Abstract
The structural state of diaplectic labradorite glass (≈An58) from the Manicouagan impact crater and of its fusion-formed glass analog have been investigated by X-ray diffraction studies. The experimental X-ray intensity distribution patterns indicate that the diaplectic and fusion-formed glasses are structurally rather similar, the former being apparently slightly less disordered. Theoretical X-ray distribution curves have been calculated using the structure of high albite as a quasi-crystalline model of the glass structure. The experimental and theoretical curves show fair similarity when the calculations are based on the complete unit cell. It is inferred therefore, that the structures of both kinds of glasses possess an average short range order comparable to that in high albite and extending to about the dimensions of the unit cell. In addition, the experimental X-ray scattering pattern and X-ray Debye-Scherrer transmission photographs of the diaplectic glass reveal the presence of relics up to about 8 nm in size of the previous crystalline lattice of the primary labradorite. The present results support Grady's shear band model according to which diaplectic glass may represent the quench product of a shock-generated high-density melt frozen in prior to total pressure release.
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References
Arndt J, Hummel W, Gonzalez-Cabeza I (1982) Diaplectic labradorite glass from the Manicouagan impact crater — I. Physical properties, crystallization, structural and genetic implications. Phys Chem Minerals 8:230–239
Dworak U (1969) Stosswellenmetamorphose des Anorthosits vom Manicouagan Krater, Quebec, Canada. Contrib Mineral Petrol 24:306–347
Grady DE, Murri WJ, DeCarli PS (1975) Hugoniot sound velocities and phase transformations in two silicates. J Geophys Res 80:4857–4861
Grady DE (1977) Processes occuring in shock wave compression of rocks and minerals. In: Manghnani MH, Akimoto SI (eds) High-pressure research. Academic Press, New York San Francisco London, pp 389–438
Grady DE (1980) Shock deformation of brittle solids. J Geophys Res 85:913–924
Horst W, Tagai T, Korekawa M, Jagodzinski H (1981) Modulated structure of a plagioclase An52: Theory and structure determination. Z Kristallogr 157:233–250
Kieffer SW, Phakey PP, Christie JM (1976) Shock processes in porous quartzite: Transmission electron microscope observations and theory. Contrib Mineral Petrol 59:41–93
Kitamura M, Goto T, Syono Y (1977) Intergrowth textures of diaplectic glass and crystal in shock-loaded p-anorthite. Contrib Mineral Petrol 61:299–304
Mashimo T, Nishii K, Soma T, Sawaoka A (1980) Some physical properties of amorphous SiO2 synthesized by shock compression of α quartz. Phys Chem Minerals 5:367–377
Müller WF (1969) Elektronenmikroskopischer Nachweis amorpher Bereiche in stoßwellenbeanspruchtem Quarz. Naturwissenschaften 56:279
Stöffler D (1974) Deformation and transformation of rock-forming minerals by natural and experimental shock processes: II. Physical properties of shocked minerals. Fortschr Mineral 51:256–289
Taylor M, Brown GE (1979) Structure of mineral glasses — I. The feldspar glasses NaAlSi3O8, KAlSi3O8, CaAl2Si2O8. Geochim Cosmochim Acta 43:61–75
Warren BE (1968) X-ray diffraction. Addison-Wesley, Reading, Massachusetts
Wyckoff RWG (1968) Crystal structures. Vol 4, 2nd Ed, Interscience, New York, p 441
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Diemann, E., Arndt, J. Diaplectic labradorite glass from the manicouagan impact crater: II. X-ray diffraction studies and structural model. Phys Chem Minerals 11, 178–181 (1984). https://doi.org/10.1007/BF00387849
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DOI: https://doi.org/10.1007/BF00387849