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  • 1
    Electronic Resource
    Electronic Resource
    New evidence on secondary twinning in albitic plagioclases (1970)
    Springer
    Contributions to mineralogy and petrology 25 (1970), S. 289-296 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Twinnings in albitic partially disordered plagioclases (An%=0–5; 2V variable between +80° and -87°) are described; they show optical-morphological features very similar to those exhibited by secondary twinning in calcic plagioclases. One of the twinning observed shows strong analogies with a phenomenon induced on a partially disordered albite in laboratory experiments (Borg and Heard, 1969). The data give new evidence on the debated existence of secondary twinning in albitic plagioclases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00399289
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Uranium in spinel peridotite inclusions in basalts from Sardinia (1976)
    Springer
    Contributions to mineralogy and petrology 54 (1976), S. 245-254 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The uranium distribution in spinel peridotite inclusions and their host basalt from Sardinia, Italy, was determined by fission-track mapping. Whole-rock U concentrations range from 14 to 55 ppb. Although the partitioning of U among major silicate phases of the inclusions — olivine, orthopyroxene and clinopyroxene — remains roughly constant, the U content in the minerals is highly variable, e.g. ranging from 27 ppb to 177 ppb in clinopyroxene. The U variation in the minerals shows no apparent correlation with their major element chemistry. Liquid which equilibrated with the assemblages of inclusions with high U content, had U concentrations higher than those found in basaltic rocks. It is suggested that the inclusions were contaminated with a phase strongly enriched in U and subsequently recrystallized. The available data show that spinel peridotite inclusions of basaltic rocks frequently have complex multistage evolution and thus cannot provide a representative picture of the upper mantle radioactivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00389406
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Uranium in metamorphic rocks (1978)
    Springer
    Contributions to mineralogy and petrology 66 (1978), S. 409-414 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The distribution of U has been studied in two metamorphic rock-series with a gradient of regional metamorphism. One series ranges from the lowest greenschist to amphibolite facies and the other one shows increasing metamorphic grade from amphibolite to granulite facies. Several medium and high pressure granulitic inclusions from alkali basalts were also analyzed. The abundances of U in the rocks do not appear to be affected by metamorphism below the granulite facies grade. Granulites are depleted in U in comparison with equivalent rocks of amphibolite facies grade. There are also differences in their U distribution, as the bulk of U in amphibolite facies rocks is located along the fractures and cleavage planes of ferro-magnesian minerals and in U-rich accessories, while in granulites, most of the U resides in accessory minerals. It seems that the depletion of U in granulites is due to a loss of U which is not located in accessory minerals or in the crystal structure of rock-forming minerals and may also be related to a migration of hydrous fluids, perhaps during dehydration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00403426
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    Paper (German National Licenses)
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