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

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.

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.

Afro-Americans and Early Pan-Africanism

Science.gov (United States)

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)

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

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

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.

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.

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 ...

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

Energy Technology Data Exchange (ETDEWEB)

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)

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

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.

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)

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

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

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 ...

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.)

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

Science.gov (United States)

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

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

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

African Journals Online (AJOL)

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 ...

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

African Journals Online (AJOL)

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 ...

The African novel and the city: a reading of Zaynab Alkali's The ...

African Journals Online (AJOL)

This paper has explored the African novel in the light of the influence of city life to it. Zaynab Alkali's The Initiates was examined with a close look at how the city has influenced characters and happenings in the novel. The paper revealed that the city as presented by Alkali in The Initiates is corrupt and morally bankrupt.

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

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

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.

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.

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.

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.

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.

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...

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.

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 ...

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 ...

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 ...

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 ...

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, ...

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,

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

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

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

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 ...

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)

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.

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

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 ...

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)

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…

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

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 ...

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 ...

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 ...

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.

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.

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.)

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.

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 ...

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 ...

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.

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

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

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

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)

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.

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

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.

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)

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,

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.

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.)

Archean inheritance in zircon from late Paleozoic granites from the Avalon zone of southeastern New England: an African connection

Science.gov (United States)

Zartman, R.E.; Don, Hermes O.

1987-01-01

In southeastern New England the Narragansett Pier Granite locally intrudes Carboniferous metasedimentary rocks of the Narragansett basin, and yields a monazite UPb Permian emplacement age of 273 ?? 2 Ma. Zircon from the Narragansett Pier Granite contains a minor but detectable amount of an older, inherited component, and shows modern loss of lead. Zircon from the late-stage, aplitic Westerly Granite exhibits a more pronounced lead inheritance -permitting the inherited component to be identified as Late Archean. Such old relict zircon has not been previously recognized in Proterozoic to Paleozoic igneous rocks in New England, and may be restricted to late Paleozoic rocks of the Avalon zone. We suggest that the Archean crustal component reflects an African connection, in which old Archean crust was underplated to the Avalon zone microplate in the late Paleozoic during collision of Gondwanaland with Avalonia. ?? 1987.

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.

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

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

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)

Les granitoïdes néoprotérozoïques de Khzama, Anti-Atlas central, Maroc: marqueurs de l'évolution d'un magmatisme d'arc à un magmatisme alcalineNeoproterozoic granitoids from Khzama, central Anti-Atlas, Morocco: evolution markers from arc magmatism to alkaline magmatism

Science.gov (United States)

El-Khanchaoui, T.; Lahmam, M.; El-Boukhari, A.; El-Beraaouz, H.

2001-05-01

Petrological study and zircon typology provide important information that is related to the classification and genesis of Neoproterozoic granitoids in the Khzama area (northeast Siroua). The Pan-African granitoids show a transition from island-arc magmatism to alkaline magmatism. A space and time zonation of magmatism from the north to the south is evident. Early Pan-African granitoids were generated from various magma sources through different petrogenetic mechanisms. The first association corresponds to the low-K calc-alkaline plutons of Ait Nebdas, the second one correponds to high-K calc-alkaline post-collisional granites (Tamassirte-Tiferatine and Ifouachguel). Finally, shoshonitic magmatism (Irhiri) ends the magmatic evolution of the region. Thus, the late Pan-African granitic plutonism began with calc-alkaline associations and ended with K-alkaline magmatism in a transtensional setting, heralding the onset of the Moroccan Palæozoic cycle.

Neoliberal Imperialism and Pan-African Resistance

Directory of Open Access Journals (Sweden)

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.

hydrogeochemistry of shallow groundwater in kurgwi and environs ...

African Journals Online (AJOL)

complab7

predominantly calcium – sodium- bicarbonate (Ca – Na -. HCO3) type (Fig 6). Kurgwi and Environs is underlain predominantly by granitic rocks of the basement complex (Dung, 2014). These crystalline rocks are all. Pan – African Granites that differ only in texture. The vast nature of these granites may be responsible for the.

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

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

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)

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

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.

Contribution To The Geology Of Basement Rocks In The South Western Desert Of Egypt

International Nuclear Information System (INIS)

Sadek, M.F.; Khyamy, A.A.

2003-01-01

Three major Precambrian basement inliers are exposed in the South Western Desert of Egypt between Long. 29 degree E and the River Nile within the Uweinat-Bir Safsaf-Aswan E-W uplift system. These are Bir Safsaf, Gabal EI-Asr and Gabal Umm Shaghir areas. Smaller outcrops include Gabal EI-Gara El-Hamra and Gabal El-Gara EI-Soda, Gabal Siri, GabaI EI-Fantas and Aswan-Kalabsha area as well as the scattered outcrops around Darb El-Arbain road. Band ratios 5/7, 5/1, 4 of Landsat TM images were applied to delineate the borders, the lithologic units and structural features of low relief basement outcrops within the surrounding flat lying sedimentary rocks and sand plains. These basement rocks comprise ortho gneisses (assumed by many authors as related to old continent pre Pan-African rocks), G 1 tonalite-granodiorite, and G2 monzogranite-alkali feldspar granite intruded by variable dykes. The boundaries between the basement exposures and the sedimentary rocks are marked by nonconformity surfaces or sets of faults. Both basement and sedimentary rocks are intruded by Mesozoic syenite-G3 granites, rhyolite, trachytic plugs and Upper Cretaceous to Tertiary basalts. The basement exposures are structurally controlled by major E- W fault systems. Their vertical uplifting is overprinted by folding the overlying sedimentary rocks. This study revealed that, the different basement exposures in the SE of the Western Desert of Egypt are similar in appearance and field relations to the Pan-African basement rocks extending towards the east of the River Nile and exposed everywhere in the Eastern Desert of Egypt

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.

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.

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

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

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)

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.

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

Full Text Available The Mayo Salah pluton, which is located in the North-Cameroon domain of Central African Bold Belt (CAFB, is emplaced as a laccolith in volcano-sedimentary schists of Poli series, and displays features of Rare-metal Granite (RMG. It is made of two main rock groups: (1 the metaluminous barren muscovite granite (MsG and (2 the Nb-Ta bearing peraluminous leucogranite (MsL which expresses four subtypes. The evolved Rare-element MsL is subalkaline, slightly peraluminous (ASI = 1.01–1.21, and it displays flat REE chondrite-normalized patterns with a strong negative Eu anomaly (Eu/Eu* = 0.02–0.20. It belongs to the peraluminous low phosphorus Rare-element Granites and L-type igneous rocks, as shown by the relatively low Zr/Hf (4.8–14 and Nb/Ta (1.4–9.0 ratios and the positive slope of the Zr-Hf-Nb-Ta profile in spider diagrams. The rare-element-bearing mineral is represented by columbite-group minerals (CGM and other Nb-Ta-oxides (Nb-rutile and pyrochlore supergroup minerals. The CGM is classified as Mn-columbite, with Ta# and Mn# ratios increasing from core to rim. Two stages of mineralization are identified; the earliest stage (CGM-I consists in scattered tabular or prismatic euhedral grains that were related to magmatic fractionation. The latest stage (CGM-II is expressed as a Ta-rich Mn hydrothermal CGM episode represented as rims and/overgrowths around and/or as veinlet crosscutting CGM-I or in cleavage planes of muscovite. The U-Pb dating of columbite and monazite of the Mayo Salah leucogranite indicates a late-Neoproterozoic magmatic-hydrothermal mineralization event from 603.2 ± 5.3 to 581.6 ± 7.2 Ma, as consistent with both late D2 to D3 events that were recorded in the CAFB in Cameroon, and the associated continental collision environment. The Nb-Ta mineralization of the Mayo Salah pluton provides evidence for the presence of RMG in Northern Cameroon of CAFB, and its temporal association with the youngest period of metallogenic epoch

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.

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.

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)

Panafricanism, African Boundaries and Regional Integration ...

African Journals Online (AJOL)

The Pan African idea of closer unity is examined. Regional economic integration as a Pan African perspective is presented as a major way out of the deep and worsening economic crises bedeviling African economics. Attempts have been made since the 1960s to create and re-create institutions for regional economic ...

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.

Rationale and design of the Pan-African Sudden Cardiac Death survey

DEFF Research Database (Denmark)

Bonny, Aimé; Ngantcha, Marcus; Amougou, Sylvie Ndongo

2014-01-01

BACKGROUND: The estimated rate of sudden cardiac death (SCD) in Western countries ranges from 300,000 to 400,000 annually, which represents 0.36 to 1.28 per 1 000 inhabitants in Europe and the United States. The burden of SCD in Africa is unknown. Our aim is to assess the epidemiology of SCD...... of districts of interest will be checked for past medical history, circumstances of death, and autopsy report (if possible). We will also analyse the employment of resuscitation attempts during the time frame of sudden cardiac arrest (SCA) in various patient populations throughout African countries. CONCLUSION...... in Africa. METHODS: The Pan-Africa SCD study is a prospective, multicentre, community-based registry monitoring all cases of cardiac arrest occurring in victims over 15 years old. We will use the definition of SCD as 'witnessed natural death occurring within one hour of the onset of symptoms...

The scramble for Africa: pan-temperate elements on the African high mountains.

Science.gov (United States)

Gehrke, Berit; Linder, H Peter

2009-07-22

The composition of isolated floras has long been thought to be the result of relatively rare long-distance dispersal events. However, it has recently become apparent that the recruitment of lineages may be relatively easy and that many dispersal events from distant but suitable habitats have occurred, even at an infraspecific level. The evolution of the flora on the high mountains of Africa has been attributed to the recruitment of taxa not only from the African lowland flora or the Cape Floristic Region, but also to a large extent from other areas with temperate climates. We used the species rich, pan-temperate genera Carex, Ranunculus and Alchemilla to explore patterns in the number of recruitment events and region of origin. Molecular phylogenetic analyses, parametric bootstrapping and ancestral area optimizations under parsimony indicate that there has been a high number of colonization events of Carex and Ranunculus into Africa, but only two introductions of Alchemilla. Most of the colonization events have been derived from Holarctic ancestors. Backward dispersal out of Africa seems to be extremely rare. Thus, repeated colonization from the Northern Hemisphere in combination with in situ radiation has played an important role in the composition of the flora of African high mountains.

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.

Ring complexes and related rocks in Africa

Science.gov (United States)

Vail, J. R.

Over 625 igneous complexes throughout Africa and Arabia have been selected and classified on the basis of petrographic association and chronology into six broad age groups forming 29 provinces. The groups range from Mid-Proterozoic to Tertiary and include gabbro, granite, syenite, foid syenite and carbonatite plutonic rocks, the majority in the form of ring-dykes, cone-sheets, plugs, circular intrusions, and their associated extrusive phases. Pan-African late or post-orogenic complexes (720-490 Ma) are common in the Arabian-Nubian and Tuareg shields of north Africa originating from subduction zone derived magmatism. Anorogenic complexes in Egypt, NE and central Sudan, Niger, Nigeria, Cameroon, Zaïre-Burundi, Malawi, Mozambique, Zimbabwe, Namibia and Angola span 550 to 50 Ma and are dominantly alkali granites and foid syenites. Many groups occur as en-echelon bands within linear arrays, and show migrating centres of intrusion in variable directions. In W. Africa there was a progressive shift of emplacement southwards during early Ordovician to Mid-Cretaceous times. Distribution patterns suggest thatdeep seated features, such as shear zones associated with lithospheric plate movements,controlled melting, and the resultant location of the complexes. Economic mineralization is not widespread in the rocks of the African ring complexes and is mainly restricted to small deposits of Sn, W, F, U and Nb.

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.)

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

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

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

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.

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

African Anthropologist: Submissions

African Journals Online (AJOL)

Author Guidelines. The African Anthropologist is a biannual journal of the Pan African Anthropological Association. It provides a forum for African and Africanist anthropologists to publish articles, research reports, review articles, and book reviews. The views expressed in any published material are those of the authors and ...

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.

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

Journal of Earth System Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

... by extensional mechanism of Gondwana tectonics events. Similar widespread granitic activity has also beendocumented 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.

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

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.

"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.

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)

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

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

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.

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)

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)

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.

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.

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

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…

Syndrome d´Apple-Peel avec nécrose intestinale | Khattala | Pan ...

African Journals Online (AJOL)

Syndrome d´Apple-Peel avec nécrose intestinale. Khalid Khattala, Youssef Bouabdallah. Abstract. Pan African Medical Journal 2012; 13:63. Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT · AJOL African Journals Online. HOW TO USE AJOL.

Hypoglycemia revealing arachnoidocele in infant | Jellouli | Pan ...

African Journals Online (AJOL)

The patient was treated with hydrocortisone, levothyroxine and growth hormone replacement. The outcome was favorable without recourse to neurosurgery at the lack of damage to the optic nerve and the sphenoid bone, with a decline of five years otherwise the child has a delay in psychomotor acquisitions. Pan African ...

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.

Clash of pans: pan-Africanism and pan-Anglo-Saxonism and the global colour line, 1919–1945

OpenAIRE

Ledwidge, M.; Parmar, I.

2017-01-01

The article demonstrates both conceptually and empirically that pan-Anglo-Saxonist knowledge networks reconstructed and reimagined an apparently de-racialised, scientific, sober and liberal world order that outwardly abandoned, but did not eradicate the twin phenomena of racism and imperialism. Rather the new liberal (imperial) internationalists, organised in newly formed “think tanks” such as Chatham House and the Council on Foreign Relations, and through their increasingly global elite netw...

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

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

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.)

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

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

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.)

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

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.)

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.

K/Ar age dating of Oshnaviyeh plutonic complex

International Nuclear Information System (INIS)

Ghalamghash, J.; Vosoughi Abedini, M.; Bellon, H.; Emami, M.H.; Pourmafi, M.; Rashid, H.

2003-01-01

Oshnaviyeh plutonic complex, the western member of Urumiyeh-Golpayehgan intrusive plutons is located in northern part of Sanandaj-Sirjan zon. Oshnaviyeh plutonic complex, exposing in an area of about 700 km 2 , comprises 10 plutons that can be divided into three suites, i.e.,diorite,granite,and alkali syenite-alkali granite. Dioritic bodies are the oldest intrusive rocks of the region, which on the basis of the field study, their relative age of emplacement is estimated to be post-Jurassic and pre-miocene. However, with respect to the age of other similar intrusive bodies in Naghadeh area, they are most likely of post early cretaceous-pre miocene age. Hybrid intrusive rocks, occurring at the contact of dioritic and granitic rocks may suggest a simultaneous emplacement of both magmas. Syntetic pluton from alkali syenite-alkali granite has intruded dioritic and granitic rocks, in contrast, flourine bearing alkali granite pluton from this suite shows no contact with other igneous rocks in the area. K-Ar age determinations obtained on amphibole specimens from diorite suite are 91.9±2.3, 94.1±2.3 and 100±2.4 Ma, and on biotite specimens from granite suite are 100±1.5 to 98.9±1.5 Ma. Chronology study using same method on arfvedsonite specimens from syenite pluton shows 78.9±3.1, 79.6±1.9 and 81.7±2.0 Ma and on K-fled par samples of flourine bearing alkali granite pluton from the alkali syenite-alkali granite suite presents 76±3.4 and 77.1±1.8. Therefore, based on field evidence and K/Ar age dating, Oshnaviyeh plutonic complex presumably formed during two episodes: granite and diorite suites formed simultaneously at about 100 Ma, then plutons of alkali syenite-alkali granite suite emplaced at about 80 Ma

Cholera Epidemiology in Nigeria: an overview | Adagbada | Pan ...

African Journals Online (AJOL)

Pan African Medical Journal. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 12, No 1 (2012) >. 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 ...

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�

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,…

Magmatic context of Bou Skour copper deposit (Eastern Anti-Atlas, Morocco): Petrogrography, geochemistry and alterations

Science.gov (United States)

EL Azmi, Daoud; Aissa, M.; Ouguir, H.; Mahdoudi, M. L.; El Azmi, M.; Ouadjo, A.; Zouhair, M.

2014-09-01

The Bou Skour copper deposit is located in the western part of the Saghro massif (Eastern Anti-Atlas), about 50 km East of the city of Ouarzazate. It is subdivided into several areas that are, from North to South: “Panthère”, “Chaigne”, “Anne Marie”, “Chapeau de fer” and “Patte d'Oie”. The latter is economically the most important and is the object of this study. The “Patte d'Oie” district consists mainly of extrusive and intrusive igneous rocks. The extrusive rocks are represented by andesites spatially associated with pyroclastic terms (ignimbrites and pyroclastic breccias). This volcanic unit is intruded by a pink granite pluton and a I-type granodiorite with equigranular texture (Bou Skour granodiorite) showing to the border a microgranular facies (microgranodiorite). All these magmatic formations are intersected by rhyolitic dykes (NNE-SSW) and doleritic dykes (WNW-ESE to NW-SE). The granodiorite and andesite have undergone a polyphase hydrothermal alteration: (i) potassic alteration, (ii) phyllitic alteration, (iii) silicification, (iv) argillic alteration and (v) propylitic alteration. The analysis of geochemical data of granodiorite, granite, andesite and dolerite confirmed: (i) their petrographic natures, (ii) the medium-K calc-alkaline affiliation of andesite and granodiorite, which would have been set up into an active geotectonic environment, probably of island arc or collision, during the Pan-African orogeny, (iii) The high-K calc-alkaline character of granite indicating a post-collision development during the Pan-African orogeny and (iv) The alkaline affinity of the dolerite which is linked to an extensive post-orogenic setting (post-Pan-African). The copper mineralization of “Patte d'Oie” area is hosted, exclusively, in the andesitic and granodioritic facies. It is represented, essentially, by chalcopyrite and bornite minerals and is, probably, related to a porphyry system (disseminated and stockwork mineralization

African Journal of Neurological Sciences

African Journals Online (AJOL)

African Journal of Neurological Sciences (AJNS) is owned and controlled by the Pan African Association of Neurological Sciences (PAANS). The AJNS's aim is to publish scientific papers of any aspects of Neurological Sciences. AJNS is published quarterly. Articles submitted exclusively to the AJNS are accepted if neither ...

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

Basement control in the development of the early cretaceous West and Central African rift system

Science.gov (United States)

Maurin, Jean-Christophe; Guiraud, René

1993-12-01

The structural framework of the Precambrian basement of the West and Central African Rift System (WCARS) is described in order to examine the role of ancient structures in the development of this Early Cretaceous rift system. Basement structures are represented in the region by large Pan-African mobile belts (built at ca. 600 Ma) surrounding the > 2 Ga West African, Congo and Sao Francisco cratons. Except for the small Gao trough (eastern Mali) located near the contact nappe of the Pan-African Iforas suture zone along the edge of the West African craton, the entire WCARS is located within the internal domains of the Pan-African mobile belts. Within these domains, two main structural features occur as the main basement control of the WCARS: (1) an extensive network of near vertical shear zones which trend north-south through the Congo, Brazil, Nigeria, Niger and Algeria, and roughly east-west through northeastern Brazil and Central Africa. The shear zones correspond to intra-continental strike-slip faults which accompanied the oblique collision between the West African, Congo, and Sao Francisco cratons during the Late Proterozoic; (2) a steep metamorphic NW-SE-trending belt which corresponds to a pre-Pan-African (ca. 730 Ma) ophiolitic suture zone along the eastern edge of the Trans-Saharian mobile belt. The post-Pan-African magmatic and tectonic evolution of the basement is also described in order to examine the state of the lithosphere prior to the break-up which occurred in the earliest Cretaceous. After the Pan-African thermo-tectonic event, the basement of the WCARS experienced a long period of intra-plate magmatic activity. This widespread magmatism in part relates to the activity of intra-plate hotspots which have controlled relative uplift, subsidence and occasionally block faulting. During the Paleozoic and the early Mesozoic, this tectonic activity was restricted to west of the Hoggar, west of Aïr and northern Cameroon. During the Late Jurassic

Strides in Preservation of Malawi's Natural Stone

Science.gov (United States)

Kamanga, Tamara; Chisenga, Chikondi; Katonda, Vincent

2017-04-01

The geology of Malawi is broadly grouped into four main lithological units that is the Basement Complex, the Karoo Super group, Tertiary to Quaternary sedimentary deposits and the Chilwa Alkaline province. The basement complex rocks cover much of the country and range in age from late Precambrian to early Paleozoic. They have been affected by three major phases of deformation and metamorphism that is the Irumide, Ubendian and The Pan-African. These rocks comprise gneisses, granulites and schists with associated mafic, ultramafic, syenites and granite rocks. The Karoo System sedimentary rocks range in age from Permian to lower Jurassic and are mainly restricted to two areas in the extreme North and extreme Alkaline Province - late Jurassic to Cretaceous in age, preceded by upper Karoo Dolerite dyke swarms and basaltic lavas, have been intruded into the Basement Complex gneisses of southern Malawi. Malawi is endowed with different types of natural stone deposits most of which remain unexploited and explored. Over twenty quarry operators supply quarry stone for road and building construction in Malawi. Hundreds of artisanal workers continue to supply aggregate stones within and on the outskirts of urban areas. Ornamental stones and granitic dimension stones are also quarried, but in insignificant volumes. In Northern Malawi, there are several granite deposits including the Nyika, which is the largest single outcrop occupying approximately 260.5 km2 , Mtwalo Amazonite an opaque to translucent bluish -green variety of microcline feldspar that occurs in alkali granites and pegmatite, the Ilomba granite (sodalite) occurring in small areas within biotite; apatite, plagioclase and calcite. In the Center, there are the Dzalanyama granites, and the Sani granites. In the South, there are the Mangochi granites. Dolerite and gabbroic rocks spread across the country, treading as black granites. Malawi is also endowed with many deposits of marble. A variety of other igneous

Investigation of the Effect of Alkali Modification of Mucin on Some ...

African Journals Online (AJOL)

The objective of this study was to investigate the effect of alkali treatment of mucin on the mucoadhesive properties and tablet parameters of metronidazole tablets. Mucin was extracted from the African giant snails (Archachatina maginata) by differential precipitation using acetone, air-dried and pulverized. Different portion of ...

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

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

The African upper mantle and its relationship to tectonics and surface geology

Science.gov (United States)

Priestley, Keith; McKenzie, Dan; Debayle, Eric; Pilidou, Sylvana

2008-12-01

This paper focuses on the upper-mantle velocity structure of the African continent and its relationship to the surface geology. The distribution of seismographs and earthquakes providing seismograms for this study results in good fundamental and higher mode path coverage by a large number of relatively short propagation paths, allowing us to image the SV-wave speed structure, with a horizontal resolution of several hundred kilometres and a vertical resolution of ~50 km, to a depth of about 400 km. The difference in mantle structure between the Archean and Pan-African terranes is apparent in our African upper-mantle shear wave model. High-velocity (4-7 per cent) roots exist beneath the cratons. Below the West African, Congo and Tanzanian Cratons, these extend to 225-250 km depth, but beneath the Kalahari Craton, the high wave speed root extends to only ~170 km. With the exception of the Damara Belt that separates the Congo and Kalahari Cratons, any high-speed upper-mantle lid below the Pan-African terranes is too thin to be resolved by our long-period surface wave technique. The Damara Belt is underlain by higher wave speeds, similar to those observed beneath the Kalahari Craton. Extremely low SV-wave speeds occur to the bottom of our model beneath the Afar region. The temperature of the African upper mantle is determined from the SV-wave speed model. Large temperature variations occur at 125 km depth with low temperatures beneath west Africa and all of southern Africa and warm mantle beneath the Pan-African terrane of northern Africa. At 175 km depth, cool upper mantle occurs below the West African, Congo, Tanzanian and Kalahari Cratons and anomalously warm mantle occurs below a zone in northcentral Africa and beneath the region surrounding the Red Sea. All of the African volcanic centres are located above regions of warm upper mantle. The temperature profiles were fit to a geotherm to determine the thickness of the African lithosphere. Thick lithosphere exists

Chemical Th-U-total Pb isochron ages of zircon and monazite from granitic rocks of the Negele area, southern Ethiopia

International Nuclear Information System (INIS)

Yihunie, Tadesse

2003-01-01

CHIME (Chemical Th-U-total Pb Isochron Method) age determinations were made on zircon and monazite grains from granitoid samples in the Negele area of southern Ethiopia. A 611±32 Ma zircon age was obtained from a syn-tectonic hornblende-biotite granite of the Alghe domain. A 453±29 Ma zircon age and a 459±16 Ma monazite age were also obtained from post-tectonic two-mica granites of the Alghe domain and the Kenticha domain, respectively. Since these ca. 450 Ma zircon and monazite ages coincide well, as significant post-tectonic granitic magmatism appears to have occurred in southern Ethiopia in early Paleozoid time. The new CHIME age results indicate at least two episodes of granitic magmatism in southern Ethiopia in the late Proterozoic to early Paleozoic, with a ca. 150 Ma interval between syn- and post-tectonic granitic emplacements, and have a important geochronological constraint on the evolution of the East African Orogen. (author)

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.

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.

A Geothermochronologic Investigation of the Coyote Mountains Metamorphic Core Complex (AZ)

Science.gov (United States)

Borel, M.; Gottardi, R.; Casale, G.

2017-12-01

The Coyote Mountains metamorphic core complex (CM-MCC) makes up the northern end of the Baboquivari Mountain complex, which is composed of Mesozoic rocks, Tertiary granites, pegmatites, and metasediments. The CM-MCC expose the Pan Tak granite, a 58 Ma intrusive muscovite-biotite-garnet peraluminous granite. The Pan Tak and other intrusions within the Baboquivari Mountains have been interpreted as anatectic melts representing the culmination of a Laramide crustal shortening orogenic event started in the Late Cretaceous ( 70 Ma). Evidence of this magmatic episode includes polysynthetic twinning in plagioclase, myrmekitic texture in alkali feldspars, and garnet, mica and feldspar assemblages. The magmatic fabric is overprinted by a Tertiary tectonic fabric, associated with the exhumation of the CM-MCC along the Ajo road décollement and associated shear zone. In the shear zone, the Pan Tak mylonite display N-dipping foliation defined by gneissic layering and aligned muscovite, and N-trending mineral stretching lineation. Various shear sense indicators are all consistent with a top-to the-N shear sense. Preliminary argon geochronology results suggest that the shear zone was exhumed 29 Ma ago, an age similar to the onset of detachment faulting in other nearby MCCs (Catalina, Rincon, Pinaleño). In the Pan Tak mylonite, quartz grains display regime 2 to 3 microstructures and shows extensive recrystallization by subgrain rotation and grain boundary migration. The recrystallized grain size ranges between 20 and 50 µm in all samples. Quartz crystallographic preferred orientation measured using electron backscatter diffraction (EBSD) shows that recrystallization was accommodated by dominant prism and minor rhomb slip, suggesting deformation temperature ranging from 450°C to 550°C. These preliminary results constrain the timing of uplift and exhumation, and thermomechanical evolution of the CM-MCC, and improve our understanding of recycling of the continental crust in

African Journal of Neurological Sciences: Editorial Policies

African Journals Online (AJOL)

African Journal of Neurological Sciences (AJNS) is owned and controlled by the Pan African Association of Neurological Sciences (PAANS). The AJNS's aim is to publish scientific papers of any aspects of Neurological Sciences. AJNS is published quarterly. Articles submitted exclusively to the AJNS are accepted if neither ...

Preparation of Amino-Modified PAN Fibers with Triethylenetetramine as Aminating Reagents and Their Application in CO2 Adsorption

Directory of Open Access Journals (Sweden)

Wenbo Zhao

2014-01-01

Full Text Available Amino-modified polyacrylonitrile (AMPAN fiber was synthesized by the reaction of polyacrylonitrile (PAN fiber and triethylenetetramine (TETA in the presence of water. The effect of water amount, reaction temperature, and time on the weight increase degree and alkali content of the AMPAN fiber was investigated in detail. The characterization results indicated that TETA could be grafted onto the surface of PAN fiber by this method. However, the highest adsorption capacity of the AMPAN fibers was only 0.09 g/g even at 15 bar and 50°C, which was much lower than the porous materials. The reason for this result may be related to its low surface area.

Pan-pan Girls: Humiliating Liberation in Postwar Japanese Literature

Directory of Open Access Journals (Sweden)

Rumi Sakamoto

2010-09-01

Full Text Available This paper looks at some literary representations of the ‘pan-pan girls’ in postwar Japan. ‘Pan-pan’ is a derogatory term for street prostitutes who (mostly served the soldiers of the occupying forces. Immediately after World War II, the Japanese government established the RAA (Recreation Amusement Association and employed several thousand women to provide sexual services for foreign soldiers, ostensibly to protect Japanese women of middle and upper classes from rape and other violence. When the RAA was closed down in 1946 due to the US concern over widespread VD, many of the women who lost their jobs went out on the street and became private and illegal prostitutes – the pan-pan girls. With their red lipstick, cigarettes, nylon stockings and high-heel shoes, often holding onto the arms of tall, uniformed American GIs, the ‘pan-pan girls’ became a symbol of the occupation, and have been textually reproduced throughout the postwar period. This paper analyses the images and representations of the ‘pan-pan girls’ in postwar Japanese literature, to consider how the ‘pan-pan girls’ have functioned as a metaphor for the occupation and contributed to the public memory construction of the occupation. I identify some major codes of representations (victimisation, humiliation, and national trauma; eroticism and decadence; sexual freedom and materialism and argue that the highly gendered and sexualised bodies of the ‘pan-pan girls’ have continued to allow simplistic and selective remembering of the occupation at the expense of recalling the pivotal role of Japanese patriarchy in the postwar period.

Analysis of licensed South African diagnostic imaging equipment ...

African Journals Online (AJOL)

Analysis of licensed South African diagnostic imaging equipment. ... Pan African Medical Journal ... Introduction: Objective: To conduct an analysis of all registered South Africa (SA) diagnostic radiology equipment, assess the number of equipment units per capita by imaging modality, and compare SA figures with published ...

Multiple cystic lung disease in an adolescent boy | Sogut | Pan ...

African Journals Online (AJOL)

Pan African Medical Journal. Journal Home · ABOUT · Advanced Search · Current Issue · Archives · Journal Home > Vol 23, No 1 (2016) >. 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 ...

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.

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.

Pambzuka News : building a progressive pan-Africa movement

OpenAIRE

Manji, Firoze

2008-01-01

Pambzuka News is described variously as an e-newsletter or platform of website about social justice in Africa. There are some that see it as an example innovative use of information communications technology. Yet it is both all of these and none of them. Pambzuka News is an attempt to nurture and encourage the building of a progressive pan Africa movement within Africa and amongst what is popularly described as the African diaspora.

Bone metastasis as the first sign of gastric cancer | Ameur | Pan ...

African Journals Online (AJOL)

Pan African Medical Journal. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 28, No 1 (2017) >. 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 ...

Determination of granite rock massif weathering and cracking of surface layers in the oldest parts of medieval mine depending on used mining method

Czech Academy of Sciences Publication Activity Database

Lednická, Markéta; Kaláb, Zdeněk

2016-01-01

Roč. 61, č. 2 (2016), s. 381-395 ISSN 0860-7001 R&D Projects: GA MŠk(CZ) LO1406; GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : Jeroným Mine * non-destructive testing * granite Subject RIV: DH - Mining, incl. Coal Mining Impact factor: 0.550, year: 2016 http://archiwum.img-pan.krakow.pl/index.php/AMS/article/view/785/692

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.

A Call to African Unity

DEFF Research Database (Denmark)

Muchie, Mammo

This month's paper, written by Professor Mammo Muchie, examines the necessity for a pan-African monetary union.  Professor Muchie argues for the "the creation of a unified African strategy and unified approach to dealing with the outside donor world by neutralising the poison of money as honey...... that donor aid has come to be in Africa." He provides a historic and contemporary context for the unification of monetary and customs systems across Africa and argues for a dual currency system for the self-financing of African development and for sustained self-determination....

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

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.].

African Journals Online: Nigeria

African Journals Online (AJOL)

Items 51 - 100 of 221 ... International Journal of Basic, Applied and Innovative Research ... Regional headquarters of the Pan-African Gender and Peace Research Group. ... Faculty of Health Sciences and Technology and Faculty of Dentistry. Through excellence in education and research and clinical service, College of ...

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

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...

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.

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...

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.

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.

Gold and uranium metallogenesis in the framework of Neo-proterozoic crust growth and differentiation: example of the Mayo-Kebbi Massif (Chad) in the Central Africa Orogenic belt

International Nuclear Information System (INIS)

Mbaguedje, Diondoh

2015-01-01

The Mayo Kebbi massif located in southwestern Chad between the Congo craton in the South, the West African craton in the west and the Sahara meta-craton to the east exposes a segment of Neo-proterozoic juvenile crust accreted in the Central African orogenic belt during the Pan African orogeny. It consists of two greenstone belts (Zalbi and Goueygoudoum) separated by the May Kebbi calc-alkaline batholith complexes and intruded by calc-alkaline high-K granitic plutons. The whole is covered by Phanerozoic sedimentary formations. The greenstone belts contain sulphide zones hosted mainly by meta-plutonic rocks (granodiorites) and meta-basalts and meta-volcaniclastics. The mineralization comprises pyrite, pyrrhotite, arsenopyrite, chalcopyrite, pentlandite, pentlandite silver, pentlandite cobaltiferous, sphalerite, cobaltite. These sulphides are disseminated, aggregated in form of layers or are filling veins and cracks. The greenstones also contain quartz veins with calcite and chlorite comprising a mineralization made of pyrite, chalcopyrite, galena and gold. Gold is present both as native crystals and as electrum. The high-K calc-alkaline Zabili granitic pluton hosts uranium mineralization related to a superposition of: (1) ductile deformation and metasomatic alteration implying the interaction between magmatic minerals with a Na-rich fluid, of potential magmatic origin, coeval to the main deposition of uranium oxides, followed by (2) brittle deformation and deposition of secondary hydrated uranium silicates involving a Na-Ca-rich fluid. We propose that these uranium mineralizations represent the extreme expression of crustal differentiation as a result of Pan-African reworking of a Neo-proterozoic juvenile crustal segment. (author) [fr

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

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.

Pan-Gondwanaland post-collisional extension marked by 650 500 Ma alkaline rocks and carbonatites and related detrital zircons: A review

Science.gov (United States)

Veevers, J. J.

2007-07-01

Pan-Gondwanaland (650-500 Ma) tectonics is dominated by transcurrent motions driven by post-collisional oblique stresses. Extension is commonly marked by the intrusion of alkaline rocks, in particular A-type granite, nepheline syenite, and carbonatites (ARCs), during or after collision, as well as by field studies. ARCs of this age are common in Africa, South America, India, Antarctica, and Australia, and are indicated by related detrital zircons of 650-500 Ma age in Permian-Triassic and younger sediments from Australia, Antarctica, southern Africa, and India. Structural studies suggest that ARCs fill openings at releasing bends along transcurrent fractures and during reversal of the sense of motion as well as during relaxation of stress after collision. On the Paleo-Pacific margin, 550-500 Ma ARCs of the Koettlitz Glacier Alkaline Province were emplaced syn-tectonically within the Ross orogen during oblique subduction. The concentration of ARC magmas emplaced during the amalgamation of Gondwanaland is correlated with the transtension generated by the 650-570 Ma oblique subduction between Avalonia-Cadomia and the West African craton, and the 550-490 Ma oblique subduction of the Paleo-Pacific underneath Antarctica. In the Eastern Ghats and the Prince Charles Mountains of East Antarctica, ARCs and related zircons were generated 1000-900 Ma during an earlier continental collision.

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

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...

Dissection spontanée et isolée du tronc coeliaque | Mrad | Pan ...

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 ...

Evolution of Brasiliano-age granitoid types in a shear-zone environment, Umarizal-Caraubas region, Rio Grande do Norte, northeast Brazil

Science.gov (United States)

Galindo, A. C.; Dall'Agnol, R.; McReath, I.; Lafon, J. M.; Teixeira, N.

1995-01-01

A sequence of Brasiliano-age granitoid types is exposed in a small area near the cities of Umarizal and Caraúbas in Rio Grande do Norte State, Northeast Brazil. Porphyritic K-alkali-calcic monzogranite is an important facies of the oldest Caraúbas intrusion (RbSr whole rock isochron age of ca. 630 Ma), which suffered solid-state deformation due to movements on a major NE-trending shear zone. The intrusion of the Prado and part of the Quixaba bodies was probably controlled by the shear zone. These two bodies include mafic/intermediate rocks, some of which contain two pyroxenes, and have hybrid, partly alkaline and partly shoshonitic geochemical characteristics. Rock types and ages are similar to those of some Pan-African occurrences in southwestern Nigeria. The Tourão body, intruded at ca. 590 Ma, presents preferred mineral orientations which are probably largely magmatic, since little evidence is found for widespread solid-state deformation. On the other hand, its intrusion may have been facilitated by the presence of the shear-zone faults. The rocks form a monomodal felsic K-alkali-calcic suite. With the exception of the Quixaba body, all these earlier granitoids are magmatic epidote- and magnetite-bearing porphyritic monzogranites with trace element geochemical characteristics of modern syn-collisional granites. The latest intrusion at ca. 545 Ma is mainly represented by potassic quartz syenites and related rocks, some of which contain fayalite or ferrohypersthene. These rocks possess neither well developed mineral orientations of magmatic origin nor signs of solid-state deformation. They are mineralogically similar to, but younger than some of the "bauchites" of central Nigeria. Geochemical signatures are comparable with those of modern within-plate granites. All granitoids present high ( 87Sr/ 86Sr)i ratios which range from 0.708 to 0.712, and increase with decreasing age. Such ratios are compatible with important or dominant crustal contributions. On the

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 ...

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.

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

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.)

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.)

Caractéristiques gravimétriques de la partie nord des dahomeyides : chaîne de collision-aggréegation continenetale et lissage gravimétrique au Pan-Africain (600 ± 100 Ma.)

Science.gov (United States)

El-Hadj Tidjani, M.; Affaton, P.; Louis, P.; Lesquer, A.; Socohou, A.; Caby, R.

1993-08-01

The surveyed area straddles the s.s. West-African and The Nigeria-Beninian plates (Fig. 1). It corresponds to the northern part of the Volta Basin, the external and internal structural units, and the suture zone of the Dahomeyide Pan-African Orogen. The main gravity anomalies are sometimes correlated with geological outcropping formations. Numerous gravity gradient changes and discontinuities are noticed. They testify to the structural and geological complexity of this region. This complexity suggests two main hypothese: that of aggregation of micro-continents during the Pan-African; and that of a "gravity smoothing" following the great tangential movements.

African Farmer-led Irrigation Development: re-framing agricultural policy and investment?

OpenAIRE

Woodhouse, Philip; Veldwisch, Gert Jan; Venot , Jean-Philippe; Brockington, Daniel; Komakech, Hans; Manjichi , Ângela

2017-01-01

The past decade has witnessed an intensifying focus on the development of irrigation in sub-Saharan Africa. It follows a 20-year hiatus in the wake of disappointing irrigation performance during the 1970s and 1980s. Persistent low productivity in African agriculture and vulnerability of African food supplies to increasing instability in international commodity markets are driving pan-African agricultural investment initiatives, such as the Comprehensive Africa Agricultural Development Program...

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

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.

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

Present and past microbial life in continental salt pan sediments in Southern Africa

Science.gov (United States)

Genderjahn, Steffi; Mangelsdorf, Kai; Alawi, Mashal; Kallmeyer, Jens; Wagner, Dirk

2015-04-01

The southwestern African region is characterized by strong climate variability. To get a better understanding on the climate evolution and environmental condition in Namibia and South Africa, terrestrial climate archives are investigated. Since there are almost no lakes, continental salt pans represent the only terrestrial geoarchives with the potential to preserve climate signals during sediment deposition. Climate has a strong impact on the salt pan ecosystem, causing adaptation of salt pan microorganisms to varying temperature, precipitation and salinity conditions. To reconstruct climate variability during the Holocene, the composition, diversity and abundance of indigenous microbial communities with depth and related to different soil parameters are investigated. We are using a combined approach of microbiological and lipid biomarker analyses to demonstrate the response of the microbial communities due to environmental changes. For microbiological analyses outcrops were conducted or short cores (0-100 cm) were drilled at four different salt pans in Aminuis, Koes and Witpan region having rather different geochemical properties. The current work focused on changes within the microbial communities due to the impact of long-term climate variation and the associated environmental changes and is part of the project 'Signals of climate and landscape change preserved in southern African GeoArchives' in the scope of the SPACES program, which is funded by the German Federal Ministry of Education and Research (BMBF). For a quantitative characterization of microbial communities molecular techniques such as polymerase chain reaction (PCR) and real-time quantitative PCR (qPCR) based on the 16S rRNA genes are used. Moreover, 454 sequencing technique is utilized to describe the diversity and abundance of microorganisms in detail. Soil parameters are described by standard soil scientific methods. Furthermore, microbial lipid biomarker analyses were done to characterize living

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.

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 ...

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)

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 ...

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.

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

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)

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)

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)

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.

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

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.

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)

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 ...

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 ...

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.

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

Lead isotopic study of aplites from the Precambrian basement rocks near Ibadan, southwestern Nigeria

International Nuclear Information System (INIS)

Oversby, V.M.

1975-01-01

Pb isotopic compositions for three total-rock samples of aplite and their constituent K-feldspars from the Nigerian basement assemblage near Ibadan show lead homogenization during the Pan-African thermo-tectonic event. A secondary isochron formed by the K-feldspars data points is used to calculate a primary age of about 2750 m.y. for the aplites. The aplites do not register any Pb isotopic effect from the intrusion of granite gneiss in the area at 2330m.y. (Auth.)

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

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)

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.

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)

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

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)

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

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

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.

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

Analyses of the soil surface dynamic of South African Kalahari salt pans based on hyperspectral and multitemporal data

Science.gov (United States)

Milewski, Robert; Chabrillat, Sabine; Behling, Robert; Mielke, Christian; Schleicher, Anja Maria; Guanter, Luis

2016-04-01

The consequences of climate change represent a major threat to sustainable development and growth in Southern Africa. Understanding the impact on the geo- and biosphere is therefore of great importance in this particular region. In this context the Kalahari salt pans (also known as playas or sabkhas) and their peripheral saline and alkaline habitats are an ecosystem of major interest. They are very sensitive to environmental conditions, and as thus hydrological, mineralogical and ecological responses to climatic variations can be analysed. Up to now the soil composition of salt pans in this area have been only assessed mono-temporally and on a coarse regional scale. Furthermore, the dynamic of the salt pans, especially the formation of evaporites, is still uncertain and poorly understood. High spectral resolution remote sensing can estimate evaporite content and mineralogy of soils based on the analyses of the surface reflectance properties within the Visible-Near InfraRed (VNIR 400-1000 nm) and Short-Wave InfraRed (SWIR 1000-2500 nm) regions. In these wavelength regions major chemical components of the soil interact with the electromagnetic radiation and produce characteristic absorption features that can be used to derive the properties of interest. Although such techniques are well established for the laboratory and field scale, the potential of current (Hyperion) and upcoming spaceborne sensors such as EnMAP for quantitative mineralogical and salt spectral mapping is still to be demonstrated. Combined with hyperspectral methods, multitemporal remote sensing techniques allow us to derive the recent dynamic of these salt pans and link the mineralogical analysis of the pan surface to major physical processes in these dryland environments. In this study we focus on the analyses of the Namibian Omongwa salt pans based on satellite hyperspectral imagery and multispectral time-series data. First, a change detection analysis is applied using the Iterative

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.)

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.

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.

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

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

Excess Ar in biotites from the Broderick Falls (Webuye) area, western Kenya: implications for the tectonothermal history of the Mozambique Belt and its Archaean foreland

Science.gov (United States)

Shibata, K.; Suwa, K.; Uchiumi, S.; Agata, T.

1996-10-01

RbSr whole rock and KAr mineral age determinations were made on rocks from the Broderick Falls (Webuye) area, western Kenya. Granitic rocks yielded a RbSr whole rock isochron age of 2555 ± 101 Ma with an initial {87Sr}/{86Sr} ratio of 0.70121 ± 0.00038. This age represents the time of granitoid emplacement. KAr mineral ages range from 574 to 3420 Ma, which is very variable with respect to mineral type and locality. Mylonitic granodiorite very close to the Nandi Escarpment gave a KAr age of 916 Ma from biotite, suggesting the time of the activity of the Nandi Fault, which may be an earlier phase of the Pan-African Orogeny. Ages of biotites in a zone between 4 and 6 km northeast of the Nandi Fault are anomalously high compared to those of coexisting hornblende and the RbSr isochron age, confirming the existence of excess 40Ar in biotite. Excess 40Ar was probably introduced into biotite under the appropriate temperature conditions prevailing near the Nandi Fault. Taramite, a rare sodic-calcic amphibole, was found in a cordierite-biotite gneiss of the Kavirondian Supergroup and gave a typical Pan-African KAr age of 574 Ma. The last Pan-African metamorphism occurred in the terrane east of the Surongai Thrust.

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.

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)

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

Superficial Velocity Effects on HZ-PAN and AgZ-PAN for Kr/Xe Capture

Energy Technology Data Exchange (ETDEWEB)

Welty, Amy Keil [Idaho National Lab. (INL), Idaho Falls, ID (United States); Garn, Troy Gerry [Idaho National Lab. (INL), Idaho Falls, ID (United States); Greenhalgh, Mitchell Randy [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2016-04-01

Nearly all previous testing of HZ-PAN and AgZ-PAN was conducted at the same flow rate in order to maintain consistency among tests. This testing was sufficient for sorbent capacity determinations, but did not ensure that sorbents were capable of functioning under a range of flow regimes. Tests were conducted on both HZ-PAN and AgZ-PAN at superficial velocities between 20 and 700 cm/min. For HZ-PAN, Kr capacity increased from 60 mmol/kg to 110 mmol/kg as superficial velocity increased from 21 to 679 cm/min. Results for AgZ-PAN were similar, with capacity ranging from 72 to 124 mmol/kg over the same range of superficial. These results are promising for scaling up to process flows, demonstrating flexibility to operate in a broad range of superficial velocities while maintaining sorbent capacity. While preparing for superficial velocity testing it was also discovered that AgZ-PAN Xe capacity, previously observed to diminish over time, could be recovered with increased desorption temperature. Further, a substantial Xe capacity increase was observed. Previous room temperature capacities in the range of 22-25 mmol Xe/kg AgZ-PAN were increased to over 60 mmol Xe/kg AgZ-PAN. While this finding has not yet been fully explored to optimize activation and desorption temperatures, it is encouraging.

Assistance and Conflict: The African Diaspora and Africa's ...

African Journals Online (AJOL)

sulaiman.adebowale

2007-12-26

Dec 26, 2007 ... In these later years, in the spirit of 'racial Pan-. Africanism', some .... not only to serve as a home to returning Black Americans, but it was also to serve as 'a ..... In the face of white capital flight from Africa, blacks in the diaspora.

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.

Effects of peroxyacetyl nitrate (PAN) on vegetation. I. Herbaceous plants PAN injury symptoms

Energy Technology Data Exchange (ETDEWEB)

Nouchi, I.; Iijima, T.; Oodaira, T.

1975-01-01

A series of exposure experiments were conducted in a controlled-atmosphere exposure chamber equipped with artificial light apparatus, using PAN synthesized from ultraviolet irradiation of ethyl nitrite vapor in oxygen. Exposures of 6 approx. 16 hours and 10 pphm PAN caused serious damage like caving with glazing or bronzing in caved lesions to the lower surface of younger leaves. Leaves of white-flowered petunia were found to be most sensitive to PAN and were damaged even by a 3 pphm exposure. Microscopic examinations showed that the PAN characteristically caused injuries of spongy cells and that these cells collapsed and turned brown. Leaf injury symptoms on herbaceous plants caused by synthesized PAN in the exposure experiments were found to be quite similar to those seen in the field under high oxidant emergence. Therefore, it seems that the said type of injuries to leaf beet, kidney bean, and head lettuce observed in the field were caused by PAN. 21 references. 4 figures, 3 tables.

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)

Comparison studies of surface cleaning methods for PAN-based carbon fibers with acetone, supercritical acetone and subcritical alkali aqueous solutions

International Nuclear Information System (INIS)

Meng Linghui; Fan Dapeng; Huang Yudong; Jiang Zaixing; Zhang Chunhua

2012-01-01

Highlights: ► Cleaning with supercritical acetone is appropriate to wipe off the oxygenated contaminants. ► Cleaning with supercritical acetone causes smaller damage to bulk strength of carbon fibers. ► Cleaning with subcritical alkali aqueous solution can thoroughly remove silicious contaminants. - Abstract: Four kinds of polyacrylonitrile-based carbon fibers were cleaned by three methods and were characterized by X-ray photoelectron spectroscopy, monofilament tensile strength test and atomic force microscopy (AFM). Experimental results of these tests reveal that the method using supercritical acetone or subcritical potassium hydroxide aqueous solution act as the processing medium shows a better cleaning effect compared to the traditional method, Soxhlet extraction with acetone. The method using supercritical acetone is more appropriate to wipe off the oxygenated contaminants on carbon fibers’ surfaces and causes a relatively smaller damage to the bulk strength of each carbon fiber. As far as treating method using the subcritical alkali aqueous solution, it can thoroughly remove silicious contaminants on the surfaces of treated fibers.

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...

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

Analysis list: pan [Chip-atlas[Archive

Lifescience Database Archive (English)

Full Text Available pan Embryo,Larvae,Pupae + dm3 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/target.../pan.1.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/target/pan.5.tsv http://dbarchive.biosciencedbc.jp.../kyushu-u/dm3/target/pan.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/colo/pan.Embryo.tsv,http://dbarchive.bioscience...dbc.jp/kyushu-u/dm3/colo/pan.Larvae.tsv,http://dbarchive.bioscience...dbc.jp/kyushu-u/dm3/colo/pan.Pupae.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/colo/Embryo.gml,http://dbarchive.bioscience

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.

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)

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

Assessment of Physicochemical Properties of Biodiesel from African ...

African Journals Online (AJOL)

The African Grape (Lannea microcarpa) seed oil was extracted and subjected to fuel properties tests according to standard method for oil and fuel analysis to evaluate its suitability as oil crop for biodiesel production in Nigeria. The oil was transesterified using alkali hydrolysis to biodiesel. The yields of the oil and its methyl ...

The Transformation of African Smallholders into Customer Value Creating Businesses

NARCIS (Netherlands)

Teklehaimanot, Mebrahtu L.; Ingenbleek, Paul T.M.; Trijp, van Hans C.M.

2017-01-01

<p>An increasing number of the 600 million African smallholders are becoming integrated into the supply chains of supermarkets, fast food chains, and exporters. This process gradually transforms the smallholders into profit-oriented businesses that can make important contributions to rural

The Experience of Salafi Islam in the West African Sub

African Journals Online (AJOL)

question of the relationship between religion and the Pan-African ideal. It seeks to ... conversion to the Islamic way of life is taking place in university campuses ... Muslims to preserve their identity by maintaining continuity with the culture that ...

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

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.

TRANSATLANTIC DIALOGUES: AFRICANITY, BLACKNESS AND IDENTITY CONSTRUCTION

OpenAIRE

Deolinda Adão

2011-01-01

The article explores the aesthetic and ideological dialogs between Pan­-African movements, such as the Harlem Renaissance, the French Negri­tude movement, and the artistic, particularly the literary production of the student of the Casa do Império in general and that of Francisco José Ten­reiro in particular.

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

Building A Spirit of Inclusion: Pan Am and The Cultural Revolution

Directory of Open Access Journals (Sweden)

Mirembe B. Birigwa

2014-10-01

Full Text Available The legendary Pan American World Airways remains a bastion of nostalgia and cultural significance and serves as a case study in how airlines adapted their hiring practices to reflect the social movements of the 1960’s and 70’s. To maintain a competitive advantage, top companies thriving today are tasked with conveying a message of inclusion that matches the expectations of the traveler. Mirembe Birigwa interviews her mother, Sheila Nutt, about what it was like to be one of the first African American flight attendants.

On-chip fabrication of alkali-metal vapor cells utilizing an alkali-metal source tablet

International Nuclear Information System (INIS)

Tsujimoto, K; Hirai, Y; Sugano, K; Tsuchiya, T; Tabata, O; Ban, K; Mizutani, N

2013-01-01

We describe a novel on-chip microfabrication technique for the alkali-metal vapor cell of an optically pumped atomic magnetometer (OPAM), utilizing an alkali-metal source tablet (AMST). The newly proposed AMST is a millimeter-sized piece of porous alumina whose considerable surface area holds deposited alkali-metal chloride (KCl) and barium azide (BaN 6 ), source materials that effectively produce alkali-metal vapor at less than 400 °C. Our experiments indicated that the most effective pore size of the AMST is between 60 and 170 µm. The thickness of an insulating glass spacer holding the AMST was designed to confine generated alkali metal to the interior of the vapor cell during its production, and an integrated silicon heater was designed to seal the device using a glass frit, melted at an optimum temperature range of 460–490 °C that was determined by finite element method thermal simulation. The proposed design and AMST were used to successfully fabricate a K cell that was then operated as an OPAM with a measured sensitivity of 50 pT. These results demonstrate that the proposed concept for on-chip microfabrication of alkali-metal vapor cells may lead to effective replacement of conventional glassworking approaches. (paper)

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

Contribution to uranium geochemistry in intrusive granites; Contribution a la geochimie de l'uranium dans les granites intrusifs

Energy Technology Data Exchange (ETDEWEB)

Coulomb, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1959-01-15

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) [French] Le but du travail presente est de situer sur le plan de la geochimie des granites en general, sur le plan de la geochimie de l'uranium en particulier, un

The Taitao Granites: I-type granites formed by subduction of the Chile Ridge and its implication in growth of continental crusts

Science.gov (United States)

Anma, Ryo

2016-04-01

Late Miocene to Early Pliocene granite plutons are exposed at the tip of the Taitao peninsula, the westernmost promontory of the Chilean coast, together with a contemporaneous ophiolite with a Penrose-type stratigraphy. Namely, the Taitao granites and the Taitao ohiolite, respectively, are located at ~30 km southeast of the Chile triple junction, where a spreading center of the Chile ridge system is subducting underneath the South America plate. This unique tectonic setting provides an excellent opportunity to study the generation processes of granitic magmas at a ridge subduction environment, and the complex magmatic interactions between the subducting ridge, overlying crust and sediments, and mantle. This paper reviews previous studies on the Taitao ophiolite/granite complex and use geochemical data and U-Pb age distributions of zircons separated from igneous and sedimentary rocks from the area to discuss the mechanism that formed juvenile magma of calc-alkaline I-type granites during ridge subduction. Our model implies that the magmas of the Taitao granites formed mainly due to partial melting of hot oceanic crust adjacent to the subducting mid-oceanic ridge that has been under influence of deep crustal contamination and/or metasomatized sub-arc mantle through slab window. The partial melting took place under garnet-free-amphibolite conditions. The juvenile magmas then incorporated a different amount of subducted sediments to form the I-type granites with various compositions. The Taitao granites provide an ideal case study field that shows the processes to develop continental crusts out of oceanic crusts through ridge subduction.

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.

TRANSATLANTIC DIALOGUES: AFRICANITY, BLACKNESS AND IDENTITY CONSTRUCTION

Directory of Open Access Journals (Sweden)

Deolinda Adão

2011-11-01

Full Text Available The article explores the aesthetic and ideological dialogs between Pan­-African movements, such as the Harlem Renaissance, the French Negri­tude movement, and the artistic, particularly the literary production of the student of the Casa do Império in general and that of Francisco José Ten­reiro in particular.

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

HOW TO PAN-SHARPEN IMAGES USING THE GRAM-SCHMIDT PAN-SHARPEN METHOD – A RECIPE

Directory of Open Access Journals (Sweden)

T. Maurer

2013-05-01

Full Text Available Since its publication in 1998 (Laben and Brower, 2000, the Gram-Schmidt pan-sharpen method has become one of the most popular algorithms to pan-sharpen multispectral (MS imagery. It outperforms most other pan-sharpen methods in both maximizing image sharpness and minimizing color distortion. It is, on the other hand, also more complex and computationally expensive than most other methods, as it requires forward and backward transforming the entire image. Another complication is the lack of a clear recipe of how to compute the sensor dependent MS to Pan weights that are needed to compute the simulated low resolution pan band. Estimating them from the sensor’s spectral sensitivity curves (in different ways, or using linear regression or least square methods are typical candidates which can include other degrees of freedom such as adding a constant offset or not. As a result, most companies and data providers do it somewhat differently. Here we present a solution to both problems. The transform coefficients can be computed directly and in advance from the MS covariance matrix and the MS to Pan weights. Once the MS covariance matrix is computed and stored with the image statistics, any small section of the image can be pan-sharpened on the fly, without having to compute anything else over the entire image. Similarly, optimal MS to Pan weights can be computed directly from the full MS-Pan covariance matrix, guaranteeing optimal image quality and consistency.

Draft genome sequence of Bacillus okhensis Kh10-101T, a halo-alkali tolerant bacterium from Indian saltpan

Directory of Open Access Journals (Sweden)

Pilla Sankara Krishna

2015-12-01

Full Text Available We report the 4.86-Mb draft genome sequence of Bacillus okhensis strain Kh10-101T, a halo-alkali tolerant rod shaped bacterium isolated from a salt pan near port of Okha, India. This bacterium is a potential model to study the molecular response of bacteria to salt as well as alkaline stress, as it thrives under both high salt and high pH conditions. The draft genome consist of 4,865,284 bp with 38.2% G + C, 4952 predicted CDS, 157 tRNAs and 8 rRNAs. Sequence was deposited at DDBJ/EMBL/GenBank under the project accession JRJU00000000.

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.

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.

O pan das ánimas

OpenAIRE

Antón, Fina; Mandianes Castro, Manuel

1996-01-01

O pan, ademais de cumprir una función alimenticia de primeira orde, está revestido dunha significación simbólica importante. O pan durante a vida axuda a pasa-los límites, a da-lo paso, a integrarse entre os cristiáns por cousa do bautismo e a integrarse no grupo dos homes e mulleres co adaxo da boda, pero o pan axuda, sobre todo, a pasa-lo río Xordán, que é, sen dúbida o límite que separa este mundo do outro; a serpe e as ánimas constitúen un límite e o pan facilita o seu paso. O pan está in...

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.

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.

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

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.

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.

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.)

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.)

Contribution to uranium geochemistry in intrusive granites; Contribution a la geochimie de l'uranium dans les granites intrusifs

Energy Technology Data Exchange (ETDEWEB)

Coulomb, R. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1959-01-15

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) [French] Le but du travail presente est de situer sur le plan de la geochimie des granites en general, sur le plan de la geochimie de l'uranium en particulier

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)

Geochemistry and meaning of the geotectonic position of plutonic rocks from Chapada region, Goias, Brazil

International Nuclear Information System (INIS)

Kuyumjian, R.M.

1989-01-01

In common with other orogenic belts, in which the presence of both, granitic and small basic-ultrabasic intrusions are characteristics of medium-high pressure metamorphic terranes, the geological and geochemical evidences indicate a close relationship between the granitoid, gabbroic and pyroxenitic plutons and the orogenic metabasaltic rocks from the Chapada volcano-sedimentary sequence. The granitoids are tonalitic and, on discriminant diagrams, they plot in the volcanic arc and pre-collisional fields. They display geochemical characteristics similar to the Jamaican oceanic arc-related granities. They show low LIL and HSF element abundances, low (Ta, Nb)/(K, La, etc) ratios and very low concentrations of Th, Hf, K and Y, when compared to patterns of calkaline, alkali-calcic and alkaline-peralkaline granitoids of magmatic arcs. These chemical features are characteristic of immature island arcs mantle-derived intrusives. The Chapada olivine gabbro has a chondrite-normalized spidergram, closely resembling those of island-arc basaltic lavas, the compositions of its coexisting olivine and plagioclase been similar to those from arc-related cumulate gabbros, and therefore, it could be the plutonic equivalent of the arc volcanics in the Chapada region. It is suggested that the evolution of the granitoids and gabbro intrusives from Chapada are related to a process of subduction that occurred in central Brazil during the Brasiliano/Pan-African event. (author) [pt

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.)

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

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)

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

'Beyond the rivers of Ethiopia' : Pentecostal Pan-Africanism and Ghanaian identities in the transnational domain

NARCIS (Netherlands)

Dijk, van R.A.

2004-01-01

Rev. Mensa Otabil, the founder of the International Central Gospel Church in Accra, is considered an influential representative of a new Pentecostal-inspired Pan-Africanist ideology. His book 'Beyond the Rivers of Ethiopia' lays the foundations of a Pentecostal Liberation Theology that proclaims a

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

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

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)

(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

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

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)

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.

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)

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.)

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)

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

Inter- and Intraspecific Variations in the Pectoral Muscles of Common Chimpanzees (Pan troglodytes), Bonobos (Pan paniscus), and Humans (Homo sapiens).

Science.gov (United States)

Potau, J M; Arias-Martorell, J; Bello-Hellegouarch, G; Casado, A; Pastor, J F; de Paz, F; Diogo, R

2018-01-01

We have analyzed anatomic variations in the pectoralis major and pectoralis minor muscles of common chimpanzees (Pan troglodytes) and bonobos (Pan paniscus) and compared them to anatomic variations in these muscles in humans (Homo sapiens) . We have macroscopically dissected these muscles in six adult Pan troglodytes , five Pan paniscus of ages ranging from fetus to adult, and five adult Homo sapiens . Although Pan troglodytes are thought to lack a separate pectoralis abdominis muscle, we have identified this muscle in three of the Pan troglodytes ; none of the Pan paniscus , however, had this muscle. We have also found deep supernumerary fascicles in the pectoralis major of two Pan troglodytes and all five Pan paniscus . In all six Pan troglodytes , the pectoralis minor was inserted at the supraspinatus tendon, while, in Pan paniscus and Homo sapiens , it was inserted at the coracoid process of the scapula. Some of the anatomic features and variations of these muscles in common chimpanzees and bonobos are similar to those found in humans, therefore enhancing our knowledge of primate comparative anatomy and evolution and also shedding light on several clinical issues.

Inter- and Intraspecific Variations in the Pectoral Muscles of Common Chimpanzees (Pan troglodytes, Bonobos (Pan paniscus, and Humans (Homo sapiens

Directory of Open Access Journals (Sweden)

J. M. Potau

2018-01-01

Full Text Available We have analyzed anatomic variations in the pectoralis major and pectoralis minor muscles of common chimpanzees (Pan troglodytes and bonobos (Pan paniscus and compared them to anatomic variations in these muscles in humans (Homo sapiens. We have macroscopically dissected these muscles in six adult Pan troglodytes, five Pan paniscus of ages ranging from fetus to adult, and five adult Homo sapiens. Although Pan troglodytes are thought to lack a separate pectoralis abdominis muscle, we have identified this muscle in three of the Pan troglodytes; none of the Pan paniscus, however, had this muscle. We have also found deep supernumerary fascicles in the pectoralis major of two Pan troglodytes and all five Pan paniscus. In all six Pan troglodytes, the pectoralis minor was inserted at the supraspinatus tendon, while, in Pan paniscus and Homo sapiens, it was inserted at the coracoid process of the scapula. Some of the anatomic features and variations of these muscles in common chimpanzees and bonobos are similar to those found in humans, therefore enhancing our knowledge of primate comparative anatomy and evolution and also shedding light on several clinical issues.

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.

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

Detection of Termites and Other Insects Consumed by African Great Apes using Molecular Fecal Analysis

OpenAIRE

Ibrahim Hamad; Eric Delaporte; Didier Raoult; Fadi Bittar

2014-01-01

The consumption of insects by apes has previously been reported based on direct observations and/or trail signs in feces. However, DNA-based diet analyses may have the potential to reveal trophic links for these wild species. Herein, we analyzed the insect-diet diversity of 9 feces obtained from three species of African great apes, gorilla (Gorilla gorilla gorilla), chimpanzee (Pan troglodytes) and bonobo (Pan paniscus), using two mitochondrial amplifications for arthropods. A total of 1056 c...

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.

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)

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)

ATLAS BigPanDA Monitoring

CERN Document Server

Padolski, Siarhei; The ATLAS collaboration; Klimentov, Alexei; Korchuganova, Tatiana

2017-01-01

BigPanDA monitoring is a web based application which provides various processing and representation of the Production and Distributed Analysis (PanDA) system objects states. Analyzing hundreds of millions of computation entities such as an event or a job BigPanDA monitoring builds different scale and levels of abstraction reports in real time mode. Provided information allows users to drill down into the reason of a concrete event failure or observe system bigger picture such as tracking the computation nucleus and satellites performance or the progress of whole production campaign. PanDA system was originally developed for the Atlas experiment and today effectively managing more than 2 million jobs per day distributed over 170 computing centers worldwide. BigPanDA is its core component commissioned in the middle of 2014 and now is the primary source of information for ATLAS users about state of their computations and the source of decision support information for shifters, operators and managers. In this wor...

ATLAS BigPanDA Monitoring

CERN Document Server

Padolski, Siarhei; The ATLAS collaboration

2017-01-01

BigPanDA monitoring is a web-based application that provides various processing and representation of the Production and Distributed Analysis (PanDA) system objects states. Analysing hundreds of millions of computation entities such as an event or a job BigPanDA monitoring builds different scale and levels of abstraction reports in real time mode. Provided information allows users to drill down into the reason of a concrete event failure or observe system bigger picture such as tracking the computation nucleus and satellites performance or the progress of whole production campaign. PanDA system was originally developed for the Atlas experiment and today effectively managing more than 2 million jobs per day distributed over 170 computing centers worldwide. BigPanDA is its core component commissioned in the middle of 2014 and now is the primary source of information for ATLAS users about state of their computations and the source of decision support information for shifters, operators and managers. In this work...

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

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)

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)

A 3D Magnetotelluric Perspective on the Galway Granite, Western Ireland

Science.gov (United States)

Farrell, Thomas; Muller, Mark; Vozar, Jan; Feely, Martin; Hogg, Colin

2017-04-01

Magnetotelluric (MT) and audi-magnetotelluric (AMT) data were acquired at 75 locations across the exposed calc-alkaline Caledonian Galway granite batholith and surrounding country rocks into which the granite intruded. The Galway granite is located in western Ireland on the north shore of Galway bay, and has an ESE-WNW long axis. The granite is cut by trans-batholith faults, the Shannawona Fault Zone (SFZ) in the western part of the batholith, which has a NE-SW trend, and the Bearna Fault Zone (BFZ) in the eastern sector that has a NW-SE trend. Geobarometry data indicate that the central granite block between these fault zones has been uplifted, with the interpretation being that the granite in this central block is thinned. To the west of the SFZ, much of the Galway granite is below sea level, with the majority of the southern granite contact also beneath the sea in Galway bay. To the east of the batholith, the Carboniferous successions, consisting of mainly limestone with shale, overlie the basement rocks. The country rock to the north includes the metagabbro-gneiss suite, which itself intruded the deformed Dalradian successions that were deposited on the Laurentian margin of the Iapetus Ocean. The deformation of the Dalradian rocks, the intrusion of the metagabbro-gneiss suite and the intrusion of the Galway granite were major events in the protracted closure of the Iapetus Ocean. It is clear from geological mapping, from geobarometry and from the present submergence by the sea of a large part of the Galway granite, that inversion of MT data in this structurally complex geology is likely to require a 3D approach. We present a summary of 3D inversion of the Galway MT and AMT data. The study shows that the structure of the Galway granite is quite different from the pre-existing perspective. The central block, thought by its uplifting to be thinned, is shown to be the thickest part of the batholith. A geological model of granite intrusion is offered to explain this

2005 dossier: granite. Tome: architecture and management of the geologic disposal; Dossier 2005: granite. Tome architecture et gestion 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 geologic disposal of high-level and long-lived radioactive wastes in granite formations. Content: 1 - Approach of the study: main steps since the December 30, 1991 law, ANDRA's research program on disposal in granitic formations; 2 - high-level and long-lived (HLLL) wastes: production scenarios, waste categories, inventory model; 3 - disposal facility design in granitic environment: definition of the geologic disposal functions, the granitic material, general facility design options; 4 - general architecture of a disposal facility in granitic environment: surface facilities, underground facilities, disposal process, operational safety; 5 - B-type wastes disposal area: primary containers of B-type wastes, safety options, concrete containers, disposal alveoles, architecture of the B-type wastes disposal area, disposal process and feasibility aspects, functions of disposal components with time; 6 - C-type wastes disposal area: C-type wastes primary containers, safety options, super-containers, disposal alveoles, architecture of the C-type wastes disposal area, disposal process in a reversibility logics, functions of disposal components with time; 7 - spent fuels disposal area: spent fuel assemblies, safety options, spent fuel containers, disposal alveoles, architecture of the spent fuel disposal area, disposal process in a reversibility logics, functions of disposal components with time; 8 - conclusions: suitability of the architecture with various types of French granites, strong design, reversibility taken into consideration. (J.S.)

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.)

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].

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.

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...

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

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

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

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

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...

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

Rb-Sr, Pb-Pb, U-Pb dating in the Bandja plutonic series of Western Cameroon. Donnees geochronologiques (Rb-Sr, Pb-Pb, U-Pb) sur le complexe plutonique de Bandja (Centre-Ouest Cameroun)

Energy Technology Data Exchange (ETDEWEB)

Tchankam, C N [Nancy-1 Univ., 54 (France); Vialette, Y [Clermont-Ferrand-2 Univ., 63 - Aubiere (France)

1994-08-01

The results of U-Pb zircon and Pb-Pb on minerals and whole rocks are reported on a charnockite syn-D1 from the Bandja series in the western Cameroon. Data are interpreted as representing a plutonic emplacement at 640 Ma. A syn- to post-tectonic pluton is dated at 557 [+-] 8 Ma (Rb-Sr whole rocks isochron). These results confirm the Pan-African age of the charnockitic intrusive body. Initial isotopic [sup 87]Sr/[sup 86]Sr ratios of charnockite (0.709) and granite (0.7089) show the importance of crustal imprint in the magma genesis. (authors).

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

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

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...

A comparative analysis of temporomandibular joint morphology in the African apes.

Science.gov (United States)

Taylor, Andrea B

2005-06-01

A number of researchers have suggested a functional relationship between dietary variation and temporomandibular joint (TMJ) morphology, yet few studies have evaluated TMJ form in the African apes. In this study, I compare TMJ morphology in adults and during ontogeny in Gorilla (G.g. beringei, G.g. graueri, and G.g. gorilla) and Pan (P. paniscus, P. troglodytes troglodytes, P.t. schweinfurthii, and P.t. verus). I test two hypotheses: first, compared to all other African apes, G.g. beringei exhibits TMJ morphologies that would be predicted for a primate that consumes a diet comprised primarily of moderately to very tough, leafy vegetation; and second, all gorillas exhibit the same predicted morphologies compared to Pan. Compared to all adult African apes, G.g. beringei has higher rami and condyles positioned further above the occlusal plane of the mandible, relative to jaw length. Thus, mountain gorillas have the potential to generate relatively more muscle force, more evenly distribute occlusal forces along the postcanine teeth, and generate relatively greater jaw adductor moment. G.g. beringei also exhibits relatively wider mandibular condyles, suggesting these folivorous apes are able to resist relatively greater compressive loads along the lateral and/or medial aspect of the condyle. All gorillas likewise exhibit these same shape differences compared to Pan. These morphological responses are the predicted consequences of intensification of folivory and, as such, provide support for functional hypotheses linking these TMJ morphologies to degree of folivory. The African apes to not, however, demonstrate a systematic pattern of divergence in relative condylar area as a function of intensification of folivory. The ontogenetic trajectories for gorillas are significantly elevated above those of Pan, and to a lesser but still significant degree, mountain gorillas similarly deviate from lowland gorillas (G.g. gorilla and G.g. graueri). Thus, adult shape differences in

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

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)

Precision Photometry and Astrometry from Pan-STARRS

Science.gov (United States)

Magnier, Eugene A.; Pan-STARRS Team

2018-01-01

The Pan-STARRS 3pi Survey has been calibrated with excellent precision for both astrometry and photometry. The Pan-STARRS Data Release 1, opened to the public on 2016 Dec 16, provides photometry in 5 well-calibrated, well-defined bandpasses (grizy) astrometrically registered to the Gaia frame. Comparisons with other surveys illustrate the high quality of the calibration and provide tests of remaining systematic errors in both Pan-STARRS and those external surveys. With photometry and astrometry of roughly 3 billion astronomical objects, the Pan-STARRS DR1 has substantial overlap with Gaia, SDSS, 2MASS and other surveys. I will discuss the astrometric tie between Pan-STARRS DR1 and Gaia and show comparisons between Pan-STARRS and other large-scale surveys.

Fuel and energy saving in open pan furnace used in jaggery making through modified juice boiling/concentrating pans

International Nuclear Information System (INIS)

Anwar, S.I.

2010-01-01

In this paper the concept of fins has been used for heating purpose for improving efficiency of open pan jaggery making furnace. Pan is the integral part of these furnaces where boiling/concentration of sugarcane juice take place. Parallel fins were provided to the bottom of main pan and gutter pan of IISR Lucknow 2-pan furnace. Choice for type of fins was based on movement of flames and hot flue gases generated due to combustion of bagasse. Fins helped in more heat transfer to the sugarcane juice being concentrated. Considerable improvement in heat utilization efficiency (9.44%) was observed which resulted in saving of fuel and energy (31.34%).

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)

Pan-tropical monitoring of deforestation

International Nuclear Information System (INIS)

Achard, F; DeFries, R; Eva, H; Hansen, M; Mayaux, P; Stibig, H-J

2007-01-01

This paper reviews the technical capabilities for monitoring deforestation from a pan-tropical perspective in response to the United Nations Framework Convention on Climate Change (UNFCCC) process, which is studying the technical issues surrounding the ability to reduce greenhouse gas emissions from deforestation in developing countries. The successful implementation of such policies requires effective forest monitoring systems that are reproducible, provide consistent results, meet standards for mapping accuracy, and can be implemented from national to pan-tropical levels. Remotely sensed data, supported by ground observations, are crucial to such efforts. Recent developments in global to regional monitoring of forests can contribute to reducing the uncertainties in estimates of emissions from deforestation. Monitoring systems at national levels in developing countries can also benefit from pan-tropical and regional observations, mainly by identifying hot spots of change and prioritizing areas for monitoring at finer spatial scales. A pan-tropical perspective is also required to ensure consistency between different national monitoring systems. Data sources already exist to determine baseline periods in the 1990s as historical reference points. Key requirements for implementing such monitoring programs, both at pan-tropical and at national scales, are international commitment of resources to increase capacity, coordination of observations to ensure pan-tropical coverage, access to free or low-cost data, and standardized, consensus protocols for data interpretation and analysis

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

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

(abstract) Experimental and Modeling Studies of the Exchange Current at the Alkali Beta'-Alumina/Porous Electrode/Alkali Metal Vapor Three Phase Boundary

Science.gov (United States)

Williams, R. M.; Jeffries-Nakamura, B.; Ryan, M. A.; Underwood, M. L.; O'Connor, D.; Kikkert, S.

1993-01-01

The microscopic mechanism of the alkali ion-electron recombination reaction at the three phase boundary zone formed by a porous metal electrode in the alkali vapor on the surface of an alkali beta'-alumina solid electrolyte (BASE) ceramic has been studied by comparison of the expected rates for the three simplest reaction mechanisms with known temperature dependent rate data; and the physical parameters of typical porous metal electrode/BASE/alkali metal vapor reaction zones. The three simplest reactions are tunneling of electrons from the alkali coated electrode to a surface bound alkali metal ion; emission of an electron from the electrode with subsequent capture by a surface bound alkali metal ion; and thermal emission of an alkali cation from the BASE and its capture on the porous metal electrode surface where it may recombine with an electron. Only the first reaction adequately accounts for both the high observed rate and its temperature dependence. New results include crude modeling of simple, one step, three phase, solid/solid/gas electrochemical reaction.

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

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.

Saghro Group in the Ougnat Massif (Morocco), an evidence for a continuous Cadomian basin along the northern West African Craton

Science.gov (United States)

Michard, André; Soulaimani, Abderrahmane; Ouanaimi, Hassan; Raddi, Youssef; Aït Brahim, Lahsen; Rjimati, Ech-Cherki; Baidder, Lahssen; Saddiqi, Omar

2017-03-01

The Saghro Group (SG) is a folded, low-grade volcano-sedimentary series up to 8 km thick that crops out within and to the north of the Pan-African suture zone in the central and eastern Anti-Atlas. Here we describe the SG of the Ougnat inliers that are exposed in the easternmost Anti-Atlas beneath the unconformable, Late Ediacaran Ouarzazate Group (OZG) volcanic rocks. The Ougnat SG mostly consists of volcaniclastic greywackes accumulated in a peritidal-to-shallow basin. The basin infilling was deformed by NNE-trending, mostly upright folds with axial-planar slaty cleavage and low-grade metamorphism. The deformed SG rocks were intruded by the ∼550 Ma Mellab hypovolcanic granodiorite. The latter also crosscuts the lowest OZG rocks that are dated to 574-571 Ma in the western Saghro region. The SG rocks that form the Siroua and Saghro inliers have an oldest age of 620-610 Ma and were folded at ∼610-580 Ma at the onset of the Cadomian orogenic events. We show that the SG rocks are similar to the ;Série verte; (SV) rocks that are exposed in the Ougarta and western Hoggar east of the Pan-African suture. We infer that the SG and SV rocks accumulated in a same, continuous basin that was bounding the West African Craton to the north and the east. This strongly subsiding basin formed close to a volcanic arc and was folded during the last Pan-African synmetamorphic events. Fold orientation and age of folding differ however along the edge of the West African Craton. The orogenic greywackes that form the remnants of the SG-SV basin thus constitute a precious record of the diachronic Cadomian event s.l. along the West African Craton northern margin.

Inter- and Intraspecific Variations in the Pectoral Muscles of Common Chimpanzees (Pan troglodytes), Bonobos (Pan paniscus), and Humans (Homo sapiens)

OpenAIRE

Potau, J. M.; Arias-Martorell, J.; Bello-Hellegouarch, G.; Casado, A.; Pastor, J. F.; de Paz, F.; Diogo, R.

2018-01-01

We have analyzed anatomic variations in the pectoralis major and pectoralis minor muscles of common chimpanzees (Pan\\ud troglodytes) and bonobos(Pan paniscus) and compared them to anatomic variations in these muscles in humans(Homo sapiens). We\\ud have macroscopically dissected these muscles in six adult Pan troglodytes, five Pan paniscus of ages ranging from fetus to adult, and\\ud five adult Homo sapiens. Although Pan troglodytes are thought to lack a separate pectoralis abdominis muscle, we...

Geochronological data on the Amsinassene-Tefedest Block (Central Hoggar, Algerian Sahara) and evidence for its polycyclic evolution

International Nuclear Information System (INIS)

Vialette, Y.; Vitel, G.

1979-01-01

The history of the Amsinassene-Tefedest Block, in the central Hoggar domain, is characterized by a polycyclic evolution. The unreliable 1970 Ma age obtained on the Arechchoum gneisses, known to be Suggarian-Eburnean, might represent the effect of the Eburnean orogeny. A Rb/Sr whole-rock age on the leucocratic fractions of gneisses point to a kibaran migmatization. This age confirms the existence of a Kibaran orogeny shown in the Aleksod area. The Pharusian-Pan African cycle, in this domain, is characterized by the emplacement of huge granitic bodies during two distinct magnetic phases: one of Late Proterozoic age (670 Ma) or Imezzarian phase, the other of Cambrian age as shown by the 546 and 515 Ma Rb/Sr whole-rock ages obtained on late kinematic granitic plutons, Iskelian phase. The younger mineral ages (470-430 Ma) indicate late vertical uplift of the central Hoggar. (Auth.)

Radioactivity and uranium potentialities of wadi hammad area, north eastern desert, Egypt. Vol. 3

Energy Technology Data Exchange (ETDEWEB)

Salman, A B; Shalaby, M H; Khamis, H A [Nuclear Material Authority, Cairo, (Egypt)

1996-03-01

Late proterozoic, pan-african rocks exposed at Wadi Hammad area are represented by metamorphosed and un metamorphosed sediments and volcanics in addition to different types of intensive rocks. Systematic radiometric survey is conducted at W.Hammad area in order to reveal the distribution of radioactivity and uranium potentialities. Statistical analysis of the field data collected indicate that, high level of {delta}-radioactivity is linked to the younger granites compared with the other rock types. The tree types of younger granites recorded in the area namely: porphyritic granites, biotite granites, and perthitic leucogranites differ among each other in their ground radioactivity. The increase in ground {delta}- radioactivity from the porphyritic to biotite granites to perthitic leucogranites corresponds to the increase in the uranium content of these granites. Four radioactive anomalies were discovered in the younger granites of the area of W.Hammad. The genetic relation between certain set of fractures and the distribution of {delta}- radioactivity in G. El Gulf granites indicates that the area of anomalous radioactivity are structurally controlled by joint sets trending N-S, NNE-SSW and NNW-SSE. The presence of intensive hematitization episyenitization, red and milky silica veins, aplites and pegmatite veins indicate the presence of hydrothermal activities along these fractures. It is worth to mention that, the presence of episyentizied zone associated with radioactive anomaly, represents a good indication for the possibility of hosting uranium deposits in deeper horizon. Moreover, the presence of high back-ground of magnetic uranium in the perthitic leucogranites increases studied the possibility of concentration of uranium by leaching from the granites. 12 figs., 1 tab.

Radioactivity and uranium potentialities of wadi hammad area, north eastern desert, Egypt. Vol. 3

International Nuclear Information System (INIS)

Salman, A.B.; Shalaby, M.H.; Khamis, H.A.

1996-01-01

Late proterozoic, pan-african rocks exposed at Wadi Hammad area are represented by metamorphosed and un metamorphosed sediments and volcanics in addition to different types of intensive rocks. Systematic radiometric survey is conducted at W.Hammad area in order to reveal the distribution of radioactivity and uranium potentialities. Statistical analysis of the field data collected indicate that, high level of δ-radioactivity is linked to the younger granites compared with the other rock types. The tree types of younger granites recorded in the area namely: porphyritic granites, biotite granites, and perthitic leucogranites differ among each other in their ground radioactivity. The increase in ground δ- radioactivity from the porphyritic to biotite granites to perthitic leucogranites corresponds to the increase in the uranium content of these granites. Four radioactive anomalies were discovered in the younger granites of the area of W.Hammad. The genetic relation between certain set of fractures and the distribution of δ- radioactivity in G. El Gulf granites indicates that the area of anomalous radioactivity are structurally controlled by joint sets trending N-S, NNE-SSW and NNW-SSE. The presence of intensive hematitization episyenitization, red and milky silica veins, aplites and pegmatite veins indicate the presence of hydrothermal activities along these fractures. It is worth to mention that, the presence of episyentizied zone associated with radioactive anomaly, represents a good indication for the possibility of hosting uranium deposits in deeper horizon. Moreover, the presence of high back-ground of magnetic uranium in the perthitic leucogranites increases studied the possibility of concentration of uranium by leaching from the granites. 12 figs., 1 tab

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

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

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.

Investigation of needleless electrospun PAN nanofiber mats

Science.gov (United States)

Sabantina, Lilia; Mirasol, José Rodríguez; Cordero, Tomás; Finsterbusch, Karin; Ehrmann, Andrea

2018-04-01

Polyacrylonitrile (PAN) can be spun from a nontoxic solvent (DMSO, dimethyl sulfoxide) and is nevertheless waterproof, opposite to the biopolymers which are spinnable from aqueous solutions. This makes PAN an interesting material for electrospinning nanofiber mats which can be used for diverse biotechnological or medical applications, such as filters, cell growth, wound healing or tissue engineering. On the other hand, PAN is a typical base material for producing carbon nanofibers. Nevertheless, electrospinning PAN necessitates convenient spinning parameters to create nanofibers without too many membranes or agglomerations. Thus we have studied the influence of spinning parameters on the needleless electrospinning process of PAN dissolved in DMSO and the resulting nanofiber mats.

Granite disposal of U.S. high-level radioactive waste.

Energy Technology Data Exchange (ETDEWEB)

Freeze, Geoffrey A.; Mariner, Paul E.; Lee, Joon H.; Hardin, Ernest L.; Goldstein, Barry; Hansen, Francis D.; Price, Ronald H.; Lord, Anna Snider

2011-08-01

This report evaluates the feasibility of disposing U.S. high-level radioactive waste in granite several hundred meters below the surface of the earth. The U.S. has many granite formations with positive attributes for permanent disposal. Similar crystalline formations have been extensively studied by international programs, two of which, in Sweden and Finland, are the host rocks of submitted or imminent repository license applications. This report is enabled by the advanced work of the international community to establish functional and operational requirements for disposal of a range of waste forms in granite media. In this report we develop scoping performance analyses, based on the applicable features, events, and processes (FEPs) identified by international investigators, to support generic conclusions regarding post-closure safety. Unlike the safety analyses for disposal in salt, shale/clay, or deep boreholes, the safety analysis for a mined granite repository depends largely on waste package preservation. In crystalline rock, waste packages are preserved by the high mechanical stability of the excavations, the diffusive barrier of the buffer, and favorable chemical conditions. The buffer is preserved by low groundwater fluxes, favorable chemical conditions, backfill, and the rigid confines of the host rock. An added advantage of a mined granite repository is that waste packages would be fairly easy to retrieve, should retrievability be an important objective. The results of the safety analyses performed in this study are consistent with the results of comprehensive safety assessments performed for sites in Sweden, Finland, and Canada. They indicate that a granite repository would satisfy established safety criteria and suggest that a small number of FEPs would largely control the release and transport of radionuclides. In the event the U.S. decides to pursue a potential repository in granite, a detailed evaluation of these FEPs would be needed to inform site

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.

Weathering-related origin of widespread monazite in S-type granites

Energy Technology Data Exchange (ETDEWEB)

Sawka, W N; Banfield, J F; Chappell, B W

1986-01-01

The S-type granite suites comprising more than a quarter of the extensively developed granites in the Lachlan Fold Belt, Australia, contain monazite which may be related to the chemical weathering of the sedimentary source rocks. We report a process whereby chemical weathering fixes mobile rare-earth elements (REE) in hydrous phosphate phases such as florencite and rhabdophane. This material contains up to 50 wt.% LREE and occurs as very small particles (approx. 3 ..mu..m). Dehydration of these hydrous REE phases during anatexis directly yields monazite. The low solubility of phosphorus in S-type granite melts inhibits dissolution of both monazite and apatite. Refractory monazite may be thus entrained and transported in S-type granites in a manner similar to processes resulting in inherited zircon. Since both Th and the light REE are major components in monazite, materials containing this minute phase may be of widespread geochemical significance in both granites and metamorphic rocks.

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.

Peter Pan-demien

DEFF Research Database (Denmark)

Holm, Claus

2009-01-01

Ungdommelig opførsel er moderne. I gamle dage skulle vi blive voksne. I dag skal selv gamle mænd og kvinder holde sig unge. Peter Pan-panikken er i os, og en af vores væsentligste sociale lidelser er umodenhed.......Ungdommelig opførsel er moderne. I gamle dage skulle vi blive voksne. I dag skal selv gamle mænd og kvinder holde sig unge. Peter Pan-panikken er i os, og en af vores væsentligste sociale lidelser er umodenhed....

Petrogenesis of the Yaochong granite and Mo deposit, Western Dabie orogen, eastern-central China: Constraints from zircon U-Pb and molybdenite Re-Os ages, whole-rock geochemistry and Sr-Nd-Pb-Hf isotopes

Science.gov (United States)

Chen, Wei; Xu, Zhaowen; Qiu, Wenhong; Li, Chao; Yu, Yang; Wang, Hao; Su, Yang

2015-05-01

The Dabie orogen is among the most famous continent-continent collisional orogenic belts in the world, and is characterized by intensive post-collisional extension, magmatism and Mo mineralization. However, the genetic links between the mineralization and the geodynamic evolution of the orogen remain unresolved. In this paper, the Yaochong Mo deposit and its associated granitic stocks were investigated to elucidate this issue. Our new zircon U-Pb ages yielded an Early Cretaceous age (133.3 ± 1.3 Ma) for the Yaochong granite, and our molybdenite Re-Os dating gave a similar age (135 ± 1 Ma) for the Mo deposit. The Yaochong stock is characterized by high silica and alkali but low Mg, Fe and Ca. It is enriched in light rare earth elements (LREEs) and large ion lithophile elements (LILEs: Rb, K, Th and U), but strongly depleted in heavy REEs, and high field strength elements (HFSEs: Nb, Ta, Ti and Y). The Yaochong granite has initial 87Sr/86Sr ratios of 0.7087-0.7096, and Pb isotopic ratios of (206Pb/204Pb)i = 16.599-16.704, (207Pb/204Pb)i = 15.170-15.618 and (208Pb/204Pb)i = 36.376-38.248. The granite has εNd(t) of -18.0 to -16.3 and εHf(t) values of -26.5 to -20.0. All these data indicate that the Yaochong granite is a high-K calc-alkaline fractionated I-type granite, and may have originated from partial melting of the thickened Yangtze continental crust. The Mo ores also show low radiogenic Pb isotopes similar to the Yaochong stock. Medium Re content in molybdenite (21.8-74.8 ppm) also suggests that the ore-forming materials were derived from the thickened lower crust with possibly minor mixing with the mantle. Similar to the Eastern Dabie orogen, the thickened crust beneath the Western Dabie orogen may also have experienced tectonic collapse, which may have exerted fundamental geodynamic controls on the two-stage Mo mineralization in the region.

Neoproterozoic tectonic evolution of the Jebel Saghro and Bou Azzer - El Graara inliers, eastern and central Anti-Atlas, Morocco

Science.gov (United States)

Walsh, Gregory J.; Aleinikoff, John N.; Harrison, Richard W.; Burton, William C.; Quick, James E.; Benziane, Foudad; Yazidi, Abdelaziz; Saadane, Abderrahim

2012-01-01

much of the lower Ouarzazate Supergroup volcanic rocks in the area are probably related to caldera out-flow facies and collapse. Late stage PA3 intrusive rocks include the Bouskour–Sidi Flah and Timijt rhyolitic dike swarms at about 563 Ma, the voluminous pink Isk-n-Alla granite (559 ± 5 Ma), and volumetrically minor gabbro of Tagmout (556 ± 5 Ma). Rhyolite flows from the upper part of the Ouarzazate Supergroup, above a regional angular unconformity, yielded ages of 558 ± 4 and 556 ± 4 Ma. The youngest ages place an upper limit on block faulting and weak folding during latest Pan-African tectonic activity (PA3), coincident with the departure of the Cadomian crustal fragment from the northern margin of the WAC.

Damage of plants due to peroxyacyl nitrates (PAN)

Energy Technology Data Exchange (ETDEWEB)

Fukuda, H.; Terakado, K.

1974-02-01

In Japan plant damages began to resemble those due to PAN about 1972. Exposure experiments with artifically synthesized PAN in an environment simulation room determined the concentration of PAN and its duration to examine the relationship between these data in the field and crop damage. Synthesized PAN created by irradiating a mixture of ethyl nitrate and oxygen with ultraviolet light gave results similar to those seen in fields. From the end of April to the end of November, damages to petunias seemingly due to PAN appeared 15 times. The symptoms differed with the variety of petunia. After 14 experiments in fields from September 20 to November 30 with a continuous determination of the environmental concentration of PAN, damages to petunia were confirmed on 6 days when the maximum PAN concentration range was 3.0-6.7 ppb. The duration of concentrations higher than 3 ppb was 2-13 hr. The most serious damage appeared on September 20 when a concentration of more than 5 ppb continued for 7 hours. No damage appeared with a long continuation (6-12 hr) of a lower concentration of PAN of 2 ppb. Inter-varietal grafting showed that the symptoms and the degree of damage due to PAN were influenced only by the physiological specificity of the aerial portion of the plant. Leaves which are most affected by PAN differed with the variety of petunia.

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)

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.

Geochemistry of biotite granites from the Lamas de Olo Pluton, northern Portugal

Science.gov (United States)

Fernandes, Susana; Gomes, Maria; Teixeira, Rui; Corfu, Fernando

2013-04-01

In the Central Iberian Zone (CIZ) extensive crustal recycling occurred during the post-thickening extension stage of the Variscan orogeny (~330-290 Ma). After the ductile deformation phase D3 (~320-300 Ma), characterized by the intrusion of large volumes of highly peraluminous granitic magmas, rapid and drastic tectonic changes at about 300 Ma gave rise to the brittle phase of deformation D4 that controlled the emplacement of Fe-K subalkaline granites (296-290 Ma; Dias et al. 1998). The Lamas de Olo Pluton (LOP) is controlled by NE-SW and NW-SE fracture systems, probably related to the Régua-Verin fault zone (Pereira, 1989). The LOP is a medium to coarse-grained, porphyritic biotite granite, accompanied by medium- to fine grained, porphyritic biotite granite (Alto dos Cabeços- AC) and a more leucocratic, fine-grained, slightly porphyritic biotite-muscovite granite (Barragens- BA). The contacts between LO and AC are generally diffuse, whereas those to BA are sharp. In fact, the BA granite can occur in dykes and sills cutting LO and AC. Microgranular enclaves and xenoliths are very rare. The LOP intrudes the Douro Group, presumably of Precambrian to Cambrian age, and two-mica granites from the Vila Real composite massif. The LOP granites consist of quartz, microcline, plagioclase, biotite, zircon, titanite, tourmaline apatite, fluorite, ilmenite, magnetite, and rutile, with muscovite in BA granite and rare allanite in the LO and AC granites. The plagioclase composition is of oligoclase (An12) - andesine (An35) for LO granite, albite (An9) - andesine (An30) for CA granite and albite (An5) - oligoclase (An20) for BA granite. There are decreases in: a) anorthite content from phenocryst to matrix plagioclase; b) Ba content from phenocryst to matrix microcline in all granites. The Fe2+ biotite has a composition similar to that of biotite from calc-alkaline to sub-alkaline rock series. The LO and AC granites are meta- to peraluminous with ASI variable between 1.05 and 1

Concentration of uranium on TiO-PAN and NaTiO-PAN composite absorbers

International Nuclear Information System (INIS)

Motl, Alois; Sebesta, Ferdinand; John, Jan; Spendlikova, Irena; Nemec, Mojmir

2013-01-01

Inorganic ion exchangers have been extensively tested for use in separation and concentration of uranium from Surface water. Except for separation of uranium from uranium -Contaminated waste water (e.g. waste water from mining and milling of uranium, Waste from nuclear fuel reprocessing) their main area of application has been foreseen to be their use for extraction of uranium from sea water which could partially cover future needs of uranium. Another perspective area of application is pre-concentration of uranium from natural waters followed by uranium determination via various specialized techniques such as TRLFS or AMS. Possibilities of uranium extraction from sea water have been subject of several international conferences (e.g. Topical meetings on the Recovery of Uranium from Seawater in 1980's, ACS National Meetings 2012 etc.) and are critically evaluated in a review by Bitte or recently by Kim. In the Czech Republic uranium-selective inorganic ion exchangers might be applied for treatment of various wastes from uranium industry, namely underground Water, uranium milling over-balance water, or acid waste water from underground uranium leaching and also like in other countries for determination of uranium isotopic composition focusing on anthropogenic and natural 236 U content. Among the best performing inorganic ion exchangers for the above listed purposes hydrated titanium dioxide (abbreviated as TiO) and sodium titanate (abbreviated as NaTiO) can be listed. Properties of TiO and NaTiO were reviewed by Lehto. From the point of view of ion-exchange, properties of hydrated titanium oxide and sodium titanate are very similar. The main disadvantage of these ion exchangers for industrial-scale application is their insufficient mechanical stability. To improve this property, the sorption materials can be embedded into a binding matrix. Modified polyacrylonitrile (PAN) has been proposed at the Czech Technical University in Prague as a universal binding matrix for

ATLAS BigPanDA Monitoring and Its Evolution

CERN Document Server

Wenaus, Torre; The ATLAS collaboration; Korchuganova, Tatiana

2016-01-01

BigPanDA is the latest generation of the monitoring system for the Production and Distributed Analysis (PanDA) system. The BigPanDA monitor is a core component of PanDA and also serves the monitoring needs of the new ATLAS Production System Prodsys-2. BigPanDA has been developed to serve the growing computation needs of the ATLAS Experiment and the wider applications of PanDA beyond ATLAS. Through a system-wide job database, the BigPanDA monitor provides a comprehensive and coherent view of the tasks and jobs executed by the system, from high level summaries to detailed drill-down job diagnostics. The system has been in production and has remained in continuous development since mid 2014, today effectively managing more than 2 million jobs per day distributed over 150 computing centers worldwide. BigPanDA also delivers web-based analytics and system state views to groups of users including distributed computing systems operators, shifters, physicist end-users, computing managers and accounting services. Provi...

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)

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

[Discussion on diagenesis of Xilingang pluton-constrained by X-ray Fluorescence spectroscopy, plasma mass spectrometry and Raman spectroscopy].

Science.gov (United States)

Tang, Yu-Kun; Chen, Guo-Neng; Zhang, Ke; Huang, Hai-Hua

2013-05-01

The results on Xilingang pluton, mainly consisting of red beds, granites containing numerous debris of red beds and granites, obtained by X-ray fluorescence spectroscopy, plasma mass spectrometry and Raman spectroscopy show: (1) Xilingang pluton from red beds, granites containing numerous debris of red beds to granites has obvious characteristics of decreasing silicon and alkali content, and rising ignition loss, dark mineral content and oxidation index; (2) Chondrite-normalized REE distribution curves and primitive mantle-normalized spider diagram for trace elements of redbed, granites containing numerous debris of red beds and granites have a good consistency, the distribution characteristics of elements are similar to Nanling transformation-type granite; (3) The value of Raman spectrogram characteristic peak of quartz crystal in Xilingang granite decreased from the center of quartz crystal, and FWHM is steady. According to the above, the authors believe that Xilingang granite formed was related to in-situ melting of red beds and underlying strata and magma consolidation. Volatile components were discharged continuously, and oxidation index decreased gradually in the melting process. In the process of diagenesis, the top of pluton tend to be an ongoing silicon and alkali increase, while TFeO and MgO continue to migrate to bottom, and crystallization environment is a relatively closed and steady system.

The Keimoes Suite redefined: The geochronological and geochemical characteristics of the ferroan granites of the eastern Namaqua Sector, Mesoproterozoic Namaqua-Natal Metamorphic Province, southern Africa

Science.gov (United States)

Bailie, Russell; Macey, Paul Hugh; Nethenzheni, Sedzani; Frei, Dirk; le Roux, Petrus

2017-10-01

-tectonic granites in having εNd(t) values close to zero (-2.95 to 2.83) and Meso-to Paleoproterozoic model ages (TDM: 1.38-1.99 Ga) but lower initial Sr ratios (lived duration of high-heat flow in this portion of the southern African crust at this time. Nd model ages of Meso-to Paleoproterozoic age reflect those in other granites throughout the NS suggesting extensive reworking of Paleoproterozoic crust during the 1.2-1.0 Ga Namaquan Orogeny.

Mobility of heavy metals through granitic soils using mini column infiltration test

Science.gov (United States)

Zarime, Nur'Aishah; Yaacob, W. Z. W.

2014-09-01

This study is about the mobility of cadmium through compacted granitic soils. Two granitic soils namely the Broga (BGR) and Kajang (KGR) granitic soils were collected in Selangor, Malaysia. Physical and chemical tests were applied for both granitic soils to determine the physical and chemical properties of soil materials. Physical test results shows granitic soils (BGR and KGR) have high percentage of sand ranging between 54%-63% and 46%-54% respectively, an intermediate and intermediate to high plasticity index as well as high specific gravity ie; 2.50-2.59 and 2.45-2.66 respectively. For chemical test, granitic soils shows acidic pH values ranged from 5.35-5.85 for BGR and pH 5.32-5.54 for KGR. For organic matter, SSA and CEC test, it shows low values ranged from 0.22%-0.34% and 0.39%- 0.50% respectively for organic matter test, 17.96 m2/g-21.93 m2/g and 25.76 m2/g-26.83 m2/g respectively for SSA test and 0.79 meq/100g-1.35 meq/100g and 1.31 meq/100g-1.35 meq/100g respectively for CEC test. Mini column infiltration test was conducted to determine the retention of cadmium while flowing through granite soils. This test conducted based on the falling head permeability concepts. Different G-force ranging from 231G to 1442G was used in this test. The breakthrough curves show the concentration of Cd becomes higher with the increasing of G-force for both granitic samples (BGR and KGR). The selectivity sorption for both granites ranked in the following decreasing order of; 231G>519G>923G>1442G. Results demonstrated that granitic soils also have low buffering capacity due to low resist of pH changes.

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.

Structural and petrophysical characterisation of granite: intended for radioactive waste stocking

International Nuclear Information System (INIS)

Stanek, Martin

2013-01-01

Structural and petrophysical analysis have been conducted within the Melechov massif with focus on structures controlling the porosity, permeability and thermal conductivity of the rock. The structure of the massif has been constrained based on extensive dataset including AMS and field structural measurements of ductile and brittle structures. The fracture system of the massif has been described by four sets of fractures. The measured petrophysical data have been used to characterize the effect of fracturing and alteration on pore space geometry and in turn on permeability, thermal conductivity and elastic properties of the studied granite. Distinct petrophysical properties have been identified for pristine granite, for fractured fresh granite as well as for fractured granite altered by Fe-oxide, chlorite and clay minerals. A detailed microstructural study combined with multidirectional P-wave velocity measurements at high confining pressure and with AMS analysis has been conducted on a Schlieren bearing sample of Lipnice granite. The granite VP anisotropy at low confining pressure was controlled by intergranular cracks interconnecting Schlieren-sub parallel cleavage cracks in micas and feldspars and by exfoliation fracture-sub parallel intra- or trans-granular cracks in cleavage-free quartz. Major closing of the crack porosity linked to the Schlieren granite below depth of 500 m has been interpreted in terms of crack compliance reflected by rapid increase in VP with confining pressure. (author)

The geology and geochronology of the Belmont pluton and microgranite dykes from the Margate area

International Nuclear Information System (INIS)

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

1990-01-01

Field, petrographic, geochemical and Rb-Sr isotope data are presented for two granitic units which are considered to represent amongst the youngest intrusive rocks in the Natal Metamorphic Province. These are the Belmont granite pluton and a suite of unfoliated biotite microgranite dykes from the Margate area. The data suggest that these rocks do not form part of a consanguineous suite as previously envisaged. It is concluded that the Belmont pluton (1055 ± 60Ma) should be assigned to the garnet leucogranite phase of the syntectonic Margate Suite, and that the dykes (∼965 Ma) represent the products of a discrete, late-stage magmatic event which took place towards the end of the Natal orogenesis. Furthermore, the high initial Sr isotopic ratio (∼0,715) of the dykes suggests that they were derived from the melting of pre-existing radiogenic crust. The termination of major tectono-magmatic events in the Late Proterozoic Namaqua-Natal Belt apparently youngs from west to east across South Africa. Reconstructions of Gondwanaland place the Falkland Plateau and the Maudheim Province of Antarctica off the southeast of Africa. Dates obtained from this region range from ∼1000Ma to ∼500Ma, suggesting a continued decrease in age of tectono-magmatic activity eastwards. The microgranite dykes described here are unequivocally amongst the youngest post-tectono-metamorphic intrusions of southern Natal, yet they do not preserve any whole-rock indication of Pan-African isotopic disturbances. Sparse Rb-Sr mineral isotopic data support this indication that there was no significant Pan-African activity in the Natal Metamorphic Province. 8 figs., 7 tabs., 38 refs

Panning artifacts in digital pathology images

Science.gov (United States)

Avanaki, Ali R. N.; Lanciault, Christian; Espig, Kathryn S.; Xthona, Albert; Kimpe, Tom R. L.

2017-03-01

In making a pathologic diagnosis, a pathologist uses cognitive processes: perception, attention, memory, and search (Pena and Andrade-Filho, 2009). Typically, this involves focus while panning from one region of a slide to another, using either a microscope in a traditional workflow or software program and display in a digital pathology workflow (DICOM Standard Committee, 2010). We theorize that during panning operation, the pathologist receives information important to diagnosis efficiency and/or correctness. As compared to an optical microscope, panning in a digital pathology image involves some visual artifacts due to the following: (i) the frame rate is finite; (ii) time varying visual signals are reconstructed using imperfect zero-order hold. Specifically, after pixel's digital drive is changed, it takes time for a pixel to emit the expected amount of light. Previous work suggests that 49% of navigation is conducted in low-power/overview with digital pathology (Molin et al., 2015), but the influence of display factors has not been measured. We conducted a reader study to establish a relationship between display frame rate, panel response time, and threshold panning speed (above which the artifacts become noticeable). Our results suggest visual tasks that involve tissue structure are more impacted by the simulated panning artifacts than those that only involve color (e.g., staining intensity estimation), and that the panning artifacts versus normalized panning speed has a peak behavior which is surprising and may change for a diagnostic task. This is work in progress and our final findings should be considered in designing future digital pathology systems.

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.

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

Terrestrial gamma ray dose rates on Ryoke granitic rocks in Ikoma Mountains

International Nuclear Information System (INIS)

Ikeda, Tadashi; Ueshima, Masaaki; Shibayama, Motohiko; Hiraoka, Yoshitsugu; Muslim, Dicky

2012-01-01

We measured the γ dose rate of 16 rock bodies in the field, which belonged to Ryoke granitic rocks distributed over Ikoma Mountains. The measurement points were 190 spots, and the mean dose rate was 82.0 ± 21.0 nGy/h. Results of analysis were summarized as follows. (1) The distribution of the dose rate in the Fukihata quartz diorite showed that the rocks crystallization differentiation had progressed from the south to the north. (2) The dose rate of granite tended to arise with the increase of SiO 2 quantity, but in the Iwahashiyama granite, the Takayasuyama granite, the Omichi granite and the Katakami granite, it was revealed that the dose rate was low in spite of high SiO 2 quantity. (3) It became clear that the dose rate of Ryoke granitic rocks from the first stage to the fourth stage was high to be considered as a new rock body. (4) Because the relationship between the dose rate of rocks and the main chemical elements did not show a common characteristic, it may be that those rocks were formed from different Magma. (author)

Isotopic geochronology of granitic rocks from the Central Iberian Zone: comparison of methodologies

Energy Technology Data Exchange (ETDEWEB)

Antunes, I. M. H. R.; Neiva, A. M. R.; Silva, M. M. V. G.

2010-07-01

Five granitic rocks, concentrically disposed from core to rim, were distinguished in the Castelo Branco pluton. U-Pb-Th electron microprobe monazite ages from granitic rocks are similar and ranging between 297-303 Ma. The granitic rocks from Castelo Branco pluton are 310 {+-} 1 Ma old, obtained by U-Pb (ID-TIMS) in separated zircon and monazite crystals, indicating a similar emplacement age for all granitic rocks of the pluton. Initial {sup 8}7Sr/{sup 8}6Sr isotopic ratios and {epsilon}Nd{sub 3}10 and {delta}{sup 1}8O values suggest three distinct pulses of granitic magma and that they are derived from partial melting of heterogeneous metasedimentary materials. The other granitic rocks are related by magmatic differentiation and show small variations in ({sup 8}7Sr/{sup 8}6Sr)310, {epsilon}Nd{sub 3}10 and {delta}{sup 1}8O. The granitic pluton of Castelo Branco shows a rare reverse zoning. (Author) 12 refs.

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.

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

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)

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.

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

Prevalence of oral lesions in pan vendor

Directory of Open Access Journals (Sweden)

Prakash Gadodia

2011-01-01

Full Text Available Background: Being a portal of entry to various smoking and smokeless tobacco products, oral cavity is prone to deleterious effects. Present study consist of epidemiological survey to elucidate oral lesions in pan vendors. Aims and objectives: To detect oral lesions in pan vendors and compare it with controls. To detect habit pattern and prevalence of OSMF and other lesions in pan vendors as compared to controls- To identify, recognize and evaluate the possible etiology for OSMF, encompassing various chewing and smoking habits. Materials and methods: Study population consist of 170 pan vendors with age ranging from 15 to 55 years and equal number of sex matched controls selected randomly. Results: Prevalence of oral lesions in pan vendors is statistically significantly higher as compared to controls. The habit of arecanut chewing in various forms was present in all cases. The habit of smoking and smokeless tobacco products was present in all cases. Conclusion: Pan vendors are at higher risk for oral lesions than controls. There is increase in relative risk with increase in duration and frequency of habit.

The distribution and uranium content characteristics of Indosinian granite in South China

International Nuclear Information System (INIS)

Sun Wenliang; Zhang Zhuo; Chen Wenwen; Chen Lulu; Xu Wenzheng

2014-01-01

In recent years, more and more Indosinian granite plutons has been found in South China, so some new ideas about the granity were proposed by scholars. The Indosinian granite in South China distributed in lineshape, and is controlled by some regional faults. Its formation was mainly related to geodynamic setting which began in the late Permian (about 256 Ma) by the subduction of the ancient Pacific Plate to the Eurasia. The average uranium content of Indosinian granite is 10.34ppm, much higher than the average value of world's acid rock. There occurs some couplings between the distribution of the Indosinian granite plutons and uranium mineralization belt in South China. So the Indosinian granite in South China may act as important uranium sources for the mineralization. (authors)

Mineralogy, geochemistry and petrophysics of red coloured granite adjacent to fractures

International Nuclear Information System (INIS)

Eliasson, T.

1993-03-01

Mineralogical, geochemical and petrophysical investigations were conducted of red-coloured alteration rims and of the neighbouring unaltered equivalents along fractures within granite from Aespoe. An investigation was made also of a weak to rather strong, red-coloured granite from the Stripa mine, as well as a weak brownish-red colouration, definitely no hydrothermal in origin, of weathered rinds at a glacial polished rock surface in the Bohus granite. When approaching the fracture planes in the Aespoe granite, the most diagnostic alteration features are * the saussuritisation and Fe-oxyhydroxide staining of plagioclase, * the crystallisation chlorite pseudomorphs after biotite and * the hematisation of magnetite. The porosity within the alteration zones increases generally 2 to 3 times compared with the protolith rock, whereas the densities decrease by some 5 to 10%. The oxidation of magnetite gives as much as a tenfold lowering of the magnetic susceptibility. The red colouration of the Stripa granite is caused by hematite ± Fe-oxyhydroxide formation along microfractures, grain boundaries and, subordinately, the main minerals. Oxidation and re-precipitation of iron liberated during a retrograde muscovitisation of principally chlorite is interpreted to be the cause of the formation of the ferric oxides. The rather homogeneous density and porosity values of the grey and of the red-coloured granites reflect the minor change in the mineralogy when going from fresh into altered granite. Weathering and whitening of plagioclase in the bleached, outer zone and precipitation of small quantities of Fe-oxyhydroxides/hydroxides in the brownish-red zone cause the macroscopic colouration of the weathering rind below the glacial polished rock surface of Bohus granite. There is a marked increase in porosity from the interior fresh (c. 0.4-0.5%) towards the exterior bleached zone (c.1.5-2%) of the subaerialy, weathered Bohus granite surface. The incipient decomposition of

[Study on the fine structure of K-feldspar of Qichun granite].

Science.gov (United States)

Du, Deng-Wen; Hong, Han-Lie; Fan, Kan; Wang, Chao-Wen; Yin, Ke

2013-03-01

Fine structure of K-feldspar from the Qichun granite was investigated using X-ray diffraction (XRD), Fourier infrared absorption spectroscopy (FTIR), and inductively coupled plasma mass spectrometry methods to understand the evolution of the granitic magmatism and its correlation to molybdenite mineralization. The XRD results showed that K-feldspar of the potassic alteration veins has higher ordering index and triclinicity and is namely microcline with triclinic symmetry. K-feldspar of the early cretaceous granite has relatively lower ordering index and has widening [131] peak and is locally triclinic ordering. K-feldspar of the late cretaceous granite has lowest ordering index and sharp [131] peak and is honiogeneously monoclinic. The FTIR results showed that the IR spectra of the Qichun K-feldspar are similar to that of orthoclase reported by Farmer (1974). The 640 cm-1 absorption band increases while the 540 cm-' absorption band decreases with increase in K-feldspar ordering index, also, the 1,010 cm-1 absorption band separates into 1,010 and 1,046 cm-1 absorption bands, with a change in the band shape from widening to sharp outline. The ICP-MS results suggested that K-feldspar of the early cretaceous granite has relatively higher metal elements and rare earth elements, and the granite exhibits better mineralization background, K-feldspar of the potassic alteration veins has markedly lower Sr and Ba, indicating that the alteration fluid originated from the granitic magmatism, and hence, potassic alteration is a good indicator for molybdenite exploration.

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)

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...

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...

A fractal derivative constitutive model for three stages in granite creep

Directory of Open Access Journals (Sweden)

R. Wang

Full Text Available In this paper, by replacing the Newtonian dashpot with the fractal dashpot and considering damage effect, a new constitutive model is proposed in terms of time fractal derivative to describe the full creep regions of granite. The analytic solutions of the fractal derivative creep constitutive equation are derived via scaling transform. The conventional triaxial compression creep tests are performed on MTS 815 rock mechanics test system to verify the efficiency of the new model. The granite specimen is taken from Beishan site, the most potential area for the China’s high-level radioactive waste repository. It is shown that the proposed fractal model can characterize the creep behavior of granite especially in accelerating stage which the classical models cannot predict. The parametric sensitivity analysis is also conducted to investigate the effects of model parameters on the creep strain of granite. Keywords: Beishan granite, Fractal derivative, Damage evolution, Scaling transformation

Alkali-activated blast furnace slag-zeolite cements and concretes

International Nuclear Information System (INIS)

Rakhimov, R.; Rakhimova, N.

2012-01-01

The aim of this work has been the study of alkali-activated slag-zeolite cements and concretes based on them. Various compositions have been tested and some characteristics such as the compressive strength have been measured versus zeolite additions. A table lists the specific surface area and particle size distributions of different cements. The conclusions of the study are the following. First, alkali-activated slag cements and concretes based on them are effective for immobilization of radioactive wastes and the production of building structures, designed for high radiation load. Secondly, zeolite-containing mineral additions are able to increase the immobilization capacity and radiation resistance of alkali-activated blast furnace slag cements and concretes. Thirdly, the efficiency of different zeolite-containing additions - 10% to increase alkali-activated blast furnace slag-zeolite cement strength was established. It is with alkaline components of water-glass, sodium carbonate, sodium sulphate. Fourth, the effective way of introducing zeolite additions in alkali-activated blast furnace slag-zeolite cement is inter-grinding of the slag and addition. Increase in strength of alkali-activated blast furnace slag-zeolite cement stone is 40% higher than that of the stone of a mixture of separately milled components. Fifth, Alkali-activated blast furnace slag-zeolite cements with zeolite-containing additions with a compressive strength of 10.1 to 140 MPa; alkali-activated blast furnace slag-zeolite cements mortars with compressive strength from 35.2 to 97.7 MPa; alkali-activated blast furnace slag-zeolite cements concretes with compressive strength up to 84.5 MPa and frost resistant up to 800 cycles were obtained

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

Mobility of heavy metals through granitic soils using mini column infiltration test

International Nuclear Information System (INIS)

Zarime, Nur 'Aishah; Yaacob, W. Z.W.

2014-01-01

This study is about the mobility of cadmium through compacted granitic soils. Two granitic soils namely the Broga (BGR) and Kajang (KGR) granitic soils were collected in Selangor, Malaysia. Physical and chemical tests were applied for both granitic soils to determine the physical and chemical properties of soil materials. Physical test results shows granitic soils (BGR and KGR) have high percentage of sand ranging between 54%–63% and 46%–54% respectively, an intermediate and intermediate to high plasticity index as well as high specific gravity ie; 2.50–2.59 and 2.45–2.66 respectively. For chemical test, granitic soils shows acidic pH values ranged from 5.35–5.85 for BGR and pH 5.32–5.54 for KGR. For organic matter, SSA and CEC test, it shows low values ranged from 0.22%–0.34% and 0.39%– 0.50% respectively for organic matter test, 17.96 m 2 /g–21.93 m 2 /g and 25.76 m 2 /g–26.83 m 2 /g respectively for SSA test and 0.79 meq/100g–1.35 meq/100g and 1.31 meq/100g–1.35 meq/100g respectively for CEC test. Mini column infiltration test was conducted to determine the retention of cadmium while flowing through granite soils. This test conducted based on the falling head permeability concepts. Different G-force ranging from 231G to 1442G was used in this test. The breakthrough curves show the concentration of Cd becomes higher with the increasing of G-force for both granitic samples (BGR and KGR). The selectivity sorption for both granites ranked in the following decreasing order of; 231G>519G>923G>1442G. Results demonstrated that granitic soils also have low buffering capacity due to low resist of pH changes

Contamination in mafic mineral-rich calc-alkaline granites: a geochemical and Sr-Nd isotope study of the Neoproterozoic Piedade Granite, SE Brazil

Directory of Open Access Journals (Sweden)

Leite Renato J.

2006-01-01

Full Text Available The Piedade Granite (~600 Ma was emplaced shortly after the main phase of granite magmatism in the Agudos Grandes batholith, Apiaí-Guaxupé Terrane, SE Brazil. Its main units are: mafic mineral-rich porphyritic granites forming the border (peraluminous muscovite-biotite granodiorite-monzogranite MBmg unit and core (metaluminous titanite-bearing biotite monzogranite BmgT unit and felsic pink inequigranular granite (Bmg unit between them. Bmg has high LaN/YbN (up to 100, Th/U (>10 and low Rb, Nb and Ta, and can be a crustal melt derived from deep-seated sources with residual garnet and biotite. The core BmgT unit derived from oxidized magmas with high Mg# (~45, Ba and Sr, fractionated REE patterns (LaN/YbN= 45, 87Sr/86Sr(t~ 0.710, epsilonNd(t ~ -12 to -14, interpreted as being high-K calc-alkaline magmas contaminated with metasedimentary rocks that had upper-crust signature (high U, Cs, Ta. The mafic-rich peraluminous granites show a more evolved isotope signature (87Sr/86Sr(t = 0.713-0.714; epsilonNd(t= -14 to -16, similar to Bmg, and Mg# and incompatible trace-element concentrations intermediate between Bmg and BmgT. A model is presented in whichMBmgis envisaged as the product of contamination between a mafic mineral-rich magma consanguineous with BmgT and pure crustal melts akin to Bmg.

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

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.

Alkali-Resistant Mechanism of a Hollandite DeNOx Catalyst.

Science.gov (United States)

Hu, Pingping; Huang, Zhiwei; Gu, Xiao; Xu, Fei; Gao, Jiayi; Wang, Yue; Chen, Yaxin; Tang, Xingfu

2015-06-02

A thorough understanding of the deactivation mechanism by alkalis is of great importance for rationally designing improved alkali-resistant deNOx catalysts, but a traditional ion-exchange mechanism cannot often accurately describe the nature of the deactivation, thus hampering the development of superior catalysts. Here, we establish a new exchange-coordination mechanism on the basis of the exhaustive study on the strong alkali resistance of a hollandite manganese oxide (HMO) catalyst. A combination of isothermal adsorption measurements of ammonia with X-ray absorption near-edge structure spectra and X-ray photoelectron spectra reveals that alkali metal ions first react with protons from Brønsted acid sites of HMO via the ion exchange. Synchrotron X-ray diffraction patterns and extended X-ray absorption fine structure spectra coupled with theoretical calculations demonstrate that the exchanged alkali metal ions are subsequently stabilized at size-suitable cavities in the HMO pores via a coordination model with an energy savings. This exchange-coordination mechanism not only gives a wholly convincing explanation for the intrinsic nature of the deactivation of the reported catalysts by alkalis but also provides a strategy for rationally designing improved alkali-resistant deNOx catalysts in general.

[Enhancement of anaerobic digestion of excess sludge by acid-alkali pretreatment].

Science.gov (United States)

Yuan, Guang-Huan; Zhou, Xing-Qiu; Wu, Jian-Dong

2012-06-01

In order to enhance the efficiency of anaerobic digestion of excess sludge, acid-alkali pretreatment method was studied. Three different pretreatment methods (alkali alone,acid-alkali, alkali-acid) were compared to investigate their impacts on hydrolysis and acidification of activated sludge. In addition, their influences on methane-producing in subsequent anaerobic digestion process were also studied. The results showed that the soluble chemical oxygen demand (SCOD) of alkaline treatment alone was about 16% higher than the combining of acid and alkali treatment, SCOD concentration increased to 5406.1 mg x L(-1) after 8 d pretreatment. After treated by acid (pH 4.0, 4 d) and alkali (pH 10.0, 4 d), the acetic acid production and its content in short-chain fatty acids (SCFAs) were higher than other pretreatment methods. And the acetic acid production (as COD/VSS) could reach 74.4 mg x g(-1), accounting for 60.5% of SCFAs. After acid-alkali pretreatment, the C: N ratio of the sludge mixed liquor was about 25, and the C: P ratio was between 35-40, which was more favorable than C: N and C: P ratio of alkali alone and alkali-acid to subsequent anaerobic digestion. The control experiments showed that, after acid-alkali pretreatment, anaerobic digestion cumulative methane yield (CH4/VSS(in)) reached to 136.1 mL x g(-1) at 15 d, which was about 2.5-, 1.6-, and 1.7-fold of the blank (unpretreated), alkali alone pretreatment and alkali-acid pretreatment, respectively. After acid-alkali pretreatment for 8 d and anaerobic digestion for 15 d, the removal efficiency of VSS was about 60.9%, and the sludge reduction effect was better than other pretreatments. It is obvious that the acid-alkali pretreatment method was more favorable to anaerobic digestion and sludge reduction.

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

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...

The role of granites for the ore mineralization in South German Variscides

International Nuclear Information System (INIS)

Dill, H.G.

1987-01-01

Granites are of widespred occurrence in the South German Variscides (F.R. of Germany), the Black Forest (=BF), and the NE Bavarian Basement (=NEBB). These areas are crossed by the Saxothuringian-Moldanubian plate boundary and were also affected by crustal subdulction and nappe tectonism, both of which are thought to be responsible for granitisation and enrichment of Sn, W,U,Au, Sb,Pb,Zn,F, and Ba in veins of different kind. Heat produced by gliding of plates above each other, by decay of radioctive elements in granites as well as set free by the granites themselves caused the above-mentioned elements to be released from their protores, which formed during Late Proterozoic and Early Paleozoic rifting. These hypogene ore mineralizations may be crudely subdivided into thrustbound, granite-related and granite-induced ore deposites. During Tertiary-Quaternary these granites were exposed the pervasive weathering under subtropical conditions, so that ''U yellow ores'' and china clay deposits came into existence. The whole ore mineralization in that region may be explained by a simple four-step model: preconcentration, fracturation, activation and peneplaination. (author) [pt

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)

Geochemical characteristics and origin of the Lebowa Granite Suite, Bushveld Complex

Science.gov (United States)

Hill, M.; Barker, F.; Hunter, D.; Knight, R.

1996-01-01

The ??? 2052-Ma Lebowa Granite Suite (LGS) represents the culminating phase of an Early Proterozoic magmatic cycle in the Central Transvaal area of the Kaapvaal Province. Following extrusion of at least 200,000 km3 of intermediate to acid volcanics (Rooiberg Felsite), mafic and ultramafic magmas intruded at 2065 Ma to form the Rustenburg Layered Suite (RLS). The LGS includes the Nebo, Makhutso, Bobbejaankop, Lease, and Klipkloof granites. The Nebo Granite intruded the Rooiberg Felsite as sheets up to 4 km thick above the RLS. Smaller stocks of the other granites crosscut the Nebo. We determined major- and trace-element compositions and oxygen, Rb-Sr, and Sm-Nd isotope ratios for samples of: Nebo Granite; Rooiberg Felsite; granophyre and granophyric granite; Makhutso, Bobbejaankop, and Lease granites; and feldspar porphyry from areas throughout the exposed area of the LGS (Dennilton, Verena Balmoral, Enkeldoorn, Sekhukhune Plateau, Zaaiplaats-Potgeitersrus, and Western Transvaal). Coherent floor-to-roof geochemical trends exist in some areas, although it is not possible to model them convincingly. Regional variations in geochemistry exist and likely are related to source variations in the estimated 200,000 km3 of the Nebo Granite sheets. ??18O for the LGS range from +5.9??? to +9.5???; if these are approximate primary magmatic values, pelitic sediments cannot have been an important source for the LGS. The Rb-Sr isotope system has been altered, a finding consistent with previous studies. A mineral isochron for Nebo Granite near Dennilton yields a York regression age of 1995 ?? 99 Ma, with initial 143Nd/144Nd = 0.50978??8 and ???CHUR=-5.12. Samples from the Sekhukhune Plateau have higher 143Nd/144Nd ratios than do Dennilton-area samples, suggesting that the former originated from older or less LREE-enriched sources. We suggest that intrusion of mafic to ultramafic magmas at depth in the continental crust triggered melting of Archean quartzofeldspathic crystalline

Petrography, Gamma Radiation Measurements and Dose Rate, Northeastern Um Ara Area, South Eastern Desert, Egypt

International Nuclear Information System (INIS)

Moghazy, N.M.

2016-01-01

The northern part of Um Ara alkali feldspar micro granite has subjected to extensive post-magmatic metasomatic reworking resulting in development of amazonitized and albitized zones, reflecting K- and Na metasomatism leading to gross enrichment in U and Th towards the more evolved phases (e.g., albitized zones). Spectrometric survey data indicate that eU in Dokhan volcanics has the range of 2 to 42 ppm with an average value of 10 ppm and in monzogranites. It varies from 3 to 13 ppm with an average of 7 ppm while in alkali feldspar microgranites eU contents vary from 3 to 282 ppm with an average value of 30 ppm. The (eTh) contents in Dokhan volcanics ranges from 5-51 ppm with an average 18 ppm, in monzogranites their content was in the range of 11 to 47 ppm with an average value of 27 ppm where it ranges from 14 to 83 ppm with an average 46 ppm in alkali feldspar granite. The enhanced uranium content in altered zones was attributed to disseminated and fracture filling uranophane, autonite, in addition to other U and Th bearing minerals (such as columbite, zircon, monazite, xenotime and fluorite). Gamma-radiation dose rate and annual effective dose equivalents in mSv/y, Radium equivalent activity, external (H e x) and internal hazard index (H i n) and gamma activity index (Iγ) for all investigated samples were calculated to assess the potential radiation hazard for people living in dwellings made of the studied granites. Alkali feldspar granite activities would suggest that caution must be taken when using granites as building materials because they have radioactivity above the proposed acceptable level.

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.

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.)

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.

[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.

A coupled channel study on a binding mechanism of positronic alkali atoms

International Nuclear Information System (INIS)

Kubota, Yoshihiro; Kino, Yasushi

2008-01-01

In order to investigate the binding mechanism of weakly bound states of positronic alkali atoms, we calculate the energies and wavefunctions using the Gaussian expansion method (GEM) where a positronium (Ps)-alkali ion channel and a positron-alkali atom channel are explicitly introduced. The energies of the bound states are updated using a model potential that reproduces well the observed energy levels of alkali atoms. The binding mechanism of the positronic alkali atom is analyzed by the wavefunctions obtained. The structure of the positronic alkali atom has been regarded as a Ps cluster orbiting the alkali ion, which is described by the Ps-alkali ion channel. We point out that the fraction having the positron-alkali atom configuration is small but plays an indispensable role for the weakly bound system

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

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).

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

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 ...

On-line alkali monitoring - Part 1; Kontinuerlig alkalimaetning - Etapp 1

Energy Technology Data Exchange (ETDEWEB)

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

Chemical and isotopic studies of granitic Archean rocks, Owl Creek Mountains, Wyoming: Geochronology of an Archean granite, Owl Creek Mountains, Wyoming

International Nuclear Information System (INIS)

Hedge, C.E.; Simmons, K.R.; Stuckless, J.S.

1986-01-01

Rubidium-strontium analyses of whole-rock samples of an Archean granite from the Owl Creek Mountains, Wyo., indicate an intrusive age of 2640 ± 125 Ma. Muscovite-bearing samples give results suggesting that these samples were altered about 2300 Ma. This event may have caused extensive strontium loss from the rocks as potassium feldspar was altered to muscovite. Alteration was highly localized in nature as evidence by unaffected rubidium-strontium mineral ages in the Owl Creek Mountains area. Furthermore, the event probably involved a small volume of fluid relative to the volume of rock because whole-rock δ 18 O values of altered rocks are not distinct from those of unaltered rocks. In contrast to the rubidium-strontium whole-rock system, zircons from the granite have been so severely affected by the alteration event, and possibly by a late-Precambrian uplift event, that the zircon system yields little usable age information. The average initial 87 Sr/ 86 Sr (0.7033 ± 0.0042) calculated from the isochron intercept varies significantly. Calculated initial 87 Sr/ 86 Sr ratios for nine apparently unaltered samples yield a range of 0.7025 to 0.7047. These calculated initial ratios correlate positively with whole-rock δ 18 O values; and, therefore, the granite was probably derived from an isotopically heterogeneous source. The highest initial 87 Sr/ 86 Sr ratio is lower than the lowest reported for the metamorphic rocks intruded by the granite as it would have existed at 2640 Ma. Thus, the metamorphic sequence, at its current level of exposure, can represent no more than a part of the protolith for the granite

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.

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

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

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.

Overview of ATLAS PanDA Workload Management

Science.gov (United States)

Maeno, T.; De, K.; Wenaus, T.; Nilsson, P.; Stewart, G. A.; Walker, R.; Stradling, A.; Caballero, J.; Potekhin, M.; Smith, D.; ATLAS Collaboration

2011-12-01

The Production and Distributed Analysis System (PanDA) plays a key role in the ATLAS distributed computing infrastructure. All ATLAS Monte-Carlo simulation and data reprocessing jobs pass through the PanDA system. We will describe how PanDA manages job execution on the grid using dynamic resource estimation and data replication together with intelligent brokerage in order to meet the scaling and automation requirements of ATLAS distributed computing. PanDA is also the primary ATLAS system for processing user and group analysis jobs, bringing further requirements for quick, flexible adaptation to the rapidly evolving analysis use cases of the early datataking phase, in addition to the high reliability, robustness and usability needed to provide efficient and transparent utilization of the grid for analysis users. We will describe how PanDA meets ATLAS requirements, the evolution of the system in light of operational experience, how the system has performed during the first LHC data-taking phase and plans for the future.

Overview of ATLAS PanDA Workload Management

International Nuclear Information System (INIS)

Maeno, T.; De, K.; Wenaus, T.; Nilsson, P.; Stewart, G.A.; Walker, R.; Stradling, A.; Caballero, J.; Potekhin, M.; Smith, D.

2011-01-01

The Production and Distributed Analysis System (PanDA) plays a key role in the ATLAS distributed computing infrastructure. All ATLAS Monte-Carlo simulation and data reprocessing jobs pass through the PanDA system. We will describe how PanDA manages job execution on the grid using dynamic resource estimation and data replication together with intelligent brokerage in order to meet the scaling and automation requirements of ATLAS distributed computing. PanDA is also the primary ATLAS system for processing user and group analysis jobs, bringing further requirements for quick, flexible adaptation to the rapidly evolving analysis use cases of the early datataking phase, in addition to the high reliability, robustness and usability needed to provide efficient and transparent utilization of the grid for analysis users. We will describe how PanDA meets ATLAS requirements, the evolution of the system in light of operational experience, how the system has performed during the first LHC data-taking phase and plans for the future.

Geometric morphometrics in primatology: craniofacial variation in Homo sapiens and Pan troglodytes.

Science.gov (United States)

Lynch, J M; Wood, C G; Luboga, S A

1996-01-01

Traditionally, morphometric studies have relied on statistical analysis of distances, angles or ratios to investigate morphometric variation among taxa. Recently, geometric techniques have been developed for the direct analysis of landmark data. In this paper, we offer a summary (with examples) of three of these newer techniques, namely shape coordinate, thin-plate spline and relative warp analyses. Shape coordinate analysis detected significant craniofacial variation between 4 modern human populations, with African and Australian Aboriginal specimens being relatively prognathous compared with their Eurasian counterparts. In addition, the Australian specimens exhibited greater basicranial flexion than all other samples. The observed relationships between size and craniofacial shape were weak. The decomposition of shape variation into affine and non-affine components is illustrated via a thin-plate spline analysis of Homo and Pan cranial landmarks. We note differences between Homo and Pan in the degree of prognathism and basicranial flexion and the position and orientation of the foramen magnum. We compare these results with previous studies of these features in higher primates and discuss the utility of geometric morphometrics as a tool in primatology and physical anthropology. We conclude that many studies of morphological variation, both within and between taxa, would benefit from the graphical nature of these techniques.

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.)

Phylogenetic relations of humans and African apes from DNA sequences in the Psi eta-globin region

Energy Technology Data Exchange (ETDEWEB)

Miyamoto, M.M.; Slightom, J.L.; Goodman, M.

1987-10-16

Sequences from the upstream and downstream flanking DNA regions of the Psi eta-globin locus in Pan troglodytes (common chimpanzee), Gorilla gorilla (gorilla), and Pongo pygmaeus (orangutan, the closest living relative to Homo, Pan, and Gorilla) provided further data for evaluating the phylogenetic relations of humans and African apes. These newly sequenced orthologs (an additional 4.9 kilobase pairs (kbp) for each species) were combined with published Psi eta-gene sequences and then compared to the same orthologous stretch (a continuous 7.1-kbp region) available for humans. Phylogenetic analysis of these nucleotide sequences by the parsimony method indicated (i) that human and chimpanzee are more closely related to each other than either is to gorilla and (ii) that the slowdown in the rate of sequence evolution evident in higher primates is especially pronounced in humans. These results indicate that features unique to African apes (but not to humans) are primitive and that even local molecular clocks should be applied with caution.

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.

Structural analysis of a fractured basement reservoir, central Yemen

Science.gov (United States)

Veeningen, Resi; Rice, Hugh; Schneider, Dave; Grasemann, Bernhard; Decker, Kurt

2013-04-01

The Pan-African Arabian-Nubian Shield (ANS), within which Yemen lies, formed as a result of Neoproterozoic collisional events between c. 870-550 Ma. Several subsequent phases of extension occurred, from the Mesozoic (due to the breakup of Gondwana) to the Recent (forming the Gulf of Aden and the Red Sea). These resulted in the formation of numerous horst- and-graben structures and the development of fractured basement reservoirs in the southeast part of the ANS. Two drill cores from the Mesozoic Marib-Shabwa Basin, central Yemen, penetrated the upper part of the Pan-African basement. The cores show both a lithological and structural inhomogeneity, with variations in extension-related deformation structures such as dilatational breccias, open fractures and closed veins. At least three deformation events have been recognized: D1) Ductile to brittle NW-SE directed faulting during cooling of a granitic pluton. U-Pb zircon ages revealed an upper age limit for granite emplacement at 627±3.5 Ma. As these structures show evidence for ductile deformation, this event must have occurred during the Ediacaran, shortly after intrusion, since Rb/Sr and (U-Th)/He analyses show that subsequent re-heating of the basement did not take place. D2) The development of shallow dipping, NNE-SSW striking extensional faults that formed during the Upper Jurassic, simultaneously with the formation of the Marib-Shabwa Basin. These fractures are regularly cross-cut by D3. D3) Steeply dipping NNE-SSW to ENE-WSW veins that are consistent with the orientation of the opening of the Gulf of Aden. These faults are the youngest structures recognized. The formation of ductile to brittle faults in the granite (D1) resulted in a hydrothermally altered zone ca. 30 cm wide replacing (mainly) plagioclase with predominantly chlorite, as well as kaolinite and heavy element minerals such as pyrite. The alteration- induced porosity has an average value of 20%, indicating that the altered zone is potentially a

ASSESSING LAND COVER CHANGES CAUSED BY GRANITE QUARRYING USING REMOTE SENSING

Directory of Open Access Journals (Sweden)

R. S. Moeletsi

2017-11-01

Full Text Available Dimension stone quarrying in the area between Rustenburg and Brits in the North West Province of South Africa has been in existence for over 70 decades. The unique characteristics of the granite deposits in South Africa resulted in making the country a global producer of the granite rocks. This led to intensified quarrying activities between Rustenburg and Brits town. However, this surface mining method, has a potential to impact the environment in a negative way causing loss in vegetation, depletion of natural resources, loss of scenic beauty and contamination of surface water resources. To assess the land cover changes caused by granite quarrying activities, remotely sensed data in the form of Landsat images between 1998 and 2015 were used. Supervised classification was used to create maps. Accuracy assessment using Google EarthTM as a reference data yielded an overall accuracy of 78 %. The post classification change detection method was used to assess land cover changes within the granite quarries. Granite quarries increased by 1174.86 ha while formation of quarry lakes increased to 5.3 ha over the 17-year period. Vegetation cover decreased by 1308 ha in area while 18.3 ha bare land was lost during the same period. This study demonstrated the utility of remote sensing to detect changes in land cover within granite quarries.

Masticatory form and function in the African apes.

Science.gov (United States)

Taylor, Andrea B

2002-02-01

This study examines variability in masticatory morphology as a function of dietary preference among the African apes. The African apes differ in the degree to which they consume leaves and other fibrous vegetation. Gorilla gorilla beringei, the eastern mountain gorilla, consumes the most restricted diet comprised of mechanically resistant foods such as leaves, pith, bark, and bamboo. Gorilla gorilla gorilla, the western lowland gorilla subspecies, consumes leaves and other terrestrial herbaceous vegetation (THV) but also consumes a fair amount of ripe, fleshy fruit. In contrast to gorillas, chimpanzees are frugivores and rely on vegetation primarily as fallback foods. However, there has been a long-standing debate regarding whether Pan paniscus, the pygmy chimpanzee (or bonobo), consumes greater quantities of THV as compared to Pan troglodytes, the common chimpanzee. Because consumption of resistant foods involves more daily chewing cycles and may require larger average bite force, the mechanical demands placed on the masticatory system are expected to be greater in folivores as compared to primates that consume large quantities of fleshy fruit. Therefore, more folivorous taxa are predicted to exhibit features that improve load-resistance capabilities and increase force production. To test this hypothesis, jaw and skull dimensions were compared in ontogenetic series of G. g. beringei, G. g. gorilla, P. t. troglodytes, and P. paniscus. Controlling for the influence of allometry, results show that compared to both chimpanzees and bonobos, gorillas exhibit some features of the jaw complex that are suggestive of improved masticatory efficiency. For example, compared to all other taxa, G. g. beringei has a significantly wider mandibular corpus and symphysis, larger area for the masseter muscle, higher mandibular ramus, and higher mandibular condyle relative to the occlusal plane of the mandible. However, the significantly wider mandibular symphysis may be an

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

Geochemistry, geochronology and Nd isotopes of the Gogó da Onça Granite: A new Paleoproterozoic A-type granite of Carajás Province, Brazil

Science.gov (United States)

Teixeira, Mayara Fraeda Barbosa; Dall'Agnol, Roberto; Santos, João Orestes Schneider; de Sousa, Luan Alexandre Martins; Lafon, Jean-Michel

2017-12-01

The Gogó da Onça Granite (GOG) comprise a stock located in the Carajás Province in the southeastern part of Amazonian Craton near its border with the Araguaia Belt. Three facies were identified in the pluton: biotite-amphibole granodiorite, biotite-amphibole monzogranite and amphibole-biotite syenogranite. The GGO crosscut discordantly the Archean country rocks and are not foliated. All Gogó da Onça Granite varieties are metaluminous, ferroan A2-subtype granites with reduced character. The major and trace element behavior suggests that its different facies are related by fractional crystallization. Zircon and titanite U-Pb SHRIMP ages show that the pluton crystallized at ∼1880-1870 Ma and is related to the remarkable Paleoproterozoic magmatic event identified in the Carajás Province. Whole-rock Nd isotope data (TDM ages 2.78 to 2.81, εNd values of -9.07 to -9.48) indicate that the GOG magmas derived from an Archaean source compatible with that of some other Paleoproterozoic suites from Carajás Province. The GOG show significant contrasts with the Jamon and Velho Guilherme Paleoproterozoic suites from Carajás Province and the inclusion of the Gogó da Onça granite in any of these suites is not justified. The GOG is more akin to the Serra dos Carajás Suite and to the Seringa and São João granites of Carajás and to the Mesoproterozoic Sherman granite of USA and the Paleoproterozoic Suomenniemi Batholith of Finland. This study puts in evidence the relevance of precise geochronological data and estimation of magma oxidation state in the characterization and correlation of A-type granites.

Uranium and selected trace elements in granites from the Caledonides of East Greenland

International Nuclear Information System (INIS)

Steenfelt, A.

1982-01-01

The Caledonian fold belt of East Greenland contains calc-alkaline granite (sensu lato) intrusions with ages ranging from c.2000 Ma to c.350 Ma. The Proterozoic granites have low U contents and the pre-Devonian Caledonian granites contents of U corresponding to the clarke value for U in granites. Some aspects of the geochemistry of U are discussed using U-K/Rb, U-Sr, U-Zr, and U-Th diagrams. Secondary enrichment and mineralization occurs in fractured and hydrothermally altered granites and rhyolites situated in or near a major NNE fault zone. The U is associated with iron oxides or hydrocarbons. It is suggested that the source of the mineralization was Devonian acid magma, which also acted as a heat source for circulating hydrothermal fluids. (author)

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

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

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

Is Pan-Asian Economic Integration Moving Forward?: Evidence from Pan-Asian Trade Statistics

OpenAIRE

Sapkota, Jeet Bahadur; Shuto, Motoko

2016-01-01

Asia is growing economically faster than any other region in the world; this led to the shift of the center of gravity of the global economy from the West to the East. However, it is not clear whether the Asian economy is integrating regionally or globally. In the context of the growing efforts of regional or sub-regional pan-Asian integration, it is worthwhile to explore the pan-Asian trade flows regionally as well as globally. Thus, this paper examines the trend and determinants of economic...

Long term mechanical properties of alkali activated slag

Science.gov (United States)

Zhu, J.; Zheng, W. Z.; Xu, Z. Z.; Leng, Y. F.; Qin, C. Z.

2018-01-01

This article reports a study on the microstructural and long-term mechanical properties of the alkali activated slag up to 180 days, and cement paste is studied as the comparison. The mechanical properties including compressive strength, flexural strength, axis tensile strength and splitting tensile strength are analyzed. The results showed that the alkali activated slag had higher compressive and tensile strength, Slag is activated by potassium silicate (K2SiO3) and sodium hydroxide (NaOH) solutions for attaining silicate modulus of 1 using 12 potassium silicate and 5.35% sodium hydroxide. The volume dosage of water is 35% and 42%. The results indicate that alkali activated slag is a kind of rapid hardening and early strength cementitious material with excellent long-term mechanical properties. Single row of holes block compressive strength, single-hole block compressive strength and standard solid brick compressive strength basically meet engineering requirements. The microstructures of alkali activated slag are studied by X-ray diffraction (XRD). The hydration products of alkali-activated slag are assured as hydrated calcium silicate and hydrated calcium aluminate.

Ternary alkali-metal and transition metal or metalloid acetylides as alkali-metal intercalation electrodes for batteries

Science.gov (United States)

Nemeth, Karoly; Srajer, George; Harkay, Katherine C; Terdik, Joseph Z

2015-02-10

Novel intercalation electrode materials including ternary acetylides of chemical formula: A.sub.nMC.sub.2 where A is alkali or alkaline-earth element; M is transition metal or metalloid element; C.sub.2 is reference to the acetylide ion; n is an integer that is 0, 1, 2, 3 or 4 when A is alkali element and 0, 1, or 2 when A is alkaline-earth element. The alkali elements are Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs) and Francium (Fr). The alkaline-earth elements are Berilium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), and Radium (Ra). M is a transition metal that is any element in groups 3 through 12 inclusive on the Periodic Table of Elements (elements 21 (Sc) to element 30 (Zn)). In another exemplary embodiment, M is a metalloid element.

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)

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.

Electrically controllable artificial PAN muscles

Science.gov (United States)

Salehpoor, Karim; Shahinpoor, Mohsen; Mojarrad, Mehran

1996-02-01

Artificial muscles made with polyacrylonitrile (PAN) fibers are traditionally activated in electrolytic solution by changing the pH of the solution by the addition of acids and/or bases. This usually consumes a considerable amount of weak acids or bases. Furthermore, the synthetic muscle (PAN) itself has to be impregnated with an acid or a base and must have an appropriate enclosure or provision for waste collection after actuation. This work introduces a method by which the PAN muscle may be elongated or contracted in an electric field. We believe this is the first time that this has been achieved with PAN fibers as artificial muscles. In this new development the PAN muscle is first put in close contact with one of the two platinum wires (electrodes) immersed in an aqueous solution of sodium chloride. Applying an electric voltage between the two wires changes the local acidity of the solution in the regions close to the platinum wires. This is because of the ionization of sodium chloride molecules and the accumulation of Na+ and Cl- ions at the negative and positive electrode sites, respectively. This ion accumulation, in turn, is accompanied by a sharp increase and decrease of the local acidity in regions close to either of the platinum wires, respectively. An artificial muscle, in close contact with the platinum wire, because of the change in the local acidity will contract or expand depending on the polarity of the electric field. This scheme allows the experimenter to use a fixed flexible container of an electrolytic solution whose local pH can be modulated by an imposed electric field while the produced ions are basically trapped to stay in the neighborhood of a given electrode. This method of artificial muscle activation has several advantages. First, the need to use a large quantity of acidic or alkaline solutions is eliminated. Second, the use of a compact PAN muscular system is facilitated for applications in active musculoskeletal structures. Third, the

The spatial variation of initial 87Sr/86Sr ratios in the Toki granite, Central Japan. Implications for the intrusion and cooling processes of a granitic pluton

International Nuclear Information System (INIS)

Yuguchi, Takashi; Tsuruta, Tadahiko; Hama, Katsuhiro; Nishiyama, Tadao

2013-01-01

The spatial variation in initial 87 Sr/ 86 Sr ratios (SrI) in the Toki granite, Central Japan, shows heterogeneity ranging from 0.708942 to 0.710069, which provides information on the intrusion and cooling processes of plutons. The Toki granite has three mineralogy-based rock facies: muscovite-biotite granite (MBG), hornblende-biotite granite (HBG) and biotite granite (BG). Large SrI values were found to be distributed at the western margin (west MBG) and the lithologically central region (central BG), while small SrI values were found at the northeast margin (northeast MBG). Regions with high and low Sr concentrations were also found in the Toki granite. In the Sr-rich samples, SrI (0.708942-0.709789) increases with 100/Sr (0.7-1.5). This geochemical trend extends towards the country sedimentary rocks of the Mino Terrane, which can be interpreted to result from assimilation and fractional crystallization (AFC) between the original granitic magma and the Mino sedimentary rocks. The SrI values in the Sr-rich regions show a correlation with the Alumina Saturation Index (ASI). In particular, the west MBG, with large SrI values, is classified as a peraluminous granitoid with large ASI, suggesting that the western margin of the pluton was strongly affected by assimilation during the intrusion process. The Sr-poor samples are present both in the central BG, with large SrI values, and in the northeast MBG, with small SrI values. The Sr-poor samples have small ASI and large differentiation indices, indicating that the central BG and the northeast MBG were generated either by different AFC process with different amounts of contaminants or by the intrusion and fractionation of different source magma with different SrI values. Overall, the geochemical spatial variations found in the Toki granite can be explained by various degrees of assimilation and fractional crystallization in the magma chamber and/or multi-stage intrusions with different degrees of crystallization of

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

Alkali-heat treatment of a low modulus biomedical Ti-27Nb alloy

International Nuclear Information System (INIS)

Zhou, Y; Wang, Y B; Zhang, E W; Cheng, Y; Xiong, X L; Zheng, Y F; Wei, S C

2009-01-01

This study focuses on the surface modification of a near β-type Ti-27 wt.% Nb alloy by alkali-heat treatment. The influence of alkali concentration, alkali-treated time and alkali-treated temperature on the microstructure and constitutional phases of the modified surface is investigated by SEM, XRD and ICP. Immersion experiments in a simulated body fluid (SBF) were carried out to examine the Ca-P phase forming ability of the modified surfaces. The SEM observation and XRD analysis revealed that a sodium titanate layer is formed after alkali-heat treatment. The morphology and Ca-P phase forming of the layer are greatly affected by the surface roughness of the samples, the alkali concentration, the alkali-treated time and alkali-treated temperature. The results of SBF immersion, which are obtained by ICP analysis, indicate that the activated sodium titanate layer prepared by alkali-heat treatment is beneficial to further improving the biocompatibility of the Ti-27 wt.% Nb alloy.

A PanDA backend for the ganga analysis interface

International Nuclear Information System (INIS)

Vanderster, D C; Elmsheuser, J; Walker, R; Liko, D; Maeno, T; Wenaus, T; Nilsson, P

2010-01-01

Ganga provides a uniform interface for running ATLAS user analyses on a number of local, batch, and grid backends. PanDA is a pilot-based production and distributed analysis system developed and used extensively by ATLAS. This work presents the implementation and usage experiences of a PanDA backend for Ganga. Built upon reusable application libraries from GangaAtlas and PanDA, the Ganga PanDA backend allows users to run their analyses on the worldwide PanDA resources, while providing the ability for users to develop simple or complex analysis workflows in Ganga. Further, the backend allows users to submit and manage 'personal' PanDA pilots: these pilots run under the user's grid certificate and provide a secure alternative to shared pilot certificates while enabling the usage of local resource allocations.

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

Thermodynamic modelling of alkali-activated slag cements

International Nuclear Information System (INIS)

Myers, Rupert J.; Lothenbach, Barbara; Bernal, Susan A.; Provis, John L.

2015-01-01

Highlights: • A thermodynamic modelling analysis of alkali-activated slag cements is presented. • Thermodynamic database describes zeolites, alkali carbonates, C–(N–)A–S–H gel. • Updated thermodynamic model for Mg–Al layered double hydroxides. • Description of phase assemblages in Na 2 SiO 3 - and Na 2 CO 3 -activated slag cements. • Phase diagrams for NaOH-activated and Na 2 SiO 3 -activated slag cements are simulated. - Abstract: This paper presents a thermodynamic modelling analysis of alkali-activated slag-based cements, which are high performance and potentially low-CO 2 binders relative to Portland cement. The thermodynamic database used here contains a calcium (alkali) aluminosilicate hydrate ideal solid solution model (CNASH-ss), alkali carbonate and zeolite phases, and an ideal solid solution model for a hydrotalcite-like Mg–Al layered double hydroxide phase. Simulated phase diagrams for NaOH- and Na 2 SiO 3 -activated slag-based cements demonstrate the high stability of zeolites and other solid phases in these materials. Thermodynamic modelling provides a good description of the chemical compositions and types of phases formed in Na 2 SiO 3 -activated slag cements over the most relevant bulk chemical composition range for these cements, and the simulated volumetric properties of the cement paste are consistent with previously measured and estimated values. Experimentally determined and simulated solid phase assemblages for Na 2 CO 3 -activated slag cements were also found to be in good agreement. These results can be used to design the chemistry of alkali-activated slag-based cements, to further promote the uptake of this technology and valorisation of metallurgical slags

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

Facies analysis and sequence stratigraphy of neoproterozoic Platform deposits in Adrar of Mauritania, Taoudeni basin, West Africa

Science.gov (United States)

Benan, C. A. A.; Deynoux, M.

The Neoproterozoic and Palaeozoic Taoudeni basin forms the flat-lying and unmetamorphosed sedimentary cover of the West African Craton. In the western part of this basin, the Char Group and the lower part of the Atar Group make up a 400-m-thick Neoproterozoic siliciclastic succession which rests on the Palaeoproterozoic metamorphic and granitic basement. Five erosional bounding surfaces of regional extent have been identified in this succession. These surfaces separate five stratigraphic units with lithofacies associations ranging from fluvial to coastal and fluvial-, tide-, or wave-dominated shallow marine deposits. Owing to their regional extent and their position within the succession, the erosive bounding surfaces correspond to relative sea-level falls, and accordingly the five stratigraphic units they bound represent allocyclic transgressive-regressive depositional sequences (S1-S5). Changes in the nature of the deposits forming the transgressive-regressive cycles reflect landward or seaward shifts of the stacked sequences. These successive relative sea-level changes are related to the reactivation of basement faults and tilting during rifting of the Pan-Afro-Brasiliano supercontinent 1000 m.y. ago. The stromatolite bearing carbonate-shale sequences which form the rest of the Atar Group mark the onset of a quiet period of homogeneous subsidence contemporaneous with the Pan-African I oceanization 800-700 m.y. ago.

Continental visions: Ann Seidman, Reginald H. Green and the economics of African unity in 1960s Ghana

OpenAIRE

Serra, Gerardo

2014-01-01

The paper presents the history of the contribution of two American economists to a radical cause: the establishment of a socialist and politically united Africa. The setting is 1960s Ghana which under Kwame Nkrumah, the man who led the country to independence from British colonial rule, emerged as the epicentre of this Pan-African vision. Ann Seidman and Reginald H. Green became, as members of the research team on 'The Economics of African Unity' established at the University of Ghana in 1963...

Pan-ebolavirus and Pan-filovirus Mouse Monoclonal Antibodies: Protection against Ebola and Sudan Viruses.

Science.gov (United States)

Holtsberg, Frederick W; Shulenin, Sergey; Vu, Hong; Howell, Katie A; Patel, Sonal J; Gunn, Bronwyn; Karim, Marcus; Lai, Jonathan R; Frei, Julia C; Nyakatura, Elisabeth K; Zeitlin, Larry; Douglas, Robin; Fusco, Marnie L; Froude, Jeffrey W; Saphire, Erica Ollmann; Herbert, Andrew S; Wirchnianski, Ariel S; Lear-Rooney, Calli M; Alter, Galit; Dye, John M; Glass, Pamela J; Warfield, Kelly L; Aman, M Javad

2016-01-01

The unprecedented 2014-2015 Ebola virus disease (EVD) outbreak in West Africa has highlighted the need for effective therapeutics against filoviruses. Monoclonal antibody (MAb) cocktails have shown great potential as EVD therapeutics; however, the existing protective MAbs are virus species specific. Here we report the development of pan-ebolavirus and pan-filovirus antibodies generated by repeated immunization of mice with filovirus glycoproteins engineered to drive the B cell responses toward conserved epitopes. Multiple pan-ebolavirus antibodies were identified that react to the Ebola, Sudan, Bundibugyo, and Reston viruses. A pan-filovirus antibody that was reactive to the receptor binding regions of all filovirus glycoproteins was also identified. Significant postexposure efficacy of several MAbs, including a novel antibody cocktail, was demonstrated. For the first time, we report cross-neutralization and in vivo protection against two highly divergent filovirus species, i.e., Ebola virus and Sudan virus, with a single antibody. Competition studies indicate that this antibody targets a previously unrecognized conserved neutralizing epitope that involves the glycan cap. Mechanistic studies indicated that, besides neutralization, innate immune cell effector functions may play a role in the antiviral activity of the antibodies. Our findings further suggest critical novel epitopes that can be utilized to design effective cocktails for broad protection against multiple filovirus species. Filoviruses represent a major public health threat in Africa and an emerging global concern. Largely driven by the U.S. biodefense funding programs and reinforced by the 2014 outbreaks, current immunotherapeutics are primarily focused on a single filovirus species called Ebola virus (EBOV) (formerly Zaire Ebola virus). However, other filoviruses including Sudan, Bundibugyo, and Marburg viruses have caused human outbreaks with mortality rates as high as 90%. Thus, cross

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.

2005 dossier: granite. Tome: architecture and management 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 geologic disposal of high-level and long-lived radioactive wastes in granite formations. Content: 1 - Approach of the study: main steps since the December 30, 1991 law, ANDRA's research program on disposal in granitic formations; 2 - high-level and long-lived (HLLL) wastes: production scenarios, waste categories, inventory model; 3 - disposal facility design in granitic environment: definition of the geologic disposal functions, the granitic material, general facility design options; 4 - general architecture of a disposal facility in granitic environment: surface facilities, underground facilities, disposal process, operational safety; 5 - B-type wastes disposal area: primary containers of B-type wastes, safety options, concrete containers, disposal alveoles, architecture of the B-type wastes disposal area, disposal process and feasibility aspects, functions of disposal components with time; 6 - C-type wastes disposal area: C-type wastes primary containers, safety options, super-containers, disposal alveoles, architecture of the C-type wastes disposal area, disposal process in a reversibility logics, functions of disposal components with time; 7 - spent fuels disposal area: spent fuel assemblies, safety options, spent fuel containers, disposal alveoles, architecture of the spent fuel disposal area, disposal process in a reversibility logics, functions of disposal components with time; 8 - conclusions: suitability of the architecture with various types of French granites, strong design, reversibility taken into consideration. (J.S.)

Uraniferous alaskitic granites with special reference to the Damara Orogenic Belt

International Nuclear Information System (INIS)

Toens, P.D.; Corner, B.

1980-10-01

The control and patterns of uranium mineralisation in the alaskitic granites of the Damara Orogenic Belt are discussed. The polyphase Damara metamorphism produced high-grade metamorphic assemblages, migmatites and syn-, late-, and post-tectonic anatectic granites through reactivation of the basement and overlying Damara rocks. During anatexis the incompatible elements, particularly the uranium derived from these formations, were incorporated into the melts which then rose, in an attempt to attain gravitational equilibrium, by varying distances depending on the depth of origin of the melts, on their water content and on the availability of tensional environments. Fractional crystallisation during ascent and increased water content concentrated the uranium into residual melts which finally crystallised as alaskitic pegmatitic granite. Structural episodes played an important part in the emplacement of the uraniferous granites and the presence of marble bands was an important factor in not only providing a structural trap for the alaskitic melts and associated uranium-rich volatiles, but also by leading to the boiling of the magma and the subsequent deposition of uranium. The present-day level of erosion is considered to be an important factor contributing to the preservation of many of the uraniferous granite bodies. In addition it is suggested that secondary enrichment occurring above the water-table in the prevailing desert environment is an important criterion in enriching the tenor of mineralisation to ore grades. The exploration techniques necessary for the location of uraniferous granite bodies are briefly outlined [af

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)

Retraction: Association between the use of biomass fuels on respiratory health of workers in food catering enterprises in Nairobi Kenya. Pan Afr Med J. 2013 May 6;15:12. doi: 10.11604/pamj.2013.15.12.1831.

Science.gov (United States)

2014-01-01

The editors of the Pan African Medical Journal retract the manuscript above. The manuscript has been the subject of a protracted and unresolved authors dispute. Not all the authors listed in this manuscript consented to the retraction.

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

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)