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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Mineralogy and petrology 41 (1989), S. 53-63 
    ISSN: 1438-1168
    Keywords: Tantalum ; niobium ; tantalite ; tapiolite ; mineralogy ; geochemistry ; pegmatite ; Ostalpen ; Austria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Zusammenfassung In einem Pegmatit von Spittal a.d. Drau, Kärnten, treten enge Verwachsungen von Ferrotantalit und Ferrotapiolit auf. Diese werden von Muskovit, Albit, Rauchquarz, Zinnstein sowie-in mikroskopischem Masstab-von Uranmikrolith und Zirkon begleitet. Die Textur der Verwachsungen lässt Rekristallisation erheblichen Ausmasses erkennen, die die primären Merkmale weitgehend auslöscht. Weder eine gemeinsame Auskristallisation der beiden Mineralphasen noch eine Bildung durch Entmischung kann mit Sicherheit erkannt werden. Trotz einander kreuzender Verbindungslinien, die einen Hinweis auf Ungleichgewicht darstellen, zeigen die Zusammensetzungen des Ferrotantalits und des Ferrotapiolits lediglich geringe Schwankungsbreiten: Mn/(Mn + Fe) 0,08–0,11, Ta/(Ta + Nb) 0,53–0,57 für den Ferrotantalit beziehungsweise 0,01–0,04 und 0,84–0,89 für den Ferrotapiolit. Dies gilt insbesondere für den Vergleich mit Zusammensetzungen solcher Mineralphasen mit jenen von Fundarten, die primäre Verwachsungstrukturen aufweisen. Bis zu einem gewissen Ausmass ist diese homogene Zusammensetzung möglicherweise auf die Rekristallisation zurück zuführen. Diese Rekristallisation könnte auch den hohen strukturellen Ordnungsgrad der beiden Mineralphasen erklären. An anderen Fundorten zeigen diese Minerale strukturell merklich geringeren Ordnungsgrad. Intensive metamorphe überprägung, wie sie für die Pegmatite in den südlichen Ostalpen und insbesondere für jenen von Spittal typisch sind, kann wahrscheinlich als Ursache der Rekristallisationsphänomene der Ta-Nb-Sn Mineralparagenese angenommen werden.
    Notes: Summary Intimate intergrowths of ferrotantalite and ferrotapiolite occur in a pegmatite in Spittal a.d. Drau, Carinthia. They are associated with muscovite, albite, smoky quartz, cassiterite, and microscopic uranmicrolite, zircon and uraninite. An assemblage of secondary uranium minerals is also present, generated by extensive alteration and leaching of the uranmicrolite and zircon. Textures of the ferrotantalite-ferrotapiolite intergrowths suggest considerable recrystallization that obliterated most of their primary features; neither coprecipitation nor exsolution can be recognized with certainty. Despite intersecting tielines indicating disequilibrium, the ferrotantalite and ferrotapiolite compositions show very restricted ranges (Mn/(Mn + Fe) 0.08–0.11, Ta/(Ta + Nb) 0.53–0.57 for ferrotantalite, and 0.01–0.04, 0.84–0.89 for ferrotapiolite, respectively), particularly in comparison with compositions from other localities featuring primary textures. A degree of compositional equilibration could have been attained during recrystallization. This process may also explain the high level of structural order characterizing both minerals; they are considerably disordered in other localities. Extensive deformation typical of pegmatites in the southern Ostalpen in general, and specifically of the Spittal pegmatite, is probably responsible for the recrystallization phenomena in the Ta, Nb, Sn-bearing mineral assemblage.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 55 (1990), S. 205-212 
    ISSN: 1570-7458
    Keywords: Olfactory sensitivity ; grasshoppers ; electroantennogram ; Larrea ; hostplant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Les réponses antennaires ont été examinées par électroantennogramme aux odeurs de plantes hôtes et non hôtes d'orthoptères Gomphocerinae de comportements alimentaires différents: Bootettix argentatus, monophage sur une dicotylédone, Larrea; Ligurotettix coquilletti, oligophage de dicotylédones; Cibolacris parviceps, polyphage; Chorthippus curtipennis, graminivore. Les types de réponse des quatre espèces étaient très voisins, mais les réponses aux odeurs de Larrea de B. argentatus et L. coquilletti, spécialistes de cette plante, étaient relativement plus fortes. Ces résultats suggèrent une similarité globale considérable dans la composition des populations de récepteurs olfactifs de ces quatre espèces d'orthoptères mais aussi une certaine spécificité pour les odeurs de la plante hôte au niveau antennaire.
    Notes: Abstract Antennal responses to host and non-host odours were recorded, using the electroantennogram technique, from four gomphocerine grasshoppers with different feeding habits: Bootettix argentatus (monophagous on Larrea, a dicotyledonous plant), Ligurotettix coquilletti (oligophagous on dicotyledonous plants), Cibolacris parviceps (polyphagous) and Chorthippus curtipennis (graminivorous). The patterns of responses across the plant odours were similar for all four grasshopper species, but there was a relatively greater response to the odour of Larrea in B. argentatus and L. coquilletti which specialise on this plant. This suggests that there is considerable overall similarity in the make up of the olfactory receptor populations of these four grasshoppers species, but that some specificity for hostplant odour does exist at the antennal level.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 14 (1988), S. 561-579 
    ISSN: 1573-1561
    Keywords: Creosote bush ; Larrea ; nordihydroguaiaretic acid ; grasshoppers ; monophagy ; Bootettix ; Ligurotettix ; Cibolacris ; Orthoptera ; Acrididae ; host selection ; feeding deterrence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The host-selection behavior of three species of grasshopper feeding on creosote bush,Larrea tridentata, in southern California was investigated. The species wereBootettix argentatus, which is monophagous;Ligurotettix coquilletti, oligophagous; andCibolacris parviceps, polyphagous. The monophagous species is stimulated to bite by nordihydroguaiaretic acid (NDGA), a compound that is characteristic of the host plant and that may comprise up to 10% of the dry weight of the leaf. Host specificity ofB. argentatus is enhanced by deterrent responses to compounds present in the surface waxes of all non-host-plant species. Both the oligophagous and polyphagous species are deterred by NDGA at naturally occurring concentrations. Their association withLarrea is probably based on tolerance of the plant chemicals rather than on dependence on specific chemicals. Factors other than the chemistry of the plant probably also contribute to the specificity ofB. argentatus andL. coquilletti.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-8868
    Keywords: data processing ; discriminant analysis ; graphics ; mapping ; sampling ; simulation ; geochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract The exploration geochemist faces a serious problem in reconciling theoretical statistics with the empirical distribution of elements in materials in the earth's crust. The results of computer-simulation experiments being conducted by the Exploration Geochemistry Group at the University of New Brunswick illustrate some of the problems of the relation between frequency distributions and spatial distributions of elements and raise some interesting questions about sampling patterns and physical size of samples. Most importantly, the simulation experiments and empirical examples support the contention that attempts to make an assumption of normality more efficient by performing log transformations on positively skewed data may defeat the purpose of statistical analysis for exploration work. New developments in computer-data presentation and interpretation, including population sorting and classification, illustrate the increasing use of the computer in exploration geochemistry.
    Type of Medium: Electronic Resource
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