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  • 1980-1984  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Anaesthesia 39 (1984), S. 0 
    ISSN: 1365-2044
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 299 (1982), S. 540-542 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] A fundamental property of normal intraplate lithosphere is that it exhibits no significant internal lateral distortion over time periods of the order of tens or hundreds of Myr as testified, for example, by the exactness of fit of the passive continental margins across the Atlantic1. This lack of ...
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    International journal of earth sciences 71 (1982), S. 22-37 
    ISSN: 1437-3262
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Abstract The characteristic structures of granite-greenstone and high-grade gneiss terrains are reviewed, using the Superior Province and the North Atlantic craton as examples, with the object of finding a suitable tectonic model to explain both. The granite-greenstone terrain exhibits a combination of gravity-driven vertical tectonics and regional horizontal compression, while the high-grade gneiss terrain shows dominantly subhorizontal high-strain foliation affected by later refoldings. A uniformitarian plate tectonic model may not be appropriate to the Archaean in the likely absence of eclogite-driven subduction and because of practical problems in explaining the deformation patterns. Various alternative mechanisms are considered to explain the structure of the high-grade gneiss terrains in particular. It is concluded that the most fruitful model is tectonic underplating, whereby the crust is thickened from beneath by the emplacement of crustal slices detached from their mantle lithosphere — itself underplated independantly. Such a process could have operated in the North Atlantic craton coevally with greenstone formation and subsequent diapirism in the Superior Province. Sub-horizontal N-S compression affected both cratons in the late Archaean, after the above processes had taken place, when the crust had become sufficiently rigid to be able to transmit regional stresses.
    Abstract: Résumé Les structures caractéristiques des domaines à granites et roches vertes, et à gneiss de haut degré de métamorphisme, sont passées en revue; les exemples utilisés sont ceux de la Province Supérieure et du craton de l'Atlantique nord, et ce, dans l'intention de trouver un modèle tectonique approprié à l'explication des deux. Le domaine à granites et roches vertes témoigne de la combinaison d'une tectonique verticale mue par la pesanteur et d'une compression horizontale régionale, tandis que les formations à gneiss de degré de métamorphisme élevé montrent principalement une foliation subhorizontale sous forte tension, affectée par des replissements ultérieurs. Un modèle de tectonique de plaque basé sur la théorie de l'actualisme ne peut pas être appropriée à l'Archéen, étant donné l'absence probable de subduction actionée par des éclogites et en raison des difficultés pratiques à expliquer les structures de déformation. Plusieurs autres mécanismes sont envisagés pour expliquer la structure des régions à gneiss de degré de métamorphisme elevé. On en arrive à conclure que la modèle le plus efficient est le «sous-placage tectonique» suivant lequel la croûte s'épaissit par la mise en place, par en-dessous, de tranches de croûte détachées de leur »manteau-lithosphère«, elles-mêmes des sous-plaques indépendantes. Un tel processus aurait pu fonctionner dans le craton de l'Atlantique nord à la même époque que la formation de roches vertes et que le diapirisme subséquent dans la Province Supérieure. La compression sub-horizontale nord-sud a agi sur les deux cratons vers la fin de l'Archéen, et après qu'eurent lieu les processus ci-dessus, quand la croûte était devenue assez rigide pour pouvoir transmettre des efforts régionaux.
    Notes: Zusammenfassung Die charakteristischen Strukturen von Granit-Grünschiefern und hochgradigen Gneisgebieten werden zusammenfassend betrachtet, wobei die Superior Province und das nordatlantische Kraton als Beispiele benutzt werden. Es wird versucht, ein geeignetes tektonisches Modell zu finden, um beide Gebiete zu erklären. Das Granit-Grünschiefergebiet stellt eine Kombination der von durch Gravitation verursachter vertikaler Tektonik und regionaler horizontaler Kompression dar, während das hochgradige Gneisgebiet eine hauptsächlich durch starke Beanspruchung verursachte subhorizontale Schichtung zeigt, beeinflußt durch spätere Faltungen. Ein uniformitarisches plattentektonisches Modell dürfte nicht für das Archaikum geeignet sein, wenn durch Eklogite verursachte Subduktion höchstwahrscheinlich nicht vorhanden ist und wenn außerdem praktische Probleme bei der Erklärung der Deformationsstrukturen auftauchen. Verschiedene alternative Mechanismen werden insbesondere für die Erklärung der Struktur des hochgradigen Gneisgebietes in Betracht gezogen. Als bestes Modell fanden wir die tektonische Anlagerung von unten, wobei die Kruste von unten her durch den Aufbau von Krustenscheiben, die vom Lithosphären-Mantel abgesplittert werden, verstärkt worden ist — wobei diese wiederum unabhängig davon Anlagerungen von unten aufweist. Solch ein Prozeß könnte im nordatlantischen Kraton stattgefunden haben, zusammen mit der Grünschieferformation und dem folgenden Diapirismus in der Superior Province. Subhorizontale N-S-Kompression beeinflußte beide Kratone im späten Archaikum, nachdem die obigen Prozesse stattgefunden hatten und als die Kruste genügend stark geworden war, um die regionalen Spannungen weiterzuleiten.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Planta 157 (1983), S. 298-306 
    ISSN: 1432-2048
    Keywords: Phloem polypeptides ; Pinus ; Sieve cell ; Xylem polypeptides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The polypeptide complement of phloem tissue and xylem tissue in trunks of Pinus sabiniana collected in spring was compared by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Two polypeptides at 24 and 25 kdalton represented over 20% of the total polypeptide complement of the phloem but were absent in xylem tissue. In an attempt to relate the 24- and 25-kdalton phloem polypeptides (PPP) to cellular constitutents, phloem tissue was fractionated by sequential differential and density-gradient centrifugation utilizing the PPP as biochemical markers. In borate buffer, the fractions containing PPP pelleted at less than 12,000 g and were subsequently enriched in sucrose gradients at densities greater than 1.22. However, the cytological entities containing the PPP were almost completely dissociated when phloem tissue was processed with a 2-amino-2-(hydroxymethyl)-1,3-propanediol (Tris) buffer containing mercaptoethanol, and the PPP were then found in the supernatant of material spun at 45,000 g for 3 h. In electron micrographs of PPP-enriched fractions processed with borate buffer an assortment of structures that are associated with mature sieve cells of pine were found, including filaments, cup-shaped arrays, polyhedral crystals, and paracrystalline bodies. Similar structures were not found in identically processed xylem tissue or in phloem tissue processed with the Tris buffer. It is suggested that the PPP represent a proteinaceous component common to these phloem structures.
    Type of Medium: Electronic Resource
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