WorldWideScience

Sample records for cerite

  1. Mineral chemistry and genesis of Zr, Th, U, Nb, Pb, P, Ce and F enriched peralkaline granites of El-Sibai shear zone, Central Eastern Desert, Egypt

    OpenAIRE

    Ali, Mohamed A.

    2013-01-01

    El-Sibai mineralized shear zone trending NNE-SSW is located at the northern segment of Gabal El-Sibai (500m in length and 0.5 to 1.5 m in width). Rocks along the shear zone show different types of alterations such ashematization, kaolinitization, fluoritization, and silicification. These alterations are good traps for rare metals ofthorite, ferrocolumbite, pyroclore, plumbopyroclore, fluorite, cerite-(Ce), zircon, Th-rich zircon, zirconolite (mixtureof zircon & columbite), fluorapatite, titan...

  2. Peculiarities of accessory zircon from the carter seamount tuffs (Sierra Leone Rise in the East Atlantic)

    Science.gov (United States)

    Petrova, V. V.; Skolotnev, S. G.; Chistyakova, N. I.

    2010-03-01

    In volcanic tuffs, dredged during Cruise 23 of the R/V Akademik Nikolaj Strakhov, accessory zircon was found; except for the mineral-forming components, there were ˜2% of ThO2 and 0.75% of Ce2O3 in zircon. During rapid uplift of magmatic masses to the ocean bottom surface, admixture elements isolated into specific minerals. As a result, destruction structures were formed in the rim parts of primary zircon crystals, and the new-formed association of zircon + thorite + cerite + thoriante + baddeleyite appeared.

  3. Mineral chemistry and genesis of Zr, Th, U, Nb, Pb, P, Ce and F enriched peralkaline granites of El-Sibai shear zone, Central Eastern Desert, Egypt

    Directory of Open Access Journals (Sweden)

    Mohamed A. Ali

    2013-06-01

    Full Text Available El-Sibai mineralized shear zone trending NNE-SSW is located at the northern segment of Gabal El-Sibai (500m in length and 0.5 to 1.5 m in width. Rocks along the shear zone show different types of alterations such ashematization, kaolinitization, fluoritization, and silicification. These alterations are good traps for rare metals ofthorite, ferrocolumbite, pyroclore, plumbopyroclore, fluorite, cerite-(Ce, zircon, Th-rich zircon, zirconolite (mixtureof zircon & columbite, fluorapatite, titanite, and monazite minerals.The detailed mineralogical study of the El-Sibai shear zone revealed its enrichment in Th, Zr, Nb, Pb, U, F, P,LREE (Ce, especially concerning the hematization processes. The close correlation of ferruginated (hematitizedsamples with high radioactivity is related to the high ability of iron oxides for adsorption of radioactive elementsfrom their solutions. The rare-metal minerals found in altered peralkaline granites (shear zone are associated withhematitization, albititization, chloritization, fluoritization, and pyritization. Electron probe microanalysis (EPMAprovides an indication of a range of solid solution between thorite and zircon, in which intermediate phases, such asTh-rich zircon were formed. These phases have higher sum of all cations per formula (2.0 to 2.09 atoms per formulaunit, for 4 oxygen atoms than that of ideal thorite and zircon. This is attributed to the presence of substantialamount of interstitial cations such as U, Y, Ca, and Al in these phases. Altered zircon enriched in Th and U (Th-richzircon preferentially involves coupled substitution Ca2+ + (Th,U4+ ↔ 2Zr4+ + 2Si4+, implying that significant amountof U and Th may enter the Zr and Si position in zircon.Thorite and Th-rich zircon are related to hydrothermal fluid. Also the genesis of the studied zircon is related tometasomatic hydrothermal zircon (MHZ. The abundantly detected zircon, Th-rich zircon, Th-bearing minerals andfluorite of demonstrably

  4. The petrogenesis of metamorphosed carbonatites in the Grenville Province, Ontario

    Energy Technology Data Exchange (ETDEWEB)

    Moecher, D.P.; Anderson, E.D.; Cook, C.A. [Univ. of Kentucky, Dept. of Geological Sciences, Lexington, Kentucky (United States)]. E-mail: moker@pop.uky.edu; Mezger, K. [Max-Planck-Institut fuer Chemie, Mainz (Germany)

    1997-09-15

    Veins and dikes of calcite-rich rocks within the Central Metasedimentary Belt boundary zone (CMBbz) in the Grenville Province of Ontario have been interpreted to be true carbonatites or to be pseudocarbonatites derived from interaction of pegmatite melts and regional Grenville marble. The putative carbonatites have been metamorphosed and consist mainly of calcite, biotite, and apatite with lesser amounts of clinopyroxene, magnetite, allanite, zircon, titanite, cerite, celestite, and barite. The rocks have high P and rare earth element (REE) contents, and calcite in carbonatite has elevated Sr, Fe, and Mn contents relative to Grenville Supergroup marble and marble melange. Values of {delta}{sup 18}O{sub SMOW} (9.9 - 13.3o/oo) and {delta}{sup 13}C{sub PDB} (-4.8 to -1.9o/oo) for calcite are also distinct from those for marble and most marble melange. Titanites extracted from clinopyroxene -calcite-scapolite skarns formed by metasomatic interaction of carbonatites and silicate lithologies yield U-Pb ages of 1085 to 1035 Ma. Zircon from one carbonatite body yields a U-Pb age of 1089 {+-} 5 Ma; zircon ages from two other bodies are 1170 {+-} 3 and 1143 {+-} 8 Ma, suggesting several carbonatite formation events or remobilization of carbonatite during deformation and metamorphism around 1080 Ma. Values of {epsilon}{sub Nd}(T) are 1.7 - 3.2 for carbonatites, -1.5 -1.0 for REE-rich granite dikes intruding the CMBbz, and 1.6 - 1.7 for marble. The mineralogy and geochemical data are consistent with derivation of the carbonatites from a depleted mantle source. Mixing calculations indicate that interaction of REE-rich pegmatites with regional marbles cannot reproduce selected major and minor element abundance, REE contents, and O and Nd isotope compositions of the carbonatites. (author)

  5. The petrogenesis of metamorphosed carbonatites in the Grenville Province, Ontario

    International Nuclear Information System (INIS)

    Veins and dikes of calcite-rich rocks within the Central Metasedimentary Belt boundary zone (CMBbz) in the Grenville Province of Ontario have been interpreted to be true carbonatites or to be pseudocarbonatites derived from interaction of pegmatite melts and regional Grenville marble. The putative carbonatites have been metamorphosed and consist mainly of calcite, biotite, and apatite with lesser amounts of clinopyroxene, magnetite, allanite, zircon, titanite, cerite, celestite, and barite. The rocks have high P and rare earth element (REE) contents, and calcite in carbonatite has elevated Sr, Fe, and Mn contents relative to Grenville Supergroup marble and marble melange. Values of δ18OSMOW (9.9 - 13.3o/oo) and δ13CPDB (-4.8 to -1.9o/oo) for calcite are also distinct from those for marble and most marble melange. Titanites extracted from clinopyroxene -calcite-scapolite skarns formed by metasomatic interaction of carbonatites and silicate lithologies yield U-Pb ages of 1085 to 1035 Ma. Zircon from one carbonatite body yields a U-Pb age of 1089 ± 5 Ma; zircon ages from two other bodies are 1170 ± 3 and 1143 ± 8 Ma, suggesting several carbonatite formation events or remobilization of carbonatite during deformation and metamorphism around 1080 Ma. Values of εNd(T) are 1.7 - 3.2 for carbonatites, -1.5 -1.0 for REE-rich granite dikes intruding the CMBbz, and 1.6 - 1.7 for marble. The mineralogy and geochemical data are consistent with derivation of the carbonatites from a depleted mantle source. Mixing calculations indicate that interaction of REE-rich pegmatites with regional marbles cannot reproduce selected major and minor element abundance, REE contents, and O and Nd isotope compositions of the carbonatites. (author)

  6. Radiological safety in extraction of rare earths in India: regulatory control

    International Nuclear Information System (INIS)

    The term 'rare earths' refers to a group of f-block elements in the periodic table including those with atomic numbers 57 (Lanthanum) to 71 (Lutetium), as well as the transition metals Yttrium (39) and Scandium (21). Economically extractable concentrations of rare earths are found in minerals such as monazite, bastnaesite, cerites, xenotime etc. Of these, monazite forms the main source for rare earths in India, which along with other heavy minerals is found abundantly in the coastal beach sands. However, in addition to rare earths, monazite also contains 0.35% U3O8 and 8-9% ThO2. Hence, extraction of rare earths involves chemical separation of the rare earths from thorium and uranium which are radioactive. The processing and extraction of rare earths from monazite therefore invariably results in occupational radiation exposure to the workers involved in these operations. In addition, in the process of removal of radioactivity from rare earths, radioactive solid waste gets generated which has 228Ra concentration in the range 2000-5000 Bq/g. Unregulated disposal of such high active waste would not only result in contamination of the soil but the radionuclides would eventually enter the food chain and lead to internal exposure of the general public. Therefore such facilities involved in recovery of rare earths from monazite attract the provisions of radiological safety regulations. Atomic Energy Regulatory Board of India has been enforcing the provisions of The Atomic Energy (Radiation Protection) Rules, 2004 and The Atomic Energy (Safe Disposal of Radioactive Waste) Rules, 1987 in these facilities. This paper shall discuss the associated radiological hazard involved in recovery of rare earths from monazite. It shall also highlight the regulatory requirements for controlling the occupational exposure of workers during design stage such as requirements on lay out of the building, ventilation, containment of radioactivity, etc and also the during operational phase such

  7. EXAMINATION OF TEACHERS’ ORGANIZATIONAL IMAGE PERCEPTIONS ABOUT THEIR SCHOOLS IN TERMS OF SOME VARIABLES

    Directory of Open Access Journals (Sweden)

    Celal Teyyar UĞURLU

    2013-06-01

    Full Text Available In our rapidly changing and developing world, organizations maintain struggle to survive in competition environment. This struggle forced the organizations to notice social factors as well as economic factors. One of the basic issues encountered by contemporary organizations is about how society perceives the organization. Organizations become more accountable to society nowadays and thus it becomes inevitable that they portray a positive image to be characterized as successful organizations. Image is a perception manner that emerges in thoughts of external participants which based on organization members for development and consist of vision, mission and values of the organization (Sabuncuoğlu, 2004. According to Hatch and Schultz (2002, image was described as overall thought about how organization creates an impression on members and others. Like other branches, education was effected by developments emerge in the current competition environment. Especially, new developments emerged right after progress of computer technologies did not enable staying in national borders and required to be operated in an international environment (Cerit, 2006. From the point of education institutions, experiences during application period, advertising and public relations and applicant providing activities are very important for the emergence of first perception and this perception plays a crucial role in decision to apply for a school (Collins and Stevens, 2001. This situation increase competition among high schools. To be a preferred high school by students, creating a positive organizational image is considered as a significant factor. Therefore, it was tried to determine teachers’ perceptions about images of high schools. At the same time, people create their perceptions about an organization as a result of interaction with this organization. For that reason, in determining level of organizational level, information related to this organization should be

  8. From the complex system leadership perspective: DNA leadership

    Directory of Open Access Journals (Sweden)

    Hasan Basri Gündüz

    2011-01-01

    management can be handled at various levels from ecosystem level to cell level (Odum, 1983. For example, human body is controlled by the brain that functions through billions of nerve cells and each of these cells is controlled by their DNAs that are placed in the nucleus. In fact DNA is the administrative unit of the cell or organism (Alberts, Bray, Lewis, Raff, Roberts & Watson, 1994; De Robertis & De Robertis, 1981. Therefore, the administration in one of the cell of the organism can be taken as a metaphor to explain the administration of an organisation in social system. Metaphors have a coherence and internal consistency, which provide insights into ideas that are not explicit or consciously held (Arnett, 1999; Tsoukas, 1991; Oxford et al., 1998; Cerit, 2008; Lakoff & Johnson, 2005; Şişman, 2002a; Morgan, 1998. Organizations within a social system can be considered as cells of the social system. Every organization has similar core structure as the cells of an organism that have the same DNA. Vision, mission, organizational culture and administrative approach of an organization constitute its core DNA. The degree of integration of an individual to an organization depends on how well he/she internalizes the philosophy, vision, mission and culture of an organization (Ball, 1997. Leader as an individual who shapes vision, mission and culture of the organization, should enable members to learn and accept organization’s vision, mission and culture. LeadershipLeadership is a subject that has long excited interest among scholars and layman alike. The term leadership means different things to different people. As is often the case when a word from the common vocabulary is incorporated into the technical vocabulary of a scientific discipline, leadership has not been precisely redefined, and it still carries extraneous connotations that create ambiguity of meaning. Further confusion is caused by the use of other imprecise terms such as power, authority, management