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  • 1995-1999  (4)
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  • 1
    Electronic Resource
    Electronic Resource
    Diamonds everywhere (1995)
    [s.l.] : Nature Publishing Group
    Nature 378 (1995), S. 17-18 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] DIAMONDS have long caused excitement not only among the general public, which appreciates them mainly for their beauty and value, but also among geologists. The latter use diamonds in a not very glam-orous way as probes of the properties of the Earth's mantle, which is otherwise rather ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/378017a0
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Petrogenesis of the Dullstroom Formation, Bushveld Magmatic Province, South Africa (1999)
    Springer
    Contributions to mineralogy and petrology 137 (1999), S. 133-146 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The Precambrian Dullstroom Formation of South Africa, which is predominantly composed of basaltic andesites interbedded with subordinate sedimentary and felsic volcanic strata, represents the first phase of an extended period of magmatism that was responsible for the Bushveld Magmatic Province, including the extrusive Rooiberg Group and the intrusive Bushveld Complex. New geochemical and isotopic data for the Dullstroom Formation are presented in an effort to elucidate the petrogenetic processes operative during the initiation of this magmatic episode. The volcanic units of the central portion of the Dullstroom Formation have been subdivided into at least three interbedded compositional groups: low Ti mafic to intermediate units, high-Ti mafic to intermediate units, and high Mg felsic units. High Ti and low Ti volcanic units are similar in some compositional characteristics to basalts of the nearby northern and southern provinces, respectively, of the Mesozoic Karoo continental flood basalts. Isotopic and compositional data for low Ti Dullstroom strata are consistent with bulk assimilation into a melt similar in composition to a southern Karoo basalt of 20% upper continental crust accompanied by 20% fractional crystallization of pyroxene and plagioclase. Isotopic and compositional data for high Ti Dullstroom strata are consistent with magma mixing of 30% northern Karoo K-rich basalt and 70% southern Karoo basalt followed by 20% assimilation of upper continental crust and 20% fractional crystallization of pyroxene and plagioclase. Compositions of high Mg felsic volcanic strata are consistent with 25% assimilation of a mixture of silica-rich sedimentary rock and upper continental crust into a melt similar in composition to low Ti volcanic units with 25% fractional crystallization of pyroxene and plagioclase. However, it has been suggested that compositions of these high Mg felsic strata may also be consistent with interaction of a crustal melt. Assimilation, fractional crystallization, and magma mixing that apparently affected these Dullstroom Formation volcanic strata may have occurred in a series of shallow magma chambers. These data are consistent with the suggestion that Dullstroom Formation volcanic rocks are the result of a mantle plume. Mantle plume origin also is suggested by the large volume of intrusive and extrusive strata associated with this magmatic episode. These data do not support the hypothesis that the Bushveld Complex and the Rooiberg Group formed by impacts of a cluster of comets or asteroids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004100050587
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Moonstruck: How Realistic Is The Moon Depicted In Classic Science Fiction Films? (1999)
    Springer
    Earth, moon and planets 85-86 (1999), S. 179-200 
    Details
    ISSN: 1573-0794
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Classical science fiction films have been depicting space voyages, aliens, trips to the moon, the sun, Mars, and other planets, known and unknown. While it is difficult to critique the depiction of fantastic places, or planets about which little was known at the time, the situation is different for the moon, about which a lot of facts were known from astronomical observations even at the turn of the century. Here we discuss the grade of realism with which the lunar surface has been depicted in a number of movies, beginning with George Méliés' 1902 classic Le Voyage dans la lune and ending, just before the first manned landing on the moon, with Stanley Kubrick's 2001: A Space Odyssey. Many of the movies present thoughtful details regarding the actual space travel (rockets), but none of the movies discussed here is entirely realistic in its portrayal of the lunar surface. The blunders range from obvious mistakes, such as the presence of a breathable atmosphere, or spiders and other lunar creatures, to the persistent vertical exaggeration of the height and roughness of lunar mountains. This is surprising, as the lunar topography was already well understood even early in the 20th century.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1017015931543
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Craters On The Moon From Galileo To Wegener: A Short History Of The Impact Hypothesis, And Implications For The Study Of Terrestrial Impact Craters (1999)
    Springer
    Earth, moon and planets 85-86 (1999), S. 209-224 
    Details
    ISSN: 1573-0794
    Keywords: History ; impact craters ; lunar craters ; lunar maps
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The origin of lunar craters has been discussed for centuries,since they were discovered by Galilei in 1609. The majority of researchers were of the opinion that they are volcanic structures, but a variety of “exotic” explanations that included tidal forces, circular glaciers, and coral atolls was also considered. The meteorite impact hypothesis had been discussed a few times, starting with Hooke in 1665, and formulated in more detail by Proctor in 1873 and Gilbert in 1893. However, this theory only gained momentum early in the 20th century, after the identification of Meteor Crater in Arizona as an impact structure, and after specific and plausible physical models for impact craters formation were devised by Öpik in 1916, Ives in 1919, and Gifford in 1924. Nevertheless, despite growing evidence for the interpretation that most craters formed by impact, proponents of the volcanic theory impact were still vociferous as late as 1965, just four years before the first samples were brought back from the moon. Important lessons could have been learned for the study of impact craters on the Earth, especially in view of evidence that large impactevents had some influence on the geologic and biologic evolution of the Earth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1017020032451
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    Paper (German National Licenses)
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