Diaplektische Gläser in den Breccien des Ries von Nördlingen als Anzeichen für Stoßwellenmetamorphose |
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| Authors: | W v Engelhardt J Arndt D Stöffler W F Müller H Jeziorkowski R A Gubser |
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| Institution: | 1. Mineralogisch-Petrographisches Institut der Universit?t Tübingen, Deutschland
2. Institut für Kristallographie und Petrographie der Eidgen?ssischen Technischen Hochschule, Zürich
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| Abstract: | Two kinds of glasses are to be found in the breccias of the Ries basin both which have been generated by shock wave action on the rocks of the crystalline basement: a) Normal glasses, containing flow structures and vesicles; they are formed by shock waves of high energy which after unloading, leave behind material, the temperature of which is above the melting point. b) Diaplectic glasses without vesicles and flow structures, preserving the grain boundaries, cleavages and twin lamellae of the primary minerals; they are formed by shock waves of lower energy which destroy the crystal lattice but after unloading, leave behind material, the temperature of which is below the melting point. — Measurements have been taken of the density and index of refraction of diaplectic quartz- and plagioclase-glasses. The values obtained proved to be higher than those of the normal glasses and lower than those of the crystalline phases. Diaplectic glasses are distinguishable from normal glasses by their physical properties. They represent intermediate stages of structural order between the crystalline and normal glass phases. |
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