtures of aluminium trifluoride and alkali fluorides in composition-dependent relative concentrations and are known to interact with the alkali counterions. We present a comparative study of the static and vibrational structures of MAlF 4 molecules (with M = any alkali), with the aim of developing and testing a refined model of the ionic interactions for applications to the Al-M fluoride mixtures. We find that, whereas an edge-bridged coordination is strongly favoured for Li in LiAIF 4 , edge-bridging and face-bridging of the alkali ion become energetically equivalent as one moves from Na to the heavier alkalis. This result is sensitive to the inclusion of alkali polarizability and may be interpreted as implying (for M = K, Rb or Cs) almost free relative rotations of the M + and (AlF 4 ) - partners at temperatures of relevance to experiment. The consistency of such a viewpoint with electron diffraction data on vapours and with Raman spectra on melts is discussed. (author)

  14. High alkali-resistant basalt fiber for reinforcing concrete

    International Nuclear Information System (INIS)

    Lipatov, Ya.V.; Gutnikov, S.I.; Manylov, M.S.; Zhukovskaya, E.S.; Lazoryak, B.I.

    2015-01-01

    Highlights: • Doping of basalt fiber with ZrSiO 4 increased its alkali resistance. • Alkali treatment results in formation of protective surface layer on fibers. • Morphology and chemical composition of surface layer were investigated. • Mechanical properties of fibers were analyzed by a Weibull distribution. • Zirconia doped basalt fibers demonstrate high performance in concrete. - Abstract: Basalt glasses and fibers with zirconia content in the range from 0 to 7 wt% were obtained using ZrSiO 4 as a zirconium source. Weight loss and tensile strength loss of fibers after refluxing in alkali solution were determined. Basalt fiber with 5.7 wt% ZrO 2 had the best alkali resistance properties. Alkali treatment results in formation of protective surface layer on fibers. Morphology and chemical composition of surface layer were investigated. It was shown that alkali resistance of zirconia doped basalt fibers is caused by insoluble compounds of Zr 4+ , Fe 3+ and Mg 2+ in corrosion layer. Mechanical properties of initial and leached fibers were evaluated by a Weibull distribution. The properties of basalt fibers with ZrSiO 4 were compared with AR-glass fibers. The performance of concrete with obtained fibers was investigated

  15. Alkali and heavy metal emissions of the PCFB-process; Alkali- ja raskasmetallipaeaestoet PCFB-prosessista

    Energy Technology Data Exchange (ETDEWEB)

    Kuivalainen, R; Eriksson, T; Lehtonen, P [Foster Wheeler Energia Oy, Karhula (Finland)

    1997-10-01

    Pressurized Circulating Fluidized Bed (PCFB) combustion technology has been developed in Karhula R and D Center since 1986. As part of the development, 10 MW PCFB test facility was built in 1989. The test facility has been used for performance testing with different coal types through the years 1990-1995 in order to gain data for design and commercialization of the high-efficiency low-emission PCFB combustion technology. The main object of the project was to measure vapor phase Na and K concentrations in the PCFB flue gas after hot gas filter and investigate the effects of process conditions and sorbents on alkali release. The measurements were performed using plasma assisted method of TUT Laboratory of Plasma Technology and wet absorption method of VTT Energy. The measurements were carried out during three test campaigns at PCFB Test Facility in Karhula. In autumn 1995 both VTT and TUT methods were used. The measurements of the following test period in spring 1996 were performed by VTT, and during the last test segment in autumn 1996 TUT method was in use. During the last test period, the TUT instrument was used as semi-continuous (3 values/minute) alkali analyzer for part of the time. The measured Na concentrations were below 30 ppb(w) in all measured data points. The results of K were below 10 ppb(w). The accuracies of the both methods are about +50 % at this concentration range. The scatter of the data covers the effects of different process variables on the alkali emission. The measured emissions are at the same order of magnitude as the guideline emission limits estimated by gas turbine manufacturers

  16. Magmatic and Crustal Differentiation History of Granitic Rocks from Hf-O Isotopes in Zircon

    Science.gov (United States)

    Kemp, , A. I. S.; Hawkesworth, , C. J.; Foster, , G. L.; Paterson, , B. A.; Woodhead, , J. D.; Hergt, , J. M.; Gray, , C. M.; Whitehouse, M. J.

    2007-02-01

    Granitic plutonism is the principal agent of crustal differentiation, but linking granite emplacement to crust formation requires knowledge of the magmatic evolution, which is notoriously difficult to reconstruct from bulk rock compositions. We unlocked the plutonic archive through hafnium (Hf) and oxygen (O) isotope analysis of zoned zircon crystals from the classic hornblende-bearing (I-type) granites of eastern Australia. This granite type forms by the reworking of sedimentary materials by mantle-like magmas instead of by remelting ancient metamorphosed igneous rocks as widely believed. I-type magmatism thus drives the coupled growth and differentiation of continental crust.

  17. Relation between the electroforming voltage in alkali halide-polymer diodes and the bandgap of the alkali halide

    International Nuclear Information System (INIS)

    Bory, Benjamin F.; Wang, Jingxin; Janssen, René A. J.; Meskers, Stefan C. J.; Gomes, Henrique L.; De Leeuw, Dago M.

    2014-01-01

    Electroforming of indium-tin-oxide/alkali halide/poly(spirofluorene)/Ba/Al diodes has been investigated by bias dependent reflectivity measurements. The threshold voltages for electrocoloration and electroforming are independent of layer thickness and correlate with the bandgap of the alkali halide. We argue that the origin is voltage induced defect formation. Frenkel defect pairs are formed by electron–hole recombination in the alkali halide. This self-accelerating process mitigates injection barriers. The dynamic junction formation is compared to that of a light emitting electrochemical cell. A critical defect density for electroforming is 10 25 /m 3 . The electroformed alkali halide layer can be considered as a highly doped semiconductor with metallic transport characteristics

  18. Elastic modulus of the alkali-silica reaction rim in a simplified calcium-alkali-silicate system determined by nano-indentation

    NARCIS (Netherlands)

    Zheng, Kunpeng; Lukovic, M.; De Schutter, Geert; Ye, G.; Taerwe, Luc

    2016-01-01

    This work aims at providing a better understanding of the mechanical properties of the reaction rim in the alkali-silica reaction. The elastic modulus of the calcium alkali silicate constituting the reaction rim, which is formed at the interface between alkali silicate and Ca(OH)2 in a

  19. Differential rates of feldspar weathering in granitic regoliths

    Science.gov (United States)

    White, A.F.; Bullen, T.D.; Schulz, M.S.; Blum, A.E.; Huntington, T.G.; Peters, N.E.

    2001-01-01

    Differential rates of plagioclase and K-feldspar weathering commonly observed in bedrock and soil environments are examined in terms of chemical kinetic and solubility controls and hydrologic permeability. For the Panola regolith, in the Georgia Piedmont Province of southeastern United States, petrographic observations, coupled with elemental balances and 87Sr/86Sr ratios, indicate that plagioclase is being converted to kaolinite at depths > 6 m in the granitic bedrock. K-feldspar remains pristine in the bedrock but subsequently weathers to kaolinite at the overlying saprolite. In contrast, both plagioclase and K-feldspar remain stable in granitic bedrocks elsewhere in Piedmont Province, such as Davis Run, Virginia, where feldspars weather concurrently in an overlying thick saprolite sequence. Kinetic rate constants, mineral surface areas, and secondary hydraulic conductivities are fitted to feldspar losses with depth in the Panola and Davis Run regoliths using a time-depth computer spreadsheet model. The primary hydraulic conductivities, describing the rates of meteoric water penetration into the pristine granites, are assumed to be equal to the propagation rates of weathering fronts, which, based on cosmogenic isotope dating, are 7 m/106 yr for the Panola regolith and 4 m/106 yr for the Davis Run regolith. Best fits in the calculations indicate that the kinetic rate constants for plagioclase in both regoliths are factors of two to three times faster than K-feldspar, which is in agreement with experimental findings. However, the range for plagioclase and K-feldspar rates (kr = 1.5 x 10-17 to 2.8 x 10-16 mol m-2 s-1) is three to four orders of magnitude lower than for that for experimental feldspar dissolution rates and are among the slowest yet recorded for natural feldspar weathering. Such slow rates are attributed to the relatively old geomorphic ages of the Panola and Davis Run regoliths, implying that mineral surface reactivity decreases significantly with

  20. Sr and Nd isotopic signature of the high-K calc-alkaline magmatism of the central Ribeira belt: the Sao Pedro Granite in Lumiar, RJ; Assinatura isotopica de Sr e Nd do magmatismo calcio-alcalino de alto-K na Faixa Ribeira central: o exemplo do Granito Sao Pedro em Lumiar, RJ

    Energy Technology Data Exchange (ETDEWEB)

    Mendes, Julio Cezar; Medeiros, Silvia Regina de; Chaves, Eduardo Amorim, E-mail: julio@geologia.ufrj.br, E-mail: silvia@geologia.ufrj.br, E-mail: edupc2@yahoo.com.br [Departamento de Geologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro (RJ) (Brazil)

    2011-09-15

    In the central-northern Ribeira belt there are many granitic to granodioritic bodies showing varied shape and size, characterizing a late- to post-collisional Ca-alkaline, cordilleran I-type province. The Sao Pedro Granite occurs in the mountain region of Rio de Janeiro State as small post-collisional bodies. It presents isotropic fabric, equigranular to seriate inequigranular texture, as well as local concentration of allanite, which gives discrete composition and texture variation to the rock. The granite has a high-K calcalkaline to alkali-calcic character and weakly peraluminous nature. Despite its short geochemical variation, high Ba, Zr and Th contents besides low concentrations of MgO and CaO are noticeable. High REE contents are associated with fractionated REE patterns showing strong negative Eu anomalies. A crustal origin for the granite can be assumed by its very negative and positive .Nd and .Sr values, respectively, as well as by 87Sr/86Sr initial ratios ranging from 0,718 to 0,740. TDM ages point to paleoproterozoic source, which agrees with geological time of intensive crust generation. (author)