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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 218 (1968), S. 1152-1154 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Most of the island of Fuerteventura is made up of volcanic rocks, chiefly alkali basalts and related tuffs. These are deeply dissected late Tertiary shield volcanoes and Quaternary preserved cinder cones and lava flows. In the western part of the island, this basaltic sequence overlies a basement ...
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2018-03-02
    Description: RECENT advances in 40Ar/39Ar dating1,2 have made it possible to date individual K-feldspar grains from Pleistocene tephra, a capability that greatly improves the reliability and temporal resolving power of the method. Here we apply these new techniques to the dating of a phonolite tephra from the East Eifel volcanic field in West Germany, which is sandwiched between loess and palaeosol (alfisol) deposits, and which was therefore erupted during the transition from a glacial to an interglacial period. Our age estimate for this transition is 215±4 kyr (1 σ), which has important implications for the marine δ18O timescale and for models of global climate change during the Pleistocene. The results show that single-grain dating can detect and compensate for the large quantities of xenocrystic contaminants which are found in many tephra deposits. This technique could be used to date the tephra layers found in marine sediment cores and the results could greatly enhance the reliability of the marine δ18O timescale for more rigorous Fourier analysis testing of the Milankovitch hypothesis.
    Type: Article , PeerReviewed
    Format: text
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  • 3
    Publication Date: 2019-05-08
    Description: ISOTOPE ratios and concentrations of incompatible trace elements are remarkably successful in discriminating the tectonic origin and magmatic source components for basalts1–5. But problems remain with discriminating the tectonic origin of some tholeiites, especially where field relations and other geological evidence are ambiguous. For example, the tectonic origin of basalts from the Troodos ophiolite (Cyprus) has been debated for several decades. Most workers have been unable to distinguish between an island-arc and/or back-arc origin for the ophiolite6–8. Here we use volatile, K2O and TiO2 contents from ∼250 fresh submarine volcanic glasses to discriminate between tholeiites from different tectonic regimes. K2O÷H2O ratios are lower (〈0.70) in spread ing-centre glasses than in those from island arcs and intraplate oceanic islands. Back-arc-basin basalts can generally be separated from mid-ocean-ridge basalts by their high H2O contents. Using this information, we show that some fresh glasses from the Troodos ophiolite have a clear back-arc-basin affinity.
    Type: Article , PeerReviewed
    Format: text
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