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  • 1975-1979  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Pre-Palaeozoic basement of the Scottish Midland Valley (1976)
    [s.l.] : Nature Publishing Group
    Nature 260 (1976), S. 517-518 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The clasts within and around the veit comprise mainly altered alkali basalt and basaltic tuff, with a wide variety of quartzitic sandstones and scarcer chers, limestones and indurated shales. Some relatively coarse-gained biotite-rich mafic and ultramafic clasts also occur andinclude (altered) ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/260517a0
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Pyrope-spinel (alkremite) xenoliths from kimberlite (1978)
    Springer
    Contributions to mineralogy and petrology 65 (1978), S. 341-346 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Xenoliths consisting of two thirds pyrope (Py73Alm14Gr13-Py15Alm18Gr31) and one third hercynite-bearing spinel with minor chromium, from Bellsbank and Jagersfontein kimberlites, South Africa, are compared with similar rocks, “alkremites”, from the Udachnaya pipe, U.S.S.R. From published experimental data and textural relationships these formed as early dense cumulates in aluminous mantle melts under restricted pressure conditions equivalent to about 75 km depth. At greater pressures very pyrope-rich garnets (Py80) are capable of being formed. The garnet spinel xenoliths are considered to have become separated from the magma prior to crystallisation of clinopyroxene, whereas complete uninterrupted fractionation and reaction would produce the more common griquaites (eclogites).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00375519
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    An experimental study of spinel clinopyroxenite xenoliths from the Duncansby Ness vent, Caithness, Scotland (1975)
    Springer
    Contributions to mineralogy and petrology 51 (1975), S. 223-230 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Xenoliths of coarse-grained spinel-clinopyroxenite up to 15 cm in size occur in tuff in an isolated Permian vent on the Caithness coast at Duncansby Ness. Highly altered fragments of chrome-spinel lherzolite and wehrlite are also found in the tuff and in a body of monchiquite within the vent. The spinel-clinopyroxenites consist of aluminous augite and aluminous pleonaste spinel (FeO/MgO = 0.9) and their texture suggests the spinel to have exsolved from the augite. Experiments on representative natural xenolith compositions at 18 kb (dry) indicate that all the spinel in the estimated average bulk composition (Sp4.9Px95.1) could have exsolved from an original homogeneous pyroxene. Initial fractionation of such a pyroxene from an alkali basaltic magma at P≥18 kb, 1450-1350 °C, would be followed by spinel exsolution at T〈 1290 ° C. A similar origin by fractionation of a highly aluminous augite (± aluminous spinel) at high pressure, with subsequent spinel exsolution is proposed for spinel-clinopyroxenites from alkali basalts elsewhere in the world. The similarity of these xenoliths suggests that such a process may form an important stage in the evolution of some undersaturated basaltic rocks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00372082
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    Paper (German National Licenses)
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